Acuity
Level of clarity, distinction, or sharpness.
Acuity test
Use of an eye chart to measure accuracy of reading and perception.
Amsler grid
A grid used for checking distortion in the vision and central vision defects.
Antiangiogenesis
Refers to a substance that prevents the development of new blood vessels.
Antioxidants
Substances produced by the body that counteract the effects of free radicals. Present in dark green, leafy vegetables such as spinach and kale, and may also be acquired through supplements.
Bilateral
Referring to both eyes.
Central visual field
The area of objects seen in the direct line of vision without moving the head or eyes.
Choroid
The layer of the eye behind the retina filled with blood vessels that nourish the retina.
Clinical testing (or trial)
Direct observation of a living patient to answer specific questions about vaccines, therapies, or new methods. The 4 phases of a clinical trial are Phase I: determination of safety and side effects on 20 to 80 people; Phase II : determination of effectiveness and safety on 200 to 300 people; Phase III : confirmation of results on 1000 to 3000 people; and Phase IV : studies done after FDA approval and public use.
Cornea
The clear front surface of the eye.
Drusen
Tiny yellow or white protein and fat deposits in the retina.
Dry AMD
The most common form of age-related macular degeneration where drusen form on the retina.
Edema
An abnormal or excess accumulation of fluid in a tissue.
FDA
Abbreviation for the United States Food and Drug Administration. Responsible for approving and regulating treatments, procedures, and pharmaceuticals.
Fluorescein angiography
A test to examine blood vessels in the retina, choroid, and iris. A special dye is injected into a vein in the arm and pictures are taken as the dye passes through blood vessels in the eye.
Fovea
The central part of the macula that provides the sharpest vision.
Intravitreal injection
The administration of a substance (such as a drug) with a needle into the vitreous fluid of the eyeball between the lens and the retina.
Iris
The colored diaphragm in the anterior chamber of the eyeball that contracts and expands to adjust for light intensity.
Laser photocoagulation
An outpatient treatment in which blood vessels are cauterized by the heat from a fine-point laser beam.
Legal blindness in the United States
1) Visual acuity of 20/200 or worse in the better eye with corrective lenses (20/200 means that a person must be 20 feet from an eye chart to see what a person with normal vision can see at 200 feet) or 2) Visual field restricted to 20 degrees diameter or less (tunnel vision) in the better eye. NOTE: These criteria are used to determine eligibility or government disability benefits and do not necessarily indicate a person’s ability to function.
Lens
The transparent part of the eye that focuses light rays onto the retina.
Low vision
Visual loss that cannot be corrected with eyeglasses or contact lenses and interferes with daily living activities.
Low-vision devices
Equipment designed to allow improved vision, usually by magnification.
Macula
The small, sensitive area of the central retina that provides vision for detailed work and reading.
Neovascularization
Growth of new, fragile blood vessels that may leak beneath the retina.
Ophthalmologist
A medical doctor who specializes in disease and surgery of the eye.
Optical coherence tomography (OCT)
A diagnostic method which uses an optical device to generate a cross-section image of the retinal layers, allowing for measurement of tissue thickness.
Optician
A technically trained specialist who sells glasses.
Optometrist
A doctor who examines vision in order to provide corrective glasses and contact lenses. May also diagnose eye disease, and in some states, can treat disease. Some optometrists specialize in low vision and are your best source for specialized devices.
Peripheral vision
Side vision; ability to see objects and movement outside of the direct line of vision.
Photodynamic therapy (PDT)
The process of blood vessel coagulation in the retina through activation of a light-sensitive drug injected into the system.
Pupil
The opening in the center of the iris that appears as a black dot, through which light enters the eye.
Retina
The light-sensitive layer of tissue that lines the back of the eyeball. Sends visual messages through the optic nerve to the brain.
Retina specialist
An ophthalmologist who specializes in diseases such as retinal detachments, advance d diabetic retinopathy, and some forms of macular degeneration.
Scotoma
An area of partial or complete loss of vision surrounded by an area of normal vision.
Snellen eye chart
The standard tool for the measurement of visual acuity, displaying letters of progressively smaller size.
20/20 vision
The ability to correctly perceive an object or letter of a designated size from a distance of 20 feet; normal visual acuity.
Vascular endothelial growth factor (VEG F)
A protein that stimulates new blood vessel growth.
Visually impaired
Persons who have some difficulty seeing with 1 or 2 eyes, even when wearing glasses.
Wet AMD
Age-related macular degeneration that involves growth of new blood vessels which can leak and destroy the cells of the macula.
