BritishJournal ofOphthalmology 1993; 77: 485-488

Treatment ofvitreous floaters with neodymiumYAGlaser

Wu-Fu Tsai, Yen-Chih Chen, Chorng-Yi Su

AbstractFifteen cases of vitreous floaters with seriouspsychological reactions have been collected.By using a direct ophthalmoscope, causalvitreous opacities were detected. The opaci-ties were photodisrupted with neodymiumYAG laser, using energy levels of 5 to 7*1 mJand total energy 71 to 742-0 mJ. Symptomscompletely disappeared immediately aftertreatment in all 15 cases. There were nointraoperative or postoperative complicationsnoted during a follow up period of at least 1year. To our knowledge, the use ofneodymiumYAG laser to treat vitreous floaters has notbeen previously described. Our initial experi-ence indicates that the treatment is simple,safe, and effective.(BrJ Ophthalmol 1993; 77: 485-488)

The perception of floaters is a common com-plaint of ophthalmic patients, and may besymptomatic of serious vitreoretinal disorders: itmay also occur commonly in otherwise normaleyes. In the latter situation floaters result fromlocalised vitreous opacities that are products ofeither vitreous degenerations or posteriorvitreous detachments. Although most of themwill resolve spontaneously, some become coarse.Their natural history cannot be predicted. Theyare harmless and need no treatment. However,there are rare patients who may react so exces-sively to vitrous floaters that they are psycho-logically incapacitated. For these patients, it isworth employing more aggressive treatment torelieve their annoyance. We found that this typeof floater usually results from localised vitreousopacities which could easily be photodisruptedto make the floaters disappear. Our report des-cribes treatment using a neodymium YAG (Nd-YAG) laser for 15 patients with excellent results.

Department ofOphthalmology, FatherFox Memorial Hospital,Tainan, Taiwan,Republic of ChinaW F TsaiY C ChenCYSu

Department ofOphthalmology, Collegeof Medicine, NationalTaiwan University,Taipei, Taiwan, Republicof ChinaW F TsaiCorrespondence to:Dr Wu-Fu Tsai, Father FoxMemorial Hospital, 901Chung Hua Road, Yung KangHsiang, Tainan, Taiwan.Accepted for publication25 March 1993

Patients and methodsBetween July 1990 and June 1991, 15 patientswith vitreous floaters were selected who met thefollowing criteria for laser treatment: the floaterswere caused by localised vitreous opacities;symptoms persisted for at least 3 months withoutevidence of regression; patients suffered fear,depression, or anxiety and strong desire for a fastcure; in some cases floaters obstructed the visualaxis and occasionally interfered with vision.None of the patients had a history of retinaldetachment, diabetic retinopathy, or otherretinal diseases. If the vitreous floaters appearedin both eyes (cases 5, 6, 10, 11, and 14) the moreseverely affected one was selected. Of these 15patients, six were men and nine were women.Their ages ranged from 42 to 70 with an averageage of 56-93 years.

Each patient had a thorough preoperativeophthalmic examination including visual acuity,tonometry, and a complete external eye examina-tion. Vitreous study was performed by slit-lampbiomicroscopy with Goldmann's three mirrorcontact lens. Ocular fundus was examinedthoroughly with indirect ophthalmoscopy and a360 degree scleral depression to rule out a retinalbreak or detachment.When taking individual patient histories, we

emphasised the duration, number, shape, size,direction of motion, and movability of thevitreous floaters. In fact, we encouraged thepatients to draw, if possible, exactly what theyhad seen.As far as laser treatment was concerned, all of

