If a patient is suffering from monocular diplopia, what is true about their vision?

Monocular diplopia, or double vision in one eye, occurs when the same eye perceives two images of a single object. This phenomenon is often due to issues related to the cornea, lens, or retinal abnormalities, rather than problems involving alignment between the two eyes that would typically be addressed through covering one eye.

When one eye is covered in a case of monocular diplopia, the double vision will persist because the underlying cause is within the affected eye itself. This means that if the patient covers the eye with the diplopia, they would still perceive the double vision as the problem exists in the functioning of that single eye.

The other choices suggest circumstances that do not apply to monocular diplopia. For instance, not all patients with monocular diplopia experience the same refractive errors, and covering one eye certainly will not eliminate the problem. Therefore, the hallmark of monocular diplopia lies in its independence from the status of the other eye, leading to the conclusion that the correct response is to indicate that double vision persists when covering the affected eye.