Lazy Eye (Amblyopia): Causes and Treatment
Author: Thomas C. Weiss : Contact: Disabled World
Published: 2010-09-14 : (Rev. 2017-05-05)
Synopsis and Key Points:
Information on Amblyopia, or lazy eye, an eye condition noted by reduced vision not correctable by glasses or contact lenses.
Amblyopia, more commonly referred to as, 'lazy eye,' is an eye condition noted by reduced vision that is not correctable by either glasses or contact lenses. Amblyopia is not caused by any form of eye disease.
Amblyopia, also called lazy eye, is a disorder of sight due to the eye and brain not working well together. It results in decreased vision in an eye that otherwise typically appears normal. It is the most common cause of decreased vision in a single eye among children and younger adults. Amblyopia is a developmental problem in the brain, not any intrinsic, organic neurological problem in the eyeball (although organic problems can lead to amblyopia which can continue to exist after the organic problem has resolved by medical intervention). The part of the brain receiving images from the affected eye is not stimulated properly and does not develop to its full visual potential.
The affected person's brain fails to fully acknowledge the images seen by their amblyopic eye. The condition nearly always affects only one of a person's eyes, although it might cause a reduction of vision in both of their eyes. An estimated three-percent of children under the age of six have some form of amblyopia.
A number of people mistake people who have a turned or crossed eye with those who have amblyopia. Strabismus - crossed or turned eye, and Amblyopia, or lazy eye, are not the same condition. Some of the confusion can be because of the fact that strabismus may cause amblyopia. Amblyopia can result from a constant unilateral strabismus, either in the person's left or right eye. Alternating or intermittent strabismus rarely causes amblyopia.
Strabismus, a large eye deviation or turn, is something that can be easily noted. Amblyopia without strabismus or associated with a minor deviation is not particularly easy to notice. An eye doctor who is comfortable with examining young children and infants has the ability to detect this type of amblyopia. For this reason, both infant and pre-school eye exams are very necessary.
A person's brain and eye work together in order to produce vision. Light enters a person's eye and is changed into nerve signals which travel along their optic nerve to their brain. Amblyopia is a term used when the vision in one of a person's eyes is reduced because their eye and brain do not work together as they should. The person's eye appears average, yet is not being used the way it should be because the person's brain is favoring the other eye.
Amblyopia is the most common cause of visual impairment in childhood today. The condition affects nearly two to three of every one-hundred children. Without successful treatment during early childhood, amblyopia often persists into adulthood. Amblyopia is the most common cause of monocular, or one-eye, visual impairment among not only children, but young and middle-aged adults.
Both of a person's eyes have to receive clear images during the critical period; anything that interferes with clear vision in either of their eyes during this critical period of time between birth and six years of age may result in amblyopia. The most common causes of amblyopia include strabismus, anisometropia, or different vision in each eye, or blockage of an eye because of lid droop, trauma or other causes. If one of a person's eyes sees clearly while the other sees a blur, their good eye and their brain will inhibit or suppress the eye with the blur. Amblyopia is a neurologically active process; the inhibition process, or suppression of one eye, may result in a permanent decrease in the vision in the suppressed eye that cannot be corrected with glasses, contact lenses, or lasik surgery. On occasion, amblyopia might be caused by other eye conditions, such as when one eye is farsighted, nearsighted, astigmatic, or the person has a cataract.
Due to the fact that amblyopia commonly occurs in one of person's eyes only, many parents and children might be unaware of the condition. Many parents fail to take their infants and children in for an early and comprehensive vision exam, leaving numbers of children undiagnosed until they receive an eye examination at a later age. The most important diagnostic tools include visual acuity tests in addition to the standard 20/20 letter charts used by schools, eye doctors, and pediatricians. An examination with cycloplegic drops might be needed to detect the condition.
When treated early, the treatment of amblyopia is usually simple and involves vision therapy, glasses, drops, and/or eye patching. Although detecting and correcting vision before the age of two is considered to be the best outcome, current research has dis-proven the belief that children over the age of seven cannot be treated successfully. There are no recent studies on the treatment of amblyopia in people over the age of seventeen, although there have been decades of successful clinical treatments of adults with amblyopia. Treating amblyopia after the age of seventeen requires more effort where vision therapy is concerned.
Treatment of amblyopia involves making the person use their eye with reduced vision. There are currently two ways to do this.
- Atropine: A drop of a drug known as atropine is placed into the person's stronger eye once each day to temporarily blur the vision in that eye so the person will prefer to use the eye with amblyopia. Treatment with atropine also stimulates vision in the person's weaker eye, helping the part of the person's brain that manages vision to develop more completely.
- Patching: Patching involves wearing an opaque adhesive patch over the person's stronger eye for a period of weeks to months. The therapy forces the person to use the eye with amblyopia. Patching stimulates vision in the person's weaker eye and helps the portion of their brain that manages vision to develop more completely.
While improvements in the vision of persons with amblyopia are possible at any age, early detection and treatment present opportunity for the best outcome. If amblyopia is not detected and treated early in a person's life it may cause permanent loss of vision with associated loss of steriopsis, or two-eyed depth perception. Amblyopia causes more vision loss in people under the age of forty than all other eye injuries and diseases combined.
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