Spectral domain optical coherence tomographic findings at convalescent stage of acute zonal occult outer retinopathy

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Authors: Kouichi Ohta, Atsuko Sato Emi Fukui

Published Date July 2009 , Volume 2009:3 Pages 423 - 428 DOI 10.2147/OPTH.S6108

Kouichi Ohta, Atsuko Sato Emi Fukui

Department of Ophthalmology, Matsumoto Dental University, Shiojiri, Nagano, Japan

Purpose: To describe the morphology of the retina at the convalescent stage of acute zonal occult outer retinopathy (AZOOR) from images obtained by spectral domain optical coherence tomography (SD-OCT).

Methods: The visual fields, electroretinograms (ERGs), and OCT images were reviewed in two women aged 24 and 33 years. The patients were followed for one and four years, respectively.

Results: In both cases, the anterior and posterior segments were almost normal, although both patients had a sudden unilateral vision decrease and photopsia. Goldmann perimetry revealed enlarged blind spots and scotomas. The ERGs were reduced in both cases. SD-OCT showed that the junction of the inner and outer segment, the IS/OS line, of the photoreceptors was irregular or lost in the affected retinas. The retina in these areas was thinner due to a decrease in the thickness of both the outer nuclear layer (ONL) and inner nuclear layer (INL) in Case 2.

Conclusions: The decrease in retinal thickness at the convalescent stage of AZOOR is most likely due to a shortening of not only the photoreceptors and ONL but also to a thinning of the INL in a severe case.

Keywords: AZOOR, SD-OCT, IS/OS, ONL

General overview: Acute zonal occult outer retinopathy (AZOOR) occurs in younger women, and is characterized by an acute decrease of retinal function of the outer layers of the retina, photopsia, minimal funduscopic changes, and electroretinographic (ERG) abnormalities. An earlier time-domain optical coherence tomography (OCT) study found an absence or irregularity of the inner and outer segment of the photoreceptors (IS/OS) line was observed in AZOOR. Recent higher resolution images obtained by the spectral-domain OCT also showed a thinning of the affected retina, but the images were obtained by a single scan. The mean retinal thickness map in two patients with AZOOR at the convalescent stage were examined by newly available Spectralis OCT. We found a reduced retinal thickness. The reduction is due not only to a shortening of the outer segments of the photoreceptors and the outer nuclear layer, but also the inner layer in a severe case.