Vision Disability

Vision Disability

The number of different conditions that can affect a person's eyesight are varied in the way they do affect the person's daily life. Some of these conditions have a minor affect, while others may have a larger affect.

Various conditions require only eyeglasses or contact lenses in order to correct the person's vision. Other conditions may require surgery. Additional health concerns can affect a person's vision as well, such as Diabetes or Glaucoma.

Vision Conditions

There are a number of eye problems and conditions that may make it more difficult for a person to see things clearly, yet do not cause loss of vision. An example of this is, 'Myopia,' or, 'Near-sightedness,' where a person sees nearby objects clearly, but has difficulty focusing on objects that are more distant. 'Hyperopia,' or, 'Far-sightedness,' is another example of a vision condition; this one involves the ability to see distant objects clearly, with difficulty focusing on nearby objects. A third example of an eye condition that does not cause loss of vision is, 'Astigmatism,' where the person's vision appears blurred at any distance. These conditions are common and can often be corrected with eyeglasses or contact lenses.

Low Vision

The term, 'Low Vision,' sometimes also referred to as, 'Vision Loss,' means that even though a person may use eyeglasses, contact lenses, medication, or surgical techniques to improve their vision; they still have difficulty seeing. Most persons develop low vision due to eye disease or health conditions. There are some common causes of low vision among adults in America. 'Diabetic Retinopathy,' is a condition in which Diabetes has damaged tiny blood vessels inside the person's retina, causing low vision. 'Age-Related Macular Degeneration,' is a condition in which the cells in a person's retina that allow them to see fine details have died. 'Glaucoma,' is a condition in which the fluid pressure in a person's eyes slowly rises, damaging their optic nerve. 'Cataracts,' are a condition that involves a clouding of the lens in a person's eye. Receiving prompt treatment for these conditions may prevent them from getting worse, making regular eye exams crucial.


As many as 10 million people around the world suffer from cataracts. In Germany alone, more than 600,000 cataract operations are performed each year. Cataracts can be either congenital or acquired; age-related opacification of the lens is the most common type. The main symptom of cataract is slowly progressive worsening of vision, but glare disability and nearsightedness can also be signs of the disease.

Cataract operations are now usually performed on an outpatient basis. The eye is anesthetized, pretreated with antibiotics, and surgically opened. New approaches permit the operation to be performed through an incision smaller than 2 mm. In the phacoemulsification technique, the lens is emulsified and aspirated away through a vibrating hollow needle. The surgeon then implants an intraocular artificial lens. Patients without any other diseases of the eye can achieve a visual acuity of 1.0 or even better. Special optical designs for the artificial lens can further optimize the quality of vision and thereby improve patient satisfaction.

Vision Terms

There are some different terms used to describe levels of vision disability. These terms include, 'Partially-Sighted,' 'Low-Vision,' 'Legally Blind,' and, 'Totally Blind.' Partially-Sighted means the person has some form of visual disability that may require special education. Low-Vision usually is used to refer to persons who experience a more severe loss of vision that is not necessarily limited to distance vision. Persons with low-vision may be unable to read a newspaper at an average distance with eyeglasses or contacts, and may need large print or Braille. Persons who are legally blind have less than 20/200 vision in their better eye, or a very limited field of vision, often 20 degrees at its widest point. Persons who are totally blind are unable to see and often use Braille or other non-visual forms of media.

Eye disorders lead to vision loss; visual impairment is a consequence of a functional loss of vision rather than the eye disorder itself. Retinal degeneration, muscular problems, albinism, corneal disorders, congenital disorders, and infections can also lead to vision impairment.


Approximately one in twelve men, and one out of every two-hundred women, experience a form of colorblindness. One misconception that many people have is that persons with colorblindness see only black and white. In actuality, there are many types and degrees of colorblindness. Monochromasy is the form most associated with colorblindness, where people see no colors. Protanomaly is referred to as, 'red-weakness,' and the person views a shift in the hue of red colors towards green and additional affects. Deuteranomaly is also referred to as, 'green-weakness,' and the person has difficulty telling differences in the red, orange, yellow and green regions of the color spectrum. Persons with Dichromasy cannot tell the difference between red, orange, yellow and green. Persons with Protanopia find that the brightness of colors such as red, orange and yellow is greatly reduced; they may appear as black or dark gray. Persons with Deuteranopia experience the same vision issues as persons with Protanopia, but the dimming is not as great.

Persons with low vision or other visual disabilities have a number of adaptive technologies available for their use.

A list of available screen readers can be found here:

There are also a range of screen magnifiers available; you can learn about them on this page:

Curious about designing websites that are accessible to persons with vision disabilities? You can learn about this subject on this page:

Vision and Eye Care