Figure 2

Chromatic contrast discrimination thresholds. (A) Example of the testing stimulus, created by the Psykinematix V1.4 (https://psykinematix.kybervision.net/). (B–D) were contrast thresholds from diabetic patients of no-DR, NPDR, and PDR groups, and controls in protan, deutan, and tritan conditions. The data are expressed in box plot (mean and standard deviation) with overlapping individual data. (*p value < 0.05, ^¶p value < 0.1 but > 0.05 for comparisons of diabetic patients with the controls).