Monocular diplopia

Monocular diplopia is double vision in one eye which persists after the other eye is covered. Image separation is slight, often described as 'ghosting.'

Common causes are:

• usually caused by abnormalities of the cornea, iris, lens, or vitreous or aqueous humour
  • for example:
    • refractive error - the commonest problem - if looking through a pinhole abolishes the diplopia then spectacles should be worn
    • developing cataract - areas of differing refractive index cause splitting of the light beam and diplopia. Usually abates as the opacification increases
    • corneal scarring

Reference:

1. Tan A. The two-minute approach to monocular diplopia. Malays Fam Physician. 2010 Dec 31;5(3):115-8.