PERIPHERAL RETINAL DEGENERATIONS

PERIPHERAL RETINAL DEGENERATIONSThe peripheral retina is defined as anterior portion of retina that begins 3mm posterior to the equator , extends past the equator into the anterior portion of retina that ends at ora-serrataOra serrata serrated junction between retina and ciliary bodyTooth like extensions of retina into parsplana dentate processAreas of parsplana between two dentate process oral bay

1. Intra-retinal Degenerations : microcystoid degenerations (Typical & Reticular) senile retinoschisis pars plana cysts2. Retino-vitreal degenerations : Lattice degeneration Snail-track degeneration White with & without pressure3. Chorioretinal degenerations : Paving stone degeneration diffuse chorioretinal degenerationPeripheral retinal degenrationsDegenerations predisposing to retinal detachement Lattice degeneration Snail-track degeneration White without pressure degenerative retinoschisis tractional tufts

Degenerations not predisposing to retinal detachement paving stone degeneration microcystoid degeneration snow flake degeneration drusen honeycomb/reticular degeneration oral pigmentary degeneration

Sharply demarcated , circumferentially oriented , spindle shaped area of retinal thinning between equator and vitreous baseDiscontinuity of ILM with variable atrophy of underlying sensory retinaSupero-temporal region6-8% of general populationBilateral in 50%MC in myopesAssociated with Marfans , sticklers , Ehler-Danlos syndromes thinning -> atrophic holes -> condensation & adhesion of overlying pocket of liquified vitreous to the LD-> traction -> tears -> rhegmatogenous RDsequelae

Sharply demarcated circumferentially oriented bands of tightly packed snow flakes which give peripheral retina a white frost like appearanceThe islands are smaller than latticeRarely associated with traction tearsMay be associated with large round holes Snail tract degenertion

White with pressureDistinctive milky white or opalescent appearance of the peripheral retina that is observed when examined with scleral depressionRetina appears normal without depression It is common and seen in around 30 to 35% of eyes Infero-nasal quadrant least likely to be affected Incidence increases with age , no sex predilection Benign condition not associated with retinal breaks Must be carefully distinguished from a subclinical peripheral RD Distinctive white appearance of the peripheral retina without indentation Whiter than the retina in white with pressure and the choroidal markings are almost obscured Margins are sharply demarcated from normal retinaElderly and myopesGaint retinal tear & RD may devalop at posterior borderWhite with out pressure

Splitting of sensory retina into outer ( choroidal ) layer inner ( vitreous ) layerSplitting occurs at the outer plexiform layer typical form nerve fibre layer reticular formFound in 5% of general population over 20yrs age70% in hyperopic eyesB/L in 60-70%Degenerative retinoschoisisAsymptomaticStarts in infero-temporal quadrants then progresses circumferentially & finally affects the entire peripheryRD can occur only when outer retinal layer hole exists

Cystic/non cystic / zonular retinal traction tuftsCystic retinal traction tuft - congenital - small pyramid like projections of whitish retinal tissues into the vitreous cavity - cystic retinal degeneration occurs at the base of the tufts - severe vitreous traction may convulse a cystic tuft leading to RDNoncystic retinal tuft - smaller , acquired , more common ,doesnt predispose to RD

Retinal tufts

Zonular retinal traction tufts -congenital -usually single -Inferotemporal quadrant MC - found in the vitreous base & zonular fibres are attached to its apex -can cause significant retinal holes multiple rounded punched-out areas of choroidal and retinal atrophy Located between ora and equator with size of one to several disc diameters More common in infero-nasal and temporal quadrants Lesions are yellow-white in color with due to sclera being partly visible through the atrophic choroid . Large choroidal vessels seen running through the base Lesions have discrete margins which may be pigmented.- May become confluent Frequently bilateral, no sexual predilectionincreasingly common with age Benign lesions not associated with complications Pavement stone degeneration

Multiple glistening yellowish white dots scattered diffusely in peripheral fundusFibrillar condensation & liquefaction of vitreous is seenAssociated with LD , SD , retinoschisisSnow flake degeneration

Most frequent intra-retinaldegenerative lesion Characterized by small bubbles or vacuoles in the peripheral retina near ora These occur in the outer plexiform and inner nuclear layers of retina Mostly symmetrical, more in temporal retina than nasal, more superiorly than inferiorly Inner wall of a cyst may be absent giving impression of that of a retinal hole which is actually a pseudo-hole Does not predispose to retinal detachmentMicrocystoid degeneration

Age related changeFine network of perivascular pigmentation which may extend posterior to the equatorCaused by RPE degenerationNasal quadrantsReticular/honeycomb degeneration Reticular degeneration microcystoid degeneration

Often surrounded by rings of pigmentClusters of pale lesions surrounded by hyperpigmented bordersPeripheral drusen

Clear bullous elevation of non-pigmented ciliary epithelium of pars plana Usually more prominent temporally underneath the vitreous base Content is usually clear and has been found to contain hyaluronic acid Seen in 5 10 % of all eyes Bilateral in one third cases and show no sex predilection These are harmless lesions not associated with serious eye complications Parspalna cysts

In the absence of retinal breaks no prophylactic treatment is necessary unless following risk factors are presentRD in the fellow eye ( 10% risk in phakic , 20-36% in aphakic )Aphakia , pseudophakia , yag capsulotomy ( upto 3 fold more chance than phakics )High myopiaStrong family history of RDAn association with systemic diseasemanagementCyrotherapySlitlamp photocoagulationIndirect photocoagulation depends on location of lesion , clarity of media , pupil sizeTreatment modalitiesSmaller lesions , peripheral , equatorial , postequatorial lesions , dilated pupilsLaser settings 200 micrometer spot size 0.1-0.2 seconds duration moderate intensity burnsSurround the lesion with two rounds of confluent burnsLaser photocoagulation

Preferred for larger areas , hazy media and smaller pupilsWhile viewing under indirect , gently indent the sclera with the tip of the probeSurround the lesion with single row of cryoapplication ( terminate freezing as soon as retina whitens )New break formation can occur with in treated area due to excessive treatmentcyrotherapy