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A. Klistorner, H. Arvind, J. Grigg, S. L. Graham; Selective Stimulation of Non-Redundant Pathways Enhances the Detection of Glaucoma Using Multifocal Vep. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5489.
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In a recent study, we demonstrated superior performance of Blue-on-Yellow pattern-onset multifocal VEP in identifying glaucomatous visual field defects as compared to black and white pattern-reversing checkerboard stimulation. We hypothesized that Blue-on-Yellow stimulation specifically targets non-redundant koniocellular visual pathways, enhancing identification of early losses. Current study was aimed at investigating comparative sensitivity of various pathways using temporally similar (pattern-onset) stimulus presentation technique.
23 patients with early perimetrically proven glaucoma (MD < 6 dB, repeatable defects) underwent mfVEP using three different pattern-onset stimulation conditions: high (98%) luminance contrast achromatic (HC), low (50%) luminance contrast achromatic (LC) and Blue-on-Yellow (BonY) stimulation to preferentially stimulate parvocellular, magmocellular and koniocellular pathways respectively. The order of tests was randomized. Normal database (30 healthy subjects) was constructed for each test condition.
The HVF identified scotomas in 28 eyes of the 23 patients. 21 of the scotomas were identified by HC mfVEP (75%), 26 were identified by BonY (93%) and all 28 (100%) by LC mfVEP. Comparison of defect severity using Accumap Severity Index (ASI) demonstrated largest averaged value for LC (62.7 + 28.5), followed by BonY (56.5 + 28.8) with HC showing less abnormality (41.5 + 31.5). ANOVA revealed significant differences between the groups, with LC and BonY ASI values significantly larger than HC (p<0.001 and p<0.01 respectively), but no significant difference between LC and BonY (p=0.16).
Both BonY and LC achromatic mfVEP performed significantly better than HC pattern-onset stimulation in identifying early glaucomatous defects. Enhanced performance of BonY and LC may be attributed to non-redundancy of the koniocellular and magnocellular pathways.
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