Clinical analysis of acute zonal occult outer retinopathy masquerading as optic neuropathy

Abstract

To analyze the clinical features of acute zonal occult outer retinopathy (AZOOR) and the reasons for misdiagnosing as optic neuropathy or intracranial lesions. Case series study. Twenty patients (23 eyes) who were all initially diagnosed as optic neuropathy or intracranial lesions were recruited in the ophthalmologic department of Beijing Tongren Hospital from November 2003 to June 2012, but they were ultimately diagnosed as AZOOR after the examinations including regular eye examination, fundus fluorescein angiography (FFA), optical coherence tomography (OCT), automatic perimetry, flash electroretinogram (F-ERG),multifocal electroretinogram (mfERG),systemic rheumatism immunological examination and neuroimaging. These 20 patients with an average age of 32.9 years (range 15 to 55 years) consisted of 17 females (85%) and 3 males (15.0%). Among them, 17 patients (85.0%) were affected unilaterally, while 3 patients (15.0%) were affected bilaterally. Sixteen of 23 eyes (69.6%) had myopia. Ten eyes (58.8%) showed relative afferent papillary defect. Inflammatory response was not found by slit lamp and fundus examination. Besides the other abnormal fundus changes of high myopia, fundus angioid streaks were found in 4 eyes and retinal pigment epithelium dystrophy was found in 3 eyes by fundus examination. FFA revealed that there was mild fluorescein leakage around the retinal vascular arch in one eye. The patterns of visual field detect in these patients were various, while temporal scotoma and blind spot enlargement were most common. Twelve of 14 patients who had been performed F-ERG showed abnormal F-ERG. mfERG of all patients showed the decreased amplitude densities of the retina in accordance with the areas of visual field defect. IS/OS layer of 17 patients who went through OCT examination were found abnormal in the corresponding areas of visual field defect. Neuroimaging examination revealed there was nothing abnormal in the patients who were diagnosed as intracranial lesions. Immunological parameters in these patients were almost normal except for one patient with an increased level of rheumatoid factor. AZOOR patients in this study rarely has ocular or systemic inflammatory. AZOOR occurs predominantly in the unilateral eye of young female patients, and are easily misdiagnosed as optic neuropathy due to the almost normal appearances of fundus. The examinations of retinal functional and morphological changes are the key to its diagnosis and differential diagnosis.