the above mentioned examinations were fordocumentation only. However, an ocular fundusexamination with direct ophthalmoscopy wasmandatory. Through the maximally dilatedpupil, the ophthalmoscopy was initially focusedon the disc, the lens wheel was moved from alower black number toward a higher blacknumber, and the patient was asked to move hiseye from left to right. The opacity was seen tofloat by. Usually, they were centrally located andwere less than three in number. The number ofopacities was equal to that ofthe floaters; a singleopacity always induced a single floater. If thenumber of opacities was larger than the numberof floaters, the more centrally located opacitieswere the ones responsible for the floaters. Thecausal relationship between vitreous opacitiesand floaters was easily determined in this way.The exact locations, sizes, and shapes of thecausal opacities were sketched in a three dimen-sional graph with the optic disc serving as areference point. When the treatment was beingperformed, this graph might serve to show theexact location of the target opacity and, moreimportantly, to show the distance of the opacityfrom the retina so as to avoid damaging it. Theactual distance of vitreous opacity from retinacould be measured by focal difference betweenthe opacity and retina as measured by directophthalmoscopy, or by ultrasonogram measure-ment.

TREATMENTInformed consent was obtained in all cases.Thirty minutes before the treatment 1%mydriacyl was applied into the eye once orseveral times to obtain maximal pupillary dilata-tion. The instrument used was LASAG micro-ruptor III which is a Q switch YAG laser. Theinstrument was properly aligned in such afashion that the aiming beam and illuminationbeam crossed each other at a 150 angle. Thepower was set at 5 or 7-1 mJ, occasionally 10 mJper burst. (There were only these three settings

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Figure IA Preoperativefundus photograph ofthe eye ofcase4 with afreefloating prepapillary opacity (arrows). Theunderlying retina appears blurry becausefocusing was on thevitreous opacity. There are medullated nervefibressurrounding the optic disc (shoum on the top ofthephotograph).

exceeding 4 mJ in the instrument which wasmanufactured in 1990). One pulse per burst wasused for all patients who required only a singletreatment session each. The contact lens usedwas a flat fundus lens. Either a fundus laser lensor a Goldmann's three mirror lens would besuitable. The image of the aiming beam was firstfocused on the retina and then moved slowlybackwards to focus on the opacity. If the opacitywas too small to be precisely focused on, then theaiming beam was focused on a spot whichincluded the opacity and its immediate vicinity.

ResultsWhether there was posterior Atreous detachmentor not, where laser treatment was concerned thelocalised opacities of the 15 cases could becategorised into two groups: prepapillary andcentrovitreal opacities.' The prepapillaryopacities were single membranous ring-shapedopacities (Weiss's ring)2 with shape and sizecorresponding to the contour of the optic disc(Fig 1A and Fig 2A). The centrovitreal opacitieswe defined were faint, discrete, fibrous opacities,floating freely near the centre of the vitreouscavity (Fig 3A and Fig 4A). The number of theseopacities varied from one to three (Table 1).The required laser energy varied with the size

of the opacity in each case, ranging from 71 0 to742-0 mJ, with an average of 286-49 mJ. If the

Figure IB Postoperative appearance. Note that the ring-shaped opacity has been completely disrupted (arrow). Thepatient's symptom has completely disappeared.

laser burst was effective, the optical breakdownwith fragmentation could be seen. In the firstfew cases ofour study, approximately one half ofthe bursts produced sparks. Gradually, as webecame more experienced, the effectivenessimproved to nearly 100%. The entire course of atreatment session for each patient usually took 20minutes; this again became shorter as our tech-nique improved. When the opacity was hit itbounded away and soon returned to the originalsite. At the same time, it gradually fragmented,became amorphous, and promptly disappeared(Figs 1B, 2B, 3B, and 4B). It took longer tocompletely disrupt the bigger prepapillaryopacities.

In the initial five cases, the intraocular pres-sure was checked daily for 3 days and a fluor-escein angiography was taken on the third day.There were no significant changes detected,therefore we discontinued these tests and onlyfollowed up the patients with regular examina-tions.There were five patients with complaints of

seeing floaters in both eyes. For these fivepatients, only one eye was treated; the fellow eyewas left untreated. We found that the floatersand opacities disappeared in all of the five treatedev es but persisted and remained unchanged inthe untreated eyes. These patients no longer hadanxiety, possibly because of assurance obtainedfrom the positive results in the treated eyes.

