Characterizing chromatic sensitivity across the central visual field in those with and without type 2 diabetes

Purpose Neural degeneration of the retina can precede clinically evident vascular changes in early diabetic retinopathy and may present with functional vision loss. While local achromatic defects and global color sensitivity losses have been reported in early diabetes, there is a lack of tests for local chromatic sensitivity. The purpose of this study was to characterize chromatic sensitivity at discrete locations within the central 10 degrees of vision in those with and without glucose dysfunction using a novel chromatic perimetry paradigm. Methods Local chromatic sensitivity was measured in the right eyes of those with glucose dysfunction (HbA1c > 5.6%, n=9) and age-matched controls (HbA1c ≤ 5.6%, n=9) using a novel chromatic perimetry paradigm. The test assesses chromatic contrast sensitivity to solid circular stimuli modulating along the cardinal axes of DKL color space at 20 discrete locations within the central 10 degrees of visual field. Visual acuity, Mars contrast sensitivity, and L’Anthony D-15 were also measured. A mixed effects modeling approach was used to estimate chromatic contrast sensitivity under correlated experimental conditions across glucose dysfunction status. Results Average chromatic contrast detection thresholds were greater for the glucose dysfunction group compared to healthy controls. After statistically controlling for age and sex, the mixed model approach revealed a significant interaction between retinal location and glucose dysfunction status on detection thresholds for the “red” condition. Conclusions Local chromatic sensitivity shows promise as a metric for diabetic changes in the eye, as evident by the increased overall thresholds in the glucose dysfunction group and interactions present in the “red” condition. It also reveals greater sensitivity over alternative assessments measured in this study. This study is the first to evaluate local color sensitivity in these groups over the posterior pole, providing a foundation for future work evaluating a broader range of diabetic disease.