Corneal transplant tolerance of cryopreservation.

PURPOSE: To study the outcome of corneal transplants performed with cryopreserved tissue. METHODS: Maisonneuve-Rosemont Hospital medical records of all corneal transplantations performed with cryopreserved tissue by one surgeon (M.L.F.) between March 1978 and April 1991 were reviewed. The Kaufman--Capella cryopreservation technique was used. Corneas were cryopreserved for periods of 3 days to 16.8 years (mean, 4.6 years) before transplantation. RESULTS: We report a mean follow-up of 54 months (range, 2.8--151.3 months). Survival analysis showed the probability of a clear graft to be 76% at 1 year and 73.2% at 2 years. At the time of the last visit, visual acuity was 20/40 or better in 61 eyes (49.2%). The mean postoperative pachometry was 0.58 mm (range, 0.50--0.75 mm). Specular microscopy performed in 57 eyes showed a mean endothelial cell count of 938 cells/mm(2) 55.1 months (range, 2.9--151.3 months) after surgery. For comparison purposes, the outcome of a subgroup of cryopreserved (n = 33) and noncryopreserved (n = 26) corneas transplanted by the same surgeon between April 1986 and April 1990 was studied. CONCLUSION: Despite an increase in the primary failure rate and higher initial endothelial cell loss, cryopreserved transplants are viable. Although we do not recommend cryopreservation of corneas for elective surgery, we consider that cryopreserved corneas can be very useful in emergency situations when tissue availability is a problem.

Contrast and glare testing in the assessment of visual performance of candidate eyes for penetrating keratoplasty.

PURPOSE: To determine whether visual acuity (VA) measurements performed at low levels of contrast and glare are a better diagnostic tool for determining whether corneal clouding warrants surgery. METHODS: Fifty-nine subjects were recruited from among the candidates for corneal graft. Monocular VA was measured with three Regan contrast VA charts: 96, 25, and 11%, with and without glare provided by the Brightness Acuity Tester (BAT). The discriminative ability of the tests was estimated using the area (AR) under receiver operating characteristic (ROC) curves. Associations between the different VA tests and the Visual Function Index (VF-14) score were studied, using Spearman coefficients. RESULTS: When comparing candidate eyes with contralateral eyes with corneal disease, lower contrasts VA tests provided greater discriminative power. VA measurements made with glare also tended to provide greater discrimination. In fact, discrimination was best with 11% contrast VA with glare, but "testability" was poor. The most practical test in a clinical setting, which retained high discriminative ability (0.798), was the 25% contrast VA with glare. The eye with the best VA correlated strongly with the VF-14, especially at 25% contrast without glare, resulting in an Rs of -0.729. CONCLUSION: Twenty-five percent contrast VA with BAT could help the practitioner to decide whether a corneal transplant is warranted when symptoms of reduced vision are more important than what high-contrast VA might indicate.

Severe toxic keratopathy secondary to topical anesthetic abuse.

OBJECTIVE: To describe the clinical findings in three cases of abuse of topically administered ophthalmic anesthetics and to review the clinical signs, diagnosis and treatment. DESIGN: Case series. SETTING: Two university-affiliated hospitals in Montreal. PATIENTS: Three patients with toxic keratopathy due to abuse of topically applied anesthetics. RESULTS: The three patients presented with a nonhealing epithelial defect, marked stromal edema, folds in Descemet's membrane and a typical stromal ring infiltrate. All three required a conjunctival flap, and two underwent penetrating keratoplasty. The drugs (0.5% tetracaine and 0.5% proparacaine) were easily obtained, at the workplace in two cases and by stealing from the ophthalmologist's examining room in the third case. CONCLUSIONS: The unrestricted availability of topically applied ophthalmic anesthetics as over-the-counter medications in Canada must be reevaluated.