Holmium laser sclerostomy via corneal approach with transconjunctival mitomycin-C in rabbits

We studied the use of the holmium laser for sclerostomy through a small lamellar corneal incision and the effects of transconjunctival mitomycin-C on the outcome of filtration surgery without conjunctival incision. The holmium laser, equipped with a straight-firing probe, was used to create sclerostomies in seven New Zealand white rabbits through a corneal lamellar incision. One eye in each rabbit was treated with transconjunctival mitomycin-C (0.4 micrograms/mL for 5 minutes), and the fellow eye underwent sclerostomy without pretreatment with mitomycin-C as a control. The reduction in intraocular pressure was greater and persisted significantly longer in the eyes pretreated with mitomycin-C than in the controls. All control eyes had flat blebs by day 7 to 12, while the treated eyes maintained a bleb throughout the study. Microscopic examination showed that sclerostomies created by the straight-firing probe induced significantly less thermal damage than those created by the stationary side-firing probe. These results demonstrate that successful transcorneal sclerostomy without conjunctival incision can be created using the straight-firing holmium laser probe, with enhancement of filtration by pretreatment with transconjunctival mitomycin-C.