Spectacle-mounted devices that are typically placed above the visual axis for spotting distance targets, such as traffic lights in jurisdictions where bioptic driving is allowed.
Charles Bonnet syndrome
A condition in individuals who have some degree of vision loss that is characterized by vivid recurrent hallucinations and insight that what is being seen is not real. Individuals may see patterns or formed images such as people, faces, or landscapes. The degree of vision loss may be moderate or severe, and the vision loss can be acuity loss or visual field loss due to ocular or neurologic disease.
Using nonfoveal fixation to view the object of regard.
A level of vision loss at which patients are entitled to certain concessions or services in various jurisdictions. Legal blindness is typically defined in the United States as visual acuity less than or equal to best corrected visual acuity of 20/200 or a visual field of equal to or less than 20° around central fixation.
Vision loss that cannot be corrected by standard eyeglasses or by medical or surgical treatment. The cause may be ocular or neurologic disease.
A perimetry device that images the retina during visual field testing. This allows more reliable perimetry evaluation of patients with unstable fixation or eccentric fixation. The retina can be imaged with a camera or scanning laser ophthalmoscopy. Macular microperimetry is also called fundus-related perimetry or macular perimetry.
Preferred retinal locus
The area of nonfoveal retina that a patient repeatedly uses for fixation, when the foveal area is impaired.
Training to enhance compensatory visual search into nonseeing areas of the visual field, such as hemianopic field loss. Methods of training include search tasks on devices with displays of lights that can be programmed, computer training programs, and scanning training practice typically implemented by occupational therapists.
Devices that combine digital cameras and viewing screens in handheld, desk, or head-mounted formats. They have also been referred to as closed-circuit televisions (CCTVs).
A multidisciplinary clinical process aimed at enabling individuals with vision loss to reach their goals for visual tasks as well as optimal personal safety and psychological and social function. The American Academy of Ophthalmology’s Preferred Practice Pattern Guideline Vision Rehabilitation for Adults outlines that comprehensive vision rehabilitation assesses and addresses 5 areas: reading, activities of daily living, safety, continued participation despite vision loss, and psychosocial well-being.
A device to provide vision substitution for individuals who are blind. Devices being implanted or under development stimulate the retina (epiretinal, subretinal, suprachoroidal) or visual cortex. A device is available that places an electrode array on the tongue.