I was driving home to Vancouver, WA from a physically tough night shift in Lake Oswego, OR on a bright, sunny Sunday morning in January 2012. I found myself struggling to decide which of two roads unfolding before me I should steer toward! I was seeing two images, one at a slightly counterclockwise tilt and displaced slightly down and to the left of the other. Fortunately, the two roads converged enough so that staying on the road did not prove to be a major issue. Still, it was a disturbing phenomenon. And it did not go away. As it turned out, it was my rather unnerving introduction to a condition the docs call binocular diplopia (in layman speak, double vision involving both eyes). In my case it has proven to be persistent and unchanging. My subsequent trip through the optometric industry has proven to be equally unnerving.
After a couple of days, I went to the Casey Eye Clinic at Oregon Health Sciences University (OHSU - up on Pill Hill, if you're familiar with Portland) to see what the heck was going on. There was quite a bit of somewhat hushed, instructional-type discussion between the Ophthalmologist and her assistant as they pulled out (dust-covered?) instruments during my exam. The diagnosis was that I had an 8 Diopter twisted displacement in my left eye. No explanation of what caused it was offered. The assistant applied a 4 D (Diopter) stick-on Fresnel prism lens by 3M to the left lens of my glasses. "We want to be conservative and just correct it enough so that the eye is able to accommodate 'naturally', as much as possible."
Well, that lens helped a bit. But the assistant had used tap water in applying it, and it developed water spots under it as that water dried out. (If you've ever watched water droplets dry out under a microscope, you'll understand that.) A few weeks later, I took it off, cleaned it up, and remounted it using distilled water. In the process of remounting it, I discovered that the assistant had mounted it upside down! So, mounting it correctly helped a bit more. Basically, the 4 D lens would bring the images up to a vertical alignment, but still leave a little twist and horizontal displacement, which the eye would have to " naturally" accomodate for. (Alternatively, by twisting the prism lens a little more, I could get the twist out, leaving a need for both vertical and horizontal 'natural' accomodation.) Still, each day as I got more tired, it became harder and then impossible to keep the images locked together.
In June of 2013, I got a dedicated pair of computer glasses (which I highly recommend to anyone that spends quite a bit of time on your computer). Needing another prism lens for them, I bought a new one online. But I cheated a bit - I got a 6 D one for my regular glasses and used the old 4 D one on the computer glasses. So that was another incremental improvement. Still, I have had the same problem with fatigue and eyestrain later in the day.
Along the way, my wife Nancy put on my glasses by mistake one day and shrieked at how much better she could see. (Our refractive corrections are pretty similar.) I believe this was with the 4 D prism on them. At her next eye exam, we had the doc check her for binocular diplopia, and BINGO! So, she had the prism ground into her new lenses.
Later, when she was having some other problems, she was scheduled for an MRI. I requested that they pay attention to the 4th Cranial Nerve to see if there were any lesions, tumors, or aneurysms impinging on it. (See the next section for why I made that request.) The report came back that they found no tumors and that the 5th Cranial Nerve was clear. (Gee, thanks!)
Since 2012, I have had two ophthalmology visits with refractory at the Northwest Eye Clinic at PeaceHealth St. Joseph's here in Bellingham. At the last, we had a discussion about the binocular diplopia, and it was clear that the doc really didn't have a clear grasp of it. Finally, last week I was very tired and, as a result, was having a lot of problems with the residual double vision and eyestrain. So, I thought maybe the 6 D prism was too much, and I switched back to the 4 D on my regular glasses. O.M.G.! It was horrible! So, I thought back to the original exam back at Casey, and the light bulb finally lit up! I immediately went online and ordered an 8 D prism. I got it yesterday and mounted it, and, viola, when I rotated it to locate the correct angle to mount it, the images came to a perfect overlay - with no twist! I am totally THRILLED!!!
The Science of Binocular Diplopia (Interesting Stuff - Really!)
To understand what causes binocular diplopia, as well as to gain an understanding of all of the muscles and nerves controlling the eyes' movements, settle back and enjoy this really entertaining 29-minute video on Cranial Nerve Palsies by Dr. Tim Root. While it is an instructional video aimed at young eye science students, it is easily followed by us lay folk, too.
So, armed with our new knowledge, we can make a pretty good guess that my sudden-onset problem stems from a little aneurysm that suddenly popped up during that tough night shift I had just worked in 2012. And since the onset of Nancy's problem was so gradual that she was never even aware of it or of the problems that it was causing her, that could argue for her problem being caused by a little tumor impinging on the 4th Cranial nerve. That could even be taken as a warning sign that she might have other tumors in her brain and/or elsewhere. Hence, my request re: her MRI.
The most obvious takeaway from our experiences is that binