Amblyopia (Lazy Eye)
Amblyopia is a condition in which the vision in one or both eyes cannot be corrected to 20/20 even after the correct eyeglasses have been prescribed.
In a child with normal visual development, the brain receives information from each eye separately and combines the two images to see one clear picture of the world. This “combining” of the information from the two eyes is called “fusing” or “fusion.” Amblyopia occurs when the brain is unable to “fuse” or combine the information coming from both eyes. The brain learns to ignore or “suppress” the information from one eye. This leads to a lack of development or deterioration of the vision in the eye that is not being used. Amblyopia is caused by a crossed eye or drifting-eye condition called strabismus or by unequal optical prescriptions in the two eyes.
There is a long standing misconception that amblyopia cannot be treated beyond a certain age. Numerous recent studies have shown that amblyopia can be treated effectively at almost any age.
Generally, amblyopia will only develop in children if the causative problem starts before 6 years of age. Fortunately, however, amblyopia can be treated effectively at almost any age. There is a long standing misconception that amblyopia cannot be treated beyond a certain age. Numerous recent studies have shown that this is not true.
The term that is sometimes used when referring to amblyopia is “lazy eye.” The problem is really in the brain, when both eyes are not able to be used together and the brain shuts off or ignores the information from one eye. In addition to reduced clarity of vision in the eye with amblyopia, other eye brain functions such as depth perception, tracking, and focusing are affected.
How is Amblyopia Treated?
Glasses, patching of the good eye for several hours a day, atropine eye drops, and vision therapy are all treatment options for amblyopia. The goal is to maximize clarity of sight (visual acuity), to normalize the tracking and focusing skills of the amblyopic eye, and to allow the brain to use both eyes together. When a child develops good binocular vision after amblyopia treatment, the chances of maintaining long term improvements are much better. When a child needs patching therapy for amblyopia, studies have shown that shorter periods of patching each day are usually as effective as longer or all day patching.
Strabismus is a general term that refers to a condition when both eyes do not point in the same direction. Larger amounts of strabismus can be noticed just by looking at someone’s eyes. Smaller amounts of strabismus are only detectable with special tests.
Strabismus can be present at all times or intermittent, meaning the eye turns only some of the time. Strabismus is often genetic, and is usually first noticed from birth to age 5. When children develop strabismus, their brain learns to turn off (or suppress) one eye to prevent double vision. Amblyopia can also be caused by strabismus when the child loses vision in the eye that is turned off.
Esotropia and exotropia are the most common types of strabismus. Exotropia is when one eye drifts outwards towards the ear, and esotropia is when one eye drifts in towards the nose.
Treatment options for strabismus include vision therapy, eye muscle surgery, and glasses. Vision therapy can be very helpful for mild to moderate strabismus, but larger amounts will usually require eye muscle surgery. Dr. Scheiman works closely with pediatric ophthalmologists who perform the surgery, and he often recommends pre- or post surgical vision therapy to obtain the best possible result. The goal of treatment is achieve cosmetically straight eyes along with normal binocular vision and depth perception. Seeing the world in 3-D helps with sports, driving, motor skills and even with the latest entertainment technology!
Adults with strabismus and poor depth perception can also be helped by vision therapy.