Dark focus of accommodation in children with accommodative esotropia and hyperopic anisometropia.

We evaluated the dark focus of accommodation, referred to as tonic accommodation, in 60 young hyperopic subjects, 20 with and 20 without accommodative esotropia, and 20 with hyperopic anisometropia. We measured the distance, dark, and cycloplegic refractive errors by the Nidek Autorefractometer AR1600. The difference between dark and cycloplegic refractive errors was defined as the dark focus. The dark focus was significantly larger in esotropic eyes than in non-esotropic eyes, despite similar cycloplegic refractive errors in both types of eyes, suggesting that tonic accommodation may be associated with ocular position. The dark focus was similar in eyes of the same subjects with hyperopic anisometropia and also in normal and amblyopic eyes, suggesting that tonic accommodation is similar in both eyes in subjects with anisometropia and amblyopia.