WHAT IS AMBLYOPIA?
Amblyopia is a decreased vision in one or both eyes due to abnormal development of vision in infancy or childhood. In amblyopia, there may not be an obvious problem of the eye. Vision loss occurs because nerve pathways between the brain and the eye aren’t properly stimulated. The brain “learns” to see only blurry images with the amblyopic eye even when glasses are used. As a result, the brain favors one eye, usually due to poor vision in the other eye. Another word for amblyopia is often “lazy eye.” It is the leading cause of vision loss amongst children.
WHAT CAUSES AMBLYOPIA?
The most common cause is a refractive error in one or both eyes that is not corrected early in childhood resulting in poor development of the visual function in the affected eye/s. This is called refractive amblyopia. Additionally, the amblyopic eye may not look any different from the normal seeing eye. Therefore, parents and pediatricians may not think there is a problem because the child’s eyes look normal. For these reasons, this kind of amblyopia in children may not be found until the child has a vision test.
This kind of amblyopia can affect one or both eyes and can be best helped if the problem is found early. Another common cause is strabismus or eye misalignment. This is called strabismic amblyopia. Rarely there is a structural anomaly that impairs the visual function like a droopy eyelid or opacity in the visual axis like cataract or corneal scar. This is called deprivation amblyopia. Multiple causative factors can coexist.
WHEN SHOULD AMBLYOPIA BE TREATED?
Early treatment is always best. If necessary, children with refractive errors (nearsightedness, farsightedness, or astigmatism) can wear glasses or contact lenses when they are as young as one week old. Children with cataracts or other “amblyogenic” conditions are usually treated promptly to minimize the development of amblyopia.
HOW OLD IS TOO OLD FOR AMBLYOPIA TREATMENT?
Some improvement in vision can be attained with amblyopia therapy initiated in younger teenagers (through age 14 years). Better treatment success is achieved when treatment starts early, however.
HOW IS AMBLYOPIA TREATED?
One of the most important treatments of amblyopia is correcting the refractive error with consistent use of glasses and/or contact lenses. Other mainstays of amblyopia treatment are to enable as clear an image as possible (for example, by removing a cataract), and forcing the child to use the weaker eye (via patching the better-seeing eye).
WHEN SHOULD PATCHING BE USED FOR AMBLYOPIA TREATMENT?
Patching is a very effective way of treating amblyopia as it allows the weaker eye to get stronger, however, it is very hard to make a young child wear a patch. It needs a lot of effort, persistence, and encouragement form the parents. The younger the child is, the faster it works in improving the vision, therefore the parents should be persistent and encouraging and not wait until the child is old enough to want to patch.
ARE THERE DIFFERENT TYPES OF PATCHES?
The classic patch is an adhesive “Band-Aid” which is applied directly to the skin around the eye. They are available in different sizes for younger and older children. For children wearing glasses, both cloth and semi-transparent stickers (Bangerter foils) may be placed over or onto the spectacles. “Pirate” patches on elastic bands are especially prone to “peeking” and are therefore only occasionally appropriate.
HOW MANY HOURS PER DAY PATCHING IS ENOUGH FOR TREATING AMBLYOPIA?
The mainstay of treating amblyopia is patching of the dominant (good) eye, either full or part-time during waking hours. The prescribed number of hours of patching will depend on the visual acuity in the amblyopic eye and can vary from 2 to 6 hours or even longer.
HOW LONG DOES AMBLYOPIA PATCHING THERAPY TAKE TO WORK?
Although vision improvement frequently occurs within weeks of beginning patching treatment, optimal results often take many months. Once vision has been improved, less (maintenance) patching may be required to keep the vision from slipping or deteriorating. This maintenance treatment may be advisable for several months to years.
DURING WHICH ACTIVITIES SHOULD PATCHING BE PERFORMED?
There is no particular activity that will improve the vision more than another activity. The most important part of treatment is keeping the patch on for the prescribed treatment time. As long as the child is conscious and has his or her eyes open, visual input will be processed by the amblyopic eye. On the other hand, the child may be more cooperative or more open to bargaining if patching is performed during certain, favorite activities (such as watching a preferred television program or video). The performance of near activities (reading, coloring, hand-held computer games) during treatment may be more stimulating to the brain and produce better or more rapid recovery of vision.
WHAT HAPPENS IF AMBLYOPIA IS NOT TREATED
If amblyopia is not treated the vision in the affected eye/s will be permanently decreased causing deficits in-depth perception and peripheral vision. Moreover, if the good eye becomes injured or affected by a disease, significant lifetime disability may result.
CAN SURGERY BE PERFORMED TO TREAT AMBLYOPIA?
There is no surgery to improve the vision for amblyopia. Surgery can be performed to straighten misaligned eyes such as crossing. Surgery to make the eyes straight can only help enable the eyes to work together as a team. Children with strabismic amblyopia still need close monitoring and treatment for the amblyopia, and this treatment is usually performed before strabismus surgery is considered.
Children who are born with cataracts may need surgery to take out cataracts. After surgery, the child will usually need vision correction with glasses or contact lenses and patching.
WHAT ARE APPROPRIATE GOALS OF AMBLYOPIA TREATMENT?
In all cases, the goal is the best possible vision in each eye. While not every child can be improved to 20/20, most can obtain a substantial improvement in vision. The earlier treatment for amblyopia, the more successful the treatment tends to be.
WHAT HAPPENS IF AMBLYOPIA TREATMENT DOES NOT WORK?
Children who have amblyopia in one eye and good vision only in their other eye can wear safety glasses and sports goggles to protect the normal eye from injury. As long as the good eye stays healthy, these children function normally in most aspects of society. In most cases loss of vision from amblyopia can be prevented or successfully treated if started early enough and if the degree of amblyopia is not extreme.