Amblyopia is a weakness of vision and occurs in approximately 4% of the population. Amblyopia is often referred to as "lazy eye", but this term is a non-medical term that is also used to describe strabismus (eye misalignment). Amblyopia is the leading cause for vision loss in children. Although amblyopia is often associated with strabismus, it is important to note amblyopia may occur completely independently of eye misalignment. Amblyopia results when the anatomy of the retina and optic nerve are intact and yet the brain is either not provided a clear image or has difficulty processing the information. Over time, the brain may become disinterested in processing a blurry image and essentially unable to correctly interpret the image of the affected eye.
There are different types of amblyopia including deprivation amblyopia, refractive amblyopia, and strabismic amblyopia. Amblyopia is a medical condition and requires intervention in order to have any hope of visual rehabilitation.
Deprivation amblyopia occurs when the visual axis is blocked from seeing correctly, such as with congenital ptosis, cataract, or corneal disease. The disease process of deprivation amblyopia may be bilateral, such as in cases of bilateral congenital cataracts. If left untreated, the child will unforunately develop poor vision.
Refractive amblyopia occurs when the refractive error of the two eyes are either very large or very unequal with respect to each other. Generally, the brain will have a blurry image from the eye that is either more far-sighted or has a high degree of astigmatism. This is demonstrated in the video that follows this discussion. In many cases, refractive amblyopia may be missed in some children with refractive amblyopia because no eye misalignment is present. The disease process of refractive amblyopia may be unilateral or bilateral.
Strabismic amblyopia occurs when the eyes are misaligned and the brain is receiving conflicting information from the turned eye. To avoid double vision or visual confusion, the child's brain will stop using the turned eye and the vision will correspondingly decrease. The treatment of strabismic amblyopia may involve glasses, surgery, patching, or a combination of all three.
Treatment for amblyopia consists primarily of glasses and patching or Atropine 1% eye drops. The patch is placed over the better seeing eye in order to encourage the brain to better develop vision in the weaker eye. The vision in your child's eyes may not improve instantaneously with initiating amblyopia treatment. The visual rehabilitation of brain generally requires time. Older children with amblyopia often requiring longer periods of treatment than younger children. Although many children will have some response to amblyopia treatment, not all children will obtain 20/20 vision. Atropine 1% eye drops are indicated if the child is unable to wear the patch and the weaker eye has vision equal to 20/100 or better. The use of Atropine 1% drops has a similar response rate compared to patching.
A recent NIH study with the Pediatric Eye Disease Investigator Group found that amblyopia may be initiated even in teenagers with some potential for improvement in the vision of the weaker eye. However, better success rates are achieved the younger the child is when treatment begins.
In cases of recalcitrant or unresponsive amblyopia, polycarbonate glasses are indicated to protect the better seeing eye.