CH42 Management of Complicated Retinal Detachment

7/28/2019 CH42 Management of Complicated Retinal Detachment

1/36

Management of Complicated

R etinal DetachmentJ M. L G W.A J C.W

the idea that dispersed retinal pigment epithelium cells thatsettle on the inferior retina due to gravitational effects playa prominent role in PVR formation.

Primary PVR can occur in a long-standing rheg-matogenous retinal detachment. More commonly, it occurssecondarily after scleral buckling,vitreous surgery, or pneu-matic retinopexy treatment for rhegmatogenous retinaldetachment, and is the leading cause of surgical failure andredetachment of the retina. Experimental study has shownthat various factors associated with surgery, such as exten-

sive application of cryotherapy (14), fibrin formation (15),and bloodretinal barrier breakdown may increase PVRformation.

Surgical Anatomy

The severity and extent of PVR can be described accord-ing to a classification system developed by the RetinaSociety in 1983 (Table 42-1) (5) and updated in 1991(Tables 42-2 and 42-3) (6).Posterior PVR (posterior to theequator) consists of focal and diffuse retinal contractions andsubretinal membranes, while anterior PVR (at or anteriorto the equator) consists of focal, diffuse, or circumferentialfull-thickness folds, anterior retinal displacement, and sub-retinal membranes. Focal contractions are star folds,whichare caused by contraction of a localized epiretinal mem-brane. Diffuse contractions involve four or more disk areasand are induced by larger membranes (Fig. 42-2). Foldswithout epiretinal membranes usually indicate the presenceof subretinal membranes.

Anterior PVR may result from deposition and pro-liferation of pigment epithelial cells on the inferior periph-eral retina along with contraction at the posterior edge ofthe vitreous base (Fig. 42-3).These membranes induce cir-cumferential contraction,shortening the circumference of the

C h a p t e r

42

Retinal detachments are considered complicated whenreparation requires more than a scleral buckle. Complicatedretinal detachments may be associated with vitreous hem-orrhage, proliferative vitreoretinopathy (PVR), giant tears,posterior holes or tears, choroidal detachments, ocularinflammatory diseases, trauma, and tractional retinal detach-ments. Complicated retinal detachments associated withgiant retinal tears,ocular inflammatory diseases, trauma, andproliferative retinopathies such as diabetic retinopathy willbe discussed elsewhere.

RETINAL DETACHMENT WITHPROLIFERATIVE VITREORETINOPATHY

Overview

PVR is the leading cause of failure in retinal detachmentsurgery,occurring in approximately 7% of all retinal detach-ments (1). During the past two decades,major advances havebeen made both in the understanding of the pathogenesisof PVR and in the surgical treatment of the disease (28).

PVR is characterized by the formation of cellular mem-branes on the retinal surface, the retinal undersurface, andin the vitreous cavity (Fig. 42-1) (9).Cells within the mem-branes are derived from the retinal pigment epithelium(10,11) and from retinal glial tissue (12,13).These cells enterthe vitreous cavity or subretinal space via breaks in theretina, undergo transformation to take on characteristics offibroblasts or macrophages, and proliferate in a sheet-likeconfiguration. Fibroblast-like transformed cells have con-tractile properties, with the ability to pull collagen fibers ina hand-over-hand manner (2).Thus the proliferative cel-lular membrane can insert into the vitreous and exert forcesleading to tractional retinal detachment. Involvement isoften most severe inferiorly; this finding is consistent with

531


2/36

retina at the posterior vitreous base,which is pulled centrally.The retina posterior to the vitreous base develops radial folds,while retina anterior to the posterior edge of the vitreousbase is smooth and pulled centrally (Fig.42-4).With chronic-ity,there may be contraction of the vitreous base,which pullsthe retina posterior to it anteriorly toward the pars plana,thusresulting in anterior retinal displacement. However, anteriorretinal displacement is more commonly seen in eyes that have

previously had a vitrectomy (Fig.42-5). In these eyes,prolif-erating cells form a membrane on the surface of the remain-ing peripheral vitreous, which contracts, pulling the retinaposterior to the vitreous base anteriorly toward the pars plana(Fig. 42-6A), the pars ciliaris (Fig. 42-6B),or even the pos-terior surface of the iris (Fig.42-6C). In the most extremeinstances, the membranes can pull the retina to the edge ofthe retracted pupil (Fig.42-6D).

532 PART III Retina and Vitreous Surgery

A

B

C

Table 42-1. The Retina Society Classification of RetinalDetachment with PVR

Grade Clinical Signs

A Minimal vitreous haze

Vitreous pigment clumps

B Moderatewrinkling of theinner retinal surfaceRolled edgeof retinal break

Retinal stiffness

Vessel tortuosity

C Marked full-thickness fixed retinal folds

C1 Onequadrant

C2 Two quadrants

C3 Threequadrants

D Massivefixed retinal folds in four quadrants

D1 Widefunnel shape

D2 Narrowfunnel shape*

D3 Closed funnel (opticnervehead not visible)

* Narrow funnel shape exists when the anterior end of the funnel can be seen by

indirect ophthalmoscope within the 45-degree field of a20 D condensing lens(Nikon or equivalent).

FI GURE 42-1.A. Migration of pigm ent epithelial and othercells into vitreous cavity an d subretina l space. B. Proliferation and

contraction of cells on retinal and vitreous interfaces. C. Fixed foldsdue to contraction of cellular mem branes. (Adapted from AbramsGW, Aaberg TM. Posterior segment vitrectom y.In: Waltm an SR (ed.).Surgery of the eye. New York: Churchil l-Livingstone, 1988:9031012.)

FI GURE 42-2. Posterior PVR: Starf old (sma ll arrow ) (posteriortype 1),diffuse contraction (large arrow) (posterior type 2).

Classification i s CP12.(Reprinted b y perm ission fro m Abram s GW,Aaberg TM. Posterior segm ent vit rectom y.In Walt m an SR (ed.).Surgery of the eye. New York: Churchill-Livingstone,1988:9031012.)

FI GURE 42-3. Contraction along posterior edge of vitreousbase with central displacement of retina.Peripheral retinastretched(*);p osterior retina in radia l folds() (an ter io r t yp e 4).(Reprinted courtesy of Ophthalm ic Publishing Company, fromMachemer R,Aaberg TM, Freem an HM, et al.An updat edclassification o f retinal detachm ent w ith proliferativevitreoretinopathy.Am J Ophthalmol 1991;112:159165.)
http://../xpdf/ch40-79/42-3x.pdfhttp://../xpdf/ch40-79/42-2x.pdf


3/36

Surgical Technique

Scleral Buckle vs. Vitrectom y

Primary retinal detachment associated with low-grade PVR(grade A or B and limited grade C) can usually be managedby retinal reattachment surgery with a scleral buckle (16).In cases where retinal detachment is associated with highergrades of PVR and in recurrent retinal detachment with

Chapter 42 Management of Complicated Retinal Detachment 533

Table 42-3. Updated Classification of PVR:Grade C PVR Described by Contraction Type

Type Location Features

1Focal Posterior Starfold posterior to vitreous base

2Diffuse Posterior Confluent starfolds posterior to

vitreous baseOpticdisk maynot bevisible

3Subretinal Posterior Proliferations under retina:

or Anterior Napkin-ringaround disk

Clotheslinemoth-eaten-

appearing sheets

4Circumferential Anterior Contraction along posterior edgeof

vitreous basewith central

displacement of theretina

Peripheral retinastretched

Posterior retinain radial folds

5Anterior displacement Anterior Vitreous basepulled anteriorlyby

proliferativetissue

Peripheral retinal trough

Ciliaryprocesses maybestretched or

maybecovered bymembrane

Iris mayberetracted

Table 42-2. Updated Classification of PVRDescribed by Grade

Grade Features

A Vitreous haze

Vitreous pigment clumpsPigment clusters on inferior retina

B Wrinkling of inner retinal surface

Retinal stiffness

Vessel tortuosity

Rolled and irregular edges of retinal break

Decreased mobilityof vitreous

C

CP112* Posterior to equator:

Focal,diffuse,or circumferential full-thickness folds

Subretinal strands

CA112 Anterior to equator:

Focal,diffuse,or circumferential full-thickness folds

Anterior displacementSubretinal strands

Condensed vitreous with strands

* Expressed in the number of clock hours involved.

A B

C

FI GURE 42-4. Proliferative vitreoretino pat hy grad e C.Type 4:circum ferential contraction w ith proliferation im mediately behindinsertion of t he posterior hyaloid pull ing retina centrally, stretchingthe retina ant erior to it,a nd creating radial fo lds posteriorly.Schematic draw ing of situation in no nvitrectomized eye (left) an dvitrectom ized eye (right). Arrowsshow direction of pull. (Adaptedcourtesy of Opht halm ic Publishing Com pany,from Machemer R,Aaberg TM, Freem an HM ,et al. An updat ed classification of retinaldetachment w ith proliferative vitreoretinopat hy.Am J Ophthalmol1991;112:159165.)

FI GURE 42-5. Anterior retin al displacement in PVR. A.Proliferation o f cells on vitreous base and retina followin g vitrectom yand scleral buckle. B.Contraction of cellular mem branes pulls retinaat p osterior vitreous base ant eriorly.C.Vitreou s base depressed intoview.Membrane exerting anteriorposterior traction is sectionedwith vertically cutting scissors.(Adapted from Abrams GW,AabergTM.Posterior segment vitrectomy.In:Waltman SR (ed.). Surgery ofthe eye. New York: Churchill-Livingstone, 1988:9031012.)

significant PVR, or anytime when it is not anticipated thata scleral buckle will adequately relieve traction to reattachthe retina, vitreous surgery is usually indicated to relievetractional membranes and successfully reattach the retina.


