Strabismus can compromise binocular vision
Refractive error is the most common cause of strabismus
There are many different causes of strabismus among children. Hyperopia (farsightedness) is the most common. Withour glasses, there is often a visible squint. Because of the hyperopia, you have to accommodate in order to see sharp. With accommodation comes convergence. If the convergence is larger than you can compensate, one eye is turned nasally. This kind of squint is sometimes referred to as accommative strabismus.
With correct prescription, the strabismus is partly or completely eliminated. It's extremely important to wear correct presciption as often as possible for the visual function to develop normally.
If the strabismus is not eliminated, it's important to train the strabismic eye to develop the visual function. It can be done by undergoing occlusion therapy. In occlusion therapy you occlude the preferred eye thus forcing the strabismic eye to see and therefore develop a better visual function. The occlusion is typically worn 2-6 hours a day.
Correcting with prisms
If there is still a misalignment of the visual axes after fully corrected the refractive error, this can be corrected with a prism. With a prism, it's possible to avoid diplopia or relief eye strain both in childs and adults.
Latent and manifest strabismus
The above described strabismus is the manifest one. About 4 % of children have a manifest strabismus. Manifest strabismus is sometimes called exotropia (squinting eye pointing temporal) or esotropia (squinting eye pointing nasally). About 70 % of the whole population have some form of latent strabismus, also called phoria. If the phoria is large, it can cause problems, especially when tired or intoxicated. Symptoms of phoria can be eye strain or temporary diplopia.