Background: Diode laser cyclophotocoagulation (cyclodiode) is gaining acceptance as a therapy for refractory or end-stage glaucoma. The aim of the study was to establish whether a reproducible dose-effect relationship exists following a single standardized cyclodiode treatment to lower intraocular pressure (IOP).
Methods: This paper reports results from a longer-term follow up of a trial involving the study of 30 patients with uncontrolled IOP and advanced glaucoma who were treated with a single episode of either a half or a full standardized dose of laser depending on clinical risk of phthisis and monitored for IOP control, visual acuity, postoperative inflammation and phthisis.
Results: A lowering of IOP at the final follow up was achieved in 83% of patients, with a mean follow-up time of 21 months. For patients receiving a full standardized laser dose, preoperative IOP was 49.4 +/- 11.2 mmHg (mean +/- SD) and postoperative IOP was 28.5 +/- 20.0 mmHg (42% reduction); 45% of patients achieved IOP < 22 mmHg and 68% gained an IOP reduction > 30%. For the half treatment cases, the preoperative IOP was 29.4 +/- 4.3 mmHg (mean +/- SD) and the postoperative IOP was 18.3 +/- 10.0 mmHg (38% reduction); 63% of patients achieved IOP < 22 mmHg and 50% gained an IOP reduction of > 30%. Of 22 sighted eyes, nine (41%) recorded no change in vision; and nine (41%) lost and four (18%) gained vision. Hypotony was seen in 4/22 (18%) of full standardized laser dose cases.
Conclusion: Longer follow-up times confirm that diode laser cyclophotocoagulation is a convenient and useful therapy in the control of IOP in end-stage glaucoma. Response of IOP to the laser therapy is highly variable, particularly in the neovascular glaucoma group, and it does not appear to be possible to predict an IOP outcome for an individual eye. Circumferential treatments in neovascular eyes should be avoided. Prospects for long-term vision retention in end-stage eyes are poor, perhaps due to progression of the underlying disease.