4/36

M ana gement w ith Scleral Buckle Only

When scleral buckling alone is judged adequate to treat aretinal detachment associated with PVR, the general goalsof retinal reattachment surgery must be achieved, includingclosure of all breaks and relief of vitreoretinal traction.The

techniques required are discussed in detail in Chapter 41,but special considerations must be made in the presenceof PVR. With few exceptions, it is necessary to supportthe vitreous base for 360 degrees by placing an encirclingelement. Sometimes a fairly high degree of indentation isnecessary to relieve anterior traction adequately. The rec-ommended width of the buckling element may vary withthe location of retinal breaks and the width of the vitreousbase.A narrower element will suffice if retinal breaks are rel-atively anteriorly located and the vitreous base is not exces-sively broad; however, a broader silicone tire or spongemight be preferable if the vitreous base extends more pos-teriorly.We use silicone tires or sponges varying from 5 to7mm in width. Scleral sutures are usually placed 2mmwider than the buckle, to increase scleral indentation andbuckle height. In general, placement of the buckle with itsanterior edge 2mm posterior to the muscle insertion ringprovides support for the posterior vitreous base and ante-rior insertion of hyaloidal traction. Obviously, specific con-ditions require modifications of these general rules ofthumb,such as long myopic eyes with altered anatomic rela-tionships. If a silicone tire and encircling band are used inan eye with PVR, it is important that the tire be extendedthroughout the inferior 180 degrees of the vitreous base,and a conscious effort may be made to achieve greater

buckle height inferiorly by varying the width of the scleralbites, since the inferior fundus is usually the most severelyinvolved with tractional membranes.

As in any retinal detachment repair, all retinal breaksmust be carefully identified and localized.Additional radial

buckling elements sutured in place beneath the encirclingelement may sometimes be helpful in rhegmatogenousretinal detachment with PVR that is treated by scleral buck-ling alone.Breaks associated with traction can sometimes besupported sufficiently to relieve tractional forces.

Opening for Pars Plana Vitrectomy

When a vitrectomy is done for an eye with PVR, if noscleral buckle is present, we recommend encircling the eyewith a scleral buckle to support the vitreous base and theretina just posterior to the vitreous base. If the eye alreadyhas an encircling scleral buckle, we usually do not revise orreplace that element. Sometimes it is necessary to supple-ment an existing scleral buckle, especially inferiorly, if thereis not adequate inferior support of the vitreous base. If theeye has previously had only a radial scleral buckle, the radialelement is usually removed and an encircling scleral buckleplaced.

If the decision is made to perform a pars plana vitrec-tomy, eyes with significant PVR still require an encirclingelement to support the vitreous base and relieve anteriortraction. Therefore, in eyes that do not have a preexistingencircling element, a 360-degree conjunctival peritomy ismade just posterior to the limbus and the rectus musclesisolated with 2-0 silk sutures.We often place the sutures for


A C

B D

E

FI GURE 42-6. Anterior PVR: Anterior retina l displacement. Retina at p osterior aspect of vitreous base is draw n to a nterior vit reous base(A),to ciliary processes(B), to posterior ir is(C),a nd to pu pil with ir is retraction(D). (E).Posterior insertion of the vitreous base drawn anteriorly creatingretinal trough. Folds that radiate posteriorly are caused by circumferential contraction.(Adapted from Lewis H, Aaberg TM. Anterior proliferativevitreoretinopathy.Am J Ophthalmol 1988;105:277.)


5/36

the scleral buckle prior to vitrectomy. At this time, the eyeis firmer and easier to place the sutures. We usually waituntil after the vitrectomy is completed to place the buck-ling element around the eye. In most cases, we use a 4.5-mm-wide encircling band to create a moderate buckle.

Some surgeons prefer to preplace scleral belt-loop inci-sions, which may be technically easier prior to vitrectomywhen the eye is firmer. The disadvantage of preplacingsutures or belt loops is that the surgeon loses the abilityto choose the type and placement of the buckle based onthe intraoperative findings; however, in our experiencewe rarely have to change the location or type of scleralbuckle following the vitrectomy.We feel that the 4.5-mmencircling band will adequately support the vitreous basein most cases of PVR following vitrectomy and that thereduced volume of the band and reduced compression ofvortex veins by the narrower element reduce complicationsrelated to the scleral buckle in comparison with broader,

bulkier elements.If the eye has an encircling element in place, it can be

left unaltered in most cases and conjunctival incisions madein the usual fashion for a vitrectomy, exposing the tempo-ral and superonasal sclera. Occasionally, modification of theprevious buckle is desirable.The buckling element is locatedby dissecting through its fibrous capsule.Then the band canbe tightened, the buckle can be repositioned, additionalsutures can be placed to increase the height or location ofthe buckle, or an additional scleral buckling element canbe placed. If, however, only a radial or segmental circum-ferential element was placed at the time of previous surgery,it is usually best removed and replaced by an encircling

element.Vitrectomy is most often performed via a 3-port pars

plana approach.Sclerotomy incisions are made 3.0mm fromthe limbus in aphakic and pseudophakic eyes, or when parsplana lensectomy is planned. In the somewhat uncommoncircumstance in which the eye is to be left phakic (seebelow), the incision is made 3.5mm from the limbus.

These distances must be modified if significant anteriordisplacement of the retina exists, in which case entry intothe vitreous cavity is made more anteriorly.

Incisions for the infusion and instruments are generallymade parallel to the limbus. When performing repeat vit-rectomy, parallel incisions intended for the instrumentsshould be separated by at least 1mm from previous incisionsso the sclerotomies do not extend into the old sclerotomysites during vitrectomy and create large scleral defects. If thesclera is thinned and macerated at the sites of the previoussclerotomies, it may be advantageous to make radial inci-sions, as these are less likely to extend into previous inci-sions. The actual entry into the vitreous cavity must becontrolled, especially if the retina is bullous, to avoid retinalperforation. In aphakic or pseudophakic eyes, the microvit-reoretinal (MVR) blade should be inserted iris-parallel, andthe tip visualized in the pupil before it is withdrawn.Theinfusion cannula is then inserted and tied permanently in

place. A 4-mm cannula is preferred in most cases, but incases with severe anterior proliferative membranes and poorvisualization, a 6-mm cannula may facilitate entry into thevitreous cavity.Before infusion to the eye is initiated, the tipof the cannula must be visualized through the pupil to

prevent subretinal infusion of fluid. This can be donethrough the operating microscope by grasping the base ofthe cannula with nontoothed forceps and rotating the eyeuntil the tip comes into view, or by using a fiberoptic lightprobe externally and looking at the eye from an acute angle(17). Once it has been positively ascertained that the tip ofthe cannula is in the vitreous cavity and is free of any mem-branes or tissue, the infusion is turned on.

If the pupil will not dilate adequately,we dilate the pupilusing mechanical pupillary stretching (Fig. 42-7). Our pre-ferred pupillary stretching devices are small plastic hooksplaced through the limbus in four quadrants (18) (FlexibleIris Retractors, Grieshaber, Inc., Kennesaw, GA). We lyse

synechiae and remove residual capsular material as much aspossible prior to placing the stretching hooks in order tominimize iris trauma. Limbal openings are made parallelwith and just anterior to the iris plane with a Ziegler-typeblade.The small hooks are secured externally at the limbuswith a small locking device.

Lensectomy

The crystalline lens, if present, should be removed in mostcases with significant PVR, even if clear.Visual rehabilita-tion is most critically related to the status of the retina, andtherefore refractive concerns must be secondary. It is notpossible to do an adequate vitreous base dissection in the

phakic eye. Removal of the lens allows more complete dis-section of the vitreous base and anterior membranes, andremoval of all capsular material may decrease the likelihood


FI GURE 42-7. Pupillary stretching using fl exible irisretractors.


6/36

of recurrent anterior PVR. In addition, with prolonged gastamponade, the lens will almost always develop a cataract.Management in the postoperative period, includingthe ability to do a fluidgas exchange and to administerpostoperative laser photocoagulation, is facilitated by remov-

ing the lens. If, on the other hand, a posterior chamberintraocular lens (IOL) is already in place, it can usuallybe left in place, as, in most cases, it does not hinder dis-section of the vitreous base and anterior membranes. Occa-sionally, proliferative tissue adherent to the residual lenscapsule must be trimmed or removed with the vitreouscutter to facilitate adequate visualization and surgical manip-ulations in the periphery. If it appears excessive membranesare adherent to the peripheral lens capsule, or if the poste-rior chamber IOL is unstable, we remove the IOL throughthe limbus.

Anterior chamber IOLs are somewhat more problematic.The optic may come in contact with and damage the

corneal endothelium if the lens is pushed forward by a gasbubble postoperatively.Gas or silicone oil can easily prolapsearound the lens into the anterior chamber, degrading visu-alization of the retina intraoperatively as well as postopera-tively. For these reasons, many surgeons prefer to removeanterior chamber IOLs.This step is completed via a limbalincision after infusion has been established to the eye, butwith the infusion in a closed position. Sodium hyaluronateor another viscoelastic material is used to maintain thevolume of the anterior chamber as well as to protect thecorneal endothelium during this procedure.

The crystalline lens is removed through the pars plana,except in cases with extremely hard nuclei, in which case

the nucleus is removed through the limbus.Following ultra-sonic fragmentation of the nucleus and removal of the cor-tical material, we recommend complete removal of the lenscapsule (19). An opening is made in the anterior capsulewith the vitrectomy instrument. One can then grasp theperipheral capsule with vitreous forceps and exert enoughtraction to expose the zonules in the pupil. While retract-ing the capsule, the zonules can then be cut with a verti-cally cutting scissor (we prefer the MPC scissor, Grieshaber,Inc.,Kennesaw,GA) placed through the opposite sclerotomysite (Fig.42-8).We feel complete removal of the lens capsulewill reduce the likelihood of recurrent anterior PVR thatcan sometimes present with membranes adherent to theperipheral lens capsule. In addition, removal of the capsulewill prevent synechiae of the iris to the lens capsule, whichcan leave a distorted, retracted, fixed pupil.

