Purpose: To compare the intraocular pressure lowering effect and the frequency of post-operative complications in two of the most used filtration surgery techniques: trabeculectomy and non-penetrating deep sclerectomy (NPDS) without collagen implants.
Methods: Thirty-four eyes of 17 patients with medically uncontrolled symmetrical primary open-angle glaucoma were included in the study. One randomly selected eye per patient had either trabeculectomy or NPDS without collagen implants as the first surgical procedure. The other eye underwent the second filtration surgery technique less than 6 weeks later. Post-operatively, the intraocular pressure (IOP) diurnal curves were determined at 1, 2, 3, 6, 12 and 18 months. The intergroup differences in IOP lowering effect were determined in an analysis of covariance (ANCOVA), with pre-operative IOP as a changing covariate. Kaplan-Meier survival curves were drawn for IOP, and intercurve analysis was performed. Comparisons of the number of post-operative antiglaucomatous medications, as well as of the complication rate, were done by 2 x 2 frequency tables. A p value of less than 0.05 was considered statistically significant.
Results: There were statistically significant differences in post-operative IOP level between the two groups at 1, 2, 3, 6, 12 and 18 months, with a lower level in the trabeculectomy group. Using the Kaplan Meier cumulative survival curve, the trabeculectomy patients had a better complete success rate than the NPDS patients at 18 months post-operatively. There were statistically significantly fewer complications in the NPDS group.
Conclusion: Trabeculectomy lowers the IOP more than the NPDS technique. However, the complication rate seems to be lower in NPDS.