Faculty Bibliography

Seven patients with acquired ptosis and normal levator function following anterior radial keratotomy are presented. Five of these patients then elected to undergo radial keratotomy of the opposite eye, and four had symmetrical lid fissures (mild bilateral ptosis) after bilateral surgery. Ptosis is a well-known complication of cataract extraction, but has not been reported following radial keratotomy. Unlike cataract extraction, radial keratotomy does not require anesthetic injections, bridle sutures, or conjunctival flaps. The rigid Knapp eyelid speculum used in these cases remains as the only apparent cause of eyelid trauma and subsequent ptosis. During radial keratotomy, the speculum was opened widely in order to provide good corneal exposure and avoid contact with the diamond knife. Contraction of the orbicularis oculi muscle against the rigid speculum may have traumatized the lid, resulting in a levator aponeurosis disinsertion and subsequent ptosis

Epikeratophakia tissue lenses for the correction of myopia were removed from two patients as a result of postoperative complications such as stromal folds, complaints of glare, and decreased visual acuity. Light and electron microscopic analysis showed protrusions in Bowman's membrane and the anterior stroma corresponding to corneal folds that had been observed clinically. The epithelial cells in these areas contained many vacuolations and a thickened basement membrane. Hemidesmosomes were decreased in number. The tissue lenses had been cut 1.5 mm larger in diameter than the trephined recipient bed into which they were placed. Excess tissue lens material in the central area may have been thrown into folds by mechanical pressure, resulting in the histological changes, clinical signs, and optical distortion that necessitated removal of these grafts. Recently, the surgical technique has been modified, in an attempt to eliminate this problem

The records of all adult patients at Louisiana State University Eye Center, New Orleans, who underwent epikeratophakia for aphakia with commercially prepared tissue since February 1984 were reviewed. The epikeratophakia lenticule was maintained in 37 (92.5%) of 40 patients; complications required the removal of three tissue lenses. The average refractive error three months after surgery was +0.67 +/- 1.97 diopters; 25 (90%) of 28 patients were within 3 D of emmetropia. At six months, the average refractive error was -0.18 +/- 2.27 D. Fourteen (58%) of 24 patients whose visual acuity was 20/40 or better with spectacles before surgery achieved 20/40 spectacle visual acuity three months after surgery, as did ten (59%) of 17 patients at six months and five (83%) of six patients at 12 months. The results in these recent cases are better than in previously reported series and reaffirm the usefulness of epikeratophakia in the treatment of aphakia

The nationwide study of epikeratophakia for the treatment of keratoconus involved 69 surgeons in the United States; they operated on 177 eyes as of Dec 31, 1985. In this first report, the results from 35 surgeons involving 82 cases with 30 or more days of follow-up after suture removal are described. In all but two patients, uncorrected visual acuity improved; 17 patients showed improvement of three Snellen lines, and 38 patients showed improvement of four or more lines. The majority of patients' vision returned to within one line of their best corrected acuity; in 78% it was 20/40 or better postoperatively. Eight patients needed no postoperative overrefraction at all. The mean flattening by keratometry readings was 9.36 diopters, and the mean decrease in myopia in terms of spherical equivalent was 5.26 D. No significant changes in intraocular pressure or endothelial cell counts were noted. Some advantages of epikeratophakia for keratoconus over the traditional penetrating keratoplasty include the lack of serious, vision-threatening complications or permanent vision loss, the reversible nature of the surgery, and the absence of potential immunogenic rejection phenomena

Thirteen eyes with recurrent pterygia were treated with excision and lamellar keratoplasty using precarved, lyophilized donor cornea. After an average follow-up of 23 months, only one eye (7.7%) required repeat excision. Two eyes (15.4%) had minor recurrences that were asymptomatic and did not progress. Minimal vascularization at the interface between donor and recipient cornea was frequent, but this completely regressed after suture removal and topical corticosteroid treatment. Limitation of movement, when present preoperatively, was improved or eliminated. Best corrected visual acuity was unchanged in eight eyes (61.5%), decreased by one line in two eyes (15.4%), and improved by one or two lines in three eyes (23.1%). Postoperative astigmatism was within 0.5 diopter of the preoperative value in 11 eyes (84.6%); one eye (7.7%) had a postoperative increase of 1 diopter and another eye (7.7%) of 2 diopters

The inhibition of collagen cross-linkage by beta-aminopropionitrile (BAPN) and D-penicillamine was tested in an attempt to enhance the myopic correction achieved by radial keratotomy. Two groups of six rabbits each underwent radial keratotomy in both eyes; one eye of each rabbit was treated with BAPN (33% in white petrolatum) or D-penicillamine (1.5 M in sterile water) three times a day for 6 weeks, while the other eye received only vehicle. In spite of previous reports of positive results with BAPN, neither BAPN nor penicillamine was found to affect keratometry readings or corneal topography after radial keratotomy. Our results suggest that factors other than collagen cross-linkage exert major influences in determining the outcome of this refractive procedure

Standard radial keratotomy was performed in both eyes of 18 rabbits. Intraocular pressure (IOP) was raised by injection of saline solution into the vitreous cavity at different times after surgery: 8 eyes at one, two, and six weeks and 12 eyes at four months. Keratometric readings at 10, 20, 40, 60, and 80 mmHg were recorded by three independent observers in a masked fashion. The same procedure was performed in eight eyes that had no surgery, as controls. Increments in IOP correlated with significant reductions in corneal power at all times after surgery and for all IOP values in the operated eyes. No changes were observed in the control eyes. The results indicate that variations in IOP, even within physiological limits, may cause changes in corneal curvature after radial keratotomy, and that patients with wide fluctuations in IOP could present a higher risk for postoperative fluctuation in visual acuity after this refractive procedure