Amblyopia

Amblyopia is an eye problem that causes poor vision and is most often diagnosed in children. The problem occurs when the connections between the eye and the brain do not develop properly. These connections are like roads - they carry vision information from the eyes to the parts of the brain that enable us to see. If these roads between the eyes and the brain do not get made, amblyopia occurs. These connections are made when children are young. After about age 10, if these roads from the eye to the brain are not made, vision may be permanently affected. Amblyopia is also called "lazy eye" in layman’s terms.

All babies are born with poor vision. Babies have vision important for their needs: seeing faces up close. As babies grow, their eyesight improves. In order for good vision to develop, it is necessary to have a clear, focused image that is the same in both eyes. If the image is not clear in one eye, or if the image isn't the same in both eyes, the vision connections or roads between the eyes and the brain do not develop properly. When these connections are not made properly when a person is young, the vision in the “bad” eye may never be normal. If a child with amblyopia does not get treated before these connections are completed (around age 10), that eye may never see 20/20. Amblyopia often affects depth perception, making it difficult for the eyes to work together. About 2 - 5% of children have amblyopia.

Types of Amblyopia:

Strabismic amblyopia occurs when strabismus (eye turn) is present and the eyes are not working together. If the brain paid attention to both eyes in someone who had strabismus, the person would see everything double. Both eyes need to work together and point straight ahead in order for the brain (and person) to see things normally. In order not to see double, the brain favors the eye that doesn’t turn. Since the brain isn’t paying attention to the eye that turns, the connections to the brain from that eye do not develop properly.

Refractive amblyopia refers to the condition when the eyes have an unequal "refractive power" or glasses prescription. One eye may be nearsighted and the other may be farsighted, or the amount of nearsightedness or farsightedness in each eye may be very different. Because the brain cannot "balance" this difference in prescription between the eyes, it picks the eye that is "easier" to see with and develops a preference to use this eye only. The same problem then occurs as with strabismic amblyopia: the proper connections between the “bad” eye and the brain do not get made.

Other causes of amblyopia include: congenital cataracts, eye tumors, ptosis (drooping eyelid) and eye trauma.

Treatment of amblyopia:

In most cases amblyopia is treatable. However, the success of treatment is dependent upon the initial level of vision, the amount of time the vision has been poor and the age of the child. The most important factor in treating amblyopia is compliance with the treatment plan.

Treatment requires "forcing" the brain to use the non-preferred eye. In most cases this means patching the normal eye for most or all of the day. Glasses may also be required to "balance" an unequal refractive power between the two eyes. Surgery may be necessary to correct an eye turn before any other treatments are started.

If a cataract is present, it may need to be removed before amblyopia treatment can be started. The initial treatment period may be difficult for the child, as he/she is being made to use their "bad" eye. This usually lasts a short period of time, as their vision improves rapidly. It cannot be overemphasized that the major reason for failure in the treatment of amblyopia is poor compliance with the treatment plan.

Glasses and/or contact lenses are often used to treat amblyopia. In addition, a program of vision therapy may be prescribed to help improve vision function. Vision therapy encourages the “bad” eye to improve by doing visually demanding tasks with that eye and training the eyes to work together as a team.

Is amblyopia preventable?

Early detection and treatment of amblyopia can help to reduce the chances of one eye becoming amblyopic. People with a family or personal history of amblyopia should realize that some of the causes of amblyopia can be hereditary and passed down to their children.

It is important for a child to have a comprehensive eye exam. The American Optometric Association recommends all children to have their first regular eye examination at six months of age. If all is normal at the six-month evaluation, the next examination is then usually recommended at three years of age, then before elementary school and every 1-2 years thereafter.

How does amblyopia affect your life?

Children with amblyopia may have difficulty in school. Vision is very important in learning; when the eyes don’t work together it can be difficult to learn to read or excel in school in general. Amblyopia usually causes a decrease in depth perception and this can make certain sports difficult. Amblyopia is a handicap as an adult because it can limit the occupational and leisure activities that you can do. Again, activities requiring good depth perception may be difficult or impossible to perform. In addition, if the “good” eye becomes injured or develops vision problems, you will only be able to see using your “bad” eye. If the vision in the “bad” eye is 20/40 or worse then it may be difficult to perform your normal daily activities.

It is important to understand that amblyopia can be treated only when a child is young. If treatment is delayed until the child is older and more understanding, the “bad” eye may never develop properly.

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