What does "phoria" refer to in terms of eye deviation?

"Phoria" refers to a latent deviation of the eyes that becomes apparent only when binocular vision is disrupted, such as when one eye is covered or when a person is asked to look at a single point with one eye. This means that while the eyes may appear to be aligned when both are open, they may not be working together effectively under certain conditions.

This latent condition contrasts with observable deviations, which would be visible without any manipulation of the visual system. "Phoria" is typically assessed during vision exams to understand how well the two eyes can coordinate their movements. In clinical settings, different types of phorias, such as esophoria or exophoria, can indicate specific issues related to binocular vision and eye alignment.

The other options relate to different aspects of vision and do not accurately define "phoria." Observable deviation signifies a constant misalignment seen in conditions like strabismus, while near-sightedness refers to a refractive error where distant objects appear blurry. The ability to focus pertains to the eye's capacity to maintain clear vision at various distances but does not directly describe the latent nature of phoria.