Double Vision

What is it? Double vision is exactly what is sounds like: a person sees two images when there is only one. There are two types, and the names give a hint as to what they are: monocular and binocular.

Monocular is double vision when one eye is closed. 

Binocular is standard vision with each eye separately, but double vision when both eyes are working together. If you close your left eye, you’ll see one image. And if you close your right eye, you’ll see one image that is in a slightly different location. When viewed together with both eyes, our brain merges the two images into one. But sometimes the eyes don’t work together quite right, so the separate images from each eye don’t exactly align. Things might simply look blurry if the images are only offset slightly, but if there’s enough offset people can actually notice two images instead of one.

It’s important to note that most double vision (aka diplopia) is temporary. That doesn’t mean that you should ignore it and wait for it to go away, because it can be indicative of something serious that needs to be treated.

Cause: There are myriad potential causes of double vision. Partly, the cause depends on the type.

Monocular double vision can be caused by cataracts, astigmatism, dry eyes, and even glasses or contacts that don’t fit properly. Obviously treating the cause will alleviate the problem.

Binocular double vision can be caused by something as simple as misaligned eyes (strabismus), or by something more serious such as neurologic disease like MS or myasthenia gravis; by problems like stroke, aneurysm, giant cell arteritis, or brain tumor; or by complications of diabetes/thyroid/Lyme diseases.

Tests: Obviously, given the possible seriousness of causes, it’s important to identify and treat the underlying cause of double vision. In addition to discovering the cause, tests will determine type and extent of the problem.

MRI can look for signs of thyroid eye disease or MS or tumor. Blood tests can check for thyroid disease, Lyme, and diabetes. Neurologic exam will test for nerve damage that might affect the eyes. The eye doctor can use a Hirschberg Red Lens test to check the eyes’ alignment. There are others, but these are at the top of the list.

Treatment for double vision is to first treat the underlying cause if they can determine one. Some double vision can be corrected with surgery – cataract removal or nerve repair. Sometimes they can add prism via a sticker on your glasses prescription to see if the prism will correct your problem. Long-term, prisms can be ground into your glasses prescription. Those bend the light before it ever hits your retina and trick your eyes into seeing just one image.

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Long long ago I visited the eye doctor to change from glasses to contact lenses. Since I was teaching swimming lessons, it seemed prudent to be able to see all my students no matter where in the pool they were. The exam went well, the doctor fitted me with a pair of trial lenses, and I was very happy as I got up to leave.

But then things deteriorated as I kept running into the wall on my way down the hall to leave. Things looked quite disorienting.

Back to the exam room I went so they could figure out what was going on. After a number of additional tests, the doctor determined that I had double vision. You might wonder (as he did) why I didn’t notice. Well, first off, it was more noticeable at a distance than up close. And second, the view from my window was beautiful and didn’t really make it noticeable that things were overlapping. Who counts trees?

But the main reason I hadn’t really noticed is that over time I had bent the frames of my wire-rimmed glasses to create my own correction. The doctor was quite puzzled why I hadn’t noticed until he asked to see my old glasses and discovered how askew they were.

Fast forward fifteen years and my eye doctor couldn’t fit our family in. I don’t expect a same-day appointment, but if we call in October to be seen over Christmas break, I would hope to get in sometime in December or early January. They didn’t have any openings until mid-February and that wasn’t the first time that appointments had to be booked three to four months in advance. For me, I don’t care. I can schedule ahead. But a college student who realizes a need for stronger prescription while away at school and wants to be seen while home on break should be squeezed in if they want to help their patients. I really felt like they didn’t care about my son so we called around and found someone who was able to schedule my kid – and since I was driving him, we scheduled me, too.

Even though I had been so happy, for years, that the eye doctor had figured out how to correct my vision, it turns out that he was negligent. As noted earlier, double vision is a huge cause for concern. When somebody has double vision, optometrists are not supposed to just throw prisms in glasses like he did. Standard of care is testing to figure out what’s going on. My new eye doctors were appalled that no testing had been done and insisted on those tests before writing a new prescription.

Eventually tests ruled out a few things, but didn’t find a cause. Sadly, things have gotten worse. I can blink and shake my head to get the images to merge, but they split again unless I’m really concentrating. Weirdly enough, people rarely split into two images – I suspect the movement keeps me concentrating enough to focus. Anyhow, I’m back to not driving because it looks like cars ahead of me in my lane are flying up into the air over oncoming traffic while oncoming traffic is veering into my lane headed straight at me.

Nobody wants me on the roads until I get new glasses.

We’re in Texas now and I’ve found a great eye doctor. She’s highly recommended. She listens to me. She explains well. And now I’m waiting because apparently they don’t like to write for more than 4 (somethings – she didn’t state any units so I don’t know what those are four of), and I’m measuring 8 and 12. She wants my old records before writing a new prescription. Meanwhile, I sit at home – still working on the unpacking process because we own too much stuff – wishing I felt safe to drive cuz even though we have really nice walls, but sometimes I get tired of staring at them and would like to go elsewhere.

Hope you are doing well.