Abstract
Purpose :
Structural reversal of disc cupping is a known phenomenon after trabeculectomy. The purpose of this study was to understand the postoperative impact and dynamics after glaucoma drainage device (GDD) implantation on morphometric parameters to measure neuroretinal tissue of the optic nerve head (ONH) in spectral domain optical coherence tomography (SD-OCT).
Methods :
This retrospective, longitudinal, cross-sectional analysis included all eyes treated by glaucoma drainage device surgery with either Baerveldt or Ahmed implant (ICP-M 5-131.60) at the center in 2016 and 2017 (n=158) and had evaluable SD-OCT examinations of the ONH to measure neuroretinal tissue before and at least at one visit during the first 18 months of follow-up after surgery. 43 eyes of 39 patients could be included in the study. Individual changes in Bruch’s membrane opening minimum rim width (BMO-MRW), Bruch’s membrane opening minimum rim area (BMO-MRA) and peripapillary retinal nerve fibre layer (RNFL) thickness as well as mean defect in 30-2 perimetry were analyzed. Changes were correlated to the course of intraocular pressure (IOP) after surgery.
Results :
The BMO-MRW significantly increased by 14.3% between baseline (BL) and follow-up (FU) examinations 50 to 180 days after surgery (171.3±77.7µm at BL vs. 195.9±95.9 at FU; p=0.031). The increase in BMO-MRW correlated negatively with the intraocular pressure at the time of the follow-up (Pearson’s rho=-0.47; p=0.049). For eyes without postoperative lowering in IOP of 20%, there was no significant change in BMO-MRW, while 71% of all eyes with lowering of IOP of 20% or more showed an increase in BMO-MRW at short-term FU (p=0.037). From six months after surgery on, there was no statistically significant change in BMO-MRW (p>0.3, respectively). RNFL thickness showed no significant changes between baseline and FU at all three FU periods (p≥0.4, respectively). Also 30-2 perimetry showed no significant change in the mean defect after surgery (p=0.4).
Conclusions :
Glaucoma drainage device surgery leads to an increase of Bruch’s membrane opening based parameters in SD-OCT in the first 6 months after surgery, known as structural reversal of disc cupping. Those changes have to be taken into account when evaluating patients’ longitudinal follow-up also after GDD implantation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.