Abstract
Abstract: :
Purpose: To use optical coherence tomography (OCT) and the Multi–focal Electroretinogram (MERG) to differentiate optic neuritis from retinal disorders. To determine whether the OCT may be used to meausure retinal nerve fiber layer (RNFL) thinning over time after a bout of optic neuritis. Methods: Sixteen patients were initially diagnosed with unilateral monophasic optic neuritis. Patients were included if they had decreased visual acuity, a relative afferent pupil defect, color vision loss, a visual field defect, and a compatible fundus examination. All 16 patients underwent a complete evaluation of Snellen visual acuity, color vision (Ishihara plates), quantification of the relative afferent pupil defect (log units), Humphrey perimetry, dilated ophthalmoscopy and testing with Stratus OCT (version 3). Four patients underwent additional MERG testing. Results: Twelve patients (10 females, mean age 38 years, range 14– 51 years) had a confirmed diagnosis of unilateral monophasic optic neuritis. In all of 12 cases, OCT testing demonstrated thinning of the RNFL after 3 or more months (mean loss of 23 microns, range 5– 44 microns) as compared to the affected eye and normative data from age–matched controls. Five patients with confirmed optic neuritis were tested at 3 month intervals, and RNFL losses were observed as early as 3 months, and progressed to 6 months after a bout of optic neuritis. Four patients (all female, mean age 42, range 18–60 years) did not develop RNFL thinning in the affected eye after a year of follow up. In all 4 cases, MERG testing demonstrated outer retinal dysfunction in the affected eye. The presumptive diagnosis in 3 of these 4 cases was acute zonal occult outer retinopathy (AZOOR). Conclusions:Optical coherence tomography and the Multifocal Electroretinogram may be used to differentiate optic neuritis from retinal disorders. OCT testing can quantify RNFL thinning after an optic neurits event, and help distinguish cases of optic neuritis from retinal disorders. MERG and OCT testing may distinguish diseases of the outer retina from disorders of the ganglion cells and/or optic nerve.
Keywords: optic disc • electroretinography: clinical • retina