Comparative Study On Contact Diode Laser Transscleral Cyclophotocoagulation And Ahmed Glaucoma Valve In The Management Of Neovascular Glaucoma

1. Jonathan Chan¹
2. Jane Yeung¹
3. Catherine Chan²
4. Clement Tham³
5. Jimmy Lai⁴

¹Queen Mary Hospital, Hong Kong
²United Christian Hospital, Hong Kong
³Dept Ophthalmology & Visual Science, Chinese University of Hong Kong, Hong Kong
⁴Eye Institute, University of Hong Kong, Hong Kong

Purpose:
To compare the effectiveness of contact diode-laser transscleral cyclophotocoagulation (TSCP) with the Ahmed Glaucoma Valve (AGV) in neovascular glaucoma (NVG).

Methods:
Twenty eyes with NVG and intraocular pressure (IOP) greater than 21mmHg were randomized to receive TSCP or AGV. They are then followed up and analyzed for their final visual outcome, IOP, need for anti-glaucomatous medications, and complications.

Results:
Six patients refused further treatment for raised IOP due to very poor residual vision in the affected eye. Successful control of IOP, in terms of a final pressure of 21 or less, was achieved in 85.7% of the eyes in both study groups if these 6 eyes were excluded from analysis. If preservation of visual acuity was also considered as a prerequisite for success, the 6 eyes that deviated from treatment protocol would be counted as failure, and the success rate drops to 62.5% for TSCP and 41.7% for the AGV. The difference in the overall success rate was not significant (p = 0.65).

Conclusion:
Both treatments were effective in lowering IOP in most eyes that had persisted with the treatment protocol. These eyes were usually the ones with a better visual outcome and occurred more frequently in the TSCP group, although the overall success rate was not significantly different for the 2 groups. Eyes that received TSCP also had fewer serious complications compared to those that had AGV. Overall, maintaining visual function appears to be the major limiting factor for a better outcome in neovascular glaucoma.