A temporal deficit in juvenile diabetics

Background: In this study we examined the temporal domain of visual functio n in diabetics without retinopathy by examining wavelength discrimination a bility at two exposure durations. The results were compared to those found by heterochromatic brightness matching and anomaloscope matches. Methods: W avelength discrimination was performed between 440 and 540 nm at exposure t imes of 1 s and 0.04 s in eight juvenile diabetic patients without retinopa thy. The monochromatic stimuli were presented in Maxwellian view and were s et to be equally bright prior to the experiment using heterochromatic brigh tness matching. In addition, Rayleigh and Moreland anomaloscope matches wer e performed. The results of the diabetic group were compared to these of an age-matched control group of eight subjects with normal colour vision. Res ults: Wavelength discrimination showed no difference between the groups for an exposure time of 1 s. With an exposure duration of 0.04 s, however, the diabetics show raised thresholds for the shortest wavelengths tested. In a ddition, brightness matches were increased at the short wavelengths, and an omaloscope matches showed a decrease in the match range for the Moreland (b lue-yellow) equation. Conclusion: The results indicate post-receptoral alte rations in diabetic patients with no visible changes in their retinae.