Vol. 99, No.3 Letters to the -loumal 365

Sodium Hyaluronate (Healon) as anAdjunct to Lacrimal Surgery

Hobart A. Lerner, M.D.,and James R. Boynton, M.D.Inquiries toJames R. Boynton,M. D., 2030Monroe Ave., Roches­ter, NY 14618.

Sodium hyaluronate (Healon) can be helpful inlacrimal surgery under certain conditions. It maysometimes be difficult to identify the lumen of thelacrimal sac during dacryocystorhinostomy. Sodiumhyaluronate can be injected into the sac via a canalic­ulus. The opposing punctum is occluded with apunctal dilator during the injection. The sodiumhyaluronate helps distend the lumen of the sac andalso serves as a visible marker when the sac lumen isentered.

In some cases of canalicular lacerations, the distalend of the severed canaliculus may be difficult tolocate. Injection of sodium hyaluronate into the op­posing canaliculus may result in extrusion of sodiumhyaluronate from the cut edge of the traumatizedcanaliculus and thus help in locating this structure.Unlike dye, sodium hyaluronate does not stain thetissue and can easily be irrigated from the surgicalfield. Experimentation to find other uses for sodiumhyaluronate during ocular adnexal surgery should beencouraged.

Potential Acuity Meter for PredictingPostoperative Visual Acuity inCataract Patients

Jonathan D. Christenbury, M.D.,and Samuel D. McPherson, M.D.Departments of Ophthalmology, McPherson Hospital andDuke Hospital.

Inquiries to Samuel D. McPherson, M.D., 1110 W. Main St.,Durham, NC 27701.

The Potential Acuity Meter projects a Snellen visualacuity chart into the eye by a minute aerial apertureapproximately 0.15 mm in diameter. When the meteris mounted on a slit lamp, potential visual acuity canbe measured by passing the light beam through clear"windows" in the cataract. The value of determiningpotential visual acuity is evident because of thefrequent co-existence of retinal and vascular diseasein cataract patients.

Minkowski, Palese, and Guyton! reported that thePotential Acuity Meter accurately predicted a success-

ful outcome in postoperative visual acuity (20/40 orbetter) in 95% of cases, and in patients with preoper­ative visual acuities of 201200 or better, the postoper­ative visual acuity was predicted to within three linesin 100% of cases.

We conducted an independent prospective studydesigned to determine the accuracy of the PotentialAcuity Meter in predicting postoperative visual acu­ity in cataract patients and to test its convenience inroutine ophthalmic practice.

From May to August 1983, 114 patients were ad­mitted to our hospital for cataract surgery. Six pa­tients were excluded from the study when surgerywas cancelled because of medical problems. Of 108patients, eight (7.4%) had cataracts too dense for themeter to be used. Of the remaining 100 patients. allhad best corrected visual acuity and Potential AcuityMeter measurements performed by one observer(I.D.C.) the day before surgery. The meter's meas­urements were performed according to the manufac­turer's manual, in a darkened room, with the pupilmaximally dilated with 10% phenylephrine and 1%tropicamide. Postoperative visual acuity was mea­sured by the operating ophthalmologist and thethree-month postoperative visual acuity was used asthe end point. The refracting ophthalmologist wasunaware of the predicted visual acuity.

The 100 cataract patients had an average age of 71years (range, 35 to 90 years); 42 were men and 58were women. Preoperative best corrected visual acui­ties ranged from 20/60 to 1/200. No patient was lost tofollow-up.

In 92 of 100 patients postoperative visual acuitywas within one line or better than the predictedvisual acuity. All eight patients who were not withinone line of the predicted level had surgical complica­tions or progression of preexisting disease, includingcystoid macular edema (three cases), Fuchs' dystro­phy (two cases), macular hemorrhage (two cases),venous thrombosis (one case), and progressive my­opic degeneration (one case).

Of 63 patients with preoperative visual acuities of20/200 or better 53 were within three lines of thepredicted postoperative visual acuity, compared to47 of 47 described by Minkowski, Palese, and Guy­ron.' We found that of the 52 eyes predicted toachieve 20/40 or better, 48 (92%) actually did, similarto the 38 of 40 (95%) described by Minkowski, Palese,and Guyton.!

The Potential Acuity Meter is a useful means ofpredicting postoperative visual acuity in patientswith mild to moderate cataracts. The meter may besomewhat less sensitive than previously reported inpredicting the actual Snellen line of vision whenpreoperative visual acuity is 20/200 or better. How­ever, the specificity is high-all patients except those

366 AMERICAN JOURNAL OF OPHTHALMOLOGY March, 1985

with postoperative complications were within oneline or better of predicted visual acuity.

