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P. M. Faria, Fá. Silva, C. Mateus, A. Reis, M. Castelo-Branco; Local Motion Discrimination Deficits in Ocular Hypertension. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1637.
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Both local and global motion perception deficits have been described in glaucoma. The goal of this work was to evaluate local speed discrimination deficits in individuals with ocular hypertension using a psychophysical technique that provides relative isolation of the magnocellular pathway. We also attempted to correlate local motion discrimination deficits with other structural and functional markers of ganglion cell damage
A computorized Local Speed Discrimination Task, based on velocity comparisons of two widely separated dots, moving with random trajectories, was used to measure local motion sensitivity accross four meridians (horizontal, vertical, 45 and 135º) with eccentricities between 7.5 e 15º). Study population - Individuals with ocular hypertension (n=16 eyes), with exclusion of any other ocular pathology. Control group: individuals with normal ophthalmological examination (n=16 eyes). We have also obtained structural and functional markers of optic neuropathy: optical coherence tomography and perimetric constrast sensitivity measures.
Local speed discrimination thresholds were significantly higher in the ocular hypertensive group, comparing the control group, for the following meridians: 45º (p=0,0169, Mann-Whitney Test), 135 (p=0,0179) and vertical (p=0,044). At the horizontal meridian, and a relatively small (7.5º) excentricity, the effect did not reach statistical significance. (p=0,3047). Our motion discrimination measures provide added values to other structural and functional markers of ganglion cell damage.
Our results indicate the presence of local speed discrimination deficits in ocular hypertension, in outer macular regions (up to 15º) regions of the visual field. This suggests that local speed discrimination deficits are a good indicator of early involvement of the visual magnocellular pathway in glaucoma.
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