Amblyopia is a term Ophthalmologists use to define what many think of as a “lazy eye.” Amblyopia, however, is a term that most people associate with eye misalignment. The term that Ophthalmologists use for a misalignment of the eyes is “strabismus.”
Strabismus can also be categorized into an eye cross, or esotropia, an eye drifting out, or exotropia, or an eye drifting up and/or down, hyper or hypotropia. All forms of strabismus can cause amblyopia if the ocular misalignment becomes constant over time. In particular, esotropia, can cause a rapid decrease in vision in the eye that is crossed. Some forms of strabismus, in particular, esotropia, can be corrected with glasses. Oftentimes, an esotropic patient is severely hyperopic or far-sighted. A lot of children are mildly far-sighted and use a mechanism called accommodation to focus through their farsightedness and see 20/20 or normally. A subset of patients, however, have to accommodate to such a degree that their eyes cross. Hyperopic glasses relax their need for accommodation and their eyes become straight. Some children cross only at near and may need a bifocal lens to correct this. Some esotropic patients need surgery. Exotropic (eyes turn out) patients usually have normal vision as through the same mechanism of accommodation, they can control their eye turning out. If they lose this control and their exotropia becomes more defined, they can lose vision from this disorder as well. The treatment for exotropia ranges from glasses to eye exercises to surgery.
Another type of amblyopia is one that is not as obvious. If a patient has a high prescription or need for glasses in one eye and has a lower prescription in the other, the eye with the higher prescription can become “lazy.” The treatment for this is glasses, correcting the difference between the 2 eyes. Many pediatricians do vision screenings in their office to monitor patients for this type of amblyopia.
In both types of amblyopia, the good eye, oftentimes, has to be patched, anywhere from 2-6 hours a day to “force” the brain to develop the visual centers in the “lazy” eye. If a patient is compliant, the vision usually improves dramatically within a few months. Compliance can be an issue, however, as a young child doesn’t understand why we are patching the good eye and now the child can’t see as well. In time, however, the vision in the lazy eye should improve and compliance should improve as well. I instruct the parents to use incentives to wear the patch…an extra snack or toy usually works.