Eye dominance in excimer laser photorefractive keratectomy.

human species and is relevant in clinical practice—to excimer laser photorefractive keratectomy (PRK) in particular. Due to the complexity of the underlying physiological mechanisms, there is no single definition that applies to all aspects of ocular dominance. Nevertheless, a clinically useful definition would be, “The dominant eye is the eye that is preferred in monocular viewing or in pointing at an object with one’s finger.” It is clear that this lateralization in eye function is the result of development of binocular vision, with overlapping of the visual fields of the two eyes.1 The resulting physiologic diplopia is suppressed from the non-sighting eye. This is thought to be the mechanism of development of ocular dominance as the input is favored from the sighting eye. Duke Elder stated that when a choice is forced between the two eyes, the vast majority of people (98%) choose one eye consistently.2 In our series of 2500 patients assessed for PRK at the Optimax Laser Clinic, we found that 68% were right eye dominant and 32% were left eye dominant. Due to the complexity of the cerebral control of the eyes, there must be many types of eye dominance. Porac and Coren1 reported at least three types of eye dominance that may be independent of each other. To this can be added a fourth type of ocular dominance related to the visual field: sighting (motoric) dominance; sensory dominance; acuity dominance; hemifield dominance. CLINICAL IMPLICATIONS Sighting dominance is the most important in clinical investigations and most clinical phenomena are related to this type of dominance.