Study on the changes in astigmatism with accommodation

Objective To investigate the changes in ocular astigmatism which were induced by the accommodation stimulus range of 1-5D. Methods This was a prospective case-control study.Forty-nine eyes of 49 normal subjects aged 23-36 years,with the best spectacle corrected visual acuity (better than 1.0).The changes of spherical and cylindrical refractive errors were measured by an open-field infrared autorefractor. Results It was found that,for most subjects in the group,the mean sphere change being (-0.932±0.165)D (F=-41.98,P =0.000),astigmatism changed in the with-the-rule direction,the mean J0 change being (0.047±0.092)D,the mean J45 change being (-0.011±0.067)D,for each diopter of accommodation response.The change of J0 was larger than the change of J45 (F =3.865,P =0.000),when effective accommodation stimulus were provided range of 1-5D. Conclusions The changes of astigmatism might reflect increases in lens tilt about a horizontal axis,caused by the combined effects of a slacker zonule and gravity.The changes in lens tilt will be expected to produce changes in with-the-rule astigmatism. Key words: Astigmatism; Accommodation; Eye