Vitrectomy

A lens ring to hold the contact lens can be placed follow-ing placement of the pupillary stretching devices.We suturea lens ring in place and utilize several lenses as necessary tovisualize the posterior and peripheral retina.We peel mostposterior membranes using a plano-concave lens, whileprism lenses are used in the periphery. A wide-angle lenssystem with image inverter is also used in selected situations

(20,21). The wide-angle lens is especially useful if there isa constricted view due to a posterior chamber lens withopacified peripheral capsule.

We remove the central vitreous with the vitreous cuttinginstrument, then remove gross peripheral vitreous. In mostcases a posterior vitreous detachment will already be presentin cases of PVR. Rarely, in eyes with high myopia or vit-reoretinal degenerations, there is incomplete or no posteriorvitreous separation. In those cases, after the core vitrectomyis completed, the posterior cortical vitreous should be

separated from the disk with the vitreous cutter, suctioncatheter, or membrane pick, then peeled from theretinal surface. If the vitreous is tightly adherent to the pos-terior retina such as seen in Stickler syndrome, vitreousshould be trimmed close to the adhesions and sectionedas much as possible with automated vertically cuttingscissors.

If there is significant anterior PVR, we delay extensiveshaving of the vitreous base and peripheral membrane dis-section until after posterior membranes have been removed,because access to and removal of these membranes are easieronce posterior membranes and midperipheral membraneswith adherent vitreous have been removed. In the absenceof anterior PVR, it is best to excise or shave the vitreousto the surface of the retina and pars plana at the vitreousbase area at this stage of the case.The posterior membranesfixate the retina and reduce mobility of the anteriorretina, which makes peripheral viteous removal safer withless risk of anterior retinal breaks. If at any point theretina is excessively mobile during peripheral vitrectomyand there is danger of peripheral retinal damage, peripheralvitrectomy can be delayed until posterior membranes havebeen removed.Then perfluorocarbon liquid (PFCL) can beused to stabilize the retina during peripheral vitreousremoval.


Central openingin lens capsule

Forceps holdinglens capsule

Capsule

MPC scissorscutting strechedzonules

FI GURE 42-8. En bloc rem oval of th e lens capsule follow ingphacofragm entation an d removal of th e nucleus and cortex ofthe lens.After openin g is m ade in th e anterior lens capsule in thepupil lary area wit h th e vitrectom y cutter,the edge of the centralcapsulotom y is grasped with vitreoretinal forceps, and the capsuleis retracted t o expose the zonules in the pu pil. The zonules aresectioned with automated,vertically cutting vitreoretinal scissors,and the capsule is rem oved through the sclerotomy site or wit h t he

vitreous cutter.


7/36

The vitreous base can be visualized with a standard lenssystem (either hand held or with a sutured lens ring) usingscleral depression, or by using a wide-angle system withoutscleral depression. Using a standard lens system,we performanterior vitrectomy by two methods. In the first method,

the vitreous cutter and the fiberoptic endoilluminationprobe are both placed in the eye.An assistant depresses theperipheral retina and vitreous base into view as the vitreousis excised (Fig. 42-9). This method is especially useful forremoving vitreous in the inferior 140 degrees and the supe-rior 100 degrees. Using this method, it is difficult to exciseall of the peripheral vitreous in the horizontal meridians.

The second method, especially useful in the horizontalmeridians,utilizes external illumination (22).The vitrectomycutter is placed through a sclerotomy site.A plug is placed

in the opposite sclerotomy site, and the surgeon depressesthe retina and vitreous base in the area 180 degrees fromwhere the vitreous cutter has entered the eye.The assistantholds the fiberoptic light probe in contact with the contactlens, directing the light toward the area to be cut (Fig.

42-10).Because the light probe actually touches the contactlens, there is no light reflection, and the visualization issimilar to that seen with endoillumination.We have foundthis method superior to that in which the microscope lightis used for peripheral visualization.

Scleral depression is not always required to visualizeand shave the vitreous base when using the 125-degreewide-angle lens with an image inversion system.A bulletlight probe is used to disperse the light over a broadarea when using the wide-angle lens system. The vitreousstructure is more easily seen when using a standardlight probe held close to the vitreous,so we have found thestandard lens system with scleral depression most useful for

PVR.

M embrane Peeling

Posterior Membranes We begin epiretinal membrane dis-section at the posterior pole. All membranes that can belocated are meticulously stripped from the retinal surface.Posterior membranes are peeled from the surface of theretina in a posterior-to-anterior fashion,so that greater forceis applied to the thicker posterior retina.The technique ofbimanual dissection, using an illuminated pick (Fig. 42-11)


Cotton tipapplicator

retina

Retina pulledforward asvitreous is cut

Perfluorocarbonliquid

Cotton tipapplicator

A

B

FI GURE 42-9. Vitrectomy removal of a nterior vitreous in aneye with bullous retinal detachm ent. A.Retina is extremely mobileand i s pulled tow ard t he vitreous cutter as vitreous is excised, riskinganterior retinal breaks. B. PFCL is injected to fl att en and stab ilize theposterior retina. PFCL is injected to the posterior edge of rema iningvitreous,h olds retina in place,and reduces retinal m obil ity duringperipheral vitrectomy.

FI GURE 42-10. Lightpipe (L) held in cont ac t w it h con ta ctlens (C) il lu m in at es vit reo us b ase p ush ed i nt o v iew by scleraldepressor (D). (Repri nt ed co ur tesy of th e Am erican M ed ica lAssociation, Chicago, IL,from Murray TG, Boldt HC,Lewis H, et al.A technique for facil i tated visualization of the vitreous base,parsplana, and pars plicata.Arch Ophthalmol 1991;109:14581459.)


8/36

and vitreous forceps, is the most effective for this purpose.There are several types of forceps that can be used to graspmembranes,but we have found that diamond-dusted forceps(see Fig. 42-11) most reliably hold the membrane duringbimanual dissection.

Membrane peeling can be initiated by either of twomethods,depending on the characteristics of the membrane:thicker membranes with prominent edges can be directlygrasped with the forceps (Fig. 42-12), and flatter, less dis-tinct membranes are best elevated with the illuminated pickprior to grasping with the forceps. Membranes can usually

be easily seen, but sometimes with extensive confluentmembranes, no edges can be identified. Signs of this typeof membrane include obscuration of portions of retinalvessels by the membrane and a stiff, smooth, gray appear-ance of the retina. Large retinal folds can be obscured bythe membranes. In this situation, the pick is placed in a foldand gently pulled toward the center of the fold in order toengage the membrane (Fig. 42-13A). Once the membraneis engaged and the edge elevated, it is grasped with theforceps for stripping (Fig. 42-13B). Some tightly adherentmembranes can be more easily engaged with a sharp-barbedblade such as the MVR blade (Fig. 42-14).

When an edge of the membrane has been partiallyelevated, it can be grasped with forceps and stripped ante-riorly, with the pick used to separate adhesions and stabilizethe retina (see Fig.42-13B). During removal of midperiph-eral membranes,the membrane is often pulled centrally withthe forceps,and the blunt edge of the pick is placed betweenthe membrane and the peripheral retina (Fig.42-15).As themembrane is pulled centrally, the blunt edge of the pick sep-arates the membrane from the retina. When a tight adhe-sion is encountered, excessive force should not be applied,as a retinal tear is likely to occur. Rather, vertically cuttingautomated scissors should be introduced to segment themembrane from the retina at the adherent site. If any retinal

breaks do occur, they should immediately be marked withintraocular diathermy.

Often, large membranes can be peeled in a single sheetfrom the retinal surface.This is especially true in so-calledmature PVR, in which several weeks have passed and themembranes have become fairly thick. In the past, someexperts recommended waiting for this point in the diseaseprocess before intervening, allowing the proliferation tomature to facilitate membrane removal.Thin immature


FI GURE 42-11. Instrum ents for mem braneremoval in PVR.Left:Diam ond-dusted vitreoretinalforceps (Grieshaber and Com pan y,Fallsingt on, PA).Right: I l luminated pick (Escalon,M ukwan ago,WI).Bending shaft of pick 30 degrees away from thel ight axis gives a broader field of i l lumina tion an dreduces the shadow cast by the pick.

FI GURE 42-12. Grasping epiretinal m embrane w ithvitreoretinal forceps.The forceps grasp the body of the membrane bypinching the surface or edge of the mem brane.While the diamond -dusted vitreoretina l forceps (see Fig.42-11) will enga ge mem braneswith thickened edges,n ewer,fi ner,pointed end-grabbing forceps aresuperior for this m aneuver.Once the m embrane is grasped wit h t heforceps,t he i l lumina ted pick is used to ap ply counter-traction on t heretina as the m emb rane is peeled.
http://../xpdf/ch40-79/42-11x.pdf


9/36

probably occurs because of incorporation of the posteriorhyaloid into membranes formed at the junction of the sep-arated posterior vitreous and the vitreous base (Fig.42-17A).With increasing and more posterior membrane formation,we suspect that the vitreous is gradually pulled in by thecontracting membranes to give a relatively posterior adher-ence of the posterior hyaloid, well posterior to the vitreousbase (Fig. 42-17B). It is important to strip the posteriorhyaloid anteriorly to its insertion into the vitreous base.We


Vitreous

Retina

Vitreous

Retina

A

B

FI GURE 42-13. Bim anual m embrane-peeling using ani l lumina ted pick an d vitreoretinal forceps. A.The edge of them embrane is elevated wit h th e i l luminated pick. If an edge is notapparent, the t ip of th e pick is placed in the trough of a retinal foldand str ipped toward t he center of a star fold unti l the m embraneis enga ged.The mem brane is usually enga ged in th e center of thestar fold. B.After the edge of the m embrane is elevated wit h th ei l lumin ated pick,th e edge is grasped w ith th e diamon d-dustedvitreoretinal forceps and pulled ant eriorly.The blunt ,p osterior edgeof the i l lum inated pick is placed against the retina adjacent to th em embrane to h old th e retina in place as the m embrane is peeledfrom t he retina.

