Prevalence of monocular amblyopia among anisometropes

Some 167 subjects showing anisometropia of at least 2 D, were selected from the records of the eye clinic of the Ramathibodi hospital in Bangkok, Thailand and 472 subjects showing anisometropia of at least 1 D were selected from the clinic records of the Indiana University, School of Optometry. The incidence of amblyopia (20/30 or less) was found to be 100% among least meridional hyperopic anisometropes of 3.5 D and greater, and among myopic anisometropes of 6.5 D and greater. Lower levels of anisometropia showed a smaller proportion of amblyopia. Comparable results were obtained for anisometropes computed in terms of mean spherical refractive error. Significant difference was not apparent for the Thai and American groups.