What Is Low Vision?
Low vision results from reduced visual acuity (sharp, detailed central vision that we use to see objects straight-ahead) or impaired visual field (peripheral or side vision) that glasses, contact lenses, or surgery cannot correct. While there is no widely accepted definition of vision impairment, vision impairments can range from mild vision loss (partially sighted) to severe vision loss, or even total blindness. A visual acuity between 20/40 and 20/63 can be considered mild vision impairment, 20/80 to 20/160 would be moderate visual impairment, and 20/200 or worse is considered a severe visual impairment (Segre 2015). The United States government defines legal blindness as having a visual acuity of 20/200 or worse (in the better-seeing eye after correction with glasses), or a visual field diameter of 20 degrees or less. This definition was established to help determine eligibility for vocational training, rehabilitation, schooling, disability benefits, and tax exemption programs (Varma 2004).
Any level of vision impairment can create difficulty for an individual during their daily activities. Low vision rehabilitation may be beneficial to provide resources that can assist with day-to-day tasks. The goal of a low vision evaluation is to improve a persons’ quality of life by providing tools that help utilize an individual’s remaining vision in order to gain or maintain independence. It is not uncommon for people with any level of vision impairment to experience feelings of isolation, frustration or despair. A visit to the low vision clinic can provide resources that help ensure a person feels connected to their community and provide guidance to other necessary resources that can improve one’s overall well-being. A low vision service team will assess many aspects of the individual’s daily life to create a practical way to improve functional vision in areas such as: occupation, errands, home management, hobbies, and social outlets.
During a low vision evaluation, there are several tools that may be recommended, depending on the type and severity of the eye condition present. Devices may be in the form of magnification, either handheld or hands-free, and illuminated or non-illuminated. Quality of vision may also be enhanced through control of lighting. A low vision exam may provide tips and suggestions for appropriate task specific lighting and glare reduction. Many vision impairments can also result in a reduction of contrast vision, which is an inability to distinguish an object from its background. This may impair reading and impose safety risks for navigating indoor and outdoor areas. Portable and desktop electronic video magnification devices (i.e. CCTV) can often provide both enhanced contrast and magnification for reading-related tasks. A low vision doctor may also recommend training in the form of sighted guide or orientation and mobility, if a person has difficulty navigating their environment safely and independently.