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Contribution of accommodation and disparity‐vergence to transient nearwork‐induced myopic shifts
Author(s) -
Rosenfield Mark,
Ciuffreda Kenneth J.,
Novogrodsky Lisa
Publication year - 1992
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1992.tb00312.x
Subject(s) - accommodation , vergence (optics) , refractive error , near vision , stimulus (psychology) , optometry , psychology , optics , audiology , physics , cognitive psychology , medicine , visual acuity
Many investigations have attempted to demonstrate a relationship between sustained near‐vision and the aetiology of environmentally‐induced myopia, but it remains unclear whether myopic development relates to the actions of either accommodation or vergence. The present study investigated the effect of varying the disparity‐vergence demand during a near‐vision task while maintaining the accommodative stimulus constant. We required 20 young subjects to perform a near task (viewing distance = 20cm) for 20 min through base‐in, zero power and base‐out prisms. The magnitude of the prisms for each individual corresponded to one‐third their near vergence range. Pre‐ and post‐task measurements of refractive state were determined objectively using an infrared optometer, with post‐task readings being recorded over the initial 50s following task completion. The results indicated no significant difference between the transient far‐point shift for the three disparity‐vergence conditions. However, combining data across conditions, a significant, mean shift in the myopic direction of 0.14 D was observed during the 10–20 s period immediately following task completion which dissipated within 20–50 s post‐task. These findings suggest that the transient post‐task myopic shift was not related lo the output of disparity‐vergence.