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H.K. Rentmeister-Bryant, W.R. Elliott, R. Hatcher, H. Zwick; Contrast/Acuity Threshold Testing and Simultaneous cSLO Retinal Imaging in Task Oriented Rhesus Monkeys . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4960.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We have developed a non-human primate (NHP) model to study the effects of acute retinal laser injury on visual function and oculomotor behavior in awake, task oriented Rhesus monkeys. Combining an in vivo, non-invasive ocular imaging device with a behavioral task, we have proven the feasibility this model for laser injury studies (Elliott et al., 2000, ARVO). In preparation for the use of this model to study the effects of long-term low level Q-switched laser exposures on the primate eye, we have developed a procedure for the measurement of contrast sensitivity thresholds. Methods: Subjects were three adult Rhesus monkeys, two female and one male. Through a multi-step program of operant conditioning, the subject’s behavior has been shaped to perform a modified Reaction Time Observing Response task (RTOR).The Landolt ring stimuli for this task were presented in the raster scan of a Rodenstock cSLO and varied in size and contrast. The use of a novel variable reward ratio and multiple supra-threshold stimuli allows the repeated measurement of contrast thresholds at 5 different spatial frequencies (gap size) each day. Stimuli were controlled and responses recorded using a custom designed computer program. Contrast thresholds for spatial frequencies ranging from 0.5-10 cylcles per degree were measured. The cSLO stimulus presentation allows high quality retinal imagery in the alert subjects while performing the acuity/contrast sensitivity task. From the retinal images provided by on-line cSLO imaging, oculomotor behavior and preferred retinal location can be derived. Results: Although inter- and intra-subject variability in viewing behavior existed, all three subjects were tested at threshold in both eyes for 5 spatial frequencies. Peak contrast sensitivity ranged from 3 to 5 cycles/degree. Conclusions: Robust performance and detailed imagery give this model powerful capability for measuring laser induced visual deficits and reasonable peak contrast sensitivities for the luminance levels provided by the cSLO raster scan.
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