Loss of photoreceptor outer segment in acute zonal occult outer retinopathy.

OBJECTIVE To describe retinal changes in acute zonal occult outer retinopathy (AZOOR). METHODS We investigated retinal function and morphologic changes in 5 patients (mean age, 33.6 years) with AZOOR and acute visual field loss in 1 or more zones using Stratus optical coherence tomography, multifocal electroretinograms, full-field electroretinograms, and Goldmann perimetry. RESULTS Goldmann perimetry showed enlarged blind spots of Mariotte bilaterally in 2 patients and unilaterally in 3 patients. Another scotoma was seen in the nasal paracentral area, the inferior midperiphery, and centrally. No visible retinal lesions corresponded to these scotomas except for inferior midperipheral retinal pigment epithelium atrophy and peripapillary depigmented lesions. The multifocal electroretinograms showed a markedly decreased response from the blind spots and scotomas. Optical coherence tomography showed loss or irregularity of the inner segment-outer segment line in the areas of decreased response on multifocal electroretinography and those with visual field defects. The outer nuclear layer disappeared in 2 cases. Areas of visible retinal pigment epithelium atrophy showed an irregular retinal pigment epithelial reflex, increased choroidal reflectivity, and retinal attenuation. CONCLUSIONS Photoreceptor outer segment dysfunction and/or degeneration seem to be the primary lesion in AZOOR. Optical coherence tomography is an important tool for detecting morphologic changes in this occult retinopathy.