Monocular diplopia

Specialty: Ophthalmology.

• double vision with one eye
• double monocular image
• refractive diplopia

Why it occurs

• High-grade corneal astigmatism or irregular pattern (apical keratoconus or corneal ectasias)
• Nuclear or cortical cataract in initial stages (generates areas of different refractive index in the lens)
• Subluxation or partial dislocation of the lens (associated with Marfan syndrome, pseudoexfoliation or previous trauma)
• Iridodialysis or post-traumatic polycoria (multiple pupillary holes that project two independent images on the retina)
• Superior giant retinal tear or retinal detachment with foveal folding
• Sequela of radial keratotomy or decentrated laser ablation

Initial workup

Simple pinhole diagnostic test (if the monocular diplopia is corrected or disappears completely when looking through the pinhole, the refractive origin or media opacity is confirmed, differentiating it from retinal or central causes); Previous and posterior elevation corneal topography to rule out irregular astigmatisms; Slit lamp biomicroscopy under maximal pharmacological mydriasis to evaluate the position and stability of the lens, the condition of the iris, and the presence of opacities.

Standard management

• Monocular diplopia does not respond to conventional pharmacological ophthalmic therapies. Its correction lies in the use of cylindrical ophthalmic lenses or adaptation of rigid gas permeable contact lenses (RGP) if the origin is a corneal irregularity. In cases of cataracts or lens dislocations, the resolving treatment is surgical (phacoemulsification with intraocular lens implantation or scleral fixation).