What is diplopia (double vision)?

Diplopia. Diplopia means that either one eye alone or both eyes together are not seeing a clear sharp image. There can be overlapping images or separate images. Common causes of monocular diplopia are astigmatism, cataracts and corneal abnormalities such as keratoconus. Binocular diplopia is usually due to neurological problems that cause misalignment of the two eyes.
Seeing two images. Diplopia, or double vision, is when someone sees two images when there should only be one. It most commonly results from the eyes not being aligned, which can occur from a variety of causes.