Reference

1. Minkowski, J. 5., Palese, M., and Guyton, D. 1.: Po­tential Acuity Meter using a minute aerial pinhole aperture.Ophthalmology 90:1360, 1983.

Argon Laser Photomydriasis DuringVitrectomy Surgery

Walter H. Stern, M.D.Department of Ophthalmology, University of California,San Francisco.

Inquiries to Walter H. Stern, M.D., 400 Parnassus Ave., Suite750A. San Francisco. CA 94143.

Maintaining pupillary dilation during vitreous sur­gery can be difficult, especially after lens fragmenta­tion or extended surgical procedures. Poor preopera­tive pupillary dilation, especially in patients withdiabetes, may further hamper intraocular visualiza­tion during vitreous surgery. I have used an argonendolaser fiberoptic probe applied to the externalcornea to produce adequate photomydriasis duringvitreous surgery in two phakic eyes.

One of the treated patients had a light brown irisand the second patient had a light blue iris. Onepatient underwent surgery for retinal detachmentcomplicated by proliferative vitreoretinopathy, andthe second patient underwent surgery for diabeticvitreous hemorrhage. The diabetic patient had corti­cal lens opacities and nuclear sclerosis. In both pa­tients pupillary dilation was adequate at the start ofthe surgical procedure but during surgery pupillarymiosis occurred, with subsequent poor intraocularvisualization. In both patients, epinephrine wasused initially in the infusion solution (0.3 ml of1:1,000 epinephrine diluted in 500 ml of BSS plus). Inboth patients, 0.1 ml of 1:10,000 epinephrine wasinjected into the anterior chamber after pupillarymiosis in an unsuccessful attempt to dilate the pupilpharmacologically.

To avoid entering the anterior chamber and per­forming a surgical iridectomy, we used an argonendolaser fiberoptic probe to perform photo­mydriasis. The fiberoptic probe was lightly placed onthe corneal epithelium and initially focused on thepupillary sphincter. The probe was angled towardthe retinal periphery rather than toward the posteri­or pole of the eye. We used a 20-gauge (0.89-mm)fiberoptic endolaser probe and a portable air-cooledargon laser. In both cases the time of application was

0.1 second and the intensity ranged from 750 mW inthe brown iris to 900 mW in the blue iris. The pupil­lary sphincter was coagulated with nonconfluentspots followed by photocoagulation of the mid iriswith confluent spots. We tried to titrate the lightintensity to a level causing physical constriction ofthe iris tissue and enlargement of the pupil withoutpigment explosion or bubble formation. The numberof burns required to produce adequate pupillarydilation ranged from 50 burns in the brown iris to 150burns in the blue iris. In both cases, the pupil dilatedan additional 3 mm, sufficient to allow completion ofthe surgical procedure.

On the first postoperative day, clinical examina­tion showed no pigment dispersion on the anteriorchamber or on the corneal epithelium. Neither pa­tient had an increased postoperative intraocularpressure.

In both patients, the pupils have remained mid­dilated after six months of follow-up despite the useof pilocarpine in the patient with the brown iris. Thebrown iris developed mild atrophic changes. Thepatient with a clear lens has maintained a clear lens.The patient with preoperative cataractous changeshas not had further changes. No retinal photocoagu­lation was noted either intraoperatively or postoper­atively. No long-term corneal changes were notedsecondary to laser photocoagulation.

Photomydriasis with xenon light and ruby andargon laser sources has been described previously. 1-5

The development of fiberoptic endolaser probes thatcan be safely used in air, in contrast to the previouslyavailable xenon arc fiberoptic probes which can onlybe used in a fluid medium, allows transcorneal intra­operative argon laser photomydriasis. The proce­dure is useful for pupils unresponsive to pharmaco­logic dilating agents and in which the surgeonwishes to avoid entering the anterior chamber andperforming a surgical iridectomy.

Complications of xenon arc photomydriasis in­clude corneal burns, iritis, and lens changes. 1-3 Thesecomplications appear to be diminished when theargon laser is used because it eliminates the infraredportion of the light spectrum and is highly absorbedby the pigment epithelium of the iris, thus prevent­ing excessive transmission to the lens." The smallspot size of the endolaser photocoagulation burn(approximately 1,000 ILm) and the limited amount ofheat applied also appear to have reduced the compli­cations noted with xenon arc photocoagulationwhich has usually been limited to aphakic eyes.Nonetheless, argon laser photomydriasis during vit­rectomy surgery may result in a fibrinous response,especially in diabetic patients. Iris atrophy may alsooccur especially in more pigmented irides (T. M.Aaberg, unpublished data).

In both patients we carefully titrated the intensityof the photocoagulation until adequate contraction