Amblyopia or lazy eye is the leading cause of vision loss in children. The condition is treatable. Typically, treatment strategy involves eye patching and corrective lenses that work well in children. New treatments have also been developed to improve vision and the smallest detectable visual depth differences (stereo-acuity) in children and adults with amblyopia.
Early recognition and effective treatment are important to prevent vision loss. Usually, effective treatment of amblyopia in children requires around 9 years. However, an adult may also benefit from the treatment if the brain retains sufficient flexibility for modification.
Currently, there are three main treatment steps involved:
- Elimination of any source of visual deprivation. For example, removal of clouding of the clear lens of the eye (cataracts) and squint (strabismus) surgery in selected cases.
- Correction of significant refractive errors with glasses.
- Promoting and encouraging the use of the lazy eye by hindering the visual input from the better eye by various methods, which include:
- Patching: In children with moderate amblyopia, 2 hours of patching daily provides the same results as 6 hours of patching. The patch should be affixed over the better eye. It should not be applied directly to eyeglasses because the child could easily look around it. In children with severe amblyopia, daily patching for 6 hours shows equal improvement as all-day patching. In children with squint and amblyopia (strabismic amblyopia), vision correction with glasses along with patching the amblyopic eye is more effective than glasses alone.
- Atropine eye drops: Administrating Atropine 1% eye drops in the better eye blocks the nerve supply to some eye structures, such as ciliary muscle and pupil. This causes temporary paralysis of accommodation (cycloplegia) and dilation of the pupil (structure provides eye color). Therefore, the better eye gets blurred, and it is unable to focus on near distance. Thus, it stimulates the brain to use the lazy (amblyopic) eye for vision, which results in subsequent visual improvement. Daily atropine eye drops are as effective as daily patching in children with moderate amblyopia. Also, Atropine given on 2 consecutive days per week is as effective as daily use in children with moderate amblyopia.
- Penalization using filters: Penalization of the better eye with a translucent Bangerter filter is as effective as 2 hours of patching daily. This filter can be applied to the eyeglass lens over the better eye if the child has moderate amblyopia. Compliance of children wearing glasses should be monitored to maximize effectiveness.
The following things should be speculated while treating amblyopia:
- The eye doctor will customize the treatment regimens based on age, visual acuity, previous treatments, adherence, and psychosocial factors.
- Amblyopia may recur in 25% of children; therefore, continuous surveillance and monitoring are necessary.
- Children younger than 7 years may show the most benefits from the treatment than older children. However, many factors contribute to this variability in treatment response. Therefore, some older children may still benefit from the above treatments.
What is amblyopia?
When the vision of one of the eyes does not develop properly and overtime decreases the eyesight, it is called amblyopia or lazy eye.
Nerve pathways between the brain and an eye are not properly stimulated, and the brain fails to process inputs from one eye. Therefore, the brain favors the better eye. This results in decreased vision in the affected eye that otherwise appears normal. This condition occurs in childhood. Overtime without treatment the brain will learn to ignore the image that comes from the weaker eye. This may result in permanent vision problems.
How do you get amblyopia?
- Refractive errors: It occurs when the eye cannot clearly focus the images from the outside world. The result of refractive errors is blurred vision, which is sometimes so severe that it causes visual impairment., such as in the case of near-sightedness, farsightedness, or distorted or blurry vision (astigmatism). When the brain gets both a blurry image and a clear one, it starts ignoring the blurry one. If this condition continues for months or years, vision in the blurry eye will get worse.
- Squint (strabismus): It is a disorder in which both eyes do not look in the same direction at the same time. One eye turns inwards, upwards, downwards, or outwards whereas the other one focuses on one spot. Then, often people see double images. In this case, the brain ignores the image from the eye that is not properly aligned.
- Cataract: Clouding of the lens inside the eye can make the vision blurry. Therefore, the vision in that eye might not develop properly.
- Droopy eyelid (ptosis): A sagging of the eyelid may also block the vision. Over time, the brain may start ignoring the image from that eye.
What are the signs and symptoms of amblyopia?
Amblyopia usually starts in childhood, usually between ages 6 and 9 years. Early identification and treatment before the age of 7 years is the best strategy to fully correct this condition. A person with a lazy eye may experience:
- Wandering of the eye.
- Trouble viewing depth perception of near or far away objects.
- Squinting or shutting one eye.
- Head tilting.
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McConaghy JR, McGuirk R. Amblyopia: Detection and Treatment. Am Fam Physician. December 15, 2019;100(12):745-750. https://pubmed.ncbi.nlm.nih.gov/31845774/