Purpose: To assess the effect of cataract surgery on trabeculectomy blebs that have previously had successful needling revision.
Study design: A retrospective controlled study.
Patients and methods: A cohort of patients undergoing needling of a poorly functioning trabeculectomy bleb was collected. From this cohort a group having had a successful needling outcome who subsequently underwent uneventful phacoemulsification was identified. Each member of this phacoemulsification group was matched with 2 controls from the cohort who had also had success from needling but who had not undergone cataract surgery. Survival analysis was performed using the date of cataract surgery as the entry time for the phacoemulsification group. For controls the entry time was the date of needling adjusted by subtracting the time between needling and cataract surgery of the matched phacoemulsification group subject. In this way an identical period had elapsed between needling and entry time for both phacoemulsification group and controls. Survival depended on (a) intraocular pressure (IOP) < or =21 mm Hg and (b) IOP <80% of preneedling IOP, on the same or fewer glaucoma drops and without further glaucoma surgery.
Results: Forty-five patients were included. Intervals from trabeculectomy to needling, needling to phacoemulsification, and from phacoemulsification to final follow-up ranged from 1 to 320, 4 to 15, and 5 to 19 months, respectively. Mean survival for the phacoemulsification group was 34.4 weeks and 190.0 for controls [hazard ratio 8.1 (95% confidence interval: 2.8-23.9) (log rank P<0.0001)]. Survival at final follow-up was 4/15 and 25/30 for cases and controls, respectively (chi2 P=0.0002).
Conclusions: Previously successful bleb needling can be significantly compromised by subsequent cataract surgery.