Phacoemulsification in trabeculectomized eyes

Purpose: To evaluate retrospectively risk indicators for cataract surgery and the effect of phacoemulsification on intraocular pressure (IOP) control in eyes that have undergone trabeculectomy. Methods: We undertook a retrospective analysis of 138 eyes with primary open-angle glaucoma (POAG) or exfoliation glaucoma (EG) in 138 consecutive patients over the age of 40 years undergoing trabeculectomy with no antimetabolites performed by one surgeon. Of the 48 eyes (35%) undergoing a cataract operation during the follow-up period of 2-5 years, 46 were included in this analysis. Their IOP, glaucoma medication and best corrected visual acuity (BCVA) before cataract surgery and at the last follow-up were compared. Risk indicators for cataract surgery were analysed. Results: Cataract operations were performed 5.1-58.1 months (median 14.4 months) after trabeculectomy. The mean length of follow-up after cataract surgery was 25.3 months (SD 12.9, median 24.8 months). Before cataract surgery, the mean IOP was 16.2 mmHg (SD 4.9) and the mean number of topical antiglaucoma medicines 0.8 (SD 1.0). At the most recent visit, mean IOP was 17.3 mmHg (SD 6.4) (p = 0.35), and the mean number of medicines was 1.3 (SD 1.1) (p = 0.0007). Of the 22 eyes in which treatment had been categorized as completely successful (IOP <= 21 mmHg without other therapy) before cataract surgery, 13 (59%) had remained so. The number of failures (IOP > 21 mmHg, or more than one medication needed or further surgery performed) increased from 14 (30%) before surgery to 28 (61%) afterwards. The proportion of failures in the cataract surgery group was twice that in the no cataract surgery group (61% versus 31%). In a proportional hazards regression, only age (73.9 years [SD 9.4] and 68.1 years [SD 9.8] in patients with and without cataract surgery, respectively) proved to be a significant (p = 0.001) indicator for surgery. Conclusion: The results of this retrospective study on consecutive clinical cases of trabeculectomy indicate that cataract progression after trabeculectomy is mainly an age-related process. In more than half the eyes with good preoperative IOP control, this good control was maintained after cataract surgery. On the other hand, in some eyes cataract surgery may compromise IOP control even when surgery avoids the area of the bleb.