What is the term for a functional eye that becomes a non-seeing eye?

The term for a functional eye that becomes a non-seeing eye is amblyopia. This condition, often referred to as "lazy eye," typically occurs when there is a disruption in the normal development of vision in one eye, leading to the brain favoring the other eye. As a result, the affected eye does not acquire the same level of visual acuity and may eventually be perceived as "non-seeing" because it does not provide clear or useful visual input.

Amblyopia can develop from various issues, such as strabismus (misalignment of the eyes), significant differences in refractive error between the two eyes, or other visual impairments. If left untreated, amblyopia can lead to permanent vision loss in the affected eye. That’s why early detection and treatment are crucial to prevent this outcome and promote normal visual development.

Other terms like phoria, tropia, and esotropia refer to different aspects of eye alignment and muscle coordination rather than a loss of function in one eye. Phoria refers to a latent eye misalignment that becomes apparent only when both eyes are not used together. Tropia is a visible misalignment where one eye turns away from the other and may lead to double vision. Esotropia specifically