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Visual acuity and the accuracy of the accommodative response
Author(s) -
Subbaram Manoj V.,
Bullimore Mark A.
Publication year - 2002
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.1475-1313.2002.00037.x
Subject(s) - visual acuity , accommodation , optometry , ophthalmology , refractive error , pupil , psychology , near vision , medicine , audiology , neuroscience
Previous investigators have observed that some subjects show large amounts of accommodative lag. We hypothesized that less accurate accommodation might be associated with poorer visual acuity and/or smaller pupil sizes. Sixty subjects (30 emmetropes and 30 myopes) aged 20–30 years, participated. All had best‐corrected visual acuity of 6/6 or better [mean=−0.10 ± 0.07 logarithm of the minimum angle of resolution (logMAR)]. Subjects monocularly viewed reduced Bailey–Lovie charts through a +6.50 D Badal lens on a Canon R1 auto‐refractor. Visual acuity, accommodative response and pupil diameter were measured for 0, 2 and 4 D accommodative stimuli. For accommodation measurements ( N =10) subjects were instructed to fixate the smallest letters that they could read. The mean accommodative response was +0.22 ± 0.28, +1.83 ± 0.23 and +3.71 ± 0.27 D for the 0, 2 and 4 D stimuli, respectively. The mean visual acuity was −0.06 ± 0.10, −0.11 ± 0.07 and −0.11 ± 0.07 logMAR for the 0, 2 and 4 D stimuli, respectively. Visual acuity for the 0 D stimulus was significantly poorer than for other conditions ( p < 0.001) and associated with increased accommodative lead ( p < 0.01). There was also an association between visual acuity and accommodative response (or lag) for the 4 D stimulus ( p =0.002). The emmetropes showed significantly better visual acuity than the myopes ( p =0.004). No significant difference was observed in the accommodative response between emmetropes and myopes. Pupil diameter was not associated with the accuracy of the accommodative response ( p > 0.17). Increased accommodative lead (0 D stimulus) and accommodative lag (4 D stimulus) are associated with decreased visual acuity. Smaller pupil diameters are not associated with increased accommodative lag.