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 (1) - 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) GP magazine (28/9/2001), 47.