Acute morphologic features of radial keratotomy.

We performed eight partially penetrating incisions in 19 eye-bank, 12 nonhuman primate, and 34 canine eyes. Evaluation of the posterior corneal surface by vital staining, correlative microscopy, with corneal incisions set from 80% to 110% of central pachymetric thickness, in three eyes demonstrated damage to the endothelium without anterior chamber perforation. Posterior folds in Descemet's membrane under an incision site was present in all specimens. Potential optical aberrations could be produced about the visual axis depending on the direction of the corneal incisions. Based on this study, the radial keratotomy procedure performed with up to eight deep incisions may produce optic defects. We recommend animal studies to assess the long-term effects of this procedure on the cornea and especially the endothelium.

Histopathology of a case of radial keratotomy.

A patient underwent a radial keratotomy (RK) to reduce residual astigmatism that occurred after a corneal transplant. The patient enjoyed immediate good vision, but later intense glare, photophobia, and pain forced him to quit work. Five months later the graft became cloudy, and superficial vascularization developed in the radial scars. An 8.5-mm penetrating keratoplasty was performed 5 1/2 months after RK. Analysis of the corneal button revealed diffuse epithelial edema, epithelial ingrowth into the incisions, an irregularly thickened epithelial basement membrane, immature hemidesmosomes, focal malapposition of Bowman's layer, marked cellularity of the stroma around the margins of the incisions, and posterior folds in Descemet's membrane. Our analysis of this specimen suggests RK may carry a risk of optical and visual aberrations by producing multiple defects in the anterior and posterior aspects of the cornea.

Recurrence of macular corneal dystrophy within grafts.

Two patients (a 41-year-old woman and a 40-year-old man) with macular corneal dystrophy developed significant visual impairment from recurrent disease within corneal grafts. One patient required regrafting 18 years after a penetrating keratoplasty, and the second patient underwent a penetrating graft 19 years after a lamellar corneal graft. In both cases the typical histochemical and electron-microscopic features of macular dystrophy were evident within donor tissue from the original grafts. The patient who originally underwent penetrating keratoplasty had recurrent disease in the corneal endothelium and within Descemet's membrane. Although the explanation of this observation is uncertain, endothelial cells of the recipient human cornea may resurface Descemet's membrane after penetrating keratoplasty, contrary to current belief. An alternative possibility is that involvement of both the corneal endothelium and Descemet's membrane in macular dystrophy is a secondary phenomenon, and that the abnormal storage product of this dystrophy is an abnormal metabolite rather than a normal compound with a defective catabolic enzyme as previously suspected.

Unilateral Rieger's anomaly.

A 53-year-old man, to our knowledge the first person described with unilateral Rieger's anomaly, had a prominent anteriorly displaced Schwalbe's ring, broad iris strands inserting into Schwalbe's ring, anterior stromal iris hypoplasia, mild microcornea, and marked astigmatism in his right eye. His left eye was entirely normal.

Correlative microscopy and tissue culture of congenital hereditary endothelial dystrophy.

A 4 1/2-year-old boy with congenital hereditary endothelial dystrophy underwent successful bilateral penetrating keratoplasties. Visual acuity in both eyes was restored to 6/18 (20/60). Correlative microscopic analysis of the corneal button obtained from the first transplant showed an irregular epithelium, a continuously thickened Bowman's layer, fragmentation and homogenization of the anterior stromal lamellae, a mildly enlarged stromal fibril diameter, abnormal collagen layers posterior to Descemet's membrane, atrophic paracentral corneal endothelium, and absent central endothelium. The endothelial cells from the second corneal button were placed in tissue culture and failed to demonstrate any growth characteristics of differentiation into normal appearing cells after 14 days. We concluded that the endothelial cells in congenital hereditary endothelial dystrophy are functionally and morphologically abnormal. Early penetrating keratoplasty can be successful in such cases.

Vitreous wick syndrome following a corneal relaxing incision.

A 55-year-old white female underwent a 7.5 mm penetrating keratoplasty for stromal scarring secondary to herpex simplex keratitis. Postoperatively, stromal vascularization and a prolonged graft rejection forced premature suture removal and a prolonged course of topical and systemic glucocorticoids. A mild anterior wound gape spontaneously closed with reduction of steroid therapy. Eighteen months after the original surgery, the patient underwent a relaxing corneal incision to correct 12 diopters of corneal astigmatism. During an inferior incision a small microperforation was noted and the procedure was terminated. Eleven days after the relaxing incision, the patient returned with a "vitreous wick" syndrome through the superior incision. The wound dehiscence and vitreous wick were repaired without incident and the astigmatism was reduced to 7 diopters. Incisions more than 3/4 depth in aphakic patients, or in patients who have required intense steroid therapy should be monitored closely for several days after surgery for microperforations or a wound dehiscence which may lead to a "vitreous wick" syndrome.

A comparison of corneal storage in moist chamber and McCarey-Kaufman medium in human keratoplasty.

We examined the graft clarity and clinical outcome of 130 patients undergoing penetrating keratoplasty with donor preservation in either McCarey-Kaufman (MK) medium or moist chamber. We found comparable results with both methods of preservation in our two best prognostic groups. We feel MK medium is an excellent alternative to moist chamber preservation when used within 48 hours after the donor's death.