Epiretinalmembrane

Vessel tortuousunder membrane

Retinalvessels

Stripping infold with MVRblade

Retina

membranes are friable and more likely to fragment, leavingresidual islands of tissue that are difficult to remove anda potential source of reproliferation. However, the dis-advantage of waiting for membranes to mature is poten-tial progression of photoreceptor degeneration, and mostauthorities no longer delay surgery for this reason.A helpfultechnique for very immature membranes is to stroke themwith a silicone brush found on the tip of the backflushbrush. Zivojnovic has found the retinal scratcher usefulfor this technique. A new instrument, a diamond-dustedsilicone cannula, is now available that is useful for theremoval of small patches of thin epiretinal membranes(Fig. 42-16) (23).

The posterior cortical vitreous is often adherent toperipheral membranes posterior to the vitreous base. This

FI GURE 42-14. Thinner,t ight m embranes m ay be difficultto engage with the blunt i l lum inated pick,so these membranes aresometimes best engaged for peeling with a sharp blade.We preferthe m icrovitreoretinal (MVR) blade.We barb the t ip of t he blade priorto m embrane peeling.The barbed MVR blade is placed in a fold

adjacent to the mem brane and str ipped toward t he memb rane.Most membranes can be elevated in this fashion.

FI GURE 42-15. Separation of peripheral m embranes andvitreous from the retina.The mem brane or vitreous is grasped wit hdiam ond-dusted vitreoretinal forceps and pulled centrally.The bluntedge of the i l luminat ed pick is placed at the junction o f the vitreousor m embrane w ith t he retina and the t issue is pulled over the pick.The membrane w il l usually separate, and vitreous wil l usuallyseparat e anteriorly to the posterior edge of th e vitreous base.


10/36

have found it useful to grasp the edge of the posteriorhyaloid with the vitreous forceps, place the blunt portion ofthe illuminated pick at the junction between the hyaloidand the peripheral retina, and pull the hyaloid centrally toallow the pick to separate the hyaloid from the retina(similar to the method described in Fig. 42-15).This tech-nique also identifies the point of permanent adherence ofthe hyaloid to the posterior border of the vitreous base.Once the peripheral hyaloid is separated to the vitreousbase, it is excised with the vitrectomy instrument. If the

retina becomes excessively mobile, PFCL can be injectedover the posterior pole to stabilize the retina during vitrec-tomy (see Fig. 42-9; see also below) (24).Anterior Membranes If anterior PVR is present, peripheralmembranes must be dissected. Membranes may be focal,diffuse, or subretinal (see Tables 42-1 and 42-2; Figs.42-342-6). Focal and diffuse membranes are peeled in afashion similar to posterior membrane peeling,although vit-reous is often adherent to the membranes. Subretinal mem-branes may not be apparent until after epiretinal membraneshave been removed. The most difficult form of anteriorPVR to manage is anterior retinal displacement, in whichthe retina at the posterior vitreous base or even more pos-teriorly is pulled anteriorly by contracting anterior vitreousand membranes (see Fig. 42-6) (4,25). A circumferentialtrough of variable depth and area may be present at thevitreous base formed between the anteriorly displaced retinaand the anterior retina and pars plana. Initially, the type ofanterior PVR must be identified.

Sometimes, in advanced forms of anterior PVR, it isdifficult to see a peripheral trough, and the surgeon mighterroneously believe that no anterior retinal displacement ispresent.The only sign of anterior retinal displacement maybe obscuration of the ora serrata and the finding of a fibrouscircumferential membrane adherent to the pars plana or

ciliary processes. Usually, however, a peripheral trough canbe seen peripheral to a circumferential fold of anteriorlydisplaced retina. The membrane that bridges from theanteriorly displaced retina toward the anterior structuresmust be cut (Fig.42-18). It is often easiest to initially openthis membrane with the sharp tip of the MVR blade(Fig. 42-18A). Then vertically cutting vitreoretinal scissorscan be inserted to section the membrane circumferentially(Fig. 42-18B). The membrane should be circumferentiallysectioned throughout the extent of anterior displacementof the retina.


Retinal break

Separated vitreous

Vitreous looselylaying on retina

RPE cells

Vitreous fusedto retina

A

B

FI GURE 42-16. Diamond-dusted membrane cannula.The tapered silicone tip has been dusted with diamonds to createa surface that wil l engage and peel diaphanou s, imm ature

membranes.

FI GURE 42-17. Reattachment of peripheral separatedvitreous to t he retina po sterior to the vitreou s base in PVR.A.Rhegmato genous retinal detachm ent wit h posterior vitreousseparation and large retinal break.Released pigment epithelialcells in th e vitreous cavity settl e on the inferior retina bet ween thedetached retina an d the vitreous.As mem branes form, the vitreousattaches to the memb ranes that are attached to the retina.B.PVRwith vitreous now fused w ith t he peripheral retina posterior to th evitreous base. As m emb ranes are peeled,t he vitreous shou ld beseparat ed anteriorly t o th e posterior aspect of th e vitreous base.


11/36

When the membrane is sectioned, the anterior-posteriorelement of traction is relieved, and the anteriorly displacedretina will fall posteriorly. Remnants of the membrane canexert circumferential traction and sometimes can be excisedwith the vitrectomy instrument. If membrane remnants are

tightly adherent,then a bimanual technique is used in whichthe membrane is fixated with an illuminated pick or illu-minated forceps as it is cut with the vertically cutting scis-sors (Fig. 42-18C). If possible, the whole extent of themembrane should be eliminated, but if this is not possible,remnants should be sectioned vertically in multiple areasalong its circumference in order to eliminate circumferen-tial traction.Vitreous in the trough should be trimmed backto the surface of the pars plana and peripheral retina withthe vitreous cutter.

The techniques of peripheral vitreous removal utilizingscleral depression or a wide angle viewing system aredescribed above. Retinal breaks are sometimes created

during the dissection process. Breaks should be identified,and all traction relieved around the area of these breaks. Insome cases, it is not possible to relieve anterior contractionadequately with dissection so a peripheral relaxing reti-notomy is necessary (see below). Because it is difficult toremove posterior and peripheral membranes after anextensive retinotomy, we wait until all of the posteriorand peripheral membranes have been removed beforeproceeding with retinectomy.

Once the posterior and peripheral membranes have beenremoved, the retina becomes quite mobile. The pars planais often detached,and any remaining vitreous is easily incar-cerated in the sclerotomy sites. There is risk of peripheral

retinal incarceration in the sclerotomy sites.The retina can

be stabilized and further peripheral vitreous removal andmembrane dissection can be facilitated by the use of PFCL(Fig. 42-19; see also Fig. 42-9).An initially small volume ofPFCL (usually about 1mL) is injected over the optic nerve.We usually wait until posterior membranes have been com-

pletely removed before injecting the PFCL.While a smallposterior retinal break is not a contraindication to the useof PFCL, we usually do not use PFCL in the presence oflarge breaks.Excessive traction on the retina in the presenceof even a small retinal break may also cause PFCL to gothrough the break. It is important not to inject the PFCLdirectly over a break as the stream of PFCL will go beneaththe retina. Initially, only enough PFCL is injected to stabi-lize the posterior retina and improve the ability to removeperipheral vitreous and membranes. Injection of too muchPFCL may cover and compress the remaining vitreous.Additional PFCL can be injected to further flatten the retinaas the dissection is carried anteriorly.

Subretinal Membranes

Subretinal membranes are less common in PVR thanepiretinal membranes, and even when present, often do notinterfere with successful retinal reattachment (26). In thesecases they can be left in place. In some cases, subretinalmembranes that appear to be elevating the retina will breakor stretch during fluidgas exchange or after injection ofPFCL, leading to release of traction (see below).

In cases in which subretinal membranes prevent retinalreattachment after fluidgas exchange or injection of PFCL,of if they are felt by an experienced surgeon to besignificant, the traction from these membranes must be

relieved (27). If a single subretinal strand is tenting the


CBA

FI GURE 42-18. Man agement o f ant erior retinal displacem ent in PVR.A circum ferential m embrane has form ed on t he peripheral vitreousand, with contraction, has pulled the retina at the posterior aspect of th e vitreous base anteriorly to the anterior pars plana.The memb raneobscures a trough of redundant retina created by th e anterior displacem ent of t he retina.A.The membrane is sectioned circumferentially withan M VR blade. B.On ce an opening is m ade in th e mem brane with the M VR blade,the au tom ated,vertically cutt ing vitreoretinal scissors use usedto section th e memb rane throughou t its extent. Anterior retinal displacem ent is most comm only found in the inferior 180 degrees of the retina.C.The trough has opened up and the retina has relaxed posteriorly.If a circum ferential m embrane remains on the posterior aspect of the vitreousbase,it should b e remo ved or radially sectioned.An il lumina ted pick or i l lumina ted forceps can be used to fixate the m embrane for removal orsectioning with autom ated,vertically cutt ing vitreoretinal scissors.Thearrowpoints at an area t hat has been radially sectioned,w hile the forcepshold s the edge of th e mem brane an d exposes it for d issection w ith t he scissors.


12/36

retina, it can be cut with scissors after creating an adjacentretinotomy with diathermy and will often retract back,allowing the retina to settle (Fig. 42-20). If not, or if mul-tiple subretinal strands or a large sheet is present, the retinot-omy is enlarged to allow the insertion of microforceps.Themembrane should be grasped and gentle traction applied ina back and forth motion, breaking adhesions and attach-

ments, while both ends are observed to ensure that theretina is not torn at a remote site (Fig.42-20C). In rare casesof extensive subretinal fibrosis with a so-called napkin ringconfiguration, where the membranes completely encirclethe optic nerve in the subretinal space, a large peripheralretinotomy must be made (see below), usually on the orderof 90 degrees or more, and the retina folded over to allowcomplete removal of the membrane.A bimanual techniqueis required, with a lighted pick or similar instrument usedto elevate and hold the inverted retina, while scissors areused to section the membrane. Then microforceps areused to grasp, tease, and regrasp the membrane until it iscompletely free (Fig. 42-21).