All patients were satisfied with the treatmentand stated that their floaters disappeared

Figure 2A Preoperativefundus photograph ofthe eye ofcase Figure 2B Postoperative appearance. Note that the opacity8 showing a prepapillary opacity (arrows). has been completely disrupted (arrow).

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Treatmentofvitreousfloaters with neodymium YAG laser

I

Figure 3A Preoperativeifndus photograph ofthe eye ofcase Figure 3B Postoperative appearance. The opacity has been10 with afibrous centrovitreal opacity (arrow). disrupted, only traces could be seen with a direct

ophthalmoscope (arrow). The patient's symptom hascompletely subsided.

immediately after the operation; their anxietywas dramatically relieved, too. During the 12month follow up period, no patient showed anysignificant visual deterioration or recurrence ofsubjective floaters.

DiscussionIn 1983, Murakami and associates' reported thevitreous changes in 148 eyes with sudden onset offloaters. They had observed that 76% of thepatients saw one or a few floaters and 24% sawmany. The floaters were located primarily in thecentral field of vision. Eighty six per cent of the136 patients were 50 years of age or older. Therewere two kinds of vitreous opacities that wereresponsible for floaters: prepapillary vitreousopacities and vitreous opacities in the posteriorvitreous cavity near the macula. Our clinicalobservation is generally in agreement withMurakami's findings in all aspects mentionedabove. In our present study, the number ofopacities was usually one for prepapillary opaci-ties and one to a few in centrovitxeal opacities.The patients were usually 50 years or older. Asfar as treatment is concerned, most of theyounger patients who complained of many float-ers were usually untreatable because no opacitycould be found using an ophthalmoscope. On theother hand, older patients who complained ofmany floaters were usually not suitable candi-dates for laser treatment because the opacitieshad usually resulted from retinal pathology,

which needed other specific treatment. Based onour experience, we estimate that about 90% ormore of all vitreous floaters are technicallytreatable, regardless of their indications.

Application of Nd-YAG laser in the posteriorsegment is not popular as in the anterior seg-ment.34 Most of the reports were on vitreolysisfor vitreoretinal tractions in proliferative dia-betic retinopathy678 or sickle cell retinopathy.9Other applications of laser for the treatment ofvitreous cysts,'0 cystoid macular oedema," orrhegmatogenous retinal detachment'2 have beenrarely reported. To our knowledge, use ofNd-YAG laser for treatment of vitreous floatershas not been previously described. The obstacleto more common application of the Nd-YAGlaser in vitreous pathology is that it is known topotentially cause damage to the chorioretina.The complications include choroidal haemor-rhage,6"1 damage to the retinal pigment epithe-lium,'4 transient retinal haemorrhage,5 andbleeding from perfused vascular bands.7However, some studies indicated that the

threshold of the retinal damage caused by Nd-YAG laser is related to the potency ofpower usedand the distance of focus from the retina. '5Because of the high power of laser energy, thefocus should be kept to a minimum of4 mm awayfrom the retina. ' Although this result wasobtained from an animal experiment, it stillcould be applied to clinical treatment. '4 Fortu-

Figure4A Preoperativefundus photograph ofthe eye ofcase Figure 4B Postoperative appearance. The opacity has been12 with a centrovitreal opacity (arrow). completely disrupted (arrow).

