The outcome of the functioning filter after subsequent cataract extraction

OBJECTIVE: To evaluate and compare the outcome of functioning filtration su rgery followed by cataract;surgery with posterior intraocular lens implanta tion by both phacoemulsification and extracapsular cataract extraction (ECC E) techniques in glaucomatous eyes. PATIENTS AND METHODS: We retrospectively evaluated the clinical course of 7 7 eyes (68 patients) that after successful trabeculectomy, underwent catara ct surgery by either phacoemulsification or ECCE techniques. We determined the frequency of partial and absolute failure following cataract surgery by either phacoemulsification or ECCE in eyes with functioning trabeculectomi es. Partial failure of intraocular pressure (IOP), control after cataract e xtraction was defined as the need for an increased number of antiglaucoma m edications or argon laser trabeculoplasty to maintain IOP less than or equa l to 21 mm Hp. Complete failure of IOP control after cataract surgery was d efined as an IOP >21 mm Hg on at least two consecutive measurements one or more weeks apart or the performance of additional filtration surgery. Failu re rates were calculated using the Kaplan-Meier actuarial method. Failure r ates between phacoemulsification and ECCE subgroups were compared using the log rank test. RESULTS: The probability of partial failure by the third postoperative year after cataract surgery was 33.5% in the phacoemulsification subgroup and 3 7.3% in the ECCE subgroup. This small difference is not statistically signi ficant (P = 0.48). The probability of complete failure by the fourth postop erative year after cataract surgery was 12.0% in the phacoemulsification su bgroup and 12.5% in the ECCE subgroup. This difference is also not statisti cally significant (P = 0.77). At the 6-month follow-up visit, visual acuity of both groups improved one or more lines in 87.0% of patients, and worsen ed one or more lines in 3.9% of patients. Sixty-one percent achieved visual acuity of 20/40 or better The most frequent complication was posterior cap sular opacification requiring laser capsulotomy that occurred in 31.2% of p atients. CONCLUSION: Cataract extraction by either phacoemulsification or ECCE follo wing trabeculectomy surgery may be associated with a partial loss of the pr eviously functioning filter and the need for more antiglaucoma medications to control IOP.