Refractive Eye Disorders - Eye, Ear, Nose, and Throat Disorders
Refractive Eye Disorders
Myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (distorted vision) are caused by differences in the length or shape of the eye. Presbyopia (aging eye) occurs when the lens inside the eye loses its focusing ability for near vision.
Biofeedback. Biofeedback can correct refractive problems. Joseph Trachtman, a New York-based optometric physician, reports in Alternative Medicine: The Definitive Guide that he has helped people with extremely poor vision to either eliminate or reduce their need to wear eyeglasses. Trachtman uses a machine which he invented called Accomotrac Vision Trainer to help patients retrain their eye muscles to overcome refractive problems.
Common Refractive Eye Defects
Amblyopia. A slightly crossed or drifting eye (called lazy eye) that can lead to permanent loss of vision.
Astigmatism. Vision is partially blurred because of irregularities in the curvature of the cornea, causing haphazard focusing on the retina of both near and far images.
Farsightedness (hyperopia). People can adjust their eyes to see distant objects clearly, but develop eye strain when trying to see things nearby.
Nearsightedness (myopia). Nearby objects can be focused on the retina, but the image of distant objects focuses in front of the retina causing blurred vision. A nearsighted person needs to squint to bring distant objects into focus.
Presbyopia. With aging, people find it more and more difficult to focus on close objects. This is caused by weakening of the eye muscles that adjust the lens, as well as a loss of elasticity in the lens itself.
Strabismus. This is found mostly in children–crossed or drifting eyes that cannot focus together on the same object.
Surgery. Acute refractive eye problems which cannot be treated with noninvasive treatments normally require corrective eye surgery. Radial keratotomy is the most common corrective eye surgery technique. During the procedure, a surgeon makes a series of spoke-like microscopic incisions that reshape the surface of the cornea. When the cuts heal, the cornea is slightly flattened, so that light rays focus directly on the retina, not in front of it. This type of surgery works best with patients who have moderate myopia. As reported by David Holzman in the January 22, 1990 issue of Insight , 90% of patients who undergo surgery for myopia achieve vision of 20/40 or better, which enables them to pass the Department of Motor Vehicles vision test without glasses. Photoreflective keratotomy, another surgical procedure, uses a new laser device to reshape the cornea. The procedure is currently being tested by the Food and Drug Administration and is not yet available.
Vision Training. In Total Vision , New York opthamologist Richard Kavner states that many cases of nearsightedness are caused by the strain of close work. He cites studies of Japanese students who, after studying intensely, developed myopia. When they were given eye exercises and relaxation techniques, they reversed their myopia. Kavner, along with the International Myopia Prevention Association, prescribes the following vision training for myopia patients to prevent eyestrain:
- Relax the eyes every few hours by closing them for five minutes.
- Look out the window or at objects 30 feet away for approximately 30 seconds.
- Hold a pencil at arm's length, and pull it slowly toward you until you see double.
- Give your eyes a mini-sauna by squeezing your hands together for a few minutes to warm them and then cupping your palms over your eyes.
- Proper reading posture is also important. Sit up straight when you read, hold the material 18 inches from your face and at a 20-degree angle.
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