Diplopia, or double vision, occurs when you see two images of a single object. This condition is often caused by an underlying issue, and identifying and treating the root cause can resolve the problem and prevent further symptoms. Double vision may affect one or both eyes and is easily identified through a simple test. Cover one eye and observe; if the double vision persists when each eye is tested individually, it likely involves both eyes. If it resolves with one eye covered, it is likely monocular double vision.

Monocular double vision typically results from an issue within the eye itself, while binocular double vision often originates from problems in the brain or the nerves connected to the eyes.

Causes of Monocular Double Vision

This less common condition arises from an issue within one eye. For many with monocular double vision, one image is clear while the other appears faint. Potential causes include:

• Severe astigmatism: Irregular corneal curvature can blur vision and cause double vision.
• Corneal deformities (keratoconus): The cornea bulges into a cone-like shape, leading to blurred and double vision.
• Cataracts: A clouding of the eye's lens that can cause various vision issues, including double vision.
• Dry eye: Insufficient lubrication in the eyes can result in burning, itching, and visual disturbances.
• Pterygium: A non-cancerous growth on the eye's surface can obstruct the cornea, leading to vision problems.

Causes of Binocular Double Vision

When both eyes cannot work together, binocular double vision occurs. Covering one eye in such cases eliminates the double image. Possible causes include:

• Nerve damage: Inflammation or damage to the nerves that connect the eyes to the brain.
• Diabetes: Can cause nerve damage leading to vision problems.
• Cranial nerve palsy: Paralysis of cranial nerves due to conditions like high blood pressure or diabetes.
• Myasthenia gravis: A neuromuscular disorder that can fatigue eye muscles and lead to double vision.
• Graves' disease: A thyroid disorder affecting the immune system that can impact vision.
• Strabismus (crossed eyes): Misaligned eye muscles, often leading to vision problems in children.

When to See a Doctor

Double vision is abnormal and requires medical evaluation to determine its cause. Often, addressing the underlying condition can resolve the issue.

Complications of Double Vision

Double vision may cause symptoms like nausea, dizziness, eye fatigue, and light or sound sensitivity. Rarely, it can result from infections or brain tumors, which may cause severe pain, headaches, and vision changes. Any headache with visual disturbances is a medical emergency.

Diagnosis

Identifying whether double vision is monocular or binocular is straightforward, but determining the cause may require comprehensive testing, including a medical history review, physical examination, blood tests, eye movement tests, blood sugar analysis, and imaging studies like CT or MRI scans.

Common Treatments for Double Vision

• Corrective glasses or specialized lenses.
• Eye patching for temporary relief.
• Eye muscle exercises to strengthen weak muscles.
• Surgery for structural or severe issues.

Most patients with double vision can recover fully with proper medical care. However, the treatment duration and methods depend on the underlying cause.