Unilateral cone dysfunction as a manifestation of acute zonal occult outer retinopathy

To report a patient with unilateral cone dysfunction (UCD) who later developed acute zonal occult outer retinopathy (AZOOR) in the contralateral eye.

A 19-year-old Japanese woman was referred complaining of decreased vision and photopsia of the left eye. Static perimetry, full-field electroretinography (ERG), and multifocal ERGs (mfERGs) were performed to evaluate her visual functions. She returned 9 months later with visual field defect and photopsia in the right eye.

The static visual field of the left eye demonstrated a scotoma that extended from the physiologic blind spot to the center of the visual field. The cone full-field ERGs were extinguished with preservation of rod function. The mfERGs were reduced throughout the posterior pole of the left eye. The patient was diagnosed with UCD. She revisited us 9 months later complaining of visual symptoms in the right eye and was found to have an arcuate scotoma in the upper visual field corresponding to decreased mfERGs. These findings were consistent with clinical signs of AZOOR.

These findings indicate that UCD is one of the clinical manifestations of AZOOR.