Corneal Light Shield as a Delivery System for Standardized Application of Mitomycin C in Excimer Surface Ablation

Abstract

To develop a simple, reproducible method of applying intraoperative mitomycin C (MMC) in excimer surface ablation surgery. A two-part protocol was developed to study several properties of corneal light shields. Part A tested the amount of MMC (0.2 mg/mL) absorbed, expansion dimension attained, and amount released to filter paper. Part B examined in vitro release of MMC to a photorefractive keratectomy (PRK)-treated enucleated pig eye. Mean MMC absorbed by corneal light shields was 63.7 +/- 5.0 mg (range: 57.4 to 72.8 mg); coefficient of variability was 7.8%. Expansion diameter and thickness were constant at 9.0 mm and 1.1 mm, respectively. Mean solution released to filter paper was 55.4 +/- 3.9 mg (range: 51.3 to 63.5 mg); coefficient of variability was 7.1%. Mean solution transferred to the PRK-treated pig eye was 2.3 +/- 0.7 mg (range: 1.1 to 3.5 mg); coefficient of variability was 33%. Mitomycin C contact surface area, amount absorbed, and amount released by each corneal light shield were reproducible. Uniform dimensions theoretically provide uniform distribution of MMC. This method may allow standardization of intraoperative MMC application in excimer surface ablation.