There are a few different terms used to describe someone who is legally blind but still has some remaining vision. The most common terms are legally blind, low vision, visually impaired, and partially sighted. Legally blind refers to someone with 20/200 vision or worse, meaning they have to be 20 feet from an object to see it as well as someone with normal vision can see it from 200 feet away. However, legal blindness includes a range of vision loss, so some people who are legally blind still have some usable vision. This is where terms like low vision, visually impaired, and partially sighted come into play.
Legally Blind
Legally blind is a legal designation meaning that someone’s vision is 20/200 or worse with their best possible correction, such as glasses or contact lenses. It also includes people with a visual field of 20 degrees or less, even if their visual acuity is better than 20/200. So someone can have relatively good central vision but have a narrowed visual field that significantly impairs their sight. In the United States, being declared legally blind makes someone eligible for certain government benefits, tax deductions, and services for the blind. Approximately 1.3 million Americans are legally blind under this definition. However, only about 10-15% of those who are legally blind have absolutely no vision at all. The rest have low vision, meaning they have some usable sight.
Causes of Legal Blindness
There are many diseases and conditions that can cause legal blindness, including:
- Macular degeneration – damage to the macula in the retina
- Diabetic retinopathy – damage to blood vessels in the retina due to diabetes
- Glaucoma – damage to the optic nerve
- Cataracts – clouding of the lens of the eye
- Retinitis pigmentosa – retina deteriorates due to lack of blood supply
- Retinopathy of prematurity – abnormal blood vessel growth in babies born prematurely
- Eye injuries or infections
- Brain injuries or stroke
So while legally blind means very poor vision, it doesn’t necessarily mean complete blindness. Many legally blind people retain some vision that allows them to perform daily tasks, often with adaptive techniques or devices.
Low Vision
Low vision is a broad term that includes people with visual impairments that are not fully correctable with glasses, contact lenses, or surgery. Low vision falls in the range between normal vision and total blindness. People with low vision have significantly reduced visual acuity and/or visual field, but they have more usable vision than those who are totally blind. Approximately 2-8 million Americans have low vision.
Some key features of low vision include:
- Visual acuity of 20/70 to 20/200 or worse
- Visual field of less than 40 degrees
- Difficulty reading standard print even with corrective lenses
- Reduced contrast sensitivity and color vision
- Light sensitivity (photophobia)
- Vision loss that fluctuates or gets worse over time
People with low vision use a combination of prescription glasses, high-powered magnifiers, and adaptive techniques to maximize their remaining vision. Many are able to continue performing daily tasks independently.
Causes of Low Vision
Common causes of low vision include:
- Macular degeneration
- Diabetic retinopathy
- Glaucoma
- Cataracts
- Retinitis pigmentosa
- Eye conditions present from birth
- Eye injuries or infections
- Stroke or brain injury
So while low vision significantly impairs sight, it does not mean complete blindness. People with low vision utilize their remaining vision for everyday activities.
Visually Impaired
Visually impaired is a broad term that includes people who have limited vision or blindness that cannot be fully corrected with regular glasses or contact lenses. This includes people who are legally blind as well as those with low vision. Approximately 8 million Americans are visually impaired.
According to the World Health Organization, visual impairment includes:
- Moderate visual impairment – visual acuity worse than 20/70 but better than 20/200
- Severe visual impairment – visual acuity worse than 20/200 but better than 20/400
- Blindness – visual acuity worse than 20/400 or visual field less than 10 degrees
- Near-total blindness – visual acuity worse than 20/1000 but some light perception
- Total blindness – no light perception at all
So while visually impaired can include legal blindness and near-total blindness, many visually impaired people have usable vision that can be enhanced with visual aids and adaptive techniques.
Causes of Visual Impairment
Common causes of visual impairment include:
- Refractive errors like near- or far-sightedness
- Cataracts
- Glaucoma
- Diabetic retinopathy
- Macular degeneration
- Retinitis pigmentosa
- Eye injury or infection
- Stroke or brain injury
- Cortical visual impairment (CVI) – visual processing problems in the brain
Partially Sighted
Partially sighted is a term sometimes used to describe people who have significant vision loss or visual impairments but are not completely blind. It is often used similarly to “low vision” to indicate usable residual vision. Some definitions of partially sighted include:
- Visual acuity between 20/70 and 20/200 with best correction
- Visual field of less than 30 degrees but more than 10 degrees
- Inability to perform visually demanding tasks without adaptive techniques or devices
Partially sighted people can benefit from many of the same services and resources as those who are legally blind while still capitalizing on their remaining vision. This includes vision rehabilitation training, low vision devices, guide dogs, braille literacy, and community services. Partially sighted people may utilize a combination of their limited natural sight, prescription glasses or contacts, and visual aids to perform daily tasks.
Causes of Partial Sight
Some common causes of partial sight include:
- Macular degeneration
- Cataracts
- Diabetic retinopathy
- Glaucoma
- Retinitis pigmentosa
- Optic nerve damage or disease
- Stroke
- Eye injury
Using Remaining Vision
Even people who meet the criteria for legal blindness often have some usable vision. This remaining vision can be maximized through various techniques and tools:
- Prescription glasses – Magnifying lenses improve blurry central vision
- Magnifiers – Handheld or stand magnifiers enlarge text and objects
- Telescopes – Miniature telescopes help with long-distance viewing
- Large print – Books, signs, and displays with enlarged text
- Audiobooks and screen readers – Hearing content read aloud
- Guide dogs – Assist with navigation and safety
- Mobility aids – White canes and electronic travel devices
- Braille – Tactile reading and writing system
- Good lighting – Proper lighting reduces glare and improves contrast
- Bold lined paper – Helps keep place when writing
- Accessible technology – Screen magnification software, screen readers, etc.
With the right interventions and training, partially sighted and legally blind people can adapt to perform most activities of daily living using their remaining vision.
Eccentric Viewing
Many people with central vision loss due to conditions like macular degeneration learn to use a preferred retinal location (PRL) outside their damaged macula for viewing. This is called eccentric viewing. They train their brains to interpret the distorted image from the eccentric area into something meaningful. With practice, eccentric viewing can allow people with a damaged central visual field to regain the ability to perform tasks like reading, watching TV, and recognizing faces. Special rehabilitation training is extremely helpful for developing effective eccentric viewing skills.
Quality of Life with Low Vision
Being declared legally blind or partially sighted does not preclude someone from having a good quality of life. With proper training, adaptive techniques and low vision aids, visually impaired people can often perform most daily living tasks independently. Many are able to continue working, enjoying hobbies, and participating in family life. However, vision rehabilitation training is a key factor in successfully adjusting to life with low vision. This training teaches things like:
- Maximizing remaining vision
- Eccentric viewing
- Using low vision devices
- Modifying the home environment
- Travel training with a white cane
- Reading and writing adapting, including braille
- Personal management and hygiene techniques
- Available community resources and services
With practice and assistive technologies, legally blind and partially sighted people can regain confidence and independence. Many describe their impairment not as a disability but just an inconvenience. They may not have “normal” vision but can still live full lives.
Conclusion
There are a range of terms for people who meet the criteria for legal blindness but retain some usable vision, including low vision, visually impaired, and partially sighted. While legally blind and partially sighted people have significantly impaired sight, they utilize their remaining vision combined with adaptive techniques and devices to perform daily activities. With proper training, legally blind and partially sighted people can enjoy full, independent lives and participate actively in their communities. Complete blindness is quite rare, with around 90% of legally blind people having some residual vision. So being legally blind does not necessarily mean living in darkness – most can still see something. With the right support and determination, visually impaired people can maximize their remaining sight.