Scleral Buckle

When all membranes have been removed from the surfaceof the retina,it should be mobile and ready to be reattached.In eyes that do not already have an encircling band, this isan appropriate time to place a scleral buckle. Determinationof the appropriate position of the scleral buckle followsmany of the same considerations discussed previously. Ifremoval of all anterior membranes and most of the anteriorvitreous was accomplished, a 3.5- or 4.5-mm encirclingelement is usually adequate to support the vitreous base. Ifcontinued peripheral vitreoretinal traction is present, espe-

cially if this traction extends postequatorially, a broaderbuckle is required.A 7-mm-wide solid silicone element willprovide broad support in this situation.

One disadvantage of placing a buckle at this stage in theprocedure is that the subretinal fluid makes it difficult toassess buckle height. However, after retinal reattachmentwith PFCL injection or fluidgas exchange, buckle height

can be reassessed and adjusted if need be.

Relaxing Retinotomies and Retinectomies

Some eyes with severe PVR, particularly those undergoingreoperation and those with anterior PVR, have areas ofretinal shortening that make reattachment impossible,despite meticulous removal of membranes. In such instances,raising the height of the scleral buckle can sometimes ade-quately relieve persistent traction. If this maneuver is notsuccessful, or if the surgeon decides against revising thescleral buckle, retinotomy with or without retinectomy isnecessary to reattach the retina (28,29). Sometimes thisdetermination is not made until air or PFCL is injected intothe eye (see below) and is noted to go subretinally througha break associated with elevated retina.

Relaxing retinotomy is usually done because of retinalcontraction due to anterior PVR, with anterior retinaldisplacement being the most common indication. How-ever, any type of contraction, especially when chronic, cansometimes require retinotomy to relieve traction. Rarely, afocal area of posterior contraction cannot be relieved byremoval of membranes, and a focal retinotomy must beperformed.

For anterior contraction, after all other membranes havebeen removed, diathermy is applied posterior to the area of


A B C

FI GURE 42-19. Use of PFCL fo r PVR.A.Following removal of posterior membranes,a small volume of PFCL is injected over the posterior

retina.The PFCL reduces retinal mobility during removal of peripheral membranes. B.After the m embranes have been removed,the retina isreattached by injecting m ore PFCL.Subretinal flu id drains into the vitreous cavity from the ant erior retinal break.C. Mo re PFCL has been injected t oreattach the retina.Sometim es a small am ount of subretinal fl uid w il l remain an terior to the PFCL.Try to avoid im mersing th e infusion cannula inthe PFCL, because bub bles wi ll obstruct th e view a nd sma ll bubb les can go th roug h large open breaks.


13/36

contraction (Fig. 42-22). For focal contraction, diathermy isused to encircle the area to be excised. It is important totreat all vessels with heavy diathermy to prevent hemor-rhage. The retinotomy should extend beyond the area ofcontraction into normal retina. The actual retinotomy isusually made with automated vertically cutting vitreous scis-sors (see Fig. 42-22A). Cutting the retina with the vitreouscutter is less controlled and can lead to hemorrhage andinadvertent excision of larger areas of the retina thandesired. For anterior retinal contractions, circumferential

retinotomies are usually performed.Radial retinotomies arerarely indicated. Radial retinotomies tend to extend poste-riorly into the posterior pole and often inadequately relievetraction. Retinotomies in the posterior pole, which involvemore functionally important retina, should also be avoided.Use of a partial fill of PFCL will stabilize the retina duringperformance of the retinotomy and prevent folding andinversion of the flap of the now giant tear after the retinais cut. If the retinotomy extends into attached retina, theretina should be carefully separated from the underlyingretinal pigment epithelium with the tip of the scissors or amembrane pick before cutting, to avoid damage to thechoroid.The ends of the retinotomy may be angled towardthe ora serrata to relieve residual traction present in theseregions (Fig. 42-22B). In most cases, we prefer to removethe anterior flap of devascularized retina to decrease the


B

Subretinalstrand

Extraction ofsubretinal strandthrough retinotomy

C

FI GURE 42-20. A.Branching subretinal strand. B.Sectioningof subretinal strand through peripheral retinotomy.Scissors areplaced throug h a small retinotom y created adjacent t o them embrane with diath ermy.If the membrane is not adherent to theretina or choroid,t he ends of the m embrane should retract aft ersectioning. C.Extraction of subretinal strand t hrough retinotom y.The membrane is grasped wit h forceps and removed with a gentle,side-to-side mot ion. If the m embrane is strongly ad herent t o retinaor choroid, it should be sectioned.(A. Courtesy of Hilel Lewis,M D,Cleveland Clinic Fandation,Cleveland,OH;B, C.Adapted fromAbram s GW.Retinoto m ies and retinectom ies. In: Ryan SJ (ed.).Retina. vol. 3. St. Louis:CV Mo sby, 1989:317346.)

A A

A B

FI GURE 42-21. A,B.Subretinal napkin r ing mem brane(posterior type 3). C.M embrane sectioned and remo ved through

peripheral retinotom y.(A.Courtesy of Hilel Lewis,MD,ClevelandClinic Fandation ,Cleveland,OH;B,C.Adapt ed from Abram s GW.Retinot om ies and retin ectom ies. In Ryan SJ (ed.).Retina.vo l .3.St .Louis:CV M osby,1989:317346.)
http://../xpdf/ch40-79/42-21ax.pdfhttp://../xpdf/ch40-79/42-20ax.pdf


14/36

likelihood of reproliferation and possibly lower the risk ofrubeosis.This procedure is accomplished with the vitreouscutter, again with care taken to avoid damage to the

choroid.A retinotomy greater than 90 degrees in circumference

creates the problem of management of a giant retinal tear.The best method for reattaching the retina in the presenceof a giant tear is the use of a PFCL (discussed below) (30).PFCLs have the advantage of ease of use and do not requiremanipulation of the flap under gas or silicone oil.

If a large relaxing retinotomy (90 degrees) is performedto treat an eye with PVR, careful consideration should bemade of the type of retinal tamponade to use. Eyes under-going retinotomy and retinectomy are more likely to havepostoperative hypotony, which suggests that silicone oil maybe preferred in such eyes (31).

Reatta chment of the Retina w ith PFCL

If PFCL was used to stabilize the retina during membraneremoval or retinotomy, additional PFCL is injected to reat-tach the retina (24). If PFCL was not used, the retina canbe reattached pneumatically with air or with PFCL, accord-ing to the characteristics of the retina. If a large retinotomyhas created a giant tear, PFCL should be used to reattachthe retina (30). If there is no giant break and a posteriorbreak exists, pneumatic reattachment can be performed,using the posterior break to simultaneously drain subretinalfluid.More often,however,breaks will be fairly anterior,and

reattachment of the retina is performed with PFCL prior tofluidair exchange.

When PFCL is to be used, the surgeon should makequite sure that all traction has been removed from aroundretinal breaks. If breaks with elevated edges are present, the

PFCL can pass through the break and move subretinally,requiring further manipulations to remove it, even includ-ing a retinotomy.

We prefer a PFCL with an index of refraction allowinggood visibility such as perfluoro-n-octane (32).The PFCLcan be injected manually with a syringe or with a surgeon-controlled automated fluid injector. We inject the PFCLthrough a silicone-tipped cannula and start injection overthe optic disk. Once a large enough bubble of PFCL ispresent over the optic nerve, the tip of the silicone cannulacan be inserted into the PFCL during subsequent injectionto ensure that a single bubble is produced (see Fig.42-19A).During injection, fluid is allowed to escape from the

sclerotomy site. As the bubble of PFCL slowly increases insize, the posterior pole should be noted to flatten, and thechoroidal pattern should become apparent. The PFCL isinjected slowly and the peripheral retina assessed duringinjection.This procedure is particularly important if a giantretinotomy has been created, because the edge can becomefolded beneath the perfluorocarbon.

In addition, it is important to observe if the peripheralretina flattens during PFCL injection. If the retina remainselevated, injection should be stopped. PFCL should beremoved to at least the posterior aspect of the remainingtraction and the traction relieved. A wide-angle viewingsystem is ideal for observation of the entire fundus during

this process. Injection is continued until the PFCL extendswell onto the scleral buckle anteriorly (see Fig.42-19C).Tryto avoid immersing the tip of the infusion port in the PFCL,because multiple bubbles of PFCL are created by the fluidflow.These bubbles may obstruct the view and go beneaththe edge of a large break. In most cases,fluid will drain fromknown or unrecognized anterior retinal breaks, and thecontour of the buckle will be apparent. Occasionally, fluidwill accumulate anteriorly, obscuring the outline of thebuckle (Fig. 42-23A). In such cases, tipping the eye so thatthe PFCL forces the fluid toward a known retinal break willsometimes flatten the retina (Fig. 42-23B). Occasionally,however, intraocular diathermy must be used to create ananterior drainage retinotomy over the buckle in an area ofnonvascular retina.This retinotomy should be made as ante-riorly as possible to avoid trapping subretinal fluid anteriorto the retinotomy (Fig. 42-23C).

