Structural Reversal of Disc Cupping After Trabeculectomy Alters Bruch Membrane Opening–Based Parameters to Assess Neuroretinal Rim

Abstract

To assess the impact of trabeculectomy for glaucoma on morphometric neuroretinal parameters of the optic nerve head (ONH) using spectral-domain optical coherence tomography (SD-OCT). Retrospective, interventional case series. Participants: Eighty-eight eyes of 88 patients who underwent trabeculectomy with mitomycin C in 2016. All patients underwent trabeculectomy in 1 eye (study eye) and had evaluable SD-OCT examinations of the ONH to measure neuroretinal tissue before and at least at 1 of the 3-, 6-, and 12-month follow-up time points after surgery. Longitudinal change in Bruch membrane opening minimum rim width (BMO-MRW), Bruch membrane opening minimum rim area (BMO-MRA), peripapillary retinal nerve fiber layer (RNFL) thickness, intraocular pressure (IOP), and mean deviation in perimetry. In study eyes, BMO-MRW significantly increased postsurgically comparing baseline and follow-up examinations at 3months (P= .012), at 6months (P= .007), and at 1 year (P= .010) after trabeculectomy. The increase in BMO-MRW 6months after surgery correlated with IOP reduction (r= 0.48; P=.001). BMO-MRA showed an equal increase (P≤.034). RNFL thickness remained stable between baseline and follow-up at 3, 6, and 12months and showed a moderate loss after 18months (P= .021) of follow-up. Structural reversal of disc cupping after trabeculectomy markedly influences Bruch membrane opening-based parameters for up to more than 1 year. Improvement in morphometry seems to correlate with the reduction of IOP while visual field function appears not to be influenced. In longitudinal follow-up of glaucoma patients by SD-OCT, evaluation of BMO-based parameters necessitates to reflect bias caused by surgery.