How does strabismus worsen?

Strabismus: Strabismus occurs when the eye are not aligned properly, so they do not work well together. In some people, this misalignment worsens over time. If it occurs only occasionally, no intervention is needed. If the misalignment worsens, double vision may result. This can be fixed with prism glasses. If special glasses don't work, surgery to straighten the eyes may be needed.

Several ways: Strabismus will typically worsen if it is related to poor vision in one eye (amblyopia) because there is a lack of fixation ie one does not use both eyes together.