Abstract
Purpose:
To examine Optic Nerve Head (ONH) morphology and functional progression in patients with open-angle glaucoma (OAG) with and without Diabetes Mellitus (DM) over a 5-year period.
Methods:
111 OAG patients (Mean age 65 yr; 20 with DM, 91 without DM) were assessed for optic nerve morphology as measured by Heidelberg retinal tomography (HRT) at baseline and every 6 months for a 5-year period. 77 patients (14 with DM, 63 without DM) were assessed at 5-year follow-up. Functional disease progression was monitored with 24-2 Swedish Interactive Thresholding Algorithm visual field exam using the Humphrey visual field machine and defined as 2 consecutive visits with a mean deviation decrease ≥2 compared to baseline and/or Advanced Glaucoma Intervention Study increase ≥2 compared to baseline. Mixed-model ANCOVA was used to test for significant change from baseline to 5-year follow-up. Time to progression was analyzed using Cox proportional hazards models. Interactions were tested to determine if the effects of the factors on progression time differed by diabetes.
Results:
In OAG patients with diabetes, baseline HRT3 parameters were: cup area 0.860 (95% CI: 0.625, 1.130), cup volume 0.286 (0.154, 0.418), cup/disk area ratio 0.404 (0.311, 0.497), linear cup/disk ratio 0.611 (0.529, 0.692), mean cup depth 0.290 (0.232, 0.349), cup shape -0.134 (-0.170, -0.098). In OAG patients without diabetes, baseline HRT3 parameters were: cup area 0.888 (0.772, 1.012), cup volume 0.297 (0.236, 0.359), cup/disk area ratio 0.419 (0.376, 0.463), linear cup/disk ratio 0.629 (0.589, 0.668), mean cup depth 0.302 (0.273, 0.331), cup shape -0.124 (-0.142, -0.105). Higher baseline cup volume and cup depth were associated with time to progression in diabetics only (p<0.05). Higher baseline cup area, cup/disk area ratio, linear cup/disk ratio, and cup shape were associated with short time to progression in all patients.
Conclusions:
ONH structural parameters at baseline were predictive of glaucomatous functional progression after 5 years in patients, with significant differences by diabetes status. These data suggest that the ONH structure in patients with diabetes may play a more prominent role in their functional progression.