193 NM EXCIMER-LASER SCLEROSTOMY IN PSEUDOPHAKIC PATIENTS WITH ADVANCED OPEN-ANGLE GLAUCOMA

A modified open mask system incorporating an en face air jet to dry th e target area during ablation and a conjunctival plication mechanism, which allows ab externo delivery of the 193 nm excimer laser without p rior conjunctival dissection, has been developed to form small bore sc lerostomies accurately and atraumatically. Full thickness sclerostomie s, and sclerostomies guarded by a smaller internal ostium can be creat ed. A pilot therapeutic trial was conducted in pseudophakic patients w ith advanced open angle glaucoma. Six full thickness sclerostomies (20 0 mu m and 400 mu m diameter) and three guarded sclerostomies were cre ated in nine patients by 193 nm excimer laser ablation (fluence per pu lse 400 mJ/cm(2), pulse rate 16 Hz, air jet pressure intraocular press ure +25 mm Hg). After 6 months' follow up, intraocular pressure was co ntrolled (less than or equal to 16 mm Hg) in eight of the nine patient s (6/9 without medication). Early postoperative complications included hyphaema (trace - 2.5 mm) (6/9), temporary fibrinous sclerostomy occl usion (4/9), profound early hypotony (ah patients without fibrinous oc clusion), and suprachoroidal haemorrhage in one case. Conjunctival las er wounds were self sealing. Small bore laser sclerostomy procedures a re functionally equivalent to conventional full thickness procedures, producing early postoperative hypotony, with an increased risk of supr achoroidal haemorrhage in association with this. Further research is r equired to improve control over internal guarding in excimer laser scl erostomy before clinical trials of this technique can safely proceed.