Accommodative convergence in hypermetropia

It has been reported that uncorrected farsightedness, or hypermetropia, (reduced ability to see objects that are close to the eyes) can cause esotropia, the inward turning of one eye relative to the other. This may be due to excessive accommodation, the process of adjustment of the eye to variations in distance. The authors had observed patients with uncorrected farsightedness who made a great effort of accommodation to obtain 20/20 vision, yet had little or no esotropia. A study was undertaken of nine children with no history of esotropia or any kind of strabismus (crossed eyes), no previous correction of farsightedness, no anisometropia (difference of refractive powers of the eyes), and minimal or no esotropia. There was a control group of 30 children with esotropia corrected by wearing glasses. These two groups were compared for clinical characteristics. In addition to the usual eye examination, information was gathered on stimulus accommodation convergence/accommodation (AC/A) ratio, near point of accommodation, and stereoacuity (accuracy of three-dimensional vision). The farsighted patients without esotropia had a low AC/C ratio compared with the patients who had esotropia corrected by glasses. This finding explains why esotropic deviations may not be found in some farsighted patients without vision correction. Both groups of patients showed defective or absent three-dimensional vision. It is recommended that optical correction be performed in children under the age of four even when there is no evidence of esotropia. (Consumer Summary produced by Reliance Medical Information, Inc.)