At So, I’m Legally Blind, I want to provide the most requested visual impairment terms, the frequently asked questions that I’m often asked as an individual who is legally blind (yes, in 2016!) and as a professional in the field of disability. In addition, I’d like to help the professionals in the field of visual impairment, people interested in learning about people who have visual impairments from all ranges of severity to various and upcoming events in the field of visual impairment and assistive technology. In regards to the terms below, these are the most frequently asked terms to define, so I pulled info from one of the best resources (in my opinion) the American Federation for the Blind. When I borrow another sites work, I believe in giving credit where credit is due.
Click on AFB to learn more.
Below are the most requested terms that I've been asked to define so I thought I'd put a quick list together for you.
Legal blindness is a level of vision loss that has been legally defined to determine eligibility for benefits. The clinical diagnosis refers to a central visual acuity of 20/200 or less in the better eye with the best possible correction, and/or a visual field of 20 degrees or less. Often, people who are diagnosed with legal blindness still have some useable vision.
Low vision is a term often used interchangeably with visual impairment and refers to a loss of vision that may be severe enough to hinder an individual's ability to complete daily activities such as reading, cooking, or walking outside safely, while still retaining some degree of useable vision.
Visual impairment is often defined clinically as a visual acuity of 20/70 or worse in the better eye with best correction, or a total field loss of 140 degrees. Additional factors influencing visual impairment might be contrast sensitivity, light sensitivity, glare sensitivity, and light/dark adaptation.
Functional limitation refers to the interaction of visual functioning and ability to perform activities of daily living/instrumental activities of daily living. Common daily activities affected by vision loss are reading, safe pedestrian travel, self-care, cooking, and recreational activities.
Visual acuity is the clinical measure of the eye's ability to distinguish details of the smallest identifiable letter or symbol. This measurement is usually given in a fraction and is based upon visible print size. Typical vision is 20/20. If an individual sees 20/200, the smallest letter that this individual can see at 20 feet could be seen by someone with typical vision at 200 feet.