Visual acuity tests using chart, line, and single optotype in healthy and amblyopic children

Purpose: The purpose of this study was to evaluate the difference between f ull chart, single line, and single optotypes visual acuity (VA) test result s in healthy and amblyopic children. Methods: Thirty-five children with amb lyopia (20 with strabismus and 15 with anisometropia) and 40 ophthalmologic ally normal age-matched children were examined. The mean age of the patient s in the study and control groups did not differ significantly (P=.9). A co mmercial projector that projected tumbling-E randomly placed optotypes was used. The VA of the amblyopic eye of the patients in the study group and th e right eye of the patients in the control group was examined first using a full chart of optotypes, then using a single line of optotypes, and finall y with individual symbols. The procedure was repeated with the other eye. R esults: LogMAR VA improved when the full chart was substituted with a singl e line, and improved by a similar increment further with single optotypes, in both the study and control groups. VA improved significantly more in eye s with amblyopia than in control subjects. Results were not influenced by a ge. Conclusion: VA testing using a single line gives better, sometimes misl eading results, than tests with a full chart because it reduces but does no t eliminate the crowding effect. When using a device that can employ more t han 1 mode, the exact test mode should be specified and maintained througho ut the follow-up.