The number of different vision 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 much larger affect.
Visual impairment (vision impairment, vision disability) is defined as a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses or medication. Visual impairment can be due to disease, trauma, or congenital or degenerative conditions. In the United States, the terms "partially sighted", "low vision", "legally blind" and "totally blind" are used by schools, colleges, and other educational institutions to describe students with visual impairments.
Eye disorders which can lead to visual impairments can include retinal degeneration, albinism, cataracts, glaucoma, muscular problems that result in visual disturbances, corneal disorders, diabetic retinopathy, congenital disorders, and infection." Visual impairment can also be caused by brain and nerve disorders, in which case it is usually termed cortical visual impairment (CVI).
Various conditions require only eyeglasses or contact lenses in order to correct the person's vision. Other conditions may require surgery.
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.
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.
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.
According to the International Classification of Diseases There are 4 levels of visual function:
Moderate visual impairment combined with severe visual impairment are grouped under the term low vision: low vision taken together with blindness represents all visual impairment.
There are some different terms used to describe levels of vision disability. These terms include, 'Partially-Sighted,' 'Low-Vision,' 'Legally Blind,' and, 'Totally Blind.'
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.
Persons with low vision or other visual disabilities have a number of adaptive technologies available for their use.
Key Vision Facts from WHO:
Facts About Blindness: