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L. P. Cunha, M. K. Oyamada, M. L. R. Monteiro; Diagnostic Ability of Multifocal Pattern Electroretinograms to Detect Hemianopic Neural Loss in Band Atrophy of the Optic Nerve. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5378.
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The multifocal pattern electroretinogram (mfPERG) is a recently available electrophysiological test that allows functional assessment of retinal ganglion cells. Band atrophy (BA) of the optic nerve from chiasmal compression, may serve as a model for evaluating the ability of any instrument to accurately measure ganglion cell function. The purpose of this study was therefore to evaluate the ability of mfPERG parameters to discriminate eyes with BA of the optic nerve from normal controls and to investigate whether mfPERG is able to detect hemianopic neural loss in eyes with temporal hemianopia.
Twenty-three eyes from 23 consecutive patients with permanent temporal hemianopic visual field defects and BA of the optic nerve from previous chiasmal compression and 23 healthy subjects were studied prospectively. A RETIScan system was used to generate a stimulus pattern of 19 hexagons. Responses were analyzed in three ways: one 19-hexagons summation and two hemianopic analyses, one nasal and one temporal. Amplitudes and peak times for the P50 and N95 response as well as the overall P50+N95 amplitude were measured. Comparisons were made using Student’s t test. Receiver operating characteristic (ROC) curves were used to describe the ability of mfPERG parameters to discriminate eyes with BA from controls.
For both total field and nasal hemifield responses, only N95 amplitude was significantly smaller in eyes with BA. However, in the temporal hemifield analyses, P50, N95 and P50+N95 amplitudes parameters showed statistically significant reduction in eyes with BA. The areas under the ROC curves (AUCs) for the best discriminating mfPERG parameters were in temporal hemifield analysis. Intra-ocular comparison between nasal and temporal parameters showed that the P50, N95 and P50+N95 amplitudes were significantly lower in the temporal hemifield of eyes with BA, while in normal controls, no significant difference was observed.
Multifocal pattern electroretinogram amplitude measurements were efficient at differentiating eyes with BA of the optic nerve from normal controls. The test was able to detect hemianopic neural loss with good agreement with the pattern of visual field defect and seems to be a promising instrument to identify localized neural loss in anterior pathway diseases.
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