• POAG Progression and Diabetes

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD

    Journal Highlights

    American Journal of Ophthalmology, May 2018

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    Risk factors for glaucoma progression have not been clearly defined, and there is long-standing debate on the role of type 2 diabetes mellitus (DM) in pri­mary open-angle glaucoma (POAG). Elevated intraocular pressure and impaired vascular supply to the optic nerve head have both been implicated in the pathophysiology of POAG—and as type 2 DM has been thought to in­volve both pathogenic processes, it may be a risk factor for POAG.

    With this in mind, Hou et al. compared rates of visual field (VF) loss and retinal nerve fiber layer (RNFL) thinning for patients with POAG and found no difference in VF progression between patients without type 2 DM and those who had type 2 DM with undetectable diabetic retinopathy. They also found that treated DM was linked to significantly slower loss of RNFL thickness.

    This study included 197 eyes. The POAG/DM group consisted of 55 eyes (32 patients) and the POAG-only group included 142 eyes (111 age-matched patients). Participants had been en­rolled in the Diagnostic Innovations in Glaucoma Study; those with type 2 DM were identified by self-reporting a history of DM and use of medication for diabetes. Univariate and multivari­able mixed-effects models were applied to compare rates of VF loss and RNFL loss between the study groups. Median follow-up time was 5.7 years.

    Results showed that the mean rate of global RNFL loss was 2-fold slower in the POAG/DM group (–0.40 vs. –0.83 μm per year; p = .01). The POAG/DM group also had slower rates of VF mean deviation and pattern standard deviation loss, but the between-group differences were not significant.

    The global and sectoral RNFL thinning rates for metformin users and nonusers in the POAG/DM group were compared to determine whether metformin could have a protective effect, but no significant difference was observed. Not surprisingly, most sub­jects in the POAG/DM group (84.4%) were taking metformin (solo or com­bined), so the subanalysis is limited by the small sample of nonusers.

    If glaucoma is diabetes of the brain, which has been proposed by some investigators, insulin and other dia­betes medications might be remedies for glaucoma. Research is needed to address this topic and assess whether such treatments could protect against glaucomatous damage.

    The original article can be found here.