1. the process of assessing individuals for eye infections or disorders, for vision deficits and impairments caused by disease (e.g., glaucoma, macular degeneration) or trauma, or for visual performance on specific tasks (e.g., driving).

2. an aversive procedure, such as holding a hand over an individual’s eyes to block visual input for a brief period, that is occasionally used in the management of aggressive, self-injurious, or stereotyped behavior of children with severe intellectual or developmental disabilities.