Diplopia, monocular
Double vision (diplopia) in only one eye.
The double vision persists when the other eye is covered.
Monocular diplopia can be caused by astigmatism (abnormal curvature of the front of the cornea), keratoconus (cone-shaped cornea), pterygium (thickening of the conjunctiva over the cornea), a cataract, dislocation of the lens, a mass in the eyelid pressing on the front of the eye, xerophthalmia (dry eye), and certain retinal problems.
Treatment depends upon the specific cause