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Selective reduction of the S cone electroretinogram in diabetes
S Yamamoto1, M Kamiyama, K Nitta
1Department of Ophthalmology, Toyama Medical and Pharmaceutical University, Japan.
Aims:
To determine whether the short wavelength sensitive (S) cone electroretinogram (ERG) is selectively altered in diabetic patients with and without retinopathy.
Methods:
Ganzfeld spectral flashes in the presence of bright white background illumination were used to elicit S cone ERGs is 15 non-retinopathic diabetics, 16 background retinopathic diabetics, and 16 age matched normal controls.
Results:
The amplitude of the S cone ERG b-wave was significantly reduced in both non-retinopathic and retinopathic diabetics. An action spectrum based on equal response criteria revealed a selective loss of S cone sensitivity in diabetics. However, no significant difference was observed in the long and middle wavelength sensitive cone ERG.
Conclusions:
Diabetic patients showed selective reduction of the S cone ERG, which is thought to reflect changes in the outer retina.