Intrascleral Concentration vs Depth Profile of Mitomycin-C after Episcleral Application: Impact of Applied Concentration and Volume of Mitomycin-C Solution

The purpose of this study was to investigate the impact of different concentrations and volumes of Mitomycin-C (MMC) on the intrascleral concentration vs depth profile of MMC in an experimental model. The episcleral sides of scleral quadrants of human donor eyes were exposed for 1min to sponges (corneal light shield, Merocel Corp.) soaked with MMC. After irrigation with 40ml saline a central 8mm diameter scleral disk was horizontally dissected with a cryotome. MMC concentrations of six layers of 140μ m thickness were analysed by means of high-performance liquid chromatography. In Experiment 1 (11 eyes) the sponges were soaked with 50μ l of 10, 100 and 200μ g ml−1MMC solutions. In Experiment 2 (12 eyes) the sponges were soaked with 10, 30, 50 and 80μ l of a 200μ g ml−1isotonic MMC solution. In Experiment 1 the MMC concentrations (μ gg−1) of layer 1 were 0.35 (±0.20; 10μ gml−1group) and 9.22 (±2.92; 200μ gml−1group). In Experiment 2 the MMC concentrations were 2.57 (±1.17; 10μ l group), 7.35 (±2.49; 30μ l group) and 11.67 (±3.25; 80μ l group). The scleral MMC concentrations were significantly influenced by the applied concentrations (layers 1–5) and by the applied volumes (all layers) of MMC solution. The intrascleral MMC concentration increased linearly with increasing concentration and not linearly with increasing volume of the applied MMC solution. To achieve more predictable scleral concentrations of MMC after trabeculectomy with MMC it seems advisable to control both the concentration and the volume of the MMC solution used to soak the sponge.