ZocdocAnswersWhy do my eyes cross and cause me to see double when I am reading things up close?

Question

Why do my eyes cross and cause me to see double when I am reading things up close?

I'm a 29 year old male who has worn glasses for 22 years. For the last 10 years the majority of my job environments have involved sitting in front of a computer. I've had two previous eye surgeries to correct my eyes being crossed: once as a child (2 years old) and again at 20. In the last 5 months or so I've had problems with my eyes crossing causing me to see double when reading things that are close to my face (i.e. books, handheld gaming consoles, smartphone). Closing then blinking my eyes a few times usually causes the double vision to correct itself. I'm currently wearing prescription bifocals that I got a couple of weeks ago. The problem still occurs when reading through the lower portion of the bifocals.

Answer

Seeing double ("diplopia") is almost always a physical problem with your eyes, where they are pointed in different directions and therefore produce two images. In rare cases, diplopia comes from a problem with the part of your brain where vision is processed. You can easily tell the difference between the two by covering one eye - if you see only one image, the problem is with the direction in which your eyes are pointing. There are many causes of diplopia, but among the most common (especially given your history) is muscular weakness or lack of coordination between the muscles which control your eyes. This is particularly characterized by diplopia that emerges after prolonged strain on the eyes (such as staring at a computer screen or focusing on objects which are close to you), and resolves with rest. This can require surgical correction or special lenses. Other rarer causes of diplopia include generalized problems with the muscles, such as a variety of poisons or a rare autoimmune disease called myasthenia gravis. These cause diplopia before other symptoms of weakness because the muscles of the eye are among the finest, and therefore weakest, of the body. Structural problems, such as trauma or a tumor of the eye, can also cause these symptoms. Given your history, and since it is not possible to make a diagnosis without a doctor's visit, I would strongly suggest you make an appointment for evaluation by an ophthalmologist, who can examine your eyes for any potential abnormalities, as well as counsel you on the potential options for surgical correction.

This answer is for general informational purposes only and is not a substitute for professional medical advice.

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