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Table I Summary of15 patients who underwent neodymium YAG laser treatmentfor vitreousfloaters

Duration Vitreous opacitiesoffloaters Laser doses

Patient before Distance Duration ofNo/Age treatment from the Burst Total follow up(years)/Sex (months) Type Number Size retina (mm) (mJ) (mJ) (months)

1/63/M 4 Centrovitreal 1 M 10 7-1 340-8 182/42/F S Centrovitreal 3 M 6-7 5 0 400 0 183/66/F 4 Prepapillary 1 L 6 5 0 600-0 184/53/F 2 Prepapillary 1 L 6 7-1 742-0 18

10-05/55/M 3 Centrovitreal 1 M 4 7-1 284-0 146/55/M 3 Centrovitreal 3 2S 5-7 7-1 217-1 14

iM7/51/F 7 Centrovitreal 1 S 9 7-1 149-1 138/54/F 3 Prepapillary 1 L 4 7-1 660-3 139/62/M 4 Prepapillary 1 S 6 7-1 149-1 1310/55/F 4 Centrovitreal 1 M 5 5 0 140-0 1311/70/M 6 Prepapillary 1 S 6 7-1 142-0 1212/52/F 4 Centrovitreal 1 S 5 5 0 140-0 1213/57/F 4 Prepapillary 1 L 7 5 0 120-0 1214/58/F 5 Centrovitreal 2 S 5-6 7-1 71-0 1215/61/F 4 Centrovitreal 2 M 6-7 7-1 142-0 12

S=small; M=medium; L=large. Size of opacity is defined as small when its diameter is smaller than1/2 disc diameter, medium: 1/2 to 1 disc diameter and large when it is larger than 1 disc diameter. Infibre-like opacities, the size is small when its length is smaller than 1 disc diameter and medium whenlarger than it.

nately, almost all of the opacities that causedfloaters in otherwise normal eyes happened to belocated beyond this distance; this could beconfirmed by ultrasonogram measurement.Moreover, the avascular nature and highmobility of opacities are additional advantagesfor laser treatment. Owing to their high mobility,it is easy to segregate the opacities from theunderlying macula, optic disc, and major vesselssimply by changing the position ofthe eyeball. Inaddition, the shield effect of the opacities mayalso reduce the amount of laser energy thatreaches the retina.'415 All of these factors makephotodisruption of vitreous opacities less riskythan expected.The importance of contact lens in vitreolysis

cannot be overemphasised.1617 Both effect andsafety should be considered in its use. We realisethat the contact lenses that are specially designed,such as Peyman's 25, 18, and 12 5 mm, areuseful for vitreolysis.3 1' However, they are notsuitable for disruption of localised vitreousopacities because their magnification is so highthat too many of the details of the vitreous bodymake the target opacity difficult to identify.Therefore, we recommend using the flat funduslens of the Goldmann three mirror contact lenseven though we realise its divergent effect onlaser energy is less than that of Peyman's. Thefocal depth of a flat fundus lens is greater, whichmakes the operator able to focus on the opacityand observe the background retina simultane-ously. This will not only give the operator a senseofsecurity but also enable him to avoid damagingthe macula, disc, and major vessels. On the otherhand, in examining the vitreous opacities, we

compared the direct ophthalmoscope withthe indirect ophthalmoscope and preferred theformer, simply because it has a higher magnifica-tion and so opacities can be localised more easily.

Theoretically, potential complications such aschorioretinal damage and lens damage might beexpected, yet we never experienced any compli-cations in our series. Fluorescein angiographyperformed after treatment disclosed no damage tothe retina, either. We believe that precise focus-ing is the most important factor in avoidingcomplications.

It was reported that vitreous floaters are highlyrelated to the posterior vitreous detachment(PVD).' In our series, there were only two cases(case 2 and case 5) with no PVD before treat-ment, while in the other 13 cases, complete PVDwas detected preoperatively. At the end of thefollow up period, the two eyes with no PVDremained unchanged. However, in case 5, theuntreated fellow eye developed complete PVDwithin 1 year. It is obvious that laser treatmentwould not influence the course ofPVD.

Although we confined the indications fortreatment to very strict criteria, by accumulatingsamples and experience, Nd-YAG laser mayprove to be a safe and ideal method for treatmentof all persistent vitreous floaters in the future.

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