New Data Reveal Diabetes Affects Corneal Thickness

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New Data Reveal Diabetes Affects Corneal Thickness

A recent cross-sectional study published in BMC Ophthalmology examined corneal endothelial changes in patients with type 2 diabetes. Researchers in India enrolled 100 adults between 40 and 60 years of age with clear corneas: 50 patients with ≥ 5 years of type 2 diabetes and 50 age-matched non-diabetic controls.

The authors found that patients with diabetes exhibited significantly greater central corneal thickness in both eyes (right eye: 593.9 µm ± 36.2 µm vs 550.9 µm ± 32.4 µm in controls; left eye: 610.5 µm ± 41.3 µm vs 593.9 µm ± 37.8 µm). Within the diabetic cohort, women demonstrated markedly thicker corneas than men (eg, 627.6 µm vs 590.7 µm), suggesting a gender-specific vulnerability.

Endothelial hexagonality was notably reduced in the diabetic group (43.2% vs 52.1%), reflecting increased pleomorphism and loss of standard cell shape. Although endothelial cell density and coefficient of variation showed trends toward abnormality, differences did not reach statistical significance in this sample.

These alterations are attributed to chronic hyperglycemia-induced osmotic stress, accumulation of advanced glycation end-products, and impaired endothelial pump function, which collectively promote progressive cell loss and subclinical stromal edema even in clinically clear corneas.

For practicing optometrists and ophthalmologists, the findings underscore the value of specular microscopy in diabetic eye care—particularly before cataract or refractive surgery, extended contact lens wear, or in patients with long-standing/poorly controlled disease. Subtle endothelial compromise may increase the risk of postoperative decompensation or corneal edema. The pronounced thickening in women with diabetes identifies a higher-risk subgroup warranting closer monitoring. While limited by its modest sample size and cross-sectional design, this study reinforces the importance of tight glycemic control to preserve corneal endothelial health and highlights the need for longitudinal research.

My Two Cents

Isn’t that interesting? If you were feeling frisky, you might make the argument that diabetes could have a protective effect against glaucoma, considering that this study found that people with diabetes having significantly greater central corneal thickness than those without diabetes. In addition, it makes sense that people with diabetes would also have slightly abnormal corneal endothelial cells, as these patients tend to suffer from more corneal edema and (due to many other reasons as well) a slower healing process after ocular surgeries!

OUTSIDE THE LANE

A New Flu to Avoid

A new mutated variant of influenza A (H3N2), known as subclade K, has emerged as a significant concern for the upcoming flu season in the Northern Hemisphere. First detected in Europe in June 2025, this strain carries seven novel mutations that appear to enhance its ability to evade immunity conferred by prior infections or the current seasonal flu vaccine. It rapidly achieved dominance in several countries, driving unusually early and severe outbreaks in regions such as Japan, the United Kingdom, and Canada, where health authorities issued warnings amid surging case numbers.

In the United States, subclade K has been identified in circulating H3N2 viruses, contributing to rising influenza activity—particularly among children—and elevated levels of flu A in wastewater surveillance. The 2024–2025 season was already classified as high severity by the CDC, and experts worry this new variant could prolong or intensify challenges, as consecutive severe seasons are uncommon but possible. H3N2 strains historically cause more hospitalizations and deaths than other seasonal types, especially in young children and older adults.

Symptoms mirror classic influenza A: sudden onset of high fever, chills, severe body aches, headache, profound fatigue (often described as feeling “hit by a truck”), cough, sore throat, and nasal congestion. Presentation can overlap significantly with COVID-19, underscoring the value of multiplex home testing.

The current 2025–2026 vaccine was formulated before subclade K emerged, offering reduced protection against this specific variant. However, vaccination remains strongly recommended, as it matches other circulating strains (H1N1 and influenza B) and continues to mitigate severe outcomes, hospitalization, and death—even against mismatched viruses. Antiviral medications are effective if started early.

Public health experts urge vaccination (it’s not too late), hand hygiene, masking in crowded indoor settings, staying home when ill, and prompt testing/treatment after holiday gatherings. While not a novel pandemic threat like H5N1 avian influenza, this H3N2 subclade highlights influenza’s ongoing evolution.

My Two Cents

As we enter the holiday season, and airport travel becomes more commonplace for many of us, it’s essential that we medical professionals know what’s out there! It seems like every few years, there is a highly virulent strain of the flu that makes headlines, threatening patients worldwide. Not only is this important for our patients, but also for our staff and families. If you’re able, strongly consider getting the most recent flu vaccine. I know after reading this, I’ll be scheduling mine as soon as possible.

CAN YOU RELATE

This past week, I took my vehicle into the shop for some recall work. It turns out my Cadillac’s fuel pump may have had a minor defect, and they were replacing it. Being from Michigan, my vehicle allegiance has always been American-made whenever possible, and the service at the dealerships has always been amazing.

When I dropped my vehicle off, I mentioned that the engine seemed to have a slight clicking sound, which I presumed was related to the fuel pump. Thinking nothing of it, I assumed it would be a whole lot of ’nothin. Fast forward to the next day and my friends at the dealership (all of whom are patients) called to say that the engine issue, although not especially concerning, falls under the powertrain warranty and that I would be getting an entirely new engine free of charge.

It got me thinking about a few things. First, excellent customer service should be acknowledged and appreciated. Second, even a minor issue that seems inconsequential could be a sign of a bigger issue festering beneath the service. Just like in eye care! The same day I took my vehicle in, a patient nonchalantly mentioned they were having issues with their central vision. A macular OCT showed an impending macular hole. The next day (when the dealership delivered the news), yet another patient mentioned that she was noticing her vision decreasing, even though her eyes didn’t hurt—and that turned out to be neurotrophic keratitis. We need to remember that, in all aspects of life, what may seem like a “little thing” could be a sign of much more serious problems lying beneath the surface. Remember to listen to your patients and address all their complaints, even the little ones!

QUOTE OF THE WEEK

“It’s the little details that are vital. Little things make big things happen.”

— John Wooden