Function of filtering bleb after Cataract Surgery in Eyes with Previous Successful Trabeculectomies

Background: It has been reported that cataract surgery can compromise the function of a filtering bleb, resulting in loss of control of intraocular pressure (IOP). In a number of retrospective studies a rise of IOP after extra capsular extraction and even after phacoemulsification in filtered glaucoma eye was shown. Objective: To evaluate the effect of temporal clear corneal Phacoemulsification with Intraocular Lens implantation (IOL) on IOP control in glaucoma patients who had previous successful trabeculectomy. Methods: The clinical course of 60 patients (60 eyes) who underwent temporal clear corneal phacoemulsification after successful trabeculetomy was studied over a period of 3 years. The number of Primary Open Angle Glaucoma (POAG) and Primary Angle Closure Glaucoma (PACG) cases was equal in our study. Comparison of pre-operative and post-operative IOP, visual acuity, bleb morphology and the number of medications was made at follow up interval of 1 month, 3 months, 6 months and 12 months respectively.Results: The mean ± SD IOP before phacoemulsification was 12.2 ± 4.608 mmHg and it increased to 14.98, 14.47, 15.44 and 15.71 after 1, 3, 6 and 12 months respectively. At each interval the mean IOP was significantly higher than the pre-operative value (p = 0.000, 0.015, 0.000, 0.001 respectively) There was also an increase in the number of antiglaucoma medications used after phacoemulsification. The mean ± SD of medication before phacoemulsification was 0.57 + 0.62 and it increased to 0.65, 0.70, 0.68, 0.67 after 1, 3, 6 and 12 months respectively. But the difference was not statistically significant. Conclusion: Temporal clear corneal phacoemulsification significantly increases IOP in eyes with pre-existing functioning filtering bleb. No statistically significant difference was found between the outcomes of POAG and PACG groups. There is a statistically significant improvement in visual acuity following phacoemulsification with intraocular lens implantation.