A comparative study of cystoid macula edema following glaucoma drainage device surgery versus trabeculectomy

To assess and compare the risk for development of cystoid macula edema (CME) after glaucoma drainage device (GDD) implantation versus conventional trabeculectomy with mitomycin (trab) for glaucoma.

Retrospective review of consecutive patients receiving trab or GDD implantation between 2016 and 2018. Inclusion criteria were availability of pre- and postoperative spectral domain optical coherence tomography (SD-OCT) of the macula. SD-OCT images were evaluated for presence of CME qualitatively, central subfield thickness (CST) and macular volume (MV).

73 eyes could be included, 42 received trab and 31 GDD surgery. Eyes receiving trab on average had 0.8 ± 0.8 previous intraocular operations, while eyes with GDD implantation had 3.1 ± 1.9 (p < 0.001). Occurrence of postoperative CME was significantly more frequent after GDD implantation (6 out of 31 (19.4%)) than after trab (2 out of 42 eyes = 4.8%), (p = 0.049). Mean preoperative CST as well as MV was comparable in both groups (CST before trab: 282.7 ± 23.0 µm, CST before GDD 284.2 ± 27.3 µm, p = 0.287; MV before trab: 7.8 ± 1.1 mm³, MV before GDD: 8.0 ± 0.8mm³, p = 0.305). Mean postoperative CST and MV were significantly higher after GDD (CST 338.5 ± 129.3 µm, MV 8.8 ± 2.6 mm³) than after trabeculectomy (CST 290.6 ± 60.2 µm, p = 0.038; MV 7.8 ± 1.2mm³, p = 0.039).

In real-life conditions, GDD surgery seems to be associated with a higher risk to develop CME when compared to conventional trabeculectomy. This information may be helpful for glaucoma surgeons to advise the patients on postoperative risks of surgery.