Photoreceptor outer segment abnormalities as a cause of blind spot enlargement in acute zonal occult outer retinopathy-complex diseases

Abstract

Purpose: To investigate the correlation between visual field (VF) defects in diseases of the acute zonal occult outer retinopathy (AZOOR)-complex and their spectral-domain optical coherence tomographic (OCT) findings.

Design: Observational case series.

Methods: Patients with AZOOR, multiple evanescent white dot syndrome (MEWDS), and multifocal choroiditis and panuveitis (MCP) examined in a private practice retinal referral center had threshold VF testing and spectral-domain OCT examination performed using a device capable of obtaining a block of 128 B-scans in a 6 x 6-mm region centered on the optic nerve and macula. The areas of defects in the boundary between the inner segments (IS) and the outer segments (OS) of the photoreceptors, termed the IS/OS boundary, were compared with the VF defects measured.

Results: There were 18 evaluable eyes among one patient with MEWDS, two with AZOOR, and seven with MCP. In the 14 eyes with blind spot enlargement [corrected] corresponding IS/OS boundary defects were found in the [corrected] peripapillary region, while no IS/OS boundary defects were found in the four [corrected] eyes without blind spot enlargement. IS/OS boundary defects were seen over chorioretinal scars and areas of neovascularization and no widespread defects were seen [corrected] elsewhere in the fundus. The IS/OS boundary defects showed improvement, as did the blind spot enlargement, spontaneously in the patient with MEWDS and after treatment with immunosuppression in the patients with AZOOR.

Conclusion: The spectral-domain OCT finding of IS/OS boundary defects, implicating photoreceptor OS perturbation, appears to explain the blind spot enlargement in patients with AZOOR-complex diseases. These defects are not necessarily permanent.