Variation in stereoacuity in the human population including fixation disparity, and the roles of aging and gender.
Item
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Title
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Variation in stereoacuity in the human population including fixation disparity, and the roles of aging and gender.
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Identifier
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AAI9997133
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identifier
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9997133
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Creator
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Zaroff, Charles M.
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Contributor
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Adviser: Thomas F. Frumkes
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Neuroscience | Psychology, Experimental
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Abstract
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Stereoacuity functions were obtained with a forced-choice staircase procedure in observers whose corrected visual acuity in each eye was at least 20/30. Accordingly, threshold disparity for detecting a 2.78° x 2.28° rectangular test stimulus was determined as a function of the disparity (varied in 11 arcminute steps from 55 arcmin uncrossed to 55 arcmin crossed) of a 5.57° x 4.8° rectangular pedestal. Stimulus duration was 100 milliseconds (ms) preventing vergence eye movements. Ordinate and abscissa values of the nadir of stereoacuity functions are defined respectively as, the observer's optimal stereoscopic threshold and fixation disparity.;Optimal stereoacuity was examined in 160 observers ages 15--79 years. When plotted logarithmically, 100 ms duration thresholds for observers <60 years of age approximated a normal distribution (mean = 1.57 log arcsec [37 linear arcsec]; standard deviation = 0.227 log arcsec). Normal stereoacuity involves thresholds between +/-2 standard deviations of the log mean (13--109 linear arcsec). For observers less than 60 years, 1% were supernormal, 88% were within the normal range, 2% had thresholds greater than 109 arcsec, 8% failed testing with 100 ms stereograms but had residual binocular depth discrimination, and 1% were stereoblind. For observers aged 60--69, 37% were stereo normal, 42% completed testing with 100 ms stimuli but with thresholds greater than 109 arcsec, while 21% were still more stereo impaired. For observers aged 70--79, 25% were stereo normal, 25% had thresholds with 100 ms stimuli greater than 109 arcsec, while 50% were still more stereo impaired. The correlation between optimal stereo threshold and age was statistically significant and involved no significant gender differences. Age-related deterioration in stereoacuity probably reflects: (a) an underlying linear correlation between age and threshold; and additionally (b) a catastrophic factor producing more marked deterioration whose incidence increases greatly after age 60.;Fixation disparity was examined in 151 observers with optimal stereo threshold values ≤108 arcsec. Approximately half were maximally sensitive with no pedestal disparity; 89% were maximally sensitive to disparities within 11 arcmin of the fixation plane. Males were more likely to be maximally sensitive to uncrossed-, while females were more likely to be maximally sensitive to crossed-disparities. All males were maximally sensitive to pedestals within 22 arcmin of the fixation plane, while 8% of female observers had fixation disparities >22 arcmin. These gender differences were statistically significant and unrelated to age.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
