Correlation of Collector Channel Fluid Wave Outflow to IOP Lowering Post Ab Interno Trabeculotomy
To determine if the pressure lowering effect of ab interno trabeculotomy (Trabectome) correlates with the presence and quality of an intraoperative episcleral venous fluid wave.
A retrospective chart review of 73 consecutive trabectome cases of 55 patients with >6 months follow-up. The extent and degree of the wave was recorded for each case and then correlated to final intraocular pressure and medications.
The average age and follow up was 73±8 years and 18±6 months respectively. Patients with an extensive fluid wave had an average pre-operative IOP of 19±6 and were on 2.8±0.8 glaucoma medications. At last follow up, the average post-operative IOP decreased to 14±3 on 1.5±1.2 glaucoma medications. Patients with a poorly defined or non-existent fluid wave had an average pre-operative IOP of 21±4 and were on 2.9±1.1 glaucoma medications. At last follow up, their average post-operative IOP was 17±4 (p < .056) on 2.3±1.4 glaucoma medications. There were no glaucoma reoperations in the extensive wave group however 33% of eyes in the minimal wave group required an additional glaucoma surgery.
There appears to be a positive correlation between intraoperative patency of the conventional collector system as seen by the fluid wave during canal-based surgery and IOP outcome. The presence of an extensive intraoperative collector channel wave may indicate improved outflow capacity while the absence of a wave may portend an atrophic collector system unresponsive to canal surgery.