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A.R. Santos, L.G. Duarte, A. Reis, M. Castelo–Branco, J.G. Cunha–Vaz; Comparison of Relative Impairment to Chromatic Pathways in Clinical and Sub–Clinical Macular Edema in Diabetes Type 2: Correlation With Retinal Thickness . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1009.
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To assess the relative impairment in the red, green and blue pathways in clinical and sub–clinical macular edema in Diabetes type 2 and to correlate the obtained measurements with the increase in retinal thickness.
A psychophysical procedure modified from Cambridge Color Test was used to assess color discrimination in three different groups: ten patients with clinical diabetic macular edema (n = 10 eyes); ten patients with sub–clinical diabetic macular edema (n = 50 eyes) and control subjects (n = 56 subjects for color contrast sensitivity measurements and a set of n = 10 subjects for retinal thickness measurements). Measurements of the length of color discrimination vectors (along Protan, Deutan and Tritan axes) were performed in CIE 1976 u’, v’ color space and were correlated with clinical data and retinal thickness measurements obtained with RTA II (Talia Mevaseret, Israel) and the OCT Stratus (Humphrey Davis, USA). All eyes had an ETDRS visual acuity of 20/20.
Patients with sub–clinical macular edema showed mild chromatic sensitive deficits, in particular along the tritan axis. Patients with clinical macular edema showed significant impairment in all color axes. Tritan impairment was also most pronounced in this group. The measures showed a deviation well above 2 SD, for all tested subjects, in particular for the tritan axis. There was a global positive correlation between test parameters and retinal thickness values.
This psychophysical test can detect visual dysfunction in eyes of patients with diabetes and sub–clinical macular edema. Macular function, particularly in the blue pathway, is affected in the early stages of the diabetic retinal disease, showing a positive correlation with the increase in retinal thickness.
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