Under binocular viewing conditions, myopic children when viewing the target through fully correcting glasses tend to show larger lags of accommodation than emmetropic children, but the lags of accommodation are usually reduced by their spectacle undercorrection.

No abstract

A model of the cross-link interactions between accommodation and convergence predicted that heterophoria can induce large accommodation errors (Schor, Ophthalmic Physiol. Opt. 1999;19:134-150). In 99 consecutive patients with intermittent tropia or decompensated phoria, we tested these interactions by comparing their accommodative responses to a 2.50-D target under binocular fused conditions (BFC) and monocular occluded conditions (MOC). The accommodative response in BFC frequently differed from that in MOC. The magnitude of the accommodative errors in BFC, ranging from an accommodative lag of 1.80 D (in an esophoric patient) to an accommodative lead of 1.56 D (in an exophoric patient), was correlated with distance heterophoria and uncorrected refractive errors. These results indicate that heterophoria affects the accuracy of accommodation to various degrees, as the model predicted, and that an accommodative error larger than the depth of focus of the eye occurs in exchange for binocular single vision in some heterophoric patients.

The CA/C ratio, like the AC/A ratio, is an independent parameter that characterizes clinical features. A lower CA/C may be beneficial for the vergence control system to compensate for ocular misalignment with minimum degradation of accommodation accuracy.

The measurements reported herein will serve as a basis for assessing changes that occur over a 3-year follow-up period. Compared with the baseline measurements in the Correction of Myopia Evaluation Trial, clear differences were observed in the mean cycloplegic autorefraction and distance prescriptions. The accommodation and heterophoria data showed characteristics similar to those recently reported in myopic children abroad.