Copyright, © 1993 AMERICAN ACADEMY OF OPTOMETRY Decreased Uncorrected Vision After a Period of Distance Fixation with Spectacle Wear

Myopes of low degree commonly report that their vision seems poorer upon removal of their spectacles com-pared to that after a period without spectacle wear. Notably, this difference in vision can he appreciated after distance fixation. In this paper, we propose and test several alternative hypotheses to explain the phe-nomenon: an accommodative response to spectacles, sensory adaptation, or altered criteria for blur of psy-chological origin. We measured visual acuity (VA), re-fractive error, and lens thickness on 10 subjects with less than 2.00 D of myopia. Testing was performed after two 90-min sessions viewing at distance. At one session, the subjects wore their current spectacle cor-rection and, at the other session, no correction was worn. VA underwent a slight but significant decrease (0.4 of a line) after the session in which spectacles were worn, but no difference in refractive error or lens thickness was found. The change in acuity in the ab-sence of a refractive shift suggests sensory adaptation to blur. However, the demonstrated change in VA ap-pears to be less than that which is subjectively re-ported; accordingly, psychological input cannot be ruled out. Key Words: myopia, adaptation, accommodation, spec-tacle wear, blur Clinicians commonly encounter patients who be-lieve that wearing spectacles makes their vision worse. The patient may report poorer vision after spectacle removal compared with that achieved fter an extended period without spectacle wear. Such reports are common and have been seized upon by authors such as Bates1 and MacFadden2 as evidence that spectacles are harmful to the eyes. Despite these claims, this phenomenon has not been subjected to scientific scrutiny. It has been demonstrated that a moderate period of nearwork will lead to an increase in accommo-dative tonus.3-6 Clearly, this increased tonus ha