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E. A. Dale, K. Y. Kay, J. G. Odel, V. Greenstein, D. C. Hood; A Comparison of Multifocal ERG and Frequency Domain OCT Changes in Patients With Abnormalities of the Outer Retina. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4032.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the ability of the multifocal electroretinogram (mfERG) and frequency-domain optical coherence tomography (fdOCT) to detect retinal abnormalities.
Between Oct. 2007 and Nov. 2008, 61 patients (9 to 79 years of age) were referred for mfERG and fdOCT testing to rule out or confirm a retinal etiology of visual loss. Patients were evaluated with mfERG (103 scaled hexagons, VERIS, EDI) and fdOCT (optic disc circular, macula 3D and horizontal line scans, 3DOCT-1000, Topcon). Amplitude and latency changes of the mfERG responses, known to indicate outer retinal abnormalities, were analyzed. The fdOCT scans were examined for changes in the outer retina (RPE, receptor and/or inner nuclear layers). Local regions of abnormal mfERG or fdOCT were compared to local regions of visual field sensitivity loss measured with static automated perimetry (24-2 Humphrey, Zeiss). The mfERG results were categorized as: 1. Normal (normal amplitude and latency); 2. Abnormal (abnormal amplitude and latency consistent with the visual field defect); or 3. Inconclusive (subtle changes or local changes that did not topographically agree with the visual field defect). The fdOCT results were categorized as: 1. Normal (normal outer retina); 2. Abnormal (abnormal outer retina consistent with the visual field defect); or 3. Inconclusive (see above).
A total of 35 eyes (24 patients) were categorized as having an abnormal outer retina based upon either the mfERG or fdOCT. Eighteen of these 35 eyes (13 patients) were abnormal on both mfERG and fdOCT. Twelve eyes (8 patients) had an abnormal mfERG, but a normal fdOCT scan. Five eyes (5 patients) had an abnormal fdOCT scan, but a normal (2 eyes/2 patients) or inconclusive (3 eyes/3 patients) mfERG. The group of 16 patients with abnormal mfERG and normal fdOCT included cone-rod dystrophy, AZOOR, vascular damage, age-related macular degeneration and acute idiopathic blind spot enlargement, while the group of 5 patients with abnormal fdOCT and normal mfERG included local foveal problems (4 patients) and local vascular damage (1). Further, a retinal etiology could not be confirmed in the remaining 37 patients due to normal mfERG and fdOCT results and/or results that did not agree with visual field defects.
Although the mfERG and fdOCT results typically agree, some retinal abnormalities are more easily detected in the mfERG, while others may be more apparent on fdOCT. Examination of the cases in which there were clear mfERG changes, but subtle fdOCT changes, improved our ability to detect abnormalities with fdOCT scans.
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