Amblyopia, also commonly known as lazy eye, is the failure of one eye to achieve the normal visual acuity even with the best corrected prescription of glasses or contact lenses. Amblyopia is caused by abnormal development of vision in early life, usually from birth up to the age of 7.
It is the leading cause of decreased vision among children as up to 3 out of 100 children may have it. Early diagnosis and proper treatment works well and can help to prevent long-term vision problems.
Symptoms
The symptoms of amblyopia can be hardly noticed as usually children having difficulties in describing what happened to their vision. Parents may noticed their kid having problems such as:
- Strabismus (one eye is turned in a direction that is different from the other eye)
- Abnormal head turn or tilt
- Squinting or closing one eye to see
- Poor depth perception
Risk factors
Some kids are born with amblyopia while others may develop it during their early childhood. Some groups of kids have higher risk of getting amblyopia such as:
- Prematurely born infants
- family history of amblyopia
- Small size at birth
- Developmental disabilities
Causes
The brain receives nerve signals from both of the eyes to see. Therefore if there are any ocular conditions that can cause abnormal development of vision of the eye and reduce its visual experience, the brain may choose to suppress or ignore the nerve signal from the poorer eye and rely only on the stronger eye. Common causes of the ocular conditions include:
1. Refractive
Usually it happens when there is uncorrected eye power (refractive errors) such as near-sightedness (having trouble seeing far away), far-sightedness (having trouble seeing things up close), and astigmatism. It may also be due to the significant difference in the eye power between both eyes, which is also known as anisometropia.
These problems can be easily treated by glasses or contact lenses. However, if it is left untreated or fails to detect in early life, the brain may choose to only rely on the stronger eye with better vision and thus lead to amblyopia.
2. Strabismic Amblyopia
Strabismus, also known as squint eye, is the imbalance of the eye muscles that cause the eyes to turn in or out, up or down, and prevents them from working together.
3. Deprivation
It happens when something prohibits the eyes to get clear vision, such as droopy eyelids and cataracts. Cataract does not only happen in the elderly, but it may appear in babies or children that are born with it.
Diagnosis
Amblyopia can be diagnosed by undergoing a full detailed eye examination that is carried out by qualified and registered optometrists and ophthalmologists. The full eye examination will include refraction, extraocular muscle test, color vision and inner ocular health check.
Treatment and management
It is better to treat amblyopia as early as possible when the eyes are still developing and building up connections with the brain. The best results occur when treatment starts before age 7, although half of the children between the ages of 7 and 17 respond to treatment.
The options of treatment depend on the cause and severity of amblyopia:
- Visual aids such as glasses or contact lenses to correct the power of the eyes.
- Patching of the stronger eye to stimulates the poorer eye to work.
- Instillation of medication eye drops such as atropine into the stronger eye will cause it to have temporarily blurry vision and thus encourage the poorer eye to see.
- Surgery can be done to remove the cataract or to fix the droopy eyelid that causes deprivation amblyopia. For those who have severe squint eyes, doctors may perform surgery to straighten the eyes.
