Patterns of chromatic sensitivity loss in AMD and DB

Abstract

Abstract Purpose Age‐Related Macular Degeneration (AMD) and Diabetic Retinopathy are leading causes of blindness in developed countries in the aged and working population, respectively. Both diseases lead to slow changes in retinal cell structure and corresponding functional loss. The aim of this study was to detect and quantify the degree of acquired loss for both disease types through the use of sensitive visual assessment of chromatic sensitivity (CS). The patterns of loss in the two groups were compared and correlated with clinical indices of disease severity. Methods Subjects with various levels of retinopathy and maculopathy were recruited for the study. Red‐Green (RG) and Yellow‐Blue (YB) CS was measured in both disease groups and in age‐matched controls using the Colour Assessment and Diagnosis Test (CAD). Similar data measured in 330 normal trichromats provided the statistical limits for RG and YB CS. Results All AMD subjects exhibited YB CS loss in the initial stages of the disease. Unequal RG and YB losses were reported in advanced AMD, with YB being the most affected. Diabetic subjects (DB) on the other hand, showed almost equal RG and YB CS losses (r=0.98), irrespective of the type of diabetes or presence of retinopathy. The extent of CS loss as assessed with the CAD test, correlated well with disease severity in AMD subjects and with HbA1c levels in DB subjects. Conclusion Two distinct patterns of CS loss emerged from this study: AMD revealed predominantly tritan‐like losses while DB showed almost equal RG and YB CS loss, irrespective of disease severity. Results suggest that accurate assessment of chromatic discrimination provides a sensitive measure of retinal function and can be used to monitor disease progression or the effectiveness of treatment.