The leading causes of blindness (in America) are different than in under developed countries. The leading causes of blindness in Africa and other countries are related to vitamin deficiencies and parasitic diseases that involve the eye. In America, the leading causes are
á macular degeneration of the retina in older people,
á diabetic retinopathy,
á optic nerve diseases
á injury or trauma
á strabismus or sensory crossing of the eye.
Diabetes leads to blindness because delicate blood vessels inside the retina are damaged and become leaky, allowing blood and lipid and fluid to damage the delicate retina. Also, the blood vessels become closed off, creating lack of nutrition or ischaemia to the retina, resulting in growth and proliferation of abnormal or new blood vessels which then bleed or cause scarring, which leads to traction or detachment of the retina.
Innovative surgery in the 90's
There are many innovative surgeries related to the eye at the present time. New surgeries on the optic nerve, allow splitting of the sheath of the optic nerve behind the eye that may be constricting the flow of information from the eye to the brain. The use of modern vitreous and retinal techniques, now allow surgery of the scar tissues that grow beneath the retina, and with some people have marked restoration of vision. Cataract surgery is now routinely performed through tiny incisions, many times with no sutures. Surgery to relieve nearsightedness is rapidly progressing through the use of excimer laser and other surgical advances. There are many other applications of the laser that apply to the diseases of the retina and now the laser is being used to resurface and smooth the skin around the eyes.
Causes and Treatments of Macular Degeneration
Macular degeneration is usually caused by an aging degeneration of the back layers of the eye. Proven treatments include laser photocoagulation for leakage and new blood vessel growth underneath the retina. Promising therapies include nutritional supplementation and vitrectomy surgery to remove diseased tissue beneath the retina. Low vision therapy, meaning the proper use of agents that increase magnification and contrast and utilise proper illumination are also tremendously important.
Wet and Dry Versions
Macular degeneration of the retina is the leading cause of blindness in older individuals in the western countries today. It almost never causes complete blindness, but individuals with it may lose the ability to read, drive, and experience a blackness of their centre vision. The "wet" version is caused by a leakage of blood, fluid, or fatty material from new blood vessels growing beneath the retina. The "dry" version is related to an atrophy of the pigmented layer of the retina and the vascular layer that underlies it. The wet version is the worse type as it frequently causes a greater loss of vision but is the only type that is treatable today.
It is now recognised that careful control of one's blood sugar is tremendously important in the prevention of almost all diabetic complications. All individuals with diabetes should try to keep their blood sugar normal, their blood pressure normal, their weight normal, and by doing so may reduce complication rates by 50-70 percent.
Speed of Progression of Glaucoma
There are many types of glaucoma. Acute angle closure glaucoma can cause total blindness within one day, but fortunately its symptoms are extreme pain and blurred vision so that individuals affected usually seek eye care on an emergency basis so that blindness may be prevented. The usual kind of glaucoma is slow in progression, painless, and is a silent thief of vision, taking years to cause its damage. Blindness occurs most often with advancing age, with half of all blind people generally considered to be over sixty-five. A significant number of blind people, however, are children or young adults. There are many causes of blindness, but the major ones include:
Cataracts - opacities and clouding of the eye's lens. May form and block the passage of light through the eye. Some people are born with cataracts, but the incidence increases with age. They are not painful and the only symptom is blurred, dimmed or double vision. Not all require surgery, but those large enough to cause serious visual problems require surgical removal of the lens, implantation of an intraocular lens and corrective glasses or contact lenses.
Diabetic retinopathy - the increased lifespan of diabetics has increased the incidence of this disorder. Changes in the tiny blood vessels of the diabetic's retina can cause blindness. Abnormal blood vessels are formed, some may burst and the retina may even break loose from the back of the eye. Laser treatments to "seal" blood vessels or reattach the retina may help if undertaken early. Some diabetics do not experience vision loss.
Glaucoma - perhaps one in every seven or eight cases of blindness is due to this disorder, in which the transparent fluid inside the forward part of the eye does not drain normally and excess pressure is built up within the eye. If the pressure is not controlled, the delicate structure of the eye is increasingly damaged, resulting in blurred vision, a narrowed field of sight and eventually total blindness. Early symptoms may include blurred vision, halos around lights and reduced side vision. In the acute type, there is great pain as eye pressure rises quickly from blocked drainage canals. In the more common chronic type there is no pain and vision loss is gradual. Many cases are controlled very well by medication, but surgery is sometimes necessary. Early detection is important.
Macular degeneration - as the inner surface or lining at the back of the eye, the retina functions a little like the film in a camera. The macula is the part of the retina which forms the centre of the "picture'' and the sharpest image. Degeneration or breakdown of the retina may occur, especially with increased age. The disorder may be slow or rapid, but peripheral vision usually remains good. Magnifiers may help, and a few people may be helped by laser treatment to seal off blood vessels which have grown beneath the retina or to repair the macular's weak spots by removing wornout tissue and allowing new tissue growth.
Retinitis pigmentosa - frequently beginning as what is called "night blindness," this condition brings degeneration of the retina and the choroid (a related vascular area), usually involving an abnormal development of excess pigment. It is hereditary, with a variety of patterns of inheritance and development. The most common pattern of development is that at approximately age ten or twelve, the youngster begins to experience some difficulty in seeing at night and in poorly lighted areas. His visual field also begins to narrow, frequently resulting in what is commonly termed "tunnel vision" although he may not realise this at first. The visual loss is progressive, so that the individual is usually legally blind by young adulthood and slowly loses more and more vision thereafter. Many adults with retinitis pigmentosa have a very tiny field of vision in which they see well under a good light but which is so small as to be of little use. Total blindness often results. There is no known treatment.