Longitudinal Changes in Bleb Height, Vascularity, and Conjunctival Microcysts After Trabeculectomy.

Abstract

The objective of this article was to study longitudinal changes in bleb morphology (presence of microcysts and bleb height and vascularity) in subjects enrolled in the Singapore 5-Fluorouracil (5-FU) trabeculectomy study. Retrospective subgroup analysis of a randomized controlled trial. Following trabeculectomy with either 5-FU or placebo, subjects were reviewed at day 1, weeks 1, 2, and 3, and months 3, 6, 9, 12, 16, 20, 24, 28, 32, and 36 and intraocular pressure (IOP), presence of microcysts and bleb height and vascularity graded and recorded. Statistical analyses were used to investigate baseline factors (demographics, eye drops use, IOP, treatment type, and comorbidities) that might account for long-term bleb changes and assess the influence of bleb morphology on mean, maximum, minimum, and variation in IOP following trabeculectomy. One hundred fifty-nine (61.2%) subjects completed follow-up and 71 subjects (44.7%) received 5-FU. Proportion of subjects with microcysts increased posttrabeculectomy till weeks 3 and 6 in 5-FU and placebo-treated eyes, respectively, before decreasing. Presence of microcysts at day 1 and week 2 was associated with lower mean (P=0.027 to 0.033), maximum (P=0.040), and minimum IOP (P=0.010). Mean bleb height decreased over 36 months and at months 20 and 36 was associated with maximum (P=0.031) and minimum IOP (P=0.032), respectively. Mean bleb vascularity decreased till month 9 and remained fairly constant after. Microcysts seen early posttrabeculectomy is associated with lower IOP. Blebs reduce in height as they remodel and the relationship between bleb vascularity and IOP is complex.