A two-year experience with excimer laser photorefractive keratectomy for myopia.

PURPOSE: This report summarizes the authors' 2-year experience with excimer laser photorefractive keratectomy (PRK) on 160 eyes of 128 patients. METHODS: All eyes were treated with an excimer laser: fluence, 160 mJ/cm2; frequency, 5 Hz; ablation zone diameter, 5.0 to 5.5 mm; and depth per pulse, 0.21 to 0.27 microns. A suction fixation ring was used in all eyes either with nitrogen flow (79 eyes) or without nitrogen flow (81 eyes) across the cornea. Follow-up ranged from 1 month (152 eyes) to 24 months (12 eyes). RESULTS: At 3 months, 82% (139) of eyes achieved an uncorrected visual acuity of 20/40 or better; 83% were corrected to within +/- 1 diopter (D) of intended correction and 30% lost one line of best-corrected visual acuity. At 6 months, 88% (124) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 15% lost one line of best-corrected visual acuity. At 12 months, 91% (71) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 17% lost one line of best-corrected visual acuity. At 24 months, 100% (12) of eyes achieved an uncorrected visual acuity of 20/40 or better; 91.6% were within +/- 1 D of intended correction and 0% lost one line of best-corrected visual acuity. CONCLUSIONS: In eyes with a follow-up of 6 to 24 months, 77% to 100% achieved an uncorrected visual acuity of 20/40 or better and 84% to 92% were corrected to within +/- 1 D of the intended correction. The authors conclude that excimer laser PRK appears to be a safe procedure capable of correcting the eyes of patients with low to moderate myopia with approximately the same degree of accuracy as radial keratotomy.

Corneal edema related to accidental Hibiclens exposure.

Five patients developed corneal edema presumably caused by accidental preoperative ocular exposure to Hibiclens. In all cases, the patients complained of ocular pain after surgery. Conjunctival inflammation and corneal epithelial defects were found in all patients. Between two and ten weeks after exposure, stromal and epithelial edema, with a predilection for the inferior cornea initially, developed in all patients. The corneal edema resolved in three patients in approximately six months, leaving mild stromal scarring and reduced endothelial cell counts. The corneal edema in the other two patients progressed to diffuse bullous keratopathy, which eventually required penetrating keratoplasty. We recommend that Hibiclens be avoided in preoperative preparation of the facial skin to prevent accidental ocular exposure.

Mycobacterium fortuitum keratitis.

Two of four cases of Mycobacterium fortuitum keratitis occurred after corneal surgery with contact lens wear, one was associated with extended contact lens wear alone, and one occurred after a foreign body injury. All cases were characterized by pain, conjunctival hyperemia, stromal inflammation, and ulceration. Diagnosis was made by culture and acid-fast staining of corneal scrapings. On the basis of published experience with amikacin for the treatment of nonocular M. fortuitum infections, three patients were treated with topical amikacin. Two patients responded clinically, but histopathologic examination of a penetrating keratoplasty specimen in one of the two disclosed persistent infection. One patient was cured of early disease by debridement alone. Rapid diagnosis and absence of corticosteroid use were the two most important determinants of successful therapy. In advanced cases, infection may be cured and useful vision restored by penetrating keratoplasty.

Mooren's ulcer after penetrating keratoplasty.

Seventeen months after penetrating keratoplasty for pseudophakic bullous keratopathy, a patient developed severe pain and a peripheral corneal ulcer that had the characteristic clinical appearance of a Mooren's ulcer. We performed a 10-mm penetrating keratoplasty that extended from the superior margin of the previously placed graft to the inferior corneoscleral limbus to encompass the ulcerated cornea. Histopathologic examination of tissue removed at surgery disclosed that the peripheral corneal ulcer extended nearly through the entire stromal thickness and that the donor corneal stroma adjacent to the ulcer was infiltrated with lymphocytes, plasma cells, and neutrophils. The conjunctiva adjacent to the peripheral corneal ulcer was packed with plasma cells and also showed some lymphocytes and neutrophils.

Corneal ulcers associated with extended-wear soft contact lenses.

We treated nine myopic and nine aphakic eyes in patients who developed corneal ulcers while wearing extended-wear soft contact lenses. Bacteria were recovered from the corneal ulcers of 13 of 18 patients with Pseudomonas aeruginosa being the pathogen most frequently isolated. Chemical disinfection was used by seven of the nine patients with myopia and eight of the nine with aphakia. Two of nine patients in the myopic group had visual loss to 20/200 and hand movements; five of nine patients in the aphakic group had visual loss to 20/50 or worse. Invasion of the corneal stroma by bacteria may occur after breakdown of the epithelial barrier by contact lens manipulation or after chronic overnight anoxic stress. Thus, the use of soft contact lenses on an extended-wear basis may be complicated by the development of corneal ulcers. Both aphakic and myopic eyes are at risk.

UCLA clinical trial of radial keratotomy. Preliminary report.

A clinical trail of radial keratotomy ws begun under a strict research protocol at the Jules Stein Eye Institute in November 1979. The results for the first 52 eyes undergoing radial keratotomy are reported three months after surgery. Preoperatively uncorrected visual acuity was less than 20/200 in all 52 eyes. and postoperative visual acuity was less than 20/200 in 11 eyes (21%). Three months postoperatively, uncorrected visual acuity was 20/40 or better in 27 eyes (52%) and 20/20 or better in 13 eyes (25%). Postoperatively the best-corrected visual acuity decreased in 10 eyes (20%), but maximum decrease in any eye was one line of snellen letters. Preoperatively mean refractive error was -4.9 (/+-2.2) diopters, and postoperatively the mean decrease in myopia was 3.4 (/+-2.2) diopters. Postoperatively 13 eyes (25%) had a hyperopic refractive error of +0.25 to +3.25 diopters, but all of these eyes were able to accommodate and obtain 20/20 visual acuity without glasses. Postoperatively there was no statistically significant change in axial length, anterior chamber depth, or scleral rigidity, but there was a mean corneal endothelial cell loss of 10% (P = 0.0002). Decrease in myopia achieved by radial keratotomy did not correlate with the steepness of corneal curvature, corneal diameter, or scleral rigidity. Three months after surgery, significant symptoms of glare were present in 10 eyes (20%0, and annoying variable visual acuity was noted in five eyes (10%).