AMBLYOPIA (LAZY EYE)
Amblyopia occurs when there is a lack of vision in one eye because the eye and the brain are not working together. Amblyopia is an early childhood condition that develops because of abnormal visual experience that changes the nerve pathways between the retina and the brain. When an individual has amblyopia, the brain focuses on one eye than the other. The weaker eye receives less visual signals. Eventually, the ability of the eyes to work together decreases and the brain ignores the visual input from the weaker eye. If the eye is not stimulated properly, the nerve cell responsible for vision fails to mature normally. Amblyopia normally only affects one eye. The affected eye appears normal but suffers from a decreased vision. It is the most common cause of decreased vision in a single eye among children. In rare cases, reduced visual acuity can occur in both eyes. Reduced vision can be avoided if amblyopia is detected early in life and promptly treated. If left untreated, the condition can cause severe visual disability in the affected eye, including legal blindness. It is estimated that 3% of children under six have some form of amblyopia.
CAUSES
During the critical period (birth to 6 years of age), it is important that both eyes receive a clear image. Anything that interferes with or obstructs vision in either eye during this period has the potential to cause the condition, this is because this is a child’s development stage.
Common causes of amblyopia include:
- Strabismus – is an imbalance in the muscles that position the eye. This causes the eye the eye to turn out or cross in making it difficult for both eyes to track objects together. This type is called strabismus amblyopia
- Refractive anisometropia – amblyopia is sometimes caused by the unequal refractive error between the two eyes. For example, one eye may suffer from uncorrected nearsighted, farsightedness, or astigmatism and the other may not. In such cases, the brain relies on the eye with less uncorrected refractive error and ignores the blurred vision from the other eye. The eye which provides the brain with the clear image becomes the dominant eye. This type is called refractive amblyopia.
- Deprivation – results from an obstruction of light into the baby’s eye. This may include congenital cataract or corneal haziness. In infancy, this requires urgent treatment to prevent permanent vision loss. This type is called deprivation amblyopia.
Factors that can increase the risk of the condition include:
- Premature birth
- A family history of lazy eye
- Developmental disabilities
SYMPTOMS
- Poor vision in one eye
- Poor depth perception
- An eye that turns/wanders either upward, downward, outward or inward
- Eyes that do not work together
DIAGNOSIS AND TREATMENT
Diagnosis of the condition early is important, preferably before the age of 6. An early eye check is equally important if there is a family history of crossed eyes, childhood cataracts, or other eye conditions.
In developed nations, children have their first eye examination between the ages of 3 and 5 years, or before starting school.
The doctor will conduct a thorough eye exam, checking for eye health, a wandering eye, a difference in vision between the two eyes or poor vision in both eyes.
TREATMENT
With early diagnosis and treatment, improved sight in a lazy eye can be accomplished. Treatment may include:
Eye patches– this involves patching or covering the dominant eye, this forces the weak eye to work harder, naturally strengthening its ability to focus.
Eye drops– an eyedrop of a medication called atropine (Isopto Atropine) may be given twice-weekly. This can temporarily blur vision in the dominant eye and encourages the child to use the weaker eye. This is an alternative for wearing patches.
Surgery- to realign muscle in the eye.
Corrective eyewear- contact lenses or glasses can correct refractive error such as nearsightedness, farsightedness, or astigmatism.