Final answer:
Tropia is a condition where the eyes are always deviated, causing misalignment and potential vision issues. It is a type of strabismus and is distinct from temporary deviations known as phoria.
Step-by-step explanation:
Tropia is a condition where the eyes are always deviated. This is in contrast to phoria, which is when the eyes are occasionally deviated. Tropia is a type of strabismus and can impact the patient's vision because the eyes do not align properly. Vision correction for conditions like tropia often involves glasses, patching, exercises, or surgery, depending on the severity and type of the eye condition. While the provided text mainly discusses common vision defects such as astigmatism, myopia (nearsightedness), and hyperopia (farsightedness), and their corrections, it is important to differentiate these from tropia, which specifically refers to the misalignment of the eyes rather than an issue related to the focusing ability of the eyes.