IT IS commonly known that temporary loss of vision in one eye may precipitate heterotropia in an infant, but ophthalmologists prescribe monocular occlusion in older children and adults with little concern that persistent esotropia may result. For example, prolonged patching of the better eye is used in the treatment of unilateral amblyopia and prolonged monocular bandaging in the treatment of corneal inflammations. The fact that esotropia has received little attention as a complication of occlusion suggests that it is rare in older children and adults ; however, a review of 1,000 cases of esotropia observed in the eye clinics of the State University of Iowa College of Medicine and the University of Oregon Medical School revealed 4 such cases. Medicolegal problems were involved in 3 of the 4 cases ; therefore, these cases are reported as representative of a serious, but little known, complication of a standard therapeutic and diagnostic procedure. An