Tilt Your Head and See Double! - Living with Trochlear Nerve Palsy

At first, it wasn't noticeable. Occasionally when I'd be tired or staring off into space I'd get brief double vision, which I could correct by just shifting my head around a bit until my eyes corrected it. Otherwise, I seemed fine. In fourth grade, though, the optometrist did a simple cover test and said I had a minor "muscle imbalance". I got glasses for nearsightedness, and was sent on my way, seldom putting on my glasses, and discarding them altogether through high school.

Then, my nearsightedness got worse. I got a pair of glasses in college with no mention of this "muscle imbalance". When I finally graduated and used my newly acquired college degree to get a job waiting tables, things started to get different. Because I would get hot, I hated wearing my glasses and kept them in my pocket. Coworkers would comment on me tilting my head and staring at things, something I didn't even realize I was doing. I didn't realize that it was a sign of something wrong, I simply thought it was a quirk that they were annoyingly pointing out.

Then I got a "real" job working for an insurance company. The training and the fear of losing this "real" job were stressful to me. About a week or two in, after spending hours reading manuals, looking at old CRT terminals, and staring at blackboards, I began to see double. In the past, a bit of head shaking and tilting would have corrected it. Now, nothing, short of covering one eye with paper would allow me to see one image. It freaked me out. I'm not normally one with health anxiety, but I started to think, "brain tumor!"

Because I could no longer drive (it's tough to drive when two lanes of traffic looks like four), my father drove me to an opthamologist. He gave me the good news. I didn't have a brain tumor. The opthomologist diagnosed me with Trochlear Nerve Palsy, or Fourth Cranial Nerve Palsy. As for why it suddenly hit me with full force, the only thing he could guess was that the increased stress and overuse of the eye had brought it on.

What is Trochlear Nerve Palsy

Trochlear Nerve Palsy is damage or defect to the the fourth cranial (trochlear) nerve. This nerve controls the superior oblique muscle in the eye. The superior oblique muscle controls the eye's movement downward and impacts its movement in other directions. In cases of trochlear nerve palsy, the affected eye can drift upward, especially as you look toward your nose with the affected eye. In cases like mine, it causes diplopia, or double vision. The resulting head tilt to correct the two images into one can also result in toritcollis.

Fixing Trochlear Nerve Palsy

The simple fix for trochlear nerve palsy is prisms in corrective eyeglasses. These prisms are used to direct the light to the proper portion of both eyes. This prevents the eyes from seeing double. When the doctor who checked my eyes was trying to determine what lenses I needed, it was like a small miracle when he put prisms in front of each eye, and BOOM, my vision was aligned. Another fix involves surgery, working on the muscles of the eyes to bring them into alignment.

Living With Trochlear Nerve Palsy

The worst part of having Trochlear Nerve Palsy is that now I cannot go without my glasses except at home. My double vision, especially when I'm tired (basically every day with a "Y" in it) is bad enough that I cannot do much except take a shower without them. Additionally, the prisms in my glasses are helpful, but not in all situations. When I'm trying to merge into traffic, and looking to either side, the double vision can become pronounced, making it hard to judge distances and sometimes which lane a car is in. When I go to the theatre, I have to sit on the side opposite my bad eye just to make sure that it doesn't act up during the movie. Unless I get the muscle surgery, it also means that contacts and lasix surgery are somewhat worthless to me.

For more information:

American Association for Pediatric Opthomology and Strabismus

Pediatric Opthalmic Consultants

Wikipedia Article on Trochlear Nerve Palsy