At this point, the entire posterior retina should be re-attached. Areas of persistent retinal elevation beneath thePFCL indicate persistent traction, which must be relieved ifsurgery is to be successful. Most remaining epiretinal mem-branes can be removed beneath the PFCL. If it is necessaryto remove the PFCL, it should be carefully aspirated into asyringe for reuse later in the case.Further membrane peelingcan then be performed, or retinotomy and retinectomy can


RPEB

A

FI GURE 42-22. A. Inferior relaxing retinotom y to relieve

traction in contracted retina. The retina to be cut is diathermized,prima rily by diathermizing blood vessels, extending in to no rmalretina on each end of contracted retina.Cut is made w ith verticallycutt ing scissors alon g the posterior edge of contracted retina .B.Retina reattached following relaxing retinotom y.Retinotom y isextended ant eriorly to ora serrata or ciliar y body (if pars plana isinvolved).The ant erior retin a is excised.(Adap ted from Abram s GW.Retinot om ies and retinectom ies. In: Ryan SJ (ed.).Retina.vo l .3.St. Louis:CV Mo sby, 1989:317346.)


15/36

be carried out as discussed above if separation of membranesis not possible.

Occasionally, retinal reattachment under PFCL is pre-vented by subretinal strands or membranes. In many cases,the retina will reattach despite such tissues. Sometimes theweight of the PFCL acting over time will relax the tractionapplied by subretinal membranes,and the surgeon may wishto wait for several minutes to reassess the retinal status. If

there appears to be less retinal elevation, more PFCL can beinjected and further observation for retinal flattening carriedout. If the PFCL does not overcome the traction from thesubretinal membranes, the PFCL should be removed byaspirating it back into the same syringe, for reuse laterin the case, and the subretinal membranes dealt with asdiscussed above.

Laser Endophotocoagulation

The PFCL affords an excellent view for application oflaser endophotocoagulation to the now reattached retina,although the field of view is less than with a gas-filled eye.All retinal breaks, previously marked with diathermy, aresurrounded with confluent laser spots (Fig.42-24).Laser canthen be applied over the scleral buckle for 360 degrees,using the prism fundus contact lens or a wide-angle viewingsystem (Fig. 42-25). Peripheral laser is facilitated by raisingthe level of the PFCL well onto the buckle, to ensure thatno subretinal fluid is present.An angled laser probe is alsohelpful for treating superior retina. Laser burns should be ofmoderate intensity and placed for two to three rows, witha separation between spots of approximately one burn width(Fig. 42-26). Confluent and overly intense peripheral pho-tocoagulation (Fig. 42-27) can occasionally lead to stasis ofvenous return from the ciliary body to the vortex system.

Occasionally, visualization of the periphery is difficult, andphotocoagulation of this region is delayed until the eye isfilled with air. We treat any posterior retinal breaks withlaser,but do not perform scatter treatment posterior to thescleral buckle.

Removal o f PFCL

On completion of laser endophotocoagulation, an inferiorperipheral iridectomy is made if silicone oil is to be usedin an aphakic eye (see below) (33). Then, fluid/PFCLairexchange is carried out. We prefer active suction with an


A B C

PFCL PFCL PFCL

Retinalbreak

Sharpdiathermyprobe

Hole inretina

FI GURE 42-23. A.Fluid trapped ant erior to retinal break follow ing retinal reattachm ent wit h PFCL. B. Eye tilted so PFCL will fo rce subretin al

fluid out of retinal break. C. I f unab le to force subretinal flu id out by t i l t in g the eye,a n ant erior drainage retinoto my is mad e with endodiath ermy toallow d rainage of subretinal fluid (arrow). In ject io n o f m or e PFCL wi ll now at tach t he a nt erior ret in a.

Retinalbreak

Laser

FI GURE 42-24. Laser endoph otocoagulation .Treated retinalbreaks with one or tw o row s of confluent laser.(Adapted fromAbram s GW.Retinot om ies and retin ectom ies. In: Ryan SJ (ed.).Retina. vol. 3. St. Louis:CV Mo sby, 1989:317346.)


16/36

reappears. This process is continued until all the fluid isremoved from the eye.

In the presence of a giant retinotomy (usually 180degrees or more), there is a risk of retinal slippage duringthe exchange of PFCL for air.This can be prevented by ade-quate dryingof the edge of the retinotomy during the airexchange (24), accomplished by filling the vitreous cavityanterior to the flap of the giant retinotomy with air,then aspirating fluid from beneath the anterior edge of theretinotomy before removing the PFCL (Fig. 42-29). Theanterior edge of the retina can be visualized during fluidairexchange with a wide-angle viewing system or,alternatively,with an indirect ophthalmoscope. If fluid is left behind theedge of the retinotomy, as PFCLair exchange proceeds,


FI GURE 42-25. Laser endopho tocoagulation using a w ide-angle system. The wide-angle view allows visualization of th eperipheral retina du ring endophotocoagulat ion.Treatm ent isapplied using a scatter technique on t he retina supported by thescleral buckle.The bullet light probe is used with the wide-angleviewing system t o give wide field i l lumination .(Adapted fromAbram s GW, Glazer LC.Proliferative vitreoretino pat hy.In: FreemanWR (ed.). Practical atlas of retinal disease and therapy.2nd ed.Philadelphia : Lippincot t-Raven, 1997:303323.)

FI GURE 42-26. One burn w idth betw een laser applicationsduring scatter treatment.(Adapted from Abrams GW,Glazer LC.Proliferative vitreoretino pat hy.In: Freema n WR (ed.).Practical atlasof retinal disease and therapy.2nd ed.Philadelphia:Lippincott-Raven,1997:303323.)

FI GURE 42-27. Excessive laser treat m ent t o periph eral retinaon scleral buckle.

aspiration silicone-tipped cannula for this purpose.Alterna-tive instruments preferred by some surgeons are backflushbrushes or extrusion needles, providing passive egress ofPFCL and intraocular fluid from the eye. In the phakic orpseudophakic eye, a biconcave contact lens is placed on thecornea to overcome the higher refractive power of theair-filled eye. With the aspiration cannula and fiberopticlight probe in the eye, the infusion line is switched fromfluid to air, with the pressure of the air pump typically setat approximately 40mmHg. Preliminary aspiration is per-formed just behind the iris plane, until air fills the anteriorvitreous cavity.Then the silicone cannula tip is placed nearthe peripheral retina at the level of the PFCLfluid inter-face, so that an airPFCL interface is achieved and there isminimal risk of reaccumulation of subretinal fluid.Next thecannula is positioned over the optic nerve, and the remain-der of the PFCL is aspirated. As the eye fills with air, thefluid level can be safely determined by the dippingmaneuver.The silicone cannula is inserted toward the opticnerve head until the bright reflex disappears, indicating thatthe tip of the cannula has reached the fluid (Fig. 42-28).Aspiration is initiated and continued until the reflex
http://../xpdf/ch40-79/42-27x.pdfhttp://../xpdf/ch40-79/42-26x.pdf


17/36

fluid forced posteriorly during the exchange will allow pos-terior slippage of the edge of the tear. If PFCL goes beneaththe retina, it must be removed, which may require refillingthe eye with fluid. Once fluid is removed from behind theanterior edge of the retina,PFCLair exchange is completed

and all PFCL is removed from the eye.Perfluoro-n-octane is easily seen and removed, andbecause of the high vapor pressure, remaining small bub-bles will evaporate in air at body temperature. How-ever,perfluorodecalin and perfluorophenanthrene, two othercommonly used liquid PFCLs, are less easily seen, have alower vapor pressure, and will not evaporate in air (32), sowe recommend dripping approximately 0.1 to 0.3mL ofbalanced saline onto the posterior retina to identify anyremaining PFCL (which will coalesce into more easily seenbubbles in the balanced saline) to facilitate removal.

The optical properties of a gas-filled eye allow a widerfield of view than those of liquid, and usually a more com-plete view of the periphery is obtained after fluidairexchange. If inadequate laser treatment of the periphery wasaccomplished under PFCL, particularly laser treatment of

retina overlying the scleral buckle,more complete endopho-tocoagulation can now be performed in many cases. Inpseudophakic eyes, condensation of fluid on the IOL canimpede visualization, as discussed below.

Reatta chment of the Retina W ithout PFCL

If PFCL is not used, we reattach the retina with a fluidairexchange. All retinal breaks should be marked with endo-diathermy prior to fluidair exchange so they can be seen


FI GURE 42-28. A. Fluidair exchange. The tip of th e suctionneedle is held just ant erior to the break. Note the fl uid m eniscus(arrow) o n sha ft of dr ai nag e n eed le. B. Removing final b i t o f fl u idover optic nerve.The needle t ip is repeatedly dipped into fluid atthe retinal b reak and over th e optic disk. A light reflex is seen todisappear as the needle tip conta cts the fluid m eniscus.(Adap tedfrom Abrams GW, Aaberg TM. Posterior segm ent vitrectomy. In:Waltman SR (ed.). Surgery of the eye. New York: Churchil l- Livingstone, 1988:9031012.)

A

BFI GURE 42-29. Unfolding flap of giant tear or largeretinotom y w ith PFCL. A. PFCL is injected over the po sterior pole tounfold fl ap of g iant t ear.With retina stabil ized with PFCL,removal ofant erior vitreous and ant erior dissection are m ade easier.PFCL canbe injected to the level of t he anterior edge of the giant tear after allmembranes are removed. B. PFCLair exchang e.The space anteriorto t he PFCL is filled wit h air.The edge of the tear is dried to preventslippage.Fluid behind the edge is aspirated with the soft-tip needleunti l t he edge is completely flat. C. PFCLair exchan ge is com pleted.All PFCL is removed with the soft-tip needle.(Adapted from AbramsGW,Glazer LC.Proliferative vitreoretinop ath y.In: Freeman W R (ed.).Practical atlas of retinal disease and therapy.2n d ed.Philadelphia:Lippincott-Raven,1997:303323.)
http://../xpdf/ch40-79/42-28bx.pdfhttp://../xpdf/ch40-79/42-28ax.pdf


18/36

and treated through the air bubble. Before switching fromfluid to air, the decision of whether to use gas or siliconeoil tamponade must be made, because if silicone oil is to beused, it is preferable to create an inferior peripheral iridec-tomy in a fluid-filled eye (see below).Air is supplied by the

air pump and fluid is usually removed with an aspirationsoft siliconetipped needle, just as described above forremoval of PFCL.There is usually a posterior or peripheralretinal break available for removal of subretinal fluid. If aposterior break is present, then it is used for subretinal fluiddrainage (Fig. 42-30). If no posterior break is present, wedo not usually make a posterior drainage retinotomy.Drainage through a peripheral break is facilitated by the useof the extendable cannulated extrusion needle in which thesoft-silicone tube can be extended through the peripheralbreak into the subretinal space posteriorly (Fig.42-31) (34).In most cases, a simple nonextendable, soft-tipped cannulawill suffice for the same purpose. If there is no accessible

break for drainage, we usually make a drainage retinotomywith the endodiathermy probe in the peripheral retina inan area to be supported by the scleral buckle.

