Diode laser cyclophotocoagulation: dose-standardized therapy in end-stage glaucoma

Abstract

Background: Ciliary body ablation in end-stage glaucoma has been widely performed with cryotherapy and neodymium:yttrium aluminium garnet (Nd:YAG) laser, both techniques frequently involving considerable pain and postoperative inflammation, with an unpredictable final intraocular pressure (IOP) and a significant risk of phthisis. Diode laser cyclophotocoagulation (cyclodiode laser) has recently been introduced in an attempt to avoid some of these problems.

Methods: Thirty patients with uncontrolled IOP and advanced glaucoma were divided on clinical grounds into two groups and were treated with either a half or a full standardized dose of laser (40 x 1500 mW for 1500 ms) and monitored for IOP control, visual acuity, postoperative inflammation and phthisis. Success of IOP control was defined as IOP < 22 mmHg or a decrease in IOP of > 30%; preservation of visual acuity or control of pain in blind eyes was also assessed.

Results: A sustained lowering of IOP was achieved in 90% of patients, with a mean follow up of 10.4 months. For the full treatment cases (group A), mean (+/-SD) pre-operative and postoperative IOP was 49.4 +/- 11.2 and 25.8 +/- 17.7 mmHg, respectively (a 48% reduction); 55% of patients achieved IOP < 22 mmHg and 68% gained an IOP reduction of > 30%. For the half-treatment cases (group B). the mean pre-operative and postoperative IOP was 29.4 +/- 4.3 and 18.9 +/- 5.7 mmHg, respectively (a 36% reduction); 63% of patients achieved IOP < 22 mmHg and 50% gained an IOP reduction of > 30%. Neovascular glaucoma was present in 60% of patients; the full-treatment subgroup of these patients achieved a mean lowering of IOP of 58%. Of 22 sighted eyes, 11 (50%) recorded no change in vision; seven (32%) eyes lost and four (18%) eyes gained vision; pain control was achieved in six of eight blind eyes (75%). There was no significant postoperative inflammation, one case of hypotony and no suggestion to date of sympathetic ophthalmia.

Conclusion: Diode laser cyclophotocoagulation appears to be simple, safe and is frequently successful in the control of IOP in end-stage glaucoma. Optimum dosage parameters remain to be determined.