Strabismus, also known as crossed eyes, is a condition where both eyes do not look in the same direction. One eye may turn inward, outward, upward, or downward. In children, strabismus often links to visual development disorders, refractive errors, or extraocular muscle abnormalities.

However, sudden onset strabismus in adults, accompanied by double vision, drooping eyelids, headaches, or dizziness, can indicate a neurological condition, according to Doctor Nguyen Thi Phuong Thao, a doctor from the Neurology - Stroke Department at Tam Anh General Hospital Hanoi.

A complex nervous system controls eye movement, including cranial nerves, extraocular muscles, and brain regions involved in eye movement control. When any of these structures are damaged, the eyes may lose synchronized coordination, leading to strabismus and double vision.

A doctor consults a patient experiencing sudden strabismus symptoms. Illustration: Tam Anh General Hospital.

Damage to ocular motor nerves

The three cranial nerves (III, IV, and VI) control the extraocular muscles. Damage to any of these nerves can cause strabismus and double vision, particularly when looking in certain directions. Depending on the affected nerve, patients may also experience drooping eyelids, dilated pupils, pain around the eye socket, or restricted eye movement.

Causes can include small vessel disease, trauma, inflammation, infection, or nerve compression.

Stroke

Strabismus or double vision resulting from a stroke occurs when the brainstem or eye movement pathways are affected. Patients may also experience dizziness, loss of balance, difficulty speaking, difficulty swallowing, weakness or numbness in limbs, facial drooping, or impaired coordination.

If these symptoms appear suddenly, patients should seek immediate medical attention at a stroke-ready facility for prompt evaluation and treatment.

Brain tumors or compressive lesions

Some brain tumors or lesions can directly affect the ocular motor nerves or increase intracranial pressure, leading to strabismus or double vision. Accompanying symptoms include progressive headaches, vomiting, seizures, vision changes, altered consciousness, or additional focal neurological signs.

However, strabismus does not always mean a brain tumor. Doctors rely on symptom characteristics, neurological exams, and eye examinations to determine if imaging diagnostics like MRI or CT are necessary.

Myasthenia gravis

Myasthenia gravis is an autoimmune disease that affects nerve-to-muscle signal transmission. Some patients primarily exhibit ocular symptoms such as drooping eyelids, double vision, or strabismus.

Due to non-specific symptoms, ocular myasthenia gravis is sometimes mistaken for other eye conditions. If suspected, doctors may order specific tests to confirm the diagnosis: clinical myasthenia gravis tests, electrophysiology, or medication trials.

Doctor Phuong Thao advises adults to seek medical attention if they experience unusual strabismus, especially if it occurs suddenly or is accompanied by double vision, drooping eyelids, severe headaches, dizziness, loss of balance, weakness or numbness in limbs, facial drooping, difficulty speaking, or difficulty swallowing.

Depending on the case, doctors may evaluate eye movement, vision, pupils, neurological reflexes, and other neurological signs, along with ordering laboratory tests or imaging diagnostics like MRI or CT scans when necessary.

Hieu Nguyen