Double vision (Diplopia) is a visual problem that occurs when images from both eyes fail to merge properly, causing objects to appear duplicated. This condition can interfere with daily activities such as reading, driving, and walking, and may compromise safety. Understanding the causes and undergoing early diagnosis can lead to more accurate and effective treatment.

Double vision, or diplopia, refers to seeing one object as two. This condition can be highly disruptive to daily life, affecting activities such as driving, reading, and even walking, and may cause dizziness or balance problems.
Double vision can be classified into two main types:

Double vision does not have a single cause and may result from various factors, depending on the type and characteristics of the symptom.
This type is usually caused by structural problems within the eye itself, such as the cornea, lens, or retina, and is typically not related to eye muscles or nerves controlling eye movement.
Cataracts occur when the normally clear lens becomes cloudy, causing light to scatter before reaching the retina. This results in blurred or double vision that gradually worsens with age.
Corneal edema occurs when fluid accumulates in the cornea, causing swelling and cloudiness that impair vision and may lead to double vision.
Corneal scars or ulcers caused by infection or injury can alter light refraction and result in double vision.
Keratoconus is a condition in which the cornea gradually thins and bulges into a cone shape, causing irregular refraction and visual distortion.
Astigmatism occurs when the cornea has an irregular curvature, leading to distorted or duplicated images.
In patients who have undergone cataract surgery, displacement or malfunction of an intraocular lens may also cause double vision.
Binocular diplopia often indicates more serious problems involving the eye muscles, the nerves controlling eye movement, or the brain, and requires prompt evaluation.
Each eye is controlled by six extraocular muscles. Weakness or poor coordination among these muscles can prevent both eyes from moving synchronously.
Examples include:
Graves’ Disease
This condition causes inflammation and swelling of the eye muscles, leading to abnormal eye movement.
Myasthenia Gravis
An autoimmune disorder that causes muscle weakness throughout the body, including the muscles controlling eye movement, resulting in strabismus and double vision.
Cranial nerves III, IV, and VI control eye movement. Damage to these nerves due to disease or injury can disrupt eye alignment.
Common causes include:
The brain processes visual signals from both eyes. Any abnormality affecting this process can result in double vision, including:

Early consultation with an ophthalmologist is essential for accurate diagnosis and appropriate treatment. Diagnostic steps include:
The ophthalmologist will assess symptom onset, frequency, whether double vision resolves when one eye is closed, the direction of image separation (horizontal or vertical), associated symptoms such as headache or dizziness, history of head injury, and underlying medical conditions.
A comprehensive eye examination is performed, including visual acuity testing, corneal and lens evaluation, and assessment of eye muscle function.
Blood tests may be ordered to detect systemic conditions such as diabetes or thyroid disease.
If a neurological cause is suspected, CT scan or MRI imaging may be recommended to evaluate the brain and cranial nerves.

Treatment depends on identifying and addressing the underlying cause. Options include:
In addition to treatment, proper self-care can help prevent symptom worsening and complications.

Bangkok Eye Hospital offers comprehensive eye care supported by advanced technology and experienced specialist ophthalmologists. Services include:
Double vision can result from various causes, ranging from eye muscle disorders and lens abnormalities to optic nerve and brain-related conditions. Diagnosis involves thorough history-taking, eye examinations, and sometimes blood tests or imaging such as CT or MRI. Treatment depends on the cause and may include vision correction, medication, or surgery. Preventive care, including regular eye rest and avoiding excessive eye strain, is important. Patients experiencing double vision should seek evaluation from specialist ophthalmologists at Bangkok Eye Hospital for accurate diagnosis and effective treatment.
This is commonly caused by eye muscle fatigue or astigmatism, which affects focusing accuracy during prolonged screen use. Dry eye and excessive eye strain can also cause temporary double vision. Persistent or worsening symptoms should be evaluated by an ophthalmologist.
Double vision may be harmless if caused by temporary eye strain, but frequent or sudden onset—especially with symptoms such as headache, dizziness, or after head injury—may indicate serious conditions involving the eyes, nerves, or brain and requires immediate medical evaluation.
Double vision when viewing distant objects is often related to eye muscle imbalance, lens abnormalities, or displacement of an intraocular lens. In some cases, neurological or brain-related issues may be involved. A comprehensive eye examination is recommended to determine the exact cause.