DOUBLE VISION

If you see two of whatever you are looking at, you may have a condition known as double vision, also referred to as diplopia. Double and blurred vision are often thought to be the same, but they are not. In blurred vision, a single image appears unclear. In double vision, two images are seen at the same time, creating understandable confusion for anyone who has it.

What causes double vision?
There are two possible causes.

• Failure of both eyes to point at the object being viewed, a condition referred to as "strabismus" or "squint". In normal vision, both eyes look at the same object. The images seen by the two eyes are fused into a single picture by the brain. If the eyes do not point at the same object, the image seen by each eye is different and cannot be fused. The result is double vision. Why might eyes not point in the same direction? Possibly because of a defect in the muscles which control the movement of the eyes or in the control of these muscles through the nerves and brain.


• Refractive. Light from an object is split into two images by a defect in the eye's optical system. Cataracts may cause such a defect.