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H. Morris, A.R. O'Connor, Functional Significance of Stereopsis InvestigatorGroup; Binocular vs Monocular Performance of Fine Motor Skills Tasks . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2448.
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© ARVO (1962-2015); The Authors (2016-present)
Many decisions surrounding the management of strabismus are based around the assumption that stereopsis is beneficial; however there is limited evidence to prove whether this assumption is true. In order to explore this concept, subjects with no manifest ocular motor deviation carried out tasks that require fine motor skills and their binocular and monocular performances were compared.
Motor skills were assessed using 3 methods: Purdue Pegboard (number of pegs placed in holes during 30 second period), threading large beads onto a large needle (time taken in seconds to place 30 beads) and a relatively more difficult task involving threading small beads onto a small needle (time taken in seconds to place 22 beads). Forty subjects aged 14–26 years performed each test 3 times under binocular conditions and 3 times under monocular conditions. The subjects had no ocular motor deviation, based on responses from the Cover Test, Ocular motility assessment and 4Δ prism test. Levels of stereoacuity ranged from 120–15'' with a median of 60'' on TNO and from 200–10'' with a median of 20'' on Preschool Randot stereotest. A paired samples t–test was used to analyse the differences in binocular and monocular performances on each of the 3 tests.
These findings indicate that there is a statistically significant difference between the binocular and monocular conditions. Under monocular conditions the deficit was greater with the small bead task compared to the large bead task suggesting that the deficit increases with the increased difficulty of the task.
These data demonstrate that the presence of stereopsis provides a quantifiable benefit to carrying out tasks that require fine motor skills, and suggests that the magnitude of the stereoscopic deficit under monocular conditions is directly related to the difficulty of the task.
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