Once the retina is reattached under air, confluent laserendophotocoagulation is applied to surround all breaks,identification of which is facilitated by previous labelingwith diathermy as discussed above. If a retinal burn is notnoted despite adequate power and laser application interval,residual subretinal fluid is likely present at the margin of thebreak,and further aspiration should be performed.Treatmentof all breaks is followed by peripheral laser treatment overthe scleral buckle as described above in conjunction withPFCL.

Not uncommonly, visibility will deteriorate after fluidair exchange due to the appearance of corneal striae, ordue to condensation of fluid on the IOL in pseudophakiceyes, occasionally to the point where completion ofendolaser treatment becomes difficult or impossible. Use

of a wide-angle viewing system can often improve fundusvisualization.The posterior surface of the IOL can be moreevenly wetted by application of a soft-tipped cannula ina sweeping fashion. Another maneuver that is often helpfulis the application of sodium hyaluronate to the cornealendothelium. A small amount of viscoelastic injectedonto the endothelial surface often dramatically improvesvisibility.

Silicone IOLs may create significant problems duringfluidair exchange (35). Because of the hydrophobic natureof the silicone, condensation will reoccur during fluidairexchange, even if it is wiped away with a silicone-tippedcannula, obscuring the view of the retina in the air-filled

eye. It may be possible to dry the posterior surface with asteady stream of air from the air pump via a needle heldagainst the posterior surface of the IOL during fluidairexchange (36).


Air insufflation

Soft tipneedle

Air

Subretinal fluidaspiration

FI GURE 42-30. Fluidair exchange.Subretinal fluidis aspirated t hroug h th e posterior retinal break as the eye issimu ltaneously filled by the air pum p.(Adapted from Abrams GW.Retinot om ies and retinectom ies. In: Ryan SJ (ed.).Retina.vo l .3.St .Louis:CV M osby,1989:317346.)

FI GURE 42-31. Fluidair exchange using a peripheral retinalbreak.Drainage retinotomy is created anteriorly over the scleralbuckle.Extendable soft silicone tubing of the cannulated extrusionneedle is passed through the retinotomy into the posterior subretinalspace for flu idair exchange. (Adapted from Abram s GW,Glazer LC.Proliferative vitreoretino pat hy. In: Freeman WR (ed.).Practical atlasof retinal disease and therapy.2nd ed.Philadelphia:Lippincott-Raven,1997:303323.)


19/36

AirGas Exchan ge

Following laser treatment, two sclerotomy sites are closed,usually with 7-0 polyglycolic acid sutures.At least 25mL ofa nonexpansile mixture of C3F8 gas (12% to 14%) are flushedthrough the eye (37).We have shown experimentally that a

predictable gas concentration can be obtained using thismethod.The gas mixture is insufflated through the infusionport and allowed to egress through a 27-gauge, 1/2-inch-length needle inserted through the pars plana and vented toatmosphere.A tuberculin syringe with the plunger removedcan be used as a handle for the needle. Following the gasflush, the needle is removed, then the infusion port isremoved and that site closed.We then reform the eye to anormal pressure with the gas mixture via a 30-gauge needlethrough the pars plana. We try to leave the intraocularpressure at approximately 10mmHg at the completion ofsurgery.

The conjunctiva can be closed with absorbable suture

such as 6-0 plain gut, bringing the flap of conjunctiva tothe limbus and assuring that all sclerotomies are wellcovered. In eyes that have undergone multiple prior surgi-cal procedures, this can be quite difficult and time consum-ing,but must be done in careful fashion. If the conjunctivais retracted, it can sometimes be released by making multi-ple small circumferential cuts in the undersurface of Tenonscapsule with a sharp, rounded blade,and drawn closer to thelimbus. Subconjunctival injection of an antibiotic, while ofunproven value, is standard practice, as is subconjunctivalcorticosteroid injection, usually with dexamethasone. Place-ment of ointment in the palpebral fissure and an eye patchcompletes the procedure.

Silicone Oil

The Silicone Study found that visual and anatomic resultsin eyes with PVR were similar in most analyses regardlessof whether silicone oil or C3F8 gas was used as the intra-ocular tamponade and both modalities were superior to SF6gas (3840). While the surgeon and patient will jointlydecide on the tamponade to use in most cases, some factorswill contribute to the decision. Gas may be preferred oversilicone oil if it is likely that silicone oil will herniate intothe anterior chamber and contact the cornea, such as whenthe iris diaphragm is not intact or when an IOL is presentwithout an intact iris-capsular-IOL diaphragm. Oil may bepreferred for patients unable to maintain prone positioningsuch as children or mentally or physically impaired patients.Silicone oil is associated with a lower incidence of postop-erative hypotony and is preferred in certain cases, includingeyes with preoperative hypotony and eyes with rubeosis orrequiring extensive anterior dissection of membranes, asthese eyes are at greater risk of postoperative hypotony.Silicone oil may be preferred in the face of a giant tear orretinotomy, which will also more likely have postoperativehypotony. Silicone oil is preferred if the patient must travelby air or if the patient must travel to a higher elevation.Silicone oil is preferred over gas in the presence of residual

vitreous or choroidal or large subretinal hemorrhage. Anobvious disadvantage of silicone oil as a means of intraoc-ular tamponae is the need for a second operation if siliconeoil is eventually removed.

When silicone oil is to be used, an inferior iridectomy

should be created in the aphakic eye (Fig.42-32) (33).Thevitreous cutter is inserted behind the inferior peripheraliris at its base, with the vitrectomy instrument facing theiris, then the iris is engaged. Excision of iris tissue mustbe controlled, and care must be taken to confine the iri-dectomy to near the iris base and not to extend it tothe pupillary margin. As partial thickness iris is removed,


FI GURE 42-32. Inferior iridectomy. A.Without inferiorir idectom y,silicone oil herniates into the anterior cham ber due topupil lary block mechanism . B. Inferior iridectom y allow s access ofaqueous into the ant erior cham ber, relieving pu pil lary block so tha taqueous no longer forces silicone oil into the anterior chamber.C.Inferior iridectomy.(Adapted from Abrams GW,Glazer LC.Proliferative vitreoretino pat hy. In: Freeman WR (ed.). Practical atlasof retinal disease and therapy.2nd ed.Philadelphia:Lippincott-Raven,1997:303323.)

Siliconeoil

A

Siliconeoil

B

C
http://../xpdf/ch40-79/42-32cx.pdf


20/36

the surgeon begins to see the tip of the vitreous cutterthrough the thin residual anterior iris stroma and can in thismanner guide placement of the instrument to complete theprocess.

If the retina has been reattached with air, then silicone

oil can be infused into the air-filled eye at the end of thecase. Alternatively, a fluidsilicone exchange or PFCLsilicone oil exchange can be performed. When infusingsilicone oil into the air-filled eye, the 5000-centistoke oilthat is most commonly used has high viscosity and requireshigh pressure tubing if injected through the infusion port.We usually inject silicone oil into the air-filled eye in thefollowing manner.With the infusion port in place and theair pump engaged to the infusion port tubing,we close onesclerotomy site and preplace a suture in the other site.Weinject the silicone oil through an 18- or 20-gauge angio-cath that has been trimmed to approximately 10mm inlength.As the silicone oil is injected, the pressure is adjusted

and maintained at the present pressure by the air pump,which remains attached to the infusion tubing.In phakic orpseudophakic eyes, injection of silicone oil is continueduntil the oil just reaches the posterior lens. The syringeis removed and the preplaced sclerotomy suture closed.

The infusion cannula can then be removed and the finalsclerotomy closed.A small amount of oil will escape duringsuturing of the final sclerotomy, helping to ensure that theeye is not overfilled with silicone oil.

In aphakic eyes, injection is continued until the oil levelis at the level of the infusion cannula.The silicone syringe isremoved from the eye, and the preplaced superotemporalsclerotomy suture is closed.Then,after clamping the air line,

the infusion cannula can be removed from the eye and thetip of the silicone oil syringe inserted into the infusion scle-rotomy.To maintain the appropriate intraocular pressure andallow the escape of air from the eye, a 30-gauge needle canbe attached to the air pump (still set at 15mmHg) andinserted into the anterior chamber through the limbus.Injec-tion is continued until the silicone oil just reaches the irisplane.Then the silicone oil syringe and needle are removedfrom the eye,and the final sclerotomy is closed.Again,a smallamount of oil will escape, helping to prevent an overfill ofsilicone oil. Regardless of the phakia status of the eye, it maybe prudent to place a plug in the sclerotomy before closingit and measure the intraocular pressure.A pressure reading ofabove 20mmHg may indicate an overfill,and a small amountof silicone oil should be removed through the open sclerot-omy and the pressure remeasured.We try to leave the closingpressure at approximately 10mmHg.The anterior chamberis left at normal depth. If the anterior chamber shallows, asmall amount of oil is removed and the anterior chamber isreformed with air injected through the limbus. It is impor-tant that the intraocular pressure be left at a low-normal levelso as not to inadvertently overfill or underfill the eye withsilicone oil.

