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Relationship between visual acuity and observation distance
Author(s) -
Heron G.,
Furby H. P.,
Walker R. J.,
Lane C. S.,
Judge O. J. E.
Publication year - 1995
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 - 10.1046/j.1475-1313.1995.9592788.x
Subject(s) - accommodation , autorefractor , visual acuity , vernier acuity , stimulus (psychology) , optometry , retinoscopy , near vision , psychology , audiology , refractive error , ophthalmology , medicine , neuroscience , psychotherapist
Summary The visual acuities of 17 young emmetropes and corrected ametropes were measured over the range of 7.5–0.19m using a Bailey‐Lovie chart. Accommodation stimulus‐response measures were also taken over this range using retinoscopy to establish whether variations in visual acuity with observation distance could be attributed to accommodation behaviour. Tonic accommodation was recorded using the Canon R1 autorefractor and was compared with visual acuity and stimulus‐response results. In general, visual acuity was found to be dependent on stimulus distance, being significantly reduced for most observers for the closest targets. There were three categories of observer performance for visual acuity as a function of observation distance; one group showing no change in visual acuity with distance, a second showing a flat function for distances 7.55–0.5m, and then a decrease in visual acuity for shorter distances; and a third category that showed a maximum visual acuity in the 1.2–1.6m region. This behaviour was unrelated to individual stimulus‐response characteristics and there was no significant relationship between tonic accommodation and the distance where acuity was best for the third category observers.