Blind | Visual Impairments
Visual impairment refers to a reduced ability to see that cannot be fully corrected through conventional means such as glasses or contact lenses, and which significantly affects daily functioning.
People with visual impairments may experience challenges with everyday activities including reading, mobility, driving, recognising faces, and social interaction. The impact can range from low vision to complete blindness, depending on the nature and severity of the condition.
According to the World Health Organization, an estimated 285 million people worldwide were living with visual impairment as of 2012. Of these, approximately 246 million had low vision and 39 million were blind. Importantly, up to 80% of visual impairment is considered preventable or treatable through timely diagnosis and appropriate care.
What Are You Looking For?
Types of Visual Impairments
A. Blind and Partial Blindness
1. Classification
2. Degrees of Visual Impairments
3. Causes of Blindness
4. Diagnosis of Blindness
5. Communication
6. Language Development
7. About Colour Blindness
Types of Visual Impairments
Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses. Some also include those who have a decreased ability to see because they do not have access to glasses or contact lenses. Visual Impairment can be divided into 3 categories: Blind, Visual Impairments and Colour Blind.
Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses. Some also include those who have a decreased ability to see because they do not have access to glasses or contact lenses. The term blindness is used for complete or nearly complete vision loss. Visual impairment may cause people difficulties with normal daily activities such as driving, reading, socializing, and walking.
The World Health Organization estimates that as of 2012 there were 285 million people who were visually impaired in the world, of which 246 million had low vision and 39 million were blind. The majority of people with poor vision are in the developing world and are over the age of 50 years. 80% of visual impairment is either preventable or curable with treatment.
Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work. In South Africa, the terms blindness and visual impairment are defined in line with the World Health Organization (WHO) standards and the Department of Health / Department of Social Development disability policies:
In terms of South Africa’s White Paper on the Rights of Persons with Disabilities (2016), blindness and visual impairment are defined within a rights-based and social model of disability—focusing not only on medical conditions, but on how societal barriers restrict participation.
The White Paper recognises that:
– Blindness and visual impairments refer to long-term or permanent loss of vision that, when combined with attitudinal, environmental, and institutional barriers, limits a person’s full and effective participation in society on an equal basis with others.
It shifts the focus from the individual’s impairment to the need for accessibility, reasonable accommodation, and inclusion in all areas of life—such as education, employment, transport, and information access.
The White Paper defines blindness and visual impairment not just by loss of sight, but by how environmental and social barriers prevent people from enjoying equal rights and opportunities.
1. Classification of Visual Impairments
The World Health Organization uses the following classifications of visual impairment.
When the vision in the better eye with best possible glasses correction is:
20/30 to 20/60
20/70 to 20/160
20/200 to 20/400
20/500 to 20/1,000
More than 20/1,000
No light perception
– is considered mild vision loss, or near-normal vision
– is considered moderate visual impairment, or moderate low vision
– is considered severe visual impairment, or severe low vision
– is considered profound visual impairment, or profound low vision
– is considered near-total visual impairment, or near total blindness
– is considered total visual impairment, or total blindness
2. Degrees of Visual Impairments
Visual impairments may take many forms and be of varying degrees. Some people who fall into this category can use their considerable residual vision (their remaining sight) to complete daily tasks without relying on alternative methods.
People with significantly reduced acuity may benefit from training conducted by individuals trained in the provision of technical aids. Low vision rehabilitation professionals, can provide advice on lighting and contrast to maximize remaining vision. These professionals also have access to non-visual aids, and can instruct patients in their uses.
The subjects making the most use of rehabilitation instruments, who lived alone, and preserved their own mobility and occupation were the least depressed, with the lowest risk of suicide and the highest level of social integration.
Those with worsening sight and the prognosis of eventual blindness are at comparatively high risk of suicide and thus may be in need of supportive services. These observations advocate the establishment and extension of therapeutic and preventative programs to include patients with impending and current severe visual impairment improving the quality of life of these patients. Such intervention should occur in the early stages of diagnosis.
Classification of Legal Blindness in South Africa
A person is considered blind if their best corrected visual acuity – with glasses or contact lenses – is 6/60 (20/200) or worse in the better eye, or If their visual field is 20 degrees or less, even if central vision is better. This means they can see at 6 metres what a normally sighted person can see at 60 metres, or they have tunnel vision.
3. Causes of Blindness and Partial Blindness
The most common causes of visual impairment globally are:
– uncorrected refractive errors (43%)
– cataracts (33%)
– glaucoma (2%)
– age related macular degeneration
– age related macular degeneration
– diabetic retinopathy
– corneal clouding
– childhood blindness
– infections
– stroke
– prematurity
– trauma.
Blindness can also occur as a part of or in combination with the following :
–
– autism spectrum disorders
– cerebral palsy
– hearing impairments
– epilepsy
– intellectual disability
4. Diagnosis of Blindness
Scientists track eye movements in glaucoma patients to check vision impairment while driving
It is critical that all people be examined by someone specializing in low vision care prior to other rehabilitation training to rule out potential medical or surgical correction for the problem and to establish a careful baseline refraction and prescription of both normal and low vision glasses and optical aids. Only a doctor is qualified to evaluate visual functioning of a compromised visual system effectively.
The World Health Organization estimates that 80% of visual loss is either preventable or curable with treatment.
Poor Vision
vs
Visual Impairment
A person is considered to have a visual impairment if their vision, even after treatment and correction with lenses, is less than 6/18 but better than 6/60 in the better eye, or If they have significant restrictions in their visual field that affect daily functioning. This includes people who are not totally blind but struggle to read, move around safely, or perform tasks without assistive devices.
5. Communication
Communication with individuals who are blind or visually impaired can sometimes present unique challenges. Challenges aside however, it’s important to interact with visually impaired individuals just as you would with anyone else — with respect, naturalness, and equality — rather than focusing on their disability or offering unnecessary special treatment.
People with visual impairments develop effective ways to communicate not only with those around them, but also with their environment. Since vision is limited or absent, they rely heavily on their other senses — particularly hearing, touch, and smell — to gather information, navigate spaces, and interpret social cues.
Sound helps identify voices, movement, and environmental changes; touch provides information about objects, surfaces, and spatial orientation; and smell can help them recognize familiar places or people. Through these sensory channels, many visually impaired individuals form a rich understanding of the world and maintain meaningful, effective communication with others.
6. Language Development
Visual impairment can have a profound impact on the communication development of infants and children. Because vision plays a crucial role in learning through observation and imitation, a child who is visually impaired may experience delays in both language and social development. Sighted children acquire much of their knowledge by watching and imitating others, whereas visually impaired children require deliberate and structured instruction to develop similar skills, such as postponed imitation.
A visually impaired infant may begin babbling or imitating words at a similar or even earlier stage than a sighted child, but may show delays in combining words or forming sentences independently. They may ask fewer questions and use descriptive language less frequently. Often, their sensory experiences are not easily translated into language, leading them to memorize and repeat phrases without fully understanding their context. As a result, the language of a blind child may reflect not their understanding of the world, but rather their exposure to the speech of others.
Additionally, visually impaired children may be hesitant to explore their surroundings due to fear of the unknown, or because overprotective caregivers limit their opportunities for independent exploration. Without direct, hands-on experiences, they may struggle to form meaningful concepts or acquire the language needed to describe and think about them.