If a posterior chamber IOL is present with an intact iris-capsular-IOL diaphragm, we do not make an inferior iri-

dectomy. If the diaphragm is not intact and/or silicone oilherniates around the IOL into the anterior chamber, aninferior iridectomy will sometimes keep the silicone oilout of the anterior chamber;however,sometimes the oil willgo into the anterior chamber in spite of the iridectomy.

Residual capsular material can obstruct an iridectomy, sopatency should be confirmed at surgery. If the iridectomyis open and oil has gone into the anterior chamber, theoil can be pushed posteriorly with viscoelastic materialinjected into the anterior chamber. If the eye is makingadequate aqueous, it may be necessary to remove the IOLand capsule and reopen the iridectomy in order to keep thesilicone oil out of the anterior chamber. A stable anteriorchamber lens can be left in place if an adequate inferioriridectomy is made.Unstable anterior chamber lenses shouldbe removed.

After all sclerotomies are closed, the eye is irrigated copi-ously with saline solution to remove residual silicone oil,

and the conjunctiva is closed as described above.If the pressure is within a normal range and the retina is

stable, the silicone oil can be removed 2 months or morefollowing surgery. It is often possible to remove recurrentepiretinal membranes at the time of silicone oil removal.

The Silicone Study found that approximately 20% of retinasdetach following silicone oil removal (41).

In the presence of hypotony, it is probably best to leavethe silicone oil in the eye. Hypotonous eyes usually end upwith corneal decompensation in the presence of siliconeoil, because the silicone oil herniates forward and touchesthe corneal endothelium. Unfortunately, with silicone oilremoval, these eyes often become phthisical. Whereas

the visual prognosis is poor in either situation, the eye willprobably remain more stable with silicone oil remaining inthe eye than otherwise.

Early Postoperative Management

Eyes with PVR require significant postoperative manage-ment. Early postoperative management is directed toward1) careful control of the intraocular pressure (IOP), 2)adequate retinal tamponade, 3) control of inflammation, 4)elimination of hemorrhage and fibrin, and 5) detection andmanagement of recurrent retinal detachment.

Han et al (42) found that 36% of patients developed anintraocular pressure of 30mmHg or more following vitrec-tomy. Patients undergoing surgery for PVR have many ofthe risk factors for elevation of IOP: scleral buckle, lensec-tomy, scatter endophotocoagulation, and sometimes a fibrinpupillary membrane postoperatively.We monitor IOP care-fully in the postoperative period.We normalize IOP at theend of the case, and if the patient has preexisting glaucomaor other factors indicating high risk for elevation of the IOP(e.g., scleral buckle and scatter photocoagulation), we givetopical ocular antihypertensive medications.We check theIOP approximately 2 to 4 hours following surgery, then re-check as needed.We treat elevated IOP medically in most



21/36

cases, but extreme elevation of pressure sometimes requiresparacentesis of fluid or gas.

We ensure that the gas bubble is adequate to tamponadeall retinal breaks and laser treatment postoperatively. Weprefer to have the eye at least 80% filled with gas in the

postoperative period. If the gas bubble is inadequate post-operatively,as sometimes occurs,we do a fluidgas exchangeto top up the gas bubble. For fluidgas exchange in theaphakic eye, we prepare the eye with 5% povidine-iodinesolution to the lids and the conjunctival cul-de-sac.We makea limbal incision with a disposable Ziegler-type blade.Then,with the patient prone, we inject gas into the eye througha 30-gauge needle inserted through the limbal incision(Fig. 42-33). As gas is injected, fluid will run out aroundthe shaft of the needle through the limbal opening.Thelimbal incision is self-sealing and usually leaves a relativelynormal IOP.We usually use a 15% mixture of C3F8 for thepostoperative fluidgas exchange.

In a phakic eye or in an eye with a posterior chamberimplant, we perform the fluidgas exchange through thepars plana.We use a two-needle technique.With the patientplaced on his or her side, we insert a 30-gauge needleattached to a 10-cc syringe filled with the selectedgas mixture (usually 14% C3F8 gas) through the pars planain the most superior position and into the vitreous cavity.We then insert a 27-gauge needle attached to a 10-ccsyringe through the pars plana at the most dependentposition. We usually place the needle for air insufflation(which is now superior) nasally, and the needle for fluid

aspiration (which is now dependent, inferiorly) temporally(Fig. 42-34).

We aspirate fluid from the dependent syringe as wesimultaneously fill the eye with air from the superiorsyringe.We sequentially equalize the volume of fluid aspi-

rated through the dependent syringe with the amount ofgas injected through the superior syringe. Usually, wesequentially aspirate 0.5mL of fluid then inject 0.5mL ofgas, until the fluid is replaced with gas. As we fill theeye with air, we turn the head toward a more proneposition so we can aspirate more fluid. We aspirate as theneedle is slowly withdrawn to remove as much fluid aspossible.

To control inflammation, we give subconjunctivalDecadron (510mg) at the conclusion of surgery.We alsotreat with frequent topical corticosteroids postoperatively.We usually give the topical corticosteroids every hour whileawake for the first few days of the postoperative period.We

usually do not give systemic corticosteroids because of thepotential systemic risks involved and because the benefit hasnot been clearly demonstrated.

If significant postoperative fibrin formation causes pupil-lary block, interferes with postoperative fluidgas exchange,or interferes with the view to the extent that it complicatespostoperative evaluation and management,we lyse the fibrin


Gas bubbles

Fluid flowsout of eye

FI GURE 42-33. Postoperative fluidgas exchange in theaph akic eye. A selected gas mixtu re (5 to 10 m L) is insuffla ted intothe eye through a 30-gauge needle placed th rough a l im bal incisionmade with a Ziegler-type blade.Because the self-sealing limbalincision is larger than the diam eter of th e needle,fluid w il l drain outof th e incision as the ga s is injected.Small bu bbles will coalesce inthe first hou rs aft er the exchange.

FI GURE 42-34. Postoperative fluidgas exchange in thepha kic or pseudopha kic eye.The superior (nasal) syringe cont ainsair or gas mixt ure.The inferior (tempo ral) syringe is for aspiration offlu id in th e vitreous cavity. Exchange is done by sequentia lly injecting0.5 m L of air or gas and aspirating the same volume of fluid unti l th eflu id in t he vitreous cavity is exchanged fo r the air or g as.We use a30-gauge needle for injection and 27-gauge needle for aspiration.


22/36

with tissue plasminogen activator (tPA) (4345).We usuallywait 48 to 72 hours following surgery to administer tPA inorder to minimize the possibility of intraocular hemorrhage.We recommend injecting 3g of tPA in 0.1mL of balancedsaline with a 30-gauge needle through the limbus. In the

presence of severe fibrin formation and/or hemorrhage, weusually do a fluidgas exchange to clear the fibrin productsand/or hemorrhage after lysis with the tPA.

We closely monitor patients for the development ofrecurrent retinal detachment. Retinal detachment is mosteasily seen by looking around (not through) a gas bubble.We usually examine the patients every 1 to 2 weeksuntil the gas bubble has resolved. If retinal detachment isdetected, we look for the cause. Usually retinal detachmentindicates the presence of an untreated retinal break and/orexcessive retinal traction. The most common cause ofrecurrent retinal detachment is residual anterior traction thatopens an anterior break. Eyes with anterior contraction can

sometimes be reattached successfully with a repeat fluidgasexchange.

After the retina is flattened, laser treatment is applied inseveral rows to the retina over the scleral buckle and some-times 360-degrees posterior to the scleral buckle.We havefound that postoperative laser photocoagulation in the air-filled eye is most easily administered using a laser with along wavelength, such as krypton red or diode laser, and apanfunduscopic contact lens.

Although some degree of retinal detachment anterior tothe scleal buckle may remain, often fluid can be demarcated,and the posterior retina will remain attached.This is com-patible with long-term stability and recovery of functional

visual acuity in some cases; however, some cases with ante-rior retinal detachment will become hypotonus. If there issignificant retinal contraction posterior to the scleral buckle,we do not recommend doing a fluidair exchangebecause of the risk of further contraction and posteriortear formation.With posterior contraction, we recommendreoperation.

Eyes with silicone oil can have unique postoperative con-siderations, including herniation of the silicone oil into theanterior chamber and pupillary block glaucoma due to thesilicone oil. Both problems usually result from closure ofthe peripheral iridectomy. Sometimes, however, the oil willbe in the anterior chamber in the first few days followingsurgery in spite of an open iridectomy. If the eye is pro-ducing adequate aqueous, the silicone oil will recede behindthe pupil as flow of aqueous is established through theperipheral iridectomy. Keeping the patient in an uprightposition with the face tilted forward will help establish theproper aqueous flow. If the eye is not making adequateaqueous, the oil will continue to herniate forward. Usually,if the silicone oil has pushed the iris forward with shallow-ing of the anterior chamber following surgery, simply posi-tioning the patient upright with the face tilted forward orhaving the patient lie prone will cause it to recede to itsnormal position.

Fibrin can close a peripheral iridectomy and cause pupil-lary block with shallowing of the anterior chamber andglaucoma or herniation of the silicone oil into the anteriorchamber.Sometimes the fibrin will resolve with topical cor-ticosteroids, but if it persists more than 48 to 72 hours, we

inject tPA (3g) to lyse the fibrin. If postoperative fibrinformation has caused adherence of the peripheral iris to thecornea, surgically reforming the anterior chamber may benecessary. In the surgical suite, we inject viscoelastic toreform the anterior chamber. Removing a small amount ofsilicone oil may occasionally be necessary.

Results

There has been slow, steady improvement in the surgicalresults of PVR management in the past 25 years. Grizzardand Hilton (16) used a high encircling scleral buckle tech-nique and reported a 35% retinal reattachment rate in eyes

with the equiva

Documents

CH42 Management of Complicated Retinal Detachment