Blindness is the inability to see from light to dark or just the inability to see at all. In some cases it leads to total loss of vision. Visual impaired is a severe reduction of vision that can’t be fully treated by medical treatment or lenses. Blindness and visual impairment are often used as synonyms, in the sports world. The International Blind Sports Association (IBSA) and the U.S. Association for Blind Athletes (USABA) serve persons whose vision varies from 20/200 ft to total blindness after corrections made by glasses. About 285 million people are visually impaired worldwide; 39 million are blind and 246 have low vision. Proper training, specialized equipment, and opportunity will help make life easier for individuals with blindness and visual impaired.
There are three sport classifications, which are based on a Snellen chart measure of acuity and assessment of field vision. Visual acuity is sharpness of vision and acuteness of the vision determined by a comparison with the normal ability to define certain letters at a give distance. Field of vision refers to the area within which object can be seen when the eyes are fixed straight ahead. A severely limited field of vision is called tunnel vision. To comprehend field of vision, look through a straw that is equivalent to a 5° field of vision. Most people have a field of vision of about180°.
B1 Classification – no light perception in either eye up to light perception and inability to recognize the shape of a hand in any direction and at any distance.
B1 encompasses two education classifications:
Total Blindness (lack of visual perception). Inability to recognize a strong light shown directly into the eye.
Light Perception (less than 3/200). Ability to distinguish a strong light at a distance of 3 ft. from the eye, but inability to detect movement of a hand at the same distance.
B2 Classification – Ability to recognize the shape of a hand up to a visual acuity of 2/60 and/or a limitation of field of vision of 5°.
B2 encompasses two educational classifications:
Motion Perception (3/200 to 5/200). Ability to see at 3 to 5 ft what the normal eye at 200 ft. This ability is limited almost entirely to motion.
Travel Vision (5/200 to 10/200). Ability to see at 5 to 10 ft what the normal eye sees at 200 ft.
B3 Classification – 2/60 to 6/60 (20/200) vision and/or field of vision between 5 and 20°
B3 is the same as legal blindness, the minimal disability condition specified by the law that permits special services: Legal Blindness (20/200). Ability to see at 20 ft what the normal eye sees at 200 ft. (i.e., 1/10 or less of normal vision)
Cause(s) of disability
Blindness can occur as a result of number of infectious noncommunicable diseases, as well as injuries. The leading causes of vision impairment and blindness in the United States are age-related eye diseases. In older persons, cataracts and diabetes are the leading causes. Other eye disorders, eye injuries and birth defects can also cause vision loss. The most common causes of blindness include:
Diabetic Retinopathy: Within 10 years of the onset of diabetes, 50% of individuals develop diabetic retinopathy, which is caused from gradual damage to the retina.
Glaucoma: A condition in which the pressure inside the eyeball rises to a point where it damages the optic nerve, first affecting peripheral vision and later causing central vision blindness.
Trachoma: Symptoms begin 5 to 12 days after being exposed to bacteria Chlamydia trachomatis. The condition begins slowly as the tissue that lines the eyelid becomes inflamed, which if untreated may lead to scarring. If the eyelids are severely irritated, the eyelashes may turn in and rub against the cornea. This may cause eye ulcers, additional scars, vision loss, and blindness.
Cataracts: Clouded or opaque spots on the lens that...