About Blindness and Low Vision

What is Blindness & Low Vision?

Vision loss represents a broad spectrum ranging from minor visual impairment to the complete inability to see. Vision loss results from varying underlying causes and can significantly impact daily living. According to the World Health Organization (WHO), globally more than 2 billion people have a vision impairment, almost half of which could have been prevented or addressed.

These key terms are often used to classify the level of vision loss:

Total Blindness

Total Blindness occurs when there is a complete lack of light perception. People with Total Blindness are unable to see anything, including light and shadows. Although people often think of total blindness when they hear the term “blind,” most people with significant vision loss have some level of light, shadow, or shape perception or some residual vision.

Legal Blindness

Legal Blindness is a term applied to vision that is severely impaired but not completely absent. In the US, Legal Blindness is when an individual has a central visual acuity of 20/200 or worse in the better-seeing eye with the best correction (using glasses or contacts) or has a visual field of twenty degrees or less in the better-seeing eye (a significantly reduced field is often referred to as tunnel vision).

Low Vision

Low Vision defines significant vision loss that does not meet the threshold of legal blindness but where eyeglasses, contact lenses, or surgery cannot fully correct vision. Based on acuity, Low Vision may be categorized as moderate or severe.

Various terms are also used to describe the type of vision loss, some of which include:

Cortical Blindness

Damage to the brain’s occipital cortex, where visual processing occurs, is called Cortical Blindness (versus damage to the eyes). Vision loss can be complete or partial.

Color Blindness

People with Color Blindness cannot distinguish some colors, often red, green, yellow, and blue. Color Vision Deficiency, or Total Color Blindness, is a rare condition in which everything is perceived in shades of gray.

Night Blindness (Nyctalopia)

Night Blindness is the inability to see well in low light or darkness and results from a retinal cell disorder that reduces one’s ability to see at night or in dim light.

The onset of vision loss is also described by terms such as:

Congenital Blindness

Blindness that occurs at birth or shortly afterward is called Congenital Blindness. This type of blindness of often the result of genetic factors, developmental issues, prenatal infection, or other causes.

Acquired Blindness

Acquired Blindness is vision loss that occurs after birth, which can result from an injury, disease, or other medical condition. Vision loss can occur suddenly due to some trauma or develop gradually through diseases such as diabetic retinopathy, age-related macular degeneration, and untreated cataracts.

Vision loss can profoundly impact an individual’s confidence, safety, independence, and quality of life, including adverse impacts across all Social Determinants of Health. Significant vision loss can also impact one’s ability to engage in activities, leading to a diminished lifestyle, isolation, and increased rates of anxiety and depression..

Vision Rehabilitation Offers Hope

Vision Rehabilitation and related programs and services provide tremendous hope for people living with blindness and low vision.

Written by VisionServe Alliance.