SEP 18, 2014
This prospective randomized study found that early aqueous suppressant treatment may improve Ahmed glaucoma valve implantation outcomes by increasing the success rate, providing better IOP control and reducing the likelihood of a hypertensive phase.
This study is the first to demonstrate the premise of the effect of pro-inflammatory cytokines in inducing the hypertensive phase of valved implants.
The study’s premise is that early aqueous suppression results in the decrease of pro-inflammatory cytokines to the plate surface, resulting in less bleb fibrosis. This assumption may or may not be correct and can only be affirmed by the measurement of the cytokine levels in the aqueous. The lowering of the pressure may also result in preventing the bleb from producing cytokines.
The investigators randomized 94 patients (94 eyes) with refractory glaucoma who underwent Ahmed glaucoma valve implantation to receive topical timolol-dorzolamide fixed-combination drops twice daily when IOP exceeded 10 mm Hg or conventional stepwise treatment (control group) when IOP exceeded target pressure (6 mm Hg < IOP < 15 mm Hg). The topical timolol-dorzolamide combination group was followed for a mean of 45 weeks and the control group for a mean of 47.2 weeks. .
Mixed model analysis revealed a significantly greater IOP reduction in the combination treatment group at all intervals (P < 0.001). At one year, that group exhibited a significantly higher success rate (63.2% vs. 33.3%; P = 0.008), defined as at least 30 percent IOP reduction, and reduced hypertensive phase frequency (23.4% vs. 66.0%; P < 0.001).
Although the results of this study may suggest that all implant surgery should be treated with aqueous suppressants as soon as the aqueous reaches the plate surface, thereby decreasing the pro-inflammatory effect of the cytokines, this can be more easily achieved by removing aqueous from the bleb, which both lowers the IOP and definitively removes excess cytokines. Decreasing the IOP prior to allowing aqueous onto the plate surface will also decrease the cytokine levels in the aqueous.