Metformin Linked to Reduced Glaucoma Risk

A new study published in the Journal of Glaucoma suggested that lower dosages of Metformin may have a protective effect on OAG risk, but higher doses had no significant impact.

“The underlying mechanisms linking cumulative metformin dosage to OAG risk are not yet fully understood, highlighting the need for future prospective clinical trials to assess the potential benefits and risks of metformin treatment for OAG in DM patients,” they concluded in their paper. “Our analysis highlights that comorbidities such as hyperthyroidism, myopia and cataract play a more substantial role in elevating OAG risk compared to DM itself or metformin use. These findings underscore the importance of considering coexisting conditions in the management of OAG risk among DM patients, suggesting that the influence of metformin may be secondary to these underlying factors.”

Huang SW Lai YR, Yang Y, Gau SY, Chung NJ, Tsai TH, Huang KH, Lee CY. Association between long-term metformin use and risk of open-angle glaucoma in patients with diabetes mellitus. Journal of Glaucoma. May 16, 2025.

Diabetic Retinopathy Risk Peaks at a Hemoglobin A1c of 9.4, Then Declines at HIgher Levels

 

HbA1c level is known to be indicative as a critical biomarker for long-term glycemic control and is linked to risk of diabetic retinopathy development.

Researchers recently published a paper in BMC Ophthalmology in which HbA1c levels were measured and the association between this and DR was analyzed.

HbA1c positively correlated with DR; however, this was demonstrated by an inverted, U-shaped association, in which DR risk reached a peak of 9.4% with HbA1c level, then started to decline.

The authors explain that they found every 1% increase in HbA1c to be associated with a 7% increase in the odds of developing DR;

The investigators say, “Patients near the 9.4% HbA1c threshold need closer monitoring and timely intervention. For patients above 9.4%, consider aggressive glycemic control with complication monitoring.”

Ling J, Xie ZL, Chen XJ, et al. Inverted U-shaped relationship between HbA1c and diabetic retinopathy in diabetic patients: a cross-sectional study. BMC Ophthalmol. 2025;25:289.

Dipeptidyl Peptidase-4 Inhibitors (DPP4i, like Januvia) Lower Glaucoma Risk in Diabetic Patients

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In a recent study, researchers investigated the association between DPP4i and the risk of primary open-angle glaucoma and normal-tension glaucoma in diabetes patients; they found patients on this drug had a significantly lower risk compared to users of first-generation diabetes medication, such as metformin, among others. 

“These antioxidative properties, combined with their ability to remodel ocular connective tissue, may explain the associations observed in our study,” the authors wrote in their paper. “This suggests that DPP4i may mitigate some of the oxidative toxicity as well as structural changes associated with glaucoma progression.”

Overall, these findings suggest that DPP4i drugs may offer benefits beyond glycemic control, possibly influencing optic nerve health through multiple mechanisms. Further research is needed to explore the underlying mechanisms and their implications for glaucoma prevention and management, the authors concluded.

Lu Y-A, Tien P-T, Cheng Y-D, et al. Association of dipeptidyl peptidase-4 inhibitors with glaucoma risk in patients with type 2 diabetes: a nationwide cohort study. Ophthalmol Sci. May 8, 2025.

SLEEP APNEA AND DRY EYE

 

It's been shown that obstructive sleep apnea doesn’t just affect sleep—the condition may also affect ocular health, including dry eye disease (DED). In a recent study presented at ARVO 2025 in Salt Lake City, researchers examined whether people with sleep apnea are more likely to have DED; they found that dry eye was indeed significantly more common in people with the condition, even after accounting for other health issues like diabetes and obesity—suggesting a strong connection between the two conditions.

Obstructive sleep apnea was found to be significantly associated with a higher risk of DED. Obstructive sleep apnea patients were more likely to have obesity, diabetes, hypertension, hyperlipidemia, hypothyroidism and cardiovascular disease. A total of 17.9% of sleep apnea patients subjects showed evidence of dry eye, compared with  6.1% in matched controls.

Zhang A, He J, Ying G-S. Association of sleep apnea with dry eye disease in the All-of-Us Program. ARVO 2025 annual meeting.

Vitamin D Deficiency Increases Dry Eye Risk

In this study, patients deficient in vitamin D had a significantly higher incidence of dry eye disease 

The researchers wrote that “identifying and addressing vitamin D deficiency could lead to appropriately managing and potentially preventing dry eye syndrome.” 

Beauchamp BC, Shmushkevich S, Kane J, Bajrami S, Parekh P. The influence of vitamin D deficiency in the development of dry eye disease. ARVO 2025 annual meeting.

Low-Dose Insulin Useful for Puncate Epithelial Corneal Defects

Previous studies have determined that topical insulin use was effective in accelerating epithelial defect closure in patients with neurotrophic keratitis. When epithelialization is not achieved in two weeks with stan­dard initial treatment, this option would is an effective first-­line treatment option.  One study found that topical insulin is a safe and effective alternative to treat epithelial defects that don’t improve despite conventional treatment.

96.8% of eyes achieved closure of the epithelial defect with this treatment.

The average closure time was shorter in non-diabetics compared to diabetics. 9.3% experienced burning and 6.25% reported pain. 

Hernandez AJI, Gomez EA, Velasco R, et al. Effectiveness and safety of topical insulin in persistent epithelial defects refractory to treatment. ARVO 2025 annual meeting.