Macular ischaemia, retinal thinning linked to reduced visual function in diabetic retinopathy

By Nikki Withers, medwireNews Reporter

Macular ischemia and retinal thinning are associated with reduced visual function in patients with diabetic retinopathy, research suggests.

Previous studies have shown that age is a contributing factor to abnormalities associated with diabetic retinopathy. However, Dawn Sim (Moorfields Eye Hospital, London, UK) and colleagues believe that age alone is unlikely to be solely responsible.

To investigate further, the team used ultra-widefield fluorescein angiography (FA) to analyse the association between peripheral and central ischaemia in patients with diabetic retinopathy.

Specifically, they examined peripheral capillary nonperfusion, peripheral leakage, foveal avascular zone (FAZ) size and optical coherence tomography (OCT)-derived central macular thickness measurements and evaluated the visual significance of these parameters.

A total of 47 eyes from 47 patients were included in the study. The median age of the patients was 55 years.

Writing in the American Journal of Ophthalmology, Sim et al report that eyes with a high peripheral ischaemia index predominantly had a larger FAZ area than those with a low peripheral ischaemia index. And patients with a large FAZ area had a significantly thinner retina than those with a small FAZ area.

A large FAZ area was also moderately associated with a high peripheral leakage index but only in laser-naïve eyes.

Neither peripheral leakage nor peripheral ischaemia were associated with retinal thickness measurements.

By contrast, a thinner retina was observed in eyes with than without macular ischaemia (217 vs 272 µm, the researchers note.

When the parameters were analysed in multiple regression models, neither peripheral ischaemia nor leakage was associated with visual function.

Indeed, the only factors that remained significant predictors of visual loss were age (r=0.33), FAZ area (r=0.45) and central retinal thickness measurements (r=0.38), the team reports.

“In light of the relationships observed in this study, we hypothesize that the pattern distribution of ischemia and vascular leakage in diabetic eyes may be suggestive of the reversibility of functional loss, thus highlighting a window of opportunity for treatment”, say Sim et al.

“These patterns may be of clinical significance and warrant future evaluation in prospective studies”, they add.

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