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Accommodative error, adaptation and myopia
Author(s) -
Rosenfield Mark,
Gilmartin Bernard
Publication year - 1999
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.1475-1313.1999.00419.x
Subject(s) - accommodation , adaptation (eye) , task (project management) , fixation (population genetics) , optometry , psychology , near vision , audiology , ophthalmology , medicine , visual acuity , neuroscience , population , management , environmental health , economics
Summary Accommodative adaptation, resulting from the sustained output of slow blur‐driven accommodation during the course of a sustained near‐vision task, has generally been assessed under open‐loop conditions. This study examined whether adaptation influences closed‐loop accommodation during the course of a sustained near‐vision task. Accommodative adaptation was assessed in 18 fully‐corrected subjects by comparing pre‐ and post‐task values of dark accommodation recorded objectively with an infra‐red optometer. Subjects performed a continuous 10 min binocular near‐vision task at a viewing distance of 33 cm, with the within‐task accommodative response being assessed at 1 min intervals during this period. Subjects were categorized into adaptors ( N =11) and non‐adaptors ( N =7) on the basis of whether their initial 10 sec post‐task adaptation exceeded +0.30D. The adapting group exhibited a significant decline in the lag of accommodation during the first 3 min of the near‐task, whereas no significant change in the within‐task response over time was observed in the non‐adapting group. These results indicate that accommodative adaptation increases the accuracy of the within‐task, closed‐loop accommodative response. Furthermore, we speculate that a deficit in accommodative adaptation, being accompanied by increased retinal defocus during near fixation, may contribute to the development of nearwork‐induced myopia.