Abstract
Purpose: :
To assess the relative alterations of chromatic vision in Diabetic Macular Edema in patients with Diabetes type 2 and establish a correlation with increase in retinal thickness.
Methods: :
Color discrimination in 57 eyes with NPDR was evaluated using a modified psychophysical procedure from Cambridge Color Test. Thirty-one eyes present clinically significant diabetic macular edema (CSME) while 26 eyes present diabetic macular edema but not CSME. The length of color discrimination vectors (along Protan, Deutan and Tritan axes) was assessed in CIE 1976 u’, v’ color space and compared with an age-matched control group (n=18).The chromatic discrimination results were correlated with retinal thickness measurements obtained with Stratus OCT (Carl Zeiss Meditec, Dublin CA, USA) and with visual acuity (BCVA according to the ETDRS Protocol).
Results: :
An increase in the length of all color discrimination vectors in all study groups, with especial emphasis in the CSME group, was found. Tritan and Deutan were the most impaired vectors. Impairment of color discrimination correlate significantly with the increase in retinal thickness (R=0,474, p <0.01) and with BCVA (R= -0,391, p<0.01). Deutan vector was the one showing the stronger correlation with structural changes and visual function.
Conclusions: :
Macular function, particularly in the green pathway, is affected in the early stages of diabetic retinal disease. Chromatic vision is impaired in eyes of patients with diabetic macular edema even when visual acuity is preserved. The modified Cambridge Color Test is, therefore, a valid method in detecting diabetic visual dysfunction.
Keywords: diabetic retinopathy • edema • color vision