Defects of Vision
...elve. Few factors outside heredity affect this condition. This vision problem may stabilize at certain points, but occasionally worsens with age. This condition is known as myopic creep. Treatment for myopia is usually eyeglasses and contact lens, which compensate for the elongated shape in the eye allowing the light to properly focus on the retina. A concave lens is used for this purpose. Another option is refractive surgery, including photorefractive keratectomy, or PRK, or situ kertomileusis, or LASIK. In PRK, the laser removes a layer of corneal tissue, which flattens the cornea and allows light to focus closer or even on the retina. In LASIK, the most common refractive procedure, a flap is cut through the top of the cornea and the laser removes some corneal tissue, following by the flap being dropped back into place. Although refractive surgery is an option, most ophthalmologists suggest that with simple myopia, eyes are treated best by the use of glasses or contact lenses. The prescription is measured by the power D of the lens, expressed in diopters, in place of the actual focal length. This is usually a negative number. Hyperopia, or far-sightedness, is a vision condition in which distant objects are usually seen clear, but close ones do not come into proper focus. The light entering the eye focuses behind the retina in this situation. This is caused by a cornea that is flatter or by an eye that is shorter in length. This vision problem affects about a fourth of the United States population. Signs and symptoms of hyperopia include difficulty seeing up close, blurred distance vision, eye fatigue when reading, eye strain and crossed eye in children. Many children are born with hyperopia, and some “outgrow” it as the eyeball lengthens with normal growth. Hyperopia is detected with a vision test called refraction. The eyes are dilated so that their far-sightedness is not hidden. The treatment for hyperopia depends on a number of factors, including the patient’s age, activities and occupation. Glasses or contact lens are required for older patients and in some children too. Refractive surgery is also an option in adults, including LASIK and LTK. In terms of the prescription, this number is positive. Another eye defect is strabismus. This is a condition in which the eyes don’t look toward the same object together. One eye mov...