193-NM EXCIMER-LASER SCLEROSTOMY USING A MODIFIED OPEN MASK DELIVERY SYSTEM IN RHESUS-MONKEYS WITH EXPERIMENTAL GLAUCOMA

Excimer laser sclerostomy is a new glaucoma filtration procedure in wh ich the argon fluoride excimer laser at 193 nm is delivered ab externo through a modified open mask system incorporating an en-face air jet to dry the target area and preserve hemostasis during ablation and a c onjunctival plication mechanism, which allows the conjunctival and scl eral wounds created by through-and-through ablation to separate once t he mask is removed. No preparatory dissection of the conjunctiva is re quired. Five 200-mu m and five 500-mu m sclerostomies were formed by a blation at a pulse repetition rate of 20 Hz and a fluence per pulse of 400 mJ/cm(2) in fellow eyes of five rhesus monkeys with experimental glaucoma. Overall, seven of the ten eyes attained a functional result, with intraocular pressures remaining below 21 mmHg for 6 +/- 1 days a nd rising to the pre-operative level after 10 +/- 3 days without adjun ctive antifibroblast medication. The duration of filtration for 200-mu m and 500-mu m sclerostomies was similar, and parallels that previous ly observed for posterior lip sclerectomy in the same animal model. Th e three eyes with no functional result all had incorrectly positioned sclerostomies. Choroidal detachment and significant shallowing of the anterior chamber did not occur. Excimer laser sclerostomy appears to b e a viable technique for filtration, provided that mask placement is a ccurate.