The impact of repeated intravitreal dexamethasone implants on the cornea in patients with macular edema due to retinal vein occlusion

PURPOSE: This study aimed to assess the impact of repeated 700 μg intravitreal dexamethasone implant (IDI) applications on corneal parameters in patients with macular edema (ME) secondary to retinal vein occlusion (RVO).
METHODS: This retrospective pilot study included 62 patients with RVO and 63 control subjects. RVO patients received two or more IDI treatments. Detailed eye examinations, including posterior segment evaluations, corneal topography, and endothelial parameters, were retrieved from the patients’ medical records.
RESULTS: The study involved 23 patients with central RVO (CRVO) and 39 with branch RVO (BRVO). Ischemic RVO was present in 52.2% of CRVO and 48.7% of BRVO patients. The mean age of RVO patients was 64.79±10.00 years; for the control group, it was 65.03±9.02 years (p=0.068). Patients received an average of 6.58±3.38 IDI injections. Eyes treated with IDI showed significantly worse best-corrected visual acuity and increased central macular thickness compared to fellow eyes and controls (p<0.001 and p=0.031, respectively). Central corneal thickness was significantly thinner in eyes that received IDI, and anterior corneal depth, anterior and posterior corneal curvature, total high-order corneal aberrations, trefoil, and spherical values were significantly higher (p<0.05). In addition, endothelial cell density was significantly lower, and the mean cell area, minimum cell area, and maximum cell area were higher in the eyes that received IDI (p<0.05).

CONCLUSION: Repeated IDI injections adversely affect corneal topographic and endothelial parameters in RVO-related ME. These changes were associated with the type and localization of RVO, ischemic status, number of IDI administrations, and lens status.

Keywords: Corneal endothelium, corneal topography, intravitreal dexamethasone implant, retinal vein occlusion, specular microscopy.