Which term describes double vision that affects only one eye?

Which term describes double vision that affects only one eye?

• A. Monocular
• B. Binocular
• C. Total Blindness
• D. Halos

Answer: (A)

Monocular diplopia is the phenomenon here: double vision that occurs with only one eye open. It means the issue is inside the affected eye’s optics or surface—things like refractive error, a corneal irregularity, cataract, or surface dryness can create two images in that eye, while the other eye contributes a single clear image. If you test by covering the other eye and the double vision persists, that points to monocular diplopia. This differs from binocular diplopia, where the double image only appears when both eyes are open and goes away if either eye is closed, indicating the problem lies in eye alignment or coordination between the eyes (such as strabismus or nerve/muscle issues). Halos are unrelated to diplopia—they’re glare around lights from optical or lens changes—so they aren’t the answer here.

Monocular diplopia is the phenomenon here: double vision that occurs with only one eye open. It means the issue is inside the affected eye’s optics or surface—things like refractive error, a corneal irregularity, cataract, or surface dryness can create two images in that eye, while the other eye contributes a single clear image. If you test by covering the other eye and the double vision persists, that points to monocular diplopia.

This differs from binocular diplopia, where the double image only appears when both eyes are open and goes away if either eye is closed, indicating the problem lies in eye alignment or coordination between the eyes (such as strabismus or nerve/muscle issues). Halos are unrelated to diplopia—they’re glare around lights from optical or lens changes—so they aren’t the answer here.