Strabismus is a misalignment of the eyes where the two eyes are pointed in different directions. Though it is a common condition which affects four percent of children, it may appear later in life. The misalignment may be permanent and always noticeable, or it may come and go, appearing normal at times and abnormal at others. One eye may be directed straight ahead while the other eye is turned inward, outward, upward, or downward. In other cases, the turned eye may straighten at times, and the straight eye may turn.
Different forms of strabismus include:
Eye Muscles
There are six muscles attached to the outside of each eye which control its movement. In each eye, two muscles move the eye right or left; the other four muscles move the eye up or down and control tilting movements. in order to line up and focus both eyes on a target, all eye muscles of each eye must be balanced and working together with the corresponding muscles of the opposite eye. When the eye muscles do not work together then misalignment of the eyes or strabismus results.
Normal alignment of both eyes during childhood allows good vision to develop in each eye. Abnormal alignment as in strabismus, may cause reduced vision or amblyopia. Amblyopia occurs in approximately one-half of children with strabismus. The brain will recognize the image of the better seeing eye and ignore the image of the weaker or amblyopic eye. Amblyopia often can be reversed by patching the preferred or better seeing eye in order to strengthen and improve the vision of the weaker one. if amblyopia is detected before the first few years of life, treatment is often successful. If adequate treatment is delayed until later, amblyopia or reduced vision generally becomes permanent. As a rule, the earlier amblyopia is treated, the better the visual result.
Causes and Symptoms
Strabismus is caused by misaligned eye muscles. However, the exact reason for the misalignment of the eyes leading to strabismus is not fully understood. It is known that strabismus may run in families. However, in many patients there are no relatives with the problem. The condition occurs equally in males and females.
The brain controls the eye muscles. This explains why children with cerebral palsy, Down's syndrome and hydrocephalus often have strabismus. If the vision of one eye is cloudy because of a cataract or injury, then the eye will also frequently turn in or out.
The primary symptom of strabismus is an eye that is not straight. Sometimes a youngster will squint one eye in bright sunlight. Faulty depth perception may even be present. Some children may have a tendency to turn or tilt their heads in a specific direction in order to use their eyes together.
Parents often get the false impression that a child may "outgrow" the problem. Though fatigue or illness may worsen strabismus, children do not outgrow strabismus. Once a child has a suspected turning of an eye, an examination by an ophthalmologist is necessary to determine the cause and begin treatment.
Detection and Diagnosis
A child should be examined by the family doctor, pediatrician, or ophthalmologist (a medical eye doctor) during infancy and preschool in order to detect any potential eye problem, particularly if a relative has had strabismus or amblyopia. Even the most observant parent may not discover strabismus without a doctor's help. It is often difficult to determine the difference between eyes that appear to be crossed and true strabismus. Young children usually have a wide, flat nose and a redundant fold of skin at the inner eyelid that tends to hide the eye during side gaze and cause concern about strabismus. An ophthalmologist can readily distinguish this from true strabismus.
It is never too early to have a child's eyes examined. Fortunately, an ophthalmologist can test even a newborn infant's eyes. If the eye examination is delayed until the child enters school, it may be too late to properly correct strabismus and amblyopia. Occasionally, a misaligned eye may be caused by a cataract or tumor within the eye. It is important to know about such conditions as early as possible so both the underlying condition and resulting strabismus can be corrected.
Treatment
The goals of treatment are to preserve vision, straighten the eyes, and restore binocular vision. Treatment of strabismus depends upon the exact cause of the misaligned eyes. It can be directed towards unbalanced muscles, cataract removal or other conditions which are causing the eyes to turn. After a complete eye examination, including a detailed study of the inner parts of the eye, an ophthalmologist can recommend appropriate optical, medical, or surgical therapy. Covering or patching the good eye to force use of the amblyopic eye may be necessary to ensure equal vision.