A comparison of intracapsular and extracapsular lens extraction combined with keratoplasty.

The clinical outcome and final visual acuities of 29 patients with intracapsular lens extraction and keratoplasty to 38 patients having extracapsular cataract extraction and keratoplasty were compared. Grafts remained clear in 89% of the intracapsular group and 82% of the extracapsular group over an average follow-up of 38 months and 21 months, respectively. Ninety-one percent of eyes with intracapsular lens extraction and 70% of eyes in the extracapsular group achieved a final visual acuity of 6/21 (20/70) or better. We found a significantly higher incidence of additional surgery in the extracapsular group and glaucoma in intracapsular combined cases. Late vitreous prolapse with vitreo-endothelial membrane formation and graft decompensation was a discouraging complication in three eyes having intracapsular extractions.

Controlled reduction of postkeratoplasty astigmatism.

Corneal transplants were performed in 50 eyes using eight deeply placed interrupted 24 micron (10--0) monofilament nylon sutures followed by a more superficial continuous 16 micron (11--0) monofilament nylon suture placed around the wound in 16 equal bites. After surgery the 24 micron sutures in the steepest corneal meridian based on central and peripheral keratometry were cut. This suture technique permitted the donor cornea to assume its normal shape more rapidly while reducing the induced postkeratoplasty astigmatism. With this technique corneal astigmatism was reduced an average of 3.4 diopters (range 0--10 diopters), which allowed patient to achieve a mean visual acuity at three months of 20/50 and at 11 to 13 months of 20/35. Although this suture technique does not eliminate postkeratoplasty astigmatism, it permits the surgeon to reduce actively high degrees of astigmatism present after corneal transplantation.

Noninfectious peripheral corneal ulceration: Mooren's ulcer or Terrien's marginal degeneration?

The clinical course is described of a 50-year-old white man with bilateral, noninfectious, peripheral corneal ulcerations. After several surgical operations which ultimately restored acceptable vision to his right eye, a peripheral penetrating keratoplasty was performed as a primary procedure in the left eye to eliminate the disease process by excising the ulcerated area. Examination of the ulceration within the corneal button by light and electron microscopy disclosed pathologic features compatible with a diagnosis of a Terrien's marginal corneal degeneration or a Mooren's ulcer. Based on the clinical course and histopathologic examination of this case, and on a review of the literature, this report posits that Terrien's marginal corneal degeneration and the peripheral corneal ulceration described as a Mooren's ulcer may represent different ends of a spectrum of noninfectious peripheral corneal ulceration.

Toxicity of selected antibiotics in vitreous replacement fluid.

Experiments with rabbits demonstrated no toxic effects on the retina after vitrectomy when the infusion fluid contained either 20 microgram/ml chloramphenicol saline, 10 microgram/ml amikacin saline, 10 microgram/ml tobramycin saline, or 10 microgram/ml clindamycin saline. We found abnormal electroretinograms and abnormal histologic findings in eyes receiving vitreous replacement with these same drugs in higher concentrations.

Corneal thickness after vitrectomy and infusion with dextran solution.

We studied with pachometry the degree of corneal endothelial decompensation in rabbits undergoing extracapsular lens extraction and vitrectomy. We used 3 different infusion solutions: (1) 0.9% sodium chloride; (2) 0.45% sodium chloride with 2.5% glucose; and (3) 0.45% sodium chloride, 2.5% glucose, and 2% dextran. Vitrectomy and vitreous replacement with the last solution demonstrated the least overall increase in corneal thickness. On the basis of these observations, dextran may be a useful colloid osmotic agent in intraocular irrigating fluids to control and decrease postoperative corneal edema.

Intraocular lysozyme in experimental uveitis in rabbits: aqueous and vitreous assay.

We determined normal aqueous and vitreous lysozyme levels in rabbit eyes and induced experimental uveitis to record the uppermost aqueous and vitreous lysozyme levels. The normal aqueous humor of the rabbit eye contained 1.05 mug per milliliter lysozyme and the normal vitreous humor contained 0.45 mug per milliliter. After the intravitreal administration of a foreign protein, the aqueous and vitreous lysozyme levels rose within one day, reaching maximum values of 38.4 mug per milliliter and 114 mug per milliliter, respectively, at 14 days, and subsequently declining to minimal values by 28 days after injection.

The natural and modified course of post-cataract astigmatism.

We performed sequential central keratometry on 52 cataract patients for six months. We found no statistically significant difference in the induced postoperative astigmatism between wound closure with interrupted and double shoelace running closure with 10-0 monofilament nylon. In 31 patients, the postoperative astigmatism was always with-the-rule. In 21 patients who underwent wound closure with 8-0 polyglactin suture, we documented a postoperative shift in induced astigmatism from with- to against-the-rule which took place between the fourth and fifth postoperative week. Based on our present study of the natural and modified course of post-cataract astigmatism and based upon previous research, we feel the cataract surgeon now has the appropriate means to reduce and/or control post-cataract astigmatism.