the effect of cycloplegia on ocular alignment and ac/a ratio

Purpose: the present study sets out to investigate the effect of cyclopentolate-induced cycloplegia on distance and near deviation and the accommodative convergence/accommodation (ac/a) ratio. methods: this prospective study was performed on 30 subjects. the inclusion criteria included a lack of any active ocular pathology and systemic diseases, no history of ocular surgery, and nonuse of various medications. refraction, near and distance deviation were measured for all subjects, and the same examinations were repeated after the administration of two drops of cyclopentolate 1% to both eyes. results: the obtained data from 30 subjects, including 19 males, with a mean age of 22.53 ± 1.74 years were analyzed. the mean ± sd of near deviation in dry and cycloplegic conditions were –6.9 ± 8.1 and +6.4 ± 9.1 prism diopters, respectively, which were statistically significant (p < 0.001). distance deviation in cycloplegic conditions demonstrated an average difference of 0.8 prism diopters, compared to dry conditions ( 0.001). ac/a ratios were 4.7 ± 2.5 and 9.7 ± 3.9 (δ/d) in non-cycloplegic and cycloplegic conditions, respectively, which was a statistically significant difference (p < 0.001). the multiple regression indicated that among all under study variables, refraction (b coefficient: –2.4; (p < 0.001) and near pre-cycloplegic deviation (b coefficient: 0.56; (p < 0.001) were significantly associated with post-cycloplegic near deviation. conclusion: the results of this study indicated that cycloplegia causes a considerable esophoric shift in near deviation and a negligible esophoric shift in distance deviation. as a result, the ac/a ratio demonstrated a significant increase due to unequal changes in near and distance deviation.