The two most common types of strabismus are esotropia, where an eye turns in and exotropia, where an eye turns out. Esotropia is the most common type of strabismus in infants. Infants born with esotropia will not learn to use their two eyes together and may lose vision in the weaker eye. In most cases, early surgery is needed to align the eyes in an effort to obtain binocular vision and prevent permanent loss of vision in and infant or child. The goal of eye surgery is to adjust the muscle tension on one or both eyes in order to pull the eyes straight. For example, in surgery for esotropia, the tight inner muscles are removed from the wall of the eye and placed further backward which weakens their pull and allows the eyes to move outward. Sometimes the outer muscles may be tightened by shortening the muscle length which further pulls the eye outward.
Another common form of esotropia that occurs in children usually after age two is caused by a need
for glasses. These children are farsighted. They have the ability to focus their eyes enough to adjust for the farsightedness, which allows them to see well for both distance and near. Some children excessively cross their eyes when they focus, which causes one eye to turn in. Wearing glasses equal in strength to their farsightedness reduces the need to focus and straightens their eyes. Sometimes the addition of bifocals is necessary to further reduce the need to focus when looking at objects up close. Occasionally, eye drops and special lenses, called prisms, can be used to help the eyes focus properly. Rarely, eye exercises (orthoptics) are necessary to help older children control the eye misalignment.
Exotropia or an outward turning of an eye is another common type of strabismus. Most commonly this occurs when a child is focusing on distant objects. Often times the exotropia will occur intermittently, particularly when the child is daydreaming, ill, or tired. Parents often notice that the child squints one eye in the bright sunlight. Although glasses and prism therapy may reduce the amount of outward turning in some patients, surgery is usually needed.
Strabismus surgery is usually a safe and effective treatment, but is not a substitute for glasses or amblyopia therapy. During surgery, the eyeball is never removed from the socket. A small incision is made within the tissues covering the eye to allow access to the eye muscles. Selection of eye muscles to be operated on depends upon the direction that the eye is turning. Despite a thorough clinical evaluation and good surgical technique, the eyes may be closely aligned after surgery, but not perfect. In these cases, fine adjustment is dependent upon the coordination between the eye and the brain. Sometimes patients may require the use of prisms or glasses following eye muscle surgery. Overcorrections or under-corrections can occur and further surgery may be needed.
One or both eyes may be operated on. General anesthesia is required in children. Some adults may prefer local anesthesia. Recovery time is rapid and the patient is usually about to return to normal activity within a few days.
Early surgery is recommended to correct strabismus because younger infants can develop normal sight once the two eyes are straightened. As a child gets older, the chance of developing normal sight decreases. Additionally, the cosmetic defect resulting from "crossed eyes" can have a negative effect on a child's self-confidence. As with any surgery, eye muscle surgery has certain risks. There is a small risk of infection, bleeding, excessive scarring, and other rare complications which can lead to loss of vision.
Who Can Treat Strabismus?
An ophthalmologist is the medical doctor (MD or osteopath) who is educated, trained, and licensed to provide total care of the eyes including the diagnosis and treatment of strabismus. Total eye care includes performing comprehensive medical eye examinations, prescribing corrective lenses, diagnosing diseases and disorders of the eye, and using the appropriate medical and surgical procedures necessary for their treatment. Only an ophthalmologist can provide total eye care. An ophthalmologist should be consulted if a child has a family history of amblyopia or strabismus, if the eyes do not appear to be straight, if there is decreased vision in one or both eyes, or if there is any evidence of cataract, glaucoma, or other medical eye conditions.
Loss of Vision is Preventable
Treatment for strabismus is most effective when the child is young. It becomes more difficult to treat strabismus and establish binocularity as the child grows older, but cosmetic straightening of the eyes remains possible at any age. There is no known prevention for strabismus, but misaligned eyes can be straightened, and loss of sight from amblyopia is preventable if treatment is begun early.
In summary:
Remember, an ophthalmologist is the only doctor who provides total eye care: medical, surgical, and optical. It's your sight---your eyes deserve the best care available!
