First Author: K.Schuerch SWITZERLAND
Co Author(s): K. Boudreault W. Lee T. Duncker S. Tsang J. Sparrow
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In patients with acute zonal occult outer retinopathy (AZOOR) spectrum disorder, we analyzed short wavelength fundus autofluorescence (SW-AF) images by quantitative fundus autofluorescence (qAF). To correlate structural changes with aberrant SW-AF signal we also analyzed scans acquired by spectral domain-optical coherence tomography (SD-OCT).
Patients were recruited prospectively in the Department of Ophthalmology, Columbia University Medical centre.
In 6 patients (aged 26-61 years) having a diagnosis of unilateral (5) or bilateral (1) AZOOR, SW-AF images (486 nm excitation) were acquired with a confocal scanning laser ophthalmoscope (Heidelberg HRA+OCT) equipped with an internal fluorescent reference to permit qAF analysis. In unaffected regions of the macula, qAF was calculated within 8 pre-determined circularly-arranged segments positioned at an eccentricity of 7-9°. Within the visible hyperautofluorescent lesion border (AZOOR line), and nasal and temporal to the border, qAF was also determined using a region of interest (ROI) approach (ROI-qAF). For both groups, qAF in AZOOR patients was compared to age-similar and race/ethnicity-matched healthy eyes at equivalent retinal locations. ROI-qAF positions also corresponded to locations traversed by horizontal SD-OCT scans. Full-field electroretinograms (FfERGs) were recorded from both eyes of 5 subjects.
In SW-AF images, 5 of 6 patients exhibited a hyperautofluorescent border (AZOOR line) delineating the peripapillary lesion. Mean ROI-qAF measured on the AZOOR line in the patient cohort was significantly elevated (p=0.025, linear mixed model), compared to age and race-matched controls at the same location. qAF8 within non-diseased macular regions was within the normal range. At the lesion border SD-OCT revealed a progressive loss of outer retinal layer integrity in all patients. Single flash cone and maximal ERG responses were significantly lower in the affected eye as compared to the fellow (healthy) eye (p=0.02 and p=0.02). The EOG light to peak ratio (Arden ratio) was lower in proportion to ERG responses in only one patient. All other patients presented with normal (>1.8) or subnormal ratios (1.6-1.8) that were symmetrical between fellow eyes. Lesions with smooth, homogeneous borders showed only minimal expansion in size over time, while a heterogeneous border progressed more rapidly.
In AZOOR patients, qAF is elevated at the border between diseased and non-diseased retina.