Foveal outer retinal function in eyes with unexplained visual symptoms or acuity loss.

OBJECTIVE

To determine whether foveal outer retinal dysfunction is common in eyes with unexplained visual symptoms or acuity loss.

DESIGN

Prospective study.

PARTICIPANTS

Seventy-three eyes of 44 consecutive patients with unexplained visual symptoms or acuity loss, 39 eyes of 39 control subjects, and 12 eyes of 7 patients with known maculopathy.

INTERVENTION

Foveal cone electroretinography (ERG) and letter recognition perimetry.

MAIN OUTCOME MEASURES

Foveal cone ERG data.

RESULTS

Abnormal foveal cone ERG data were recorded in 35 (48%) of 73 eyes (23 [52%] of 44 patients). Among these 35 eyes, amplitude was lower than in normal controls (P<.001) and was correlated with visual acuity and the number of letter recognition perimetry errors (P<.05 for both). The latter was higher in eyes with abnormal retinal responses than in symptomatic eyes with normal responses (P<.01). However, initial symptoms, visual acuity, and macular appearance did not differentiate between these 2 groups. Foveal cone ERG test vs retest data showed consistent results.

CONCLUSION

Foveal outer retinal dysfunction is a common underlying mechanism of previously unexplained visual symptoms or acuity loss. Foveal cone ERG testing should be considered early in the evaluation of eyes with this presentation.