Visually Significant Cystoid Macula Edema After Glaucoma Drainage Implant Surgery

Abstract

Purpose: This study examines the incidence of visually significant cystoid macular edema (CME) after glaucoma drainage implant (GDI) surgery and analyses risk factors associated with developing CME and prognosis with treatment.

Materials and methods: In total, 185 eyes from 185 glaucoma patients (mean age, 72.46±13.94 y) who underwent GDI surgery at a tertiary eye institute were recruited. Patients were classified based on the presence (CME) or absence (No-CME) of CME. Pre-GDI and post-GDI best-corrected visual acuity, number of intraocular pressure (IOP)-lowering medications, IOP, standard automated perimetry and post-GDI complications, were recorded and compared between the 2 groups. Optical coherence tomography (OCT) was used to quantify retinal thickness and monitor CME.

Results: In total, 41 (22.2%) eyes developed visually significant CME after GDI surgery. Patients with CME had a higher incidence of pre-GDI nonsteroidal anti-inflammatory drug (P<0.01) use and higher number of prior glaucoma surgeries (P<0.01). CME patients had a higher (P<0.01) incidence of iritis, epiretinal membrane, and hypotony. CME eyes responded well to steroids, with resolving macular edema (458.4±151.9 vs. 322.0±92.0 µm, P<0.01) and improving visual acuity (0.73±0.48 vs. 0.56±0.56 logarithm of minimum angle of resolution, P<0.01). Both CME and non-CME groups had equivalent lowering of IOP and post-GDI glaucoma medications; with no significant elevation in IOP in the steroid-treated CME group.

Conclusions: Post-GDI surgery visually significant CME rates are potentially higher in a real hospital scenario compared with controlled clinical trials. With diligent treatment, CME resolves effectively restoring visual acuity and central macular thickness.

Figure 1

OCT scans of the right eye from an 80 year old male following GDI surgery. Pre-op BCVA was 20/50; 5 months after surgery was noted to have BCVA of 20/250 with IOP 1; marked intra retinal fold (IRF) was noted on macula OCT (figure 1A; central macula thickness (CMT) 617 µm). Patient was treated with topical prednisolone acetate 1% qid, ketorolac qid and atropine 1% bid. The vision gradually improved with resolution of CME noted 3 months later (figure 1B; CMT 339 μ) with BCVA 20/30. Note patient has an epi-retinal membrane (ERM).