What is the condition called when the refractive error of one eye significantly differs from that of the other?

Anisometropia is the condition in which there is a significant difference in refractive error between the two eyes. This varies from mild to severe differences in the lenses needed to correct each eye’s vision, which can lead to various visual problems, such as difficulty with depth perception or eye strain due to the brain receiving conflicting visual signals.

In contrast, strabismus refers to a misalignment of the eyes, where one eye may turn inward, outward, up, or down instead of focusing straight ahead. Monovision is a technique often used in contact lens fitting or after certain types of refractive surgery, where one eye is corrected for distance vision while the other is corrected for near vision, rather than addressing a difference in refractive error. Presbyopia is an age-related condition characterized by the gradual loss of the eye’s ability to focus on nearby objects due to changes in the lens's elasticity, but it does not involve a significant difference in refractive error between the eyes.

Thus, the correct term for the condition of differing refractive errors in the eyes is indeed anisometropia.