Silent substitution S-cone electroretinogram in subjects with diabetes mellitus

A defect in the blue sensitive mechanism has been reported in certain ocular and systemic diseases. For example, tritanopic colour vision defects and changes to the S‐cone electroretinogram (ERG) have been demonstrated in glaucoma and diabetes mellitus. Electrophysiological methods of eliciting the S‐cone ERG, however, often result in considerable L‐ and M‐cone intrusion. We report the findings of a study employing the silent substitution S‐cone ERG technique, which is thought to represent an almost pure S‐cone signal, and the L'Anthony desaturated D15 colour vision test in subjects with Type 1 or 2 diabetes mellitus with no or minimal background retinopathy. The results of this study show a significantly increased S‐cone ERG b‐wave implicit time and significantly worse colour vision in those with background retinopathy compared with those with no diabetic retinopathy. This suggests that S‐cone pathway dysfunction may be responsible for the deterioration in colour vision found in diabetes mellitus.