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S-cone pathway sensitivity in diabetes measured with threshold versus intensity curves on flashed backgrounds
H Terasaki1, H Hirose, Y Miyake
1Department of Ophthalmology, Nagoya University School of Medicine, Japan.
Purpose:
To study sensitivity loss to short wavelength lights in patients with diabetes with or without retinopathy and to identify changes that cannot be attributed to preretinal screening.
Methods:
Flash-on-flash thresholds were measured in 41 patients with diabetes and were compared to those in age-matched normals. A 50-ms, 1 degree blue test spot was presented simultaneously with a 500-ms, 2 degree blue flash. A bright yellow background isolated the S-cone system.
Results:
The mean flash-on-flash threshold curve shifted up as the stage of retinopathy progressed in 16 patients with insulin-dependent diabetes mellitus (IDDM), including those without retinopathy. In 25 patients with noninsulin-dependent diabetes mellitus (NIDDM), those with preproliferative retinopathy revealed sensitivity loss; however, those with background retinopathy or without retinopathy showed no statistically significant change in sensitivity.
Conclusions:
The pattern of sensitivity loss in the patients with IDDM cannot be caused by changes in preretinal screening, including yellowing of the lens. Further, early functional changes in the patients with IDDM without retinopathy can be detected by this method.