A recent Translational Vision Science & Technology study has highlighted significant visual impairments in individuals with Type 2 Diabetes Mellitus (T2DM), even when these patients display no signs of diabetic retinopathy (NoDR). The research suggests that both retinal structure and higher-order visual functions are affected early in diabetes, emphasizing the need for more sensitive screening methods beyond conventional eye exams.
The researchers – from Anhui Medical University and the University of Science and Technology of China – conducted a cross-sectional study comparing 53 eyes from 33 patients with NoDR to 40 eyes from 27 healthy individuals. Using a combination of optical coherence tomography (OCT), OCT angiography (OCTA), and advanced visual psychophysical tests, they were able to assess the differences in retinal structure and visual function between the two groups.
Key findings of the research included: NoDR patients scored lower in contrast sensitivity and motion detection tests, particularly in second-order visual function tasks, which assess the brain's ability to process complex visual information; grating acuity (GA) and second-order motion contrast sensitivity (2ndM) were also significantly reduced in this cohort, indicating early neural processing deficits in diabetic patients without any visible retinal damage.
The OCTA images also revealed reduced foveal vascular density (FD-300) and abnormalities in the a circularity index (AI) of the foveal avascular zone (FAZ) in the NoDR patients, suggesting that vascular dysfunction occurs before clinical signs of DR appear.
The findings suggest that current eye exams may not be sufficient to detect early diabetic visual changes. Higher-order visual function tests, alongside advanced OCT and OCTA imaging, could therefore help to identify at-risk patients before retinal damage becomes visible, enabling earlier intervention and better long-term outcomes for diabetic patients.
Incorporating these digital visual function tests into routine diabetes screenings, the study authors note, could be a cost-effective way of detecting early neural and vascular changes. Additionally, further studies integrating retinal and brain imaging technologies may help clarify how diabetes affects the entire visual processing pathway, paving the way for better diagnostic and treatment strategies.
