When I see a patient who needs a lot of prismatic correct to align the eyes, I like to demonstrate to my staff how the patient sees without it. Putting prism in front of a person whose eyes are not misaligned gives them the same symptoms of the patient. One time, I gave a clip to my optician with prism on it for her to look out of. She put it on and said, “Wow! This is great! I see so clear!”
This optician had always complained to me of not seeing clear enough. Of course, she didn’t: she had a ghost image. She described it as things always appearing “smeary” when trying to focus. Interestingly, she did not complain of headache or dizziness at all, but she did have vertical heterophoria (VH), a type of binocular vision disorder caused by a misalignment of the eyes. With the prism glasses, her world is so much easier. Aligning her eyes gave her the binocular vision and depth perception that she was missing!
Now, anytime a patient uses the word “smeary” or just isn’t seeing sharp enough, I immediately pull out my instruments and screen for VH. Sometimes a little prism is all you need.
Double Vision and BVD
Ghost images are a type of double vision that is a sign of a binocular vision dysfunction.
There are two different types of double vision (diplopia): monocular and binocular. While monocular double vision can be caused by corneal disease or cataracts, binocular double vision can be caused by serious neurologic conditions.
If you’ve recently started experiencing symptoms of double vision, there’s a quick way to determine which type you have. If you’re experiencing double vision, try closing one eye. If you see images as double out of one eye with the other eye closed, you have monocular double vision. If you have binocular double vision, the double vision will go away when you close either eye.
How Monocular Double Vision Causes Ghost Images
Monocular double vision in one eye often presents as a “ghost” image, a shadow that overlaps with the primary image. It can affect the left eye, the right eye or both eyes at once. Monocular double vision can be caused by dry eye syndrome. When your eyes dry out, the surface of your eye becomes rough and irregular as the tear film along the surface of your eyes dries out. People with dry eye syndrome often suffer from itching, scratching, and burning sensations in their eyes, or they may feel like something has become lodged in their eye. These symptoms can get markedly worse if the patient does a lot of reading or computer work, as we unconsciously blink less while focusing on reading. The first step of treatment for dry eye syndrome is typically the use of artificial tears.
Like VH, binocular double vision is caused by eyes that are misaligned. This condition can be caused by a variety of serious factors, so it’s very important to contact a neurovisual professional as soon as possible to determine the type and cause of your double vision, and to get treatment started right away. If you are being plagued by ghost images or other double vision symptoms, give the Neuro Visual Center of New York a call today at (516) 224-4888 to schedule your evaluation.