Many conditions may cause double vision (diplopia) such as:
- orbital inflammation, including thyroid eye disease (TED)
- cranial nerve palsy
- multiple sclerosis
- myasthenia gravis
- orbital injury
- brain tumor
- vascular malformation
What Causes Double Vision?
Double vision, medically known as diplopia, is a visual condition where a person sees two overlapping images of a single object instead of the normal single, fused image. Double vision can be caused by various underlying factors, which can be broadly categorized into two main types: binocular diplopia and monocular diplopia.
Binocular Diplopia: This type of double vision occurs when both eyes are open and working together, but they are not properly aligned. Common causes of binocular diplopia include:
- Strabismus: Strabismus is a misalignment of the eyes, where one eye may turn inward, outward, upward, or downward. This misalignment disrupts the normal coordination of the eyes and results in double vision.
- Cranial Nerve Disorders: Damage or dysfunction of the cranial nerves that control eye movements (e.g., oculomotor, trochlear, and abducens nerves) can lead to difficulty in coordinating eye movements, causing double vision.
- Refractive Errors: Significant differences in refractive errors (such as a large difference in prescription between the two eyes) can cause binocular diplopia when attempting to focus on objects.
- Head Injury or Trauma: Trauma to the head, especially around the eye sockets, can damage the eye muscles or the nerves controlling them, resulting in double vision.
- Myasthenia Gravis: This autoimmune disorder affects the neuromuscular junction and can lead to muscle weakness, including the muscles that control eye movements.
Monocular Diplopia: Monocular diplopia occurs when the double vision persists even when one eye is covered. It is typically related to issues within a single eye, and common causes include:
- Refractive Errors: Uncorrected or undercorrected refractive errors like nearsightedness (myopia), farsightedness (hyperopia), or astigmatism can cause double vision in one eye.b.
- Cataracts: Advanced cataracts can scatter and distort incoming light, causing double vision in one eye.
- Dry Eye Syndrome: Insufficient tear production or poor tear quality can lead to blurred vision and ghosting of images in one eye.
- Corneal Abnormalities: Irregularities in the cornea, such as keratoconus or scarring, can cause monocular double vision.
- Macular Disease: Conditions affecting the macula, the central part of the retina responsible for sharp central vision, can result in double vision in one eye.
It is important to note that double vision can be a symptom of various underlying medical conditions, some of which may be serious. Therefore, anyone experiencing persistent or sudden double vision should seek prompt evaluation by an eye care specialist or a healthcare provider. A comprehensive eye examination and, if necessary, further medical assessments can help determine the cause of double vision and guide appropriate treatment.
Symptoms of Double Vision
Double vision is characterized by two images that are either separate or overlapping. The double vision may vary during the day, being most distinct when the eyes are tired.
Diagnosing Double Vision
If double vision occurs when only one eye is open, it generally is due to eye problems such as astigmatism, corneal irregularity or cataract, but if double vision persists when both eyes open, but resolves when looking with only one eye, the cause may be orbital, muscular or neurological. This type of double vision is caused by a misalignment of the lines of sight of the two eyes. Diagnostic evaluation will include eye examination, sensorimotor examination and may include orbital ultrasound evaluation. Additional diagnostic studies may be indicated, including blood tests, CT or MRI.
Medical issues, such as diabetes, high blood pressure, prior strokes or heart disease, cancer, or other neurological or medical conditions may lead to double vision; therefore treatment depends on the underlying cause of the double vision.
Temporarily, vision in one eye may be blocked by the use of an eye patch or covering one lens of the patient’s glasses. In some instances, prisms may help reduce the double vision. If double vision persists when both eyes are open, surgery to adjust the position of the eye muscles may be recommended, and is generally very successful in restoring single binocular vision.