Amblyopia, also known as a “lazy eye”, is basically reduced vision capability. There are some rare forms of amblyopia that involve both eyes. Amblyopia is the most common cause of partial or total blindness in one eye in children.
The term lazy eye is misleading because the eye is not actually lazy. It is a developmental problem where the brain actively ignores the visual input from the misaligned or blurry eye, leading to weak vision in that eye.
In addition to poor visual acuity, people with amblyopia are more prone to having difficulties with depth perception, eye movements related to reading, and visual decision making while driving.
Amblyopia develops in childhood due to:
Significant differences (Anisometropia) in the prescription (power) between the two eyes due to nearsightedness, farsightedness or astigmatism
Constantly misaligned eyes or crossed eyes (strabismus)
An obstruction of vision in early childhood from cataracts, ptosis (droopy eyelid) or an intraocular tumor.
It is important to note that, because amblyopia is typically a problem of infant vision development, symptoms of the condition can be difficult to detect. Symptoms may include noticeably favoring one eye over the other, an eye turn (either upward-downward, outward or inward) or a tendency to bump into objects on one side.
The best way to identify children who are at risk for amblyopia is by performing a comprehensive eye examination.
Amblyopia is best treated as early as possible. The earlier the problem is found and treated, the more successful the outcomes tend to be.
Many children who have anisometropia or unequal vision, do not know they have an eye problem because the stronger eye and the brain compensate for the weak eye. Over time, the weaker eye gets progressively worse, and amblyopia develops. Treatment may include:
Glasses correct nearsightedness, farsightedness, or astigmatism. Glasses may also correct an eye turn using power or prism. Glasses can also be used to blur the stronger eye so that the brain uses and develops the weaker eye. This is often a more socially acceptable method compared to using an eye patch over the stronger eye. Sometimes, glasses can cure the amblyopia, and no further treatment is required.
If a cataract is the cause of amblyopia, it can be removed surgically under either local or general anesthesia.
In some cases, amblyopia is caused by an eyelid that is blocking the vision to the weaker eye, in such cases, the usual treatment is surgery to lift the eyelid. Once the vision is corrected and any underlying medical issues are treated, then glasses and/or eye patching therapy can help improve vision in the weak eye.
An eye patch over the stronger eye may be required for several hours each day or all day long to strengthen the weaker eye. This will need to continue for many months to achieve improvement in the weak eye. A child should be encouraged to do close-up activities while wearing the patch, such as schoolwork, reading, or coloring. (Patches can be made colorful and fun to help the child accept it.) The younger and more consistent the eye patch is used, the better the improvement in vision will be.
Atropine drops can be used to blur vision in the stronger eye. Atropine is usually less socially awkward for a child than an eye patch, and can be just as effective. Thus, children who cannot tolerate wearing a patch may be prescribed eye drops instead.
This involves different exercises and games to improve vision development in the child's weaker eye and is done in combination with other treatments.
Surgery is sometimes necessary to improve the alignment of the eyes giving the brain a better chance at using and developing the vision in the weak eye. Surgery also improves the child's appearance by straightening the eyes. This may or may not improve vision. After surgery, glasses, eye patches or vision therapy can be done to hasten the improvement in the weaker eye.
Amblyopia often starts before there are any obvious signs that something is wrong. This is why babies and young children should have their eyes examined regularly by an Optometrist. Children should have comprehensive eye examinations with an Optometrist at the following times:
Before the child is 3 months old, if the child exhibits eye alignment or vision problems. They should be re-checked again at 6 months and 1 year of age.
At 2-3 years of age, if there are no obvious problems, and then annually thereafter
If there are any concerns that the child may be suffering from or developing a “lazy eye,” have him/her examined right away. Children with a family history of amblyopia are at a higher risk for developing amblyopia and should be checked by age 2-3.
Early diagnosing and treating increases the chance for a complete recovery. Amblyopia will not go away on its own. The eye completes visual development by the age of 9, so early treatment is crucial for success. If not diagnosed until the preteen, teen or adult years, treatment to improve visual acuity is usually ineffective. The sooner the treatment begins, the better your child's vision will be.