Your Eyes Articles
FOR USE IN WEEK STARTING September 13, 2010
COMMON EYE DISORDERS
Refractive errors are the most frequent eye problems in the United States. Refractive errors include myopia (near-sightedness), hyperopia (farsightedness), and astigmatism (distorted vision at all distances). Presbyopia is the loss of the ability to focus up close. Inability to read letters of the phone book, need to hold newspaper farther away to see clearly. Each of these conditions can be corrected by eyeglasses, contact lenses, or in some cases surgery.
Amblyopia, also referred to as ‘lazy eye,” is the most common cause of vision impairment in children. Amblyopia is the medical term used when the vision in one of the eyes is reduced because the eye and the brain are not working together properly. The eye itself looks normal, but it is not being used normally because the brain is favoring the other eye. Conditions leading to amblyopia include: strabismus, an imbalance in the positioning of the two eyes; more nearsightedness, farsightedness, or astigmatism in one eye than the other eye, and, in rare instances, other eye conditions such as cataract. Unless it is treated in early childhood, amblyopia usually persists into adulthood, and is the most common cause of permanent one-eye vision impairment among children and young and middle- aged adults. An estimated 2%—3% of the population suffers from amblyopia.
Strabismus involves an imbalance in the positioning of the two eyes. Strabismus can cause the eyes to cross in (esotropia) or turn out (esoftopia). As a result, the eyes look in different directions and do not focus simultaneously on a single point. In most cases of strabismus in children, the cause is unknown. in more than half of these cases, the problem is present at or shortly after birth (congenital strabismus).
FOR USE IN WEEK STARTING September 6, 2010
FIRST SIGN OF INJURY IN GLAUCOMA ACTUALLY OCCURS IN THE BRAIN
Glaucoma is generally considered a disease of the eye in which sensitivity to ocular pressure causes damage to the retina and optic nerve, which are components of the central nervous system and do not regenerate. The damage begins in the peripheral visual field and progresses toward the center, resulting in complete blindness unless detected early. For this reason, degeneration in glaucoma is often hard to detect.
However, recent experiments have revealed that glaucoma is very much like other central nervous system diseases. Combining this new understanding of where the first neuronal injury for glaucoma occurs, with the fact that the incidence of injury increases with age, researchers now have insight into how the loss of sensory function occurs in normal aging. Traditionally, glaucoma therapies have focused on lowering ocular pressure within the eye. But the recent study gives credence to taking a new direction of study focusing on neuronal activity in the middle of the brain where the optic nerve forms its first connections.
Using animal models with high pressure glaucoma, the team was able to see that a very early mechanism of vision loss involves the loss of communication between the optic nerve and the mid-brain, where sensory information about sound, heat, cold, pain and pressure originate.
Now scientists are working on finding drugs that can improve or restore the connectivity between the optic nerve and the mid-brain.