Different forms of strabismus include:
Eye Muscles
There are six muscles attached to the outside of each eye which control its movement. In each eye, two muscles move the eye right or left; the other four muscles move the eye up or down and control tilting movements. in order to line up and focus both eyes on a target, all eye muscles of each eye must be balanced and working together with the corresponding muscles of the opposite eye. When the eye muscles do not work together then misalignment of the eyes or strabismus results.
The eyes are designed to focus images clearly on the retina and then to relay that image to the brain. If both eyes are lined up on the same target, the visual portion of the brain can fuse the two pictures into a single 3-dimensional image. This creates depth perception and binocular vision which helps the eyes work together to transmit one "picture" to the brain. When one eye turns as in strabismus, two different pictures are sent to the brain. In the young child, the brain learns to ignore the image of the misaligned eye and sees only the image from the straight or better seeing eye. This causes loss of depth perception. Adults who develop strabismus usually have double vision because their brain is already trained to receive images from both eyes an cannot ignore the image from the weaker or turned eye.
Normal alignment of both eyes during childhood allows good vision to develop in each eye. Abnormal alignment as in strabismus, may cause reduced vision or amblyopia. Amblyopia occurs in approximately one-half of children with strabismus. The brain will recognize the image of the better seeing eye and ignore the image of the weaker or amblyopic eye. Amblyopia often can be reversed by patching the preferred or better seeing eye in order to strengthen and improve the vision of the weaker one. if amblyopia is detected before the first few years of life, treatment is often successful. If adequate treatment is delayed until later, amblyopia or reduced vision generally becomes permanent. As a rule, the earlier amblyopia is treated, the better the visual result.
Causes and Symptoms
Strabismus is caused by misaligned eye muscles. However, the exact reason for the misalignment of the eyes leading to strabismus is not fully understood. It is known that strabismus may run in families. However, in many patients there are no relatives with the problem. The condition occurs equally in males and females.
The brain controls the eye muscles. This explains why children with cerebral palsy, Down's syndrome and hydrocephalus often have strabismus. If the vision of one eye is cloudy because of a cataract or injury, then the eye will also frequently turn in or out.
The primary symptom of strabismus is an eye that is not straight. Sometimes a youngster will squint one eye in bright sunlight. Faulty depth perception may even be present. Some children may have a tendency to turn or tilt their heads in a specific direction in order to use their eyes together.
Parents often get the false impression that a child may "outgrow" the problem. Though fatigue or illness may worsen strabismus, children do not outgrow strabismus. Once a child has a suspected turning of an eye, an examination by an ophthalmologist is necessary to determine the cause and begin treatment.
Detection and Diagnosis
It is never too early to have a child's eyes examined. Fortunately, an ophthalmologist can test even a newborn infant's eyes. If the eye examination is delayed until the child enters school, it may be too late to properly correct strabismus and amblyopia. Occasionally, a misaligned eye may be caused by a cataract or tumor within the eye. It is important to know about such conditions as early as possible so both the underlying condition and resulting strabismus can be corrected.
Treatment
The goals of treatment are to preserve vision, straighten the eyes, and restore binocular vision. Treatment of strabismus depends upon the exact cause of the misaligned eyes. It can be directed towards unbalanced muscles, cataract removal or other conditions which are causing the eyes to turn. After a complete eye examination, including a detailed study of the inner parts of the eye, an ophthalmologist can recommend appropriate optical, medical, or surgical therapy. Covering or patching the good eye to force use of the amblyopic eye may be necessary to ensure equal vision.
The two most common types of strabismus are esotropia, where an eye turns in and exotropia, where an eye turns out. Esotropia is the most common type of strabismus in infants. Infants born with esotropia will not learn to use their two eyes together and may lose vision in the weaker eye. In most cases, early surgery is needed to align the eyes in an effort to obtain binocular vision and prevent permanent loss of vision in and infant or child. The goal of eye surgery is to adjust the muscle tension on one or both eyes in order to pull the eyes straight. For example, in surgery for esotropia, the tight inner muscles are removed from the wall of the eye and placed further backward which weakens their pull and allows the eyes to move outward. Sometimes the outer muscles may be tightened by shortening the muscle length which further pulls the eye outward.
Another common form of esotropia that occurs in children usually after age two is caused by a need
for glasses. These children are farsighted. They have the ability to focus their eyes enough to adjust for the farsightedness, which allows them to see well for both distance and near. Some children excessively cross their eyes when they focus, which causes one eye to turn in. Wearing glasses equal in strength to their farsightedness reduces the need to focus and straightens their eyes. Sometimes the addition of bifocals is necessary to further reduce the need to focus when looking at objects up close. Occasionally, eye drops and special lenses, called prisms, can be used to help the eyes focus properly. Rarely, eye exercises (orthoptics) are necessary to help older children control the eye misalignment.
Exotropia or an outward turning of an eye is another common type of strabismus. Most commonly this occurs when a child is focusing on distant objects. Often times the exotropia will occur intermittently, particularly when the child is daydreaming, ill, or tired. Parents often notice that the child squints one eye in the bright sunlight. Although glasses and prism therapy may reduce the amount of outward turning in some patients, surgery is usually needed.Strabismus surgery is usually a safe and effective treatment, but is not a substitute for glasses or amblyopia therapy. During surgery, the eyeball is never removed from the socket. A small incision is made within the tissues covering the eye to allow access to the eye muscles. Selection of eye muscles to be operated on depends upon the direction that the eye is turning. Despite a thorough clinical evaluation and good surgical technique, the eyes may be closely aligned after surgery, but not perfect. In these cases, fine adjustment is dependent upon the coordination between the eye and the brain. Sometimes patients may require the use of prisms or glasses following eye muscle surgery. Overcorrections or under-corrections can occur and further surgery may be needed.
One or both eyes may be operated on. General anesthesia is required in children. Some adults may prefer local anesthesia. Recovery time is rapid and the patient is usually about to return to normal activity within a few days.
Early surgery is recommended to correct strabismus because younger infants can develop normal sight once the two eyes are straightened. As a child gets older, the chance of developing normal sight decreases. Additionally, the cosmetic defect resulting from "crossed eyes" can have a negative effect on a child's self-confidence. As with any surgery, eye muscle surgery has certain risks. There is a small risk of infection, bleeding, excessive scarring, and other rare complications which can lead to loss of vision.
Who Can Treat Strabismus?
An ophthalmologist is the medical doctor (MD or osteopath) who is educated, trained, and licensed to provide total care of the eyes including the diagnosis and treatment of strabismus. Total eye care includes performing comprehensive medical eye examinations, prescribing corrective lenses, diagnosing diseases and disorders of the eye, and using the appropriate medical and surgical procedures necessary for their treatment. Only an ophthalmologist can provide total eye care. An ophthalmologist should be consulted if a child has a family history of amblyopia or strabismus, if the eyes do not appear to be straight, if there is decreased vision in one or both eyes, or if there is any evidence of cataract, glaucoma, or other medical eye conditions.
Loss of Vision is Preventable
Treatment for strabismus is most effective when the child is young. It becomes more difficult to treat strabismus and establish binocularity as the child grows older, but cosmetic straightening of the eyes remains possible at any age. There is no known prevention for strabismus, but misaligned eyes can be straightened, and loss of sight from amblyopia is preventable if treatment is begun early.
In summary:
- Children with strabismus do not outgrow the condition.
- Treatment for strabismus may be non-surgical and include eye drops or glasses.
- If surgical treatment is indicated, it is wise to align the eyes when the child is young in order to allow more normal use of the eyes together.
Remember, an ophthalmologist is the only doctor who provides total eye care: medical, surgical, and optical. It's your sight---your eyes deserve the best care available!
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