Blindness is the state of being sightless. The terms blind and blindness have been modified and include a wide range of visual impairment.
Vision impairment, or low vision, means that even with eyeglasses, contact lenses, medicine or surgery, they don't see well. Worldwide, between 300 million and 400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind.
Types of blindness
Color blindness is the inability to perceive differences between some of the colors that others can distinguish. It is most often inherited and affects about 8 % of males and under 1% of women. Color blind usually have normal vision and can function well visually. It is not true blindness.
Night blindness is a difficulty in seeing under situations of decreased clarification. It can be genetic or acquired. The majority of people who have night vision face difficulties in function well under normal lighting conditions. This is not a state of sightlessness.
Snow blindness is loss of vision after exposure of the eyes to large amounts of ultraviolet light. Snow blindness is usually temporary and is due to swelling of cells of the corneal surface. In this type individual is still able to see shapes and movement.
Causes of blindness
The leading causes of blindness include optical complications of diabetes, macular degeneration, and traumatic injuries. In third-world nations where about 85% of the world's blindness occurs, principal causes include infections, cataracts, glaucoma, injury, and inability to obtain any glasses.
Infectious causes include trachoma, onchocerciasis (river blindness), and leprosy. The most common infectious cause of blindness in developed nations is herpes simplex.
Other causes of blindness include vitamin A deficiency, retinopathy of prematurity, blood vessel disease involving the retina or optic nerve including stroke, ocular inflammatory disease, retinitis pigmentosa, primary or secondary malignancies of the eye, congenital abnormalities, hereditary diseases of the eye, and chemical poisoning from toxic agents such as methanol.
Symptoms and signs of blindness
A blind person may have no visible signs of any abnormalities. Support systems available to individuals and their psychological makeup will also modify the symptom of lack of sight.
Associated symptoms, such a discomfort in the eyes, awareness of the eyes, foreign body sensation, and pain in the eyes or discharge from the eyes may be present or absent, depending on the underlying cause of the blindness.
Blindness diagnoses
Blindness is diagnosed by visual acuity testing in each eye individually and by measuring the visual field or peripheral vision. People may have blindness in one or both eyes (unilateral or bilateral). Poor vision that is sudden in onset differs in potential causes than blindness that is progressive or chronic. The cause of blindness is made by examination of all parts of the eye by an ophthalmologist.
Treatments for blindness
The treatment of blindness depends on the cause of blindness. In third-world nations where there are many people who have poor vision as a result of a refractive error, merely prescribing and giving glasses will alleviate the problem. Nutritional causes of blindness can be addressed by dietetic changes. There are hundreds of thousands of people who are blind from cataracts. In these patients, cataract surgery would, in most cases, restore their sight. Inflammatory and infectious causes of blindness can be treated with medication in the form of drops or pills.
Prevention from blindness
Between 80-90% of the blindness in the world is preventable through a combination of education and access to good medical care. Most traumatic causes of blindness can be prevented through instruction in eye protection. Nutritional causes of blindness are preventable through proper diet. Most cases of blindness from glaucoma are preventable through early detection and appropriate treatment. Visual impairment and blindness caused by infectious diseases have been greatly reduced through international public-health measures.
The majority of blindness from diabetic retinopathy is preventable through careful control of blood-sugar levels, exercise, avoidance of obesity and smoking, and emphasis on eating foods that do not increase the sugar load (complex, rather than simple carbohydrates). Regular eye examinations may often uncover a potentially blinding illness which can then be treated before there is any visual loss.
Patients who have untreatable blindness require reorganization of their habits and reeducation to allow them to do everyday tasks in different ways. Visual aids, text-reading software, and Braille books are available, together with many simple and complex devices to provide functional improvement for the individual with blindness or low vision.
John Milton and Helen Keller are well known for their accomplishments in life despite being blind. There are countless other unnamed individuals with blindness, however, who, despite significant visual handicaps, have had full lives and enriched the lives of those who have had contact with them.
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