Loss of visual acuity is the main reason why reading addition increases after the age of sixty

Citation
Es. Macmillan et al., Loss of visual acuity is the main reason why reading addition increases after the age of sixty, OPT VIS SCI, 78(6), 2001, pp. 381-385
Citations number
15
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Optalmology
Journal title
OPTOMETRY AND VISION SCIENCE
ISSN journal
1040-5488 → ACNP
Volume
78
Issue
6
Year of publication
2001
Pages
381 - 385
Database
ISI
SICI code
1040-5488(200106)78:6<381:LOVAIT>2.0.ZU;2-Y
Abstract
Purpose. To determine why the reading addition increases after the age of 5 5 to 60 years when accommodation is zero. Methods, Distance and near visual acuities, arm length, habitual near working distance, reading addition, an d pupil diameter were measured in 44 subjects aged >60 years (mean, 72.9 +/ - 5.7). Reading addition Values were attained using three techniques: least -plus addition using both N-notation text and MN-READ text and the cross-cy linder technique. Results. The mean dioptric working distance was 2.75 +/- 0.40 D. The reading addition found using N-notation text (+2.21 +/- 0.38 D) was significantly lower than that measured using MN-READ text (+2.48 +/- 0 .49 D) or the cross-cylinder method (+2.53 +/- 0.44 D). The reading additio n was positively correlated with the dioptric working distance (r = 0.47, p < 0.01), and decreasing habitual working distance was associated with poor er visual acuity (r = -0.42, p < 0.01). Conclusions. Our results suggest th at decreases in near visual acuity after 60 years of age lead to a reductio n in habitual working distance, which increases text angular subtense. In t urn, the reduced working distance requires a greater reading addition. Incr eases in depth of field associated with both suprathreshold text (N-notatio n) and lower visual acuity lead to reading additions being less than the di optric working distance.