What is the term for the tendency of one eye to turn upwards?

The term for the tendency of one eye to turn upwards is hyperphoria. This condition refers specifically to a vertical misalignment of the eyes where one eye is higher than the other, indicating that it may be an instance of the affected eye drifting upward relative to the other when both eyes are open. Understanding this term is essential in diagnosing and addressing issues related to binocular vision, where maintaining proper alignment between the eyes is critical for effective depth perception and overall visual function.

Other terms mentioned relate to different types of eye misalignments; for example, esophoria and exophoria refer to horizontal deviations where one eye drifts inward or outward relative to the other eye, respectively. Hypophoria would refer to a downward deviation, contrasting with hyperphoria's definition. Hence, hyperphoria specifically describes the upward turning tendency of one eye, making it the correct choice in this context.