Glossary of Terms: Blindness and Visual Impairments
Access Technology
Various computers and other equipment that bridge the gap created by loss of sight.
Braille
A system of reading by touch developed in 1829 by Louis Braille. There are approximately 252 characters and word signs in braille. These signs are created by arrangements of one to six raised dots within a cell. Different arrangements of the dots indicate letters, numbers and punctuation. There are three grades, ranked according to the degree of contraction used.
Cataract
A clouding of the lens of the eye. It is estimated that 95 percent of those over 65 years of age have some degree of cataract that may or may not cause blurring of vision. If a cataract begins to cause vision loss that interferes with important activities, it can easily be surgically removed and an artificial lens implanted. This usually results in a great improvement of vision.
Glaucoma
A condition in which the fluid pressure inside the eye is too high, causing damage to the optic nerve. If left untreated, vision around the edge of the eye becomes increasingly restricted, narrowing the field of vision. Eventually, total blindness can occur. If detected early enough, the damaging affects of the disease often can be treated with various drugs. Laser or conventional surgery often can relieve pressure and prevent further sight loss.
Legal Blindness
A person is legally blind if their central vision acuity is 20/200 or less in the better eye, even with corrective lenses; or if they have central vision acuity of more than 20/200 if the peripheral field is restricted to a diameter of 20 degrees or less. Informally, those who, even with corrective lenses, cannot read the biggest letter on an eye chart are considered to be legally blind.
Low Vision Aids
Prescription and nonprescription devices that help people with low vision enhance their remaining vision. Some examples include special low vision eye glasses, telescopic lenses for driving and other distance tasks, microscopic reading glasses, magnifiers, CCTV’s (Electronic Reading Machines), large print books, check-writing guides and white canes.
Low Vision
A visual impairment that cannot be corrected by standard eyeglasses, contact lenses, medication, or surgery, that interferes with the ability to perform everyday activities. Macular degeneration, diabetic retinopathy, glaucoma, and retinitis pigmentosa, along with many other eye diseases, are causes of visual impairment or low vision.
Mainstreaming
The term used by educators to designate inclusion of children who are blind or visually impaired into classrooms with sighted children.
Optometrist
Doctors of optometry (ODs) are primary health care professionals for the eye. Optometrists examine, diagnose, treat, and manage diseases, injuries, and disorders of the eye. They prescribe glasses, contact lenses and low vision aids.
Retina
Light-sensitive tissue at the back of the eye that transmits visual impulses to the brain via the optic nerve. It is composed of sensory elements called rods and cones that are responsible for the details, color and perspective of vision.
Retinopathy of Prematurity (ROP)
A disease of infants, usually premature ones, in which excess oxygen in their incubators causes damage or destruction of the blood vessels in the retina.
Solutions in Sight
Solutions in Sight is Braille Institute's public education campaign aimed at helping visually impaired adults adapt seamlessly to their day-to-day lives.
Vistas Store
Braille Institute’s Vistas retail stores offer many devices that help make everyday tasks easier for people with diminished vision, such as signature guides, magnifiers, talking clocks and watches, large-print and braille games and books, kitchen aids, brailled greeting cards and much more.