Diplopia
Diplopia is the perception of two images (double vision) when there should only be one.
Causes
Diplopia can be of two types:
- Monocular: Present when viewing with one eye while the other eye is covered. It may be caused by astigmatism, cataracts, or other conditions that produce opacities in the transparent structures of the eye, dry eye, etc.
- Binocular: Present when both eyes are open, but disappears when one eye is covered. In other words, the patient sees double with both eyes open and does not experience double vision if one eye is closed. It is caused by a lack of proper eye alignment (strabismus) or decompensated strabismus, neurological or vascular disease (for example, in diabetic patients), ocular muscle paralysis, thyroid disease, etc.
Symptoms
Diplopia may be constant (all the time) or intermittent (appearing and disappearing). It can also be classified as horizontal, vertical, or oblique, depending on the position of the second image relative to the first.
Sometimes one eye may appear clearly deviated compared to the other (strabismus), while in other cases the deviation is minimal and difficult to detect.
Patients may also complain of eye strain, blurred or shadowed vision, difficulty perceiving depth or judging distances, dizziness, and double vision.
Treatment
Treatment focuses on correcting the underlying cause of diplopia. It may be necessary to use glasses or contact lenses, prisms, occlusion therapy, penalization techniques, botulinum toxin injections, or surgery.