What is Amblyopia?
Amblyopia, also called "lazy eye", is a decrease in the child’s vision that can happen even when there is no problem with the structure of the eye. The decrease in vision results when one or both eyes send a blurry image to the brain. The brain then “learns” to only see blurry with that eye, even when glasses are used. Only children can get amblyopia. If it is not treated it can cause permanent loss of vision.
- Amblyopia is the most common cause of visual loss in children and young adults.
- Incidence of amblyopia is between 1% and 3.5% in developed countries.
- Amblyopia is potentially reversible if detected and treated at a young age.
- Need for glasses (refractive error),
- Eye misalignment (strabismic),
- Eye pathologies that occlude the visual axis,
- Combination of the above diseases.
What causes of amblyopia?
The causes of amblyopia are
How do we treat amblyopia?
Amblyopia is potentially reversible if detected and treated at a young age. The sensitive period is from birth to ∼6 to 8 years of age called critical widow. Treatment within the critical window restores the vision to the amblyopic eye by altering the visual pathways.
Treatment may consist of:
Glasses: What have we learn from studies?
- Glasses may improve amblyopia by more than 2 lines in 77% of patients
- Complete resolution of amblyopia with glasses is in 27%
- Reached maximum improvement in visual acuity is after 15 weeks of glasses
- It is recommended to treat children with amblyopia with glasses until the visual acuity stops improving with glasses alone
Patch the good eye.
How many hours do you need to patch?
- Children with mild amblyopia (20/25-20/40)-no patching, just observe
- Children with moderate amblyopia (20/40 to 20/100)
- Children with severe amblyopia (20/100 to 20/400)
- Age <7: 79% successful rate in improvement of visual acuity
- Age 7 to 12 years: 53% successful rate in improvement of visual acuity
- Age 13 to 17 years
What is the ideal age to patch?
Younger age at initiation of treatment is associated with better final visual acuity.
Are there different types of patches?
The classic patch is an adhesive “Band-Aid” which is applied directly to the skin around the eye. These may be 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.
During which activities should patching be performed?
The particular activity is not terribly important compared to the need to keep the patch on during the allotted 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 desirable activities, such as watching a preferred television program or video.
What if my child refuses to wear the patch?
Many children will resist wearing a patch at first. Successful patching may require persistence and plenty of encouragement from family members, neighbours, teachers, etc. Children will often throw a temper-tantrum, but then eventually learn not to remove the patch. Providing the child with a reward for keeping the patch on for the prescribed period is another helpful method.
How can I encourage my child to wear the patch?
Making patching a consistent part of the daily routine is helpful in encouraging younger children to patch. One on one playtime with an infant or toddler may be the best approach to ensure the child does not remove the patch. Sometimes caregivers use Velcro wraps around the arms of infants and toddlers to prevent patch removal. Usually these need to be used just a few times to ensure compliance. Older children may need to be rewarded for good patch compliance. A calendar with stars placed on it for each episode of successful patching is motivating to some children. Offering a preferred activity (favourite TV show, video games) while patching can also be helpful.
Atropine is used as an alternative treatment to patching in children who do not comply with patching. Put one drop of Atropine 1% in the good eye every night.
- Visual outcome is the same as with patching, but the improvement in visual acuity in patching group is faster.
When do we need to stop treatment?
After adequate recovery of visual acuity has occurred, the eye doctor may consider to stop the treatment.
Continuous monitoring of visual acuity for at least 1 year after the cessation of amblyopia treatment is recommended.
The amblyopia may come back in 25% in children who discontinued patching and 21% in children discontinuing atropine. There is 4 times risk for amblyopia to come back if the treatment is not gradual tapered.
Can surgery be performed to treat amblyopia?
Surgery on the eye muscles is a treatment for strabismus – it can straighten misaligned eyes. By itself however, surgery does not usually or completely help the amblyopia. Surgery to make the eyes straight can only help enable the eyes to work together as a team. Children with strabismus amblyopia still need close monitoring and treatment for the amblyopia, and this treatment is usually performed before strabismus surgery is considered.
What happens if amblyopia treatment does not work?
In some cases, treatment for amblyopia may not succeed in substantially improving vision. It is hard to decide to stop treatment, but sometimes it is best for both the child and the family. 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 good eye from injury. As long as the good eye stays healthy, these children function normally in most aspects of society.