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 concen trations 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 1 min to sponges (co rneal light shield, Merocel Corp.) soaked with MMC. After irrigation with 4 0 ml saline a central 8 mm diameter scleral disk was horizontally dissected with a cryotome. MMC concentrations of six layers of 140 mu m thickness we re analysed by means of high-performance liquid chromatography. In Experime nt 1 (11 eyes) the sponges were soaked with 50 mu l of 10, 100 and 200 mu g ml(-1) MMC solutions. In Experiment 2 (12 eyes) the sponges were soaked Wi th 10, 30, 50 and 80 mu l of a 200 mu g ml(-1) isotonic MMC solution. In Experiment 1 the MMC concentrations (mu g g(-1)) of layer 1 were 0.35 (/- 0.20; 10 mu g ml(-1) group) and 9.22 (+/- 2.92; 200 mu g ml(-1) group). In Experiment 2 the MMC concentrations were 2.57 (+/- 1.17; 10 mu l group), 7.35 (+/- 2.49; 30 mu l group) and 11.67 (+/- 3.25; 80 mu l group). The sc leral MMC concentrations were significantly influenced by the applied conce ntrations (layers 1-5) and by the applied volumes (all layers) of MMC solut ion. The intrascleral MMC concentration increased linearly with increasing conce ntration and not linearly with increasing Volume of the applied MMC solutio n. To achieve more predictable scleral concentrations of MMC after trabecul ectomy with MMC it seems advisable to control both the concentration and th e volume of the MMC solution used to soak the sponge. (C) 2000 Academic Pre ss.