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Your left eye might be telling a different story than your right. A new study found that differences in retinal blood vessel patterns between the two eyes — particularly in the foveal avascular zone — are linked to greater diabetic retinopathy (DR) severity. Researchers say this asymmetry "may have prognostic value," potentially flagging disease progression before it's visible on standard eye exams.
Your eyes aren't always mirror images — and that gap could matter clinically.
A retrospective study published in Acta Ophthalmologica analyzed 442 eyes from 221 patients with type 2 diabetes, all with matching DR severity in both eyes. Using OCT angiography (OCT-A), researchers found that in patients with proliferative DR, the left eye consistently showed a larger foveal avascular zone (FAZ) — a key marker of retinal vascular damage — compared to the right. One proposed explanation: the anatomical origin of the left common carotid artery from the aortic arch may place greater hemodynamic stress on the left eye's vasculature.
Greater inter-eye asymmetry was associated with more advanced DR, diabetic macular edema (DME), and male sex. Notably, OCT-A picked up these microvascular differences even when both eyes were graded at the same DR stage on standard fundus exam.
Key Takeaways:
Why it matters: These findings suggest that evaluating both eyes — not just one — may be essential in DR research and clinical practice. If macular microvascular changes are asymmetric, randomly selecting a single eye for study enrollment could skew results and miss the full picture of disease burden.
