‘If only I could have just one more….’
We hear people saying this so many times for something or the other that they lack. But have you ever heard anyone complain that they have too much money or too much to eat? Sounds ridiculous right?
Well, when it comes to your vision, both a lack and double can be equally frustrating….
Diplopia is where you see 2 images of a single object either all or some of the time. Both the images may be seen either one above the other or besides each other, or it could be a mix of both. Diplopia is commonly referred to as double vision.
You may suffer from double vision in either just one eye or both your eyes.
Double vision in only one eye is called monocular double vision. This type of double vision is not too common. You can make out if you have monocular double vision by covering each eye separately and checking your vision. Double vision in one eye and normal in the other can be caused by:
• Cataracts (clouding of your lens) and other abnormalities of your lens.
• Astigmatism: This is a refractive disorder in which your cornea is shaped irregularly.
• Dry eye syndrome: Here, your eye does not produce sufficient or good quality tears.
• Abnormalities in your cornea (the dome shaped, transparent, front surface of your eye) like herpes infection, scarring and dryness.
• Macular degeneration (a painless condition which leads to loss of vision) and other abnormalities of your retina (the light sensitive screen at the back of your eye).
Double Vision because both your eyes do not work together is called as binocular double vision. In this type of double vision, if you cover one eye and check your vision, it will usually be normal for either of your eyes. This occurs when both your eyes point at little different angles and send differing images of the same object to your brain.
• Squint: This is when both your eyes point at different directions because of which your brain gets two different images and you see double vision. This is a common cause in children. Sometimes in an adult, a childhood squint may return to cause double vision.
• Thyroid Disorder: This can affect the muscles of your eyes.
• Stroke or Transient Ischemic Attacks: These are conditions where the blood vessels that supply your brain or nerves controlling eye muscles are affected.
• Diabetes: This damages the blood vessels which supply your eye.
• Brain Cancer / Tumour: When this occurs behind your eye. It prevents free movement of your eye and damages the nerves that supply your eye muscles.
• Aneurysm: This is a weakness in a vessel wall that causes it to bulge.
• Head Injury: Damage to the brain or nerves controlling the eye muscles or to the socket of your eye that prevents the eye muscles from normal movement can cause double vision.
• Multiple Sclerosis and Myasthenia Gravis are conditions that affect the nerves and muscles respectively and thus cause double vision.
Double Vision can sometimes be confused with a blurry vision. In case of a blurred vision, your vision will be unclear and you will only see a single image. In diplopia, you can see two images at the same time.
Sometimes, rather than a clear double image, you may see a partial or ghost image around an object especially light sources. These can occur after you have a corneal surgery like LASIK, PRK or corneal transplant surgeries. These usually disappear after the surgery has healed.
Double vision may be transient or it may be constantly there. Sometimes it can occur only when you look in one particular direction.
Crossing of your eyes may also be seen due to weakness of your eye muscles.
In children, they may not be able to describe that they are suffering from double vision. You can suspect something is wrong if you notice them narrowing their eyes or covering one eye in their effort to see clearly. Sometimes, they may turn their head unusually or look sideways.
Routine Vision Tests
Tests for checking binocular vision
Slit lamp examination
Ct Scan or MRI of brain or eye muscles may also be advised.
Treatment will largely depend on the cause for your double vision and whether is monocular or binocular.
Monocular Diplopia: Depending on the cause of your double vision,
• Astigmatism: Glasses or Contact Lenses or Laser Surgery
• Cataracts: Cataract Surgery
• Special eye exercises
• Fixing prisms on your glasses: These bend light rays before they enter your eyes.
• Botulinum Toxin: This is injected into one of your eye muscles to relax it and preventing it from moving. Thus the other eye muscles can take over to straighten your eye.
• Squint Surgery
• Opaque Intraocular Lenses