What condition does diplopia refer to?

Diplopia refers specifically to double vision, where a person perceives two images of a single object. This can occur in various directions, such as horizontal or vertical, and can affect one eye or both. The condition arises from problems with the eye muscles or the nerves controlling them, leading to a misalignment of the eyes. Understanding diplopia is crucial for vision assessment and determining the underlying issues that might be causing this visual disturbance.

The other options relate to different ocular conditions that do not involve double vision. Decreased moisture of the eye pertains to dry eye syndrome, spots in the visual field indicate conditions such as floaters or retinal problems, and intolerance of light refers to photophobia. Each of these addresses distinct symptoms or disorders unrelated to the phenomenon of seeing two images.