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The eye is just like any other organ of the body as infections and also diseases can damage it. Below are several eye diseases and disorders defined.
Conjunctivitis, or pinkeye, is an inflammation of the inner lining of the eyelid. This lining touches the front outer layer of the eye. With conjunctivitis the white part of the eye may turn red and feel gritty. After the eye has been closed for a long time, a yellow fluid collects and dries on the eye. The eye itches, becomes red and swollen, when the yellow fluid is present the lids stick together. Bacteria, pollen, cosmetics, or other substances touching the eye cause conjunctivitis. Fingertips or a cloth can spread this infection. A doctor may prescribe medicines to help cure this infection.
Sties are small pimple-like infection of one of the sebaceous glands along the eyelid. The agent usually responsible is a staphy lococcus germ. Hot compresses applied every hour or so may help the sty to open and drain, but never try to squeeze. Sties are sometimes caused by eyestrain. Bacteria collect at the base of the follicle of the eyelash, causing swelling and pain. Pain continues until the sty drains as it relieves pressure. This usually takes about a week to drain.
Ophthalmic Gonorhea is a more serious disorder of the eye, an infection of gonorrhea. Even a newborn baby can be infected in the conjunctiva of his eye while passing through the birth canal. Sometimes infection is acquired after birth from the hands of those infected with this disease. It is a serious disorder which must be promptly checked by a doctor as blindness can result.
Glaucoma is one of the more common causes of blindness. It is actually a disease with very common characteristics. The internal pressure of the fluids of the eye causes hardening of eyeball. The canals, which drain the fluid of the eye, are stopped up. It is caused by a buildup of pressure in the eyeball that damages the optic nerve and the blood vessels around it. Glaucoma usually occurs when fluid fails to drain normally from the eye. Acute symptoms, which will strike suddenly, are cloudy vision, followed by very sharp pain. The chronic type is more common and occurs quite painlessly. The symptoms can be very vague, and may come and go. Vision may be foggy, blurred, problems adjusting to the dark, or even seeing colored haloes around lights. The loss of side vision usually follows. The disease occurs most often among people over the age of 40. There is a simple test that measures the pressure in the eye and can detect glaucoma before permanent damage occurs; therefore, have this test done when you have your eye exam. The test is done by a tonometer, an instrument for recording the pressure of this disorder. One out of every eight blind people has usually lost their sight from glaucoma.
Trachoma is another serious disorder of the eye; it is a chronic disease of the conjunctive and is very contagious. A virus causes trachoma. It is characterized by granulations, which produce scars on the lid, and by the stoppage of tears. Severe cases can result in blindness. It is very commonly associated with poverty especially among Native Americans and among people living in remote sections of the Appalachian Mountains. Practicing good hygiene is the best prevention of this disease. Antibiotics are especially helpful when treating Trachoma.
A cataract is a cloudiness of the crystalline lens of the eye, making the lens partly or wholly opaque. It is a deterioration of the eye's lens. The lens become cloudy and blocks light from entering the eye. One stage of the disease is a swelling and temporary increase in the refractive powers of the lens, so that for a time the patient actually loses their vision. The most common cause of cataract is aging, although some babies are born with cataracts. There are some forms of cataracts that are hereditary, as explains congenital types of defects in infancy. Other factors leading to the development of a cataract are injury, inflammation, or diabetes. The loss of transparency is usually a slow, progressive process. The pupil in later stages will have a grayish appearance. It can be induced by overexposure to heat and light, a blow over the eye, or even poisoning by such drugs as dinitrophenol. To treat a cataract, the clouded lens may be surgically removed; a healthy lens can then be implanted in the eye. If both eyes are involved with cataracts then surgery is performed on one eye then the other. It has a 90 percent or better recovery rate.
Damage to the retina impairs vision because some or all of the light receptors do not function properly. It is the separation of the retina from the choroids, the nourishing middle layer of the eye. The early signs of a detached retina include flashes of light and loss of peripheral vision. Part of the retina falls away from the tissue supporting it. This condition often results from normal aging, eye tumors, or from sudden blows to the head such as in a sporting injury. The most common warning signs include the sudden appearance of floating spots that may decrease over a period of weeks and odd "flashes of light" that appear when the eye moves. If it is left untreated, the retina may detach completely and cause total blindness in the affected eye. Laser therapy is normally used as treatment although a procedure such as placing a tight collar around the eyeball to increase pressure within the eye is also used. The high pressure of the vitreous humor holds the retina in place against the rear of the eyeball.
Diabetes mellitus, a disorder involving the hormone insulin, may cause a condition known as diabetic retinopathy. This disorder is caused by small hemorrhages in the retinal blood vessels, which disrupt the oxygen supply to the photoreceptors. The eye responds by building new yet abnormal vessels, which block vision and may cause detachment of the retina. In the United States diabetic retinopathy is considered one of the leading causes of blindness. Laser therapy seals off hemorrhaging retinal vessels; this procedure has brought much success.
Nyctalopia or "night blindness" can be caused by a deficiency of vitamin A. This is also caused by a degeneration of the retina. Photopigment is a light-sensitive chemical that triggers stimulation of the visual nerve pathway. A lack of vitamin A may result in a lack of photopigment in rods.
A corneal transplant is performed to correct poor vision or even blindness. It is the removal of a damaged cornea, which then is replaced with healthy corneal tissue from a donor. The cornea is sewn in place with tiny stitches. There is a great need for corneas for corneal transplants.
Age-related macular degeneration is the leading cause of progressive yet permanent blindness in the elderly. This condition affects the part of the retina that is most essential to good vision, the central region called the macula. The exact cause of the degeneration is unknown, but the risk for developing this condition increases with age after 50; smokers are at high risk to this degeneration.
Color blindness is a form of retinal disorder, which is sometimes inherited. Genes on the x-chromosome that produce abnormal photopigments in the cones cause it. Each of these three photopigments is sensitive to one of the primary colors of light: green, blue, and red. In many color-blind individuals, the green-sensitive photopigment is missing or deficient; at other times, the red-sensitive photopigment is abnormal. Deficiency of the blue-sensitive photopigment is very rare. Because color blindness is an X-linked genetic trait, more men have this condition. It is usually not considered a clinical disease.
A condition called scotoma is a certain form of neuritis often association with multiple sclerosis; it causes a loss of the center of the visual field. Damage to the visual pathway does not always result in loss of sight. Depending on where the damage occurs, only a part of the visual field may be affected. Acquired cortical color blindness is damage to an area that processes information about colors. This condition is characterized by difficulty in distinguishing any color, not just one or two colors as in the more common inherited forms of color blindness.
Strabismus is a condition that results when the positioning of the eyes cannot be coordinated. Strabismus or "cross-eyes" is a common condition in which the eyes are so far off their center focus that the brain cannot mesh the two resulting images into a single picture. In some cases, the eyes either face outward, or cross. Usually the brain compensates for missing or unusual elements in the visual field, but in with strabismus the abnormality is too severe for the brain to recompense. If this condition is not corrected early, visual centers in the brain will learn to ignore information from one eye, causing permanent blindness. Strabismus is usually caused by paralysis, weakness, or other abnormalities affecting the external muscles of the eye. Whatever the cause, strabismus can often be corrected by exercising the eyes, by corrective lenses, or by corrective surgery.
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