Double Vision - Why It Happens?

Our eyes work in tandem to produce an image. However, what happens when both your eyes produce dissimilar pictures of the same object?
This is exactly what happens in a medical condition of the eye, called diplopia, which makes you see a double image of one object.

Causes
Before we explore diplopia further, a word of caution double vision can sometimes be a symptom of a serious disease or condition. So please take care to see an eye expert straight away if you suffer from this condition. The serious conditions that can cause double vision are -

• Diseases of the thyroid
• Diseases of arteries
• Multiple sclerosis
• Brain stroke

There are several types of diplopia, and there are numerous causes for double vision. In simple words, double vision happens when the brain cannot combine the images from each of your eyes, into a single image. This happens usually because the two images are not similar enough, due to problems with the eye muscles or nerves that control where each eye is looking. Normally these two images from each of your eyes are combined by the brain into a single image.

Diplopia - Types and their Treatments
Double vision can be horizontal, where the two images appear side by side or vertical, where the images appear one above the other; or diagonal, where the images are both vertically and horizontally displaced from one another.

There are other two main types of double vision i.e. binocular and monocular.

• Binocular diplopia is the most common type of diplopia and it occurs when your eyes are unable to align with each other forming a double vision. The treatment for this type of diplopia is straightforward. Usually, it can be cured by covering either of your eyes. The most common cause of binocular double vision is a squint, but if it occurs suddenly, it could be a symptom of a serious medical condition. So, you should rush to a doctor immediately.
• Monocular diplopia is double vision in one of your eyes only. It is much less common than binocular diplopia. It is usually caused by an abnormality within the eye itself, like:
  • Refractive error like astigmatism commonly called lazy eye
  • A certain rare type of cataract
  • Abnormalities of the iris, lens, or fluid within the eye
  • Dry eye syndrome

Treatment is generally given to cover the affected eye and to make the double image disappear. Since, double vision makes it difficult for you to see objects at any distance and it also affects your spatial awareness, therefore you should not drive.

It is very important to treat children with double vision promptly; otherwise, they can lead to a permanent squint or might develop abnormalities in their upper spine due to constantly twisting their head in an unusual way to try to see properly.

In case you have a concern or query you can always consult an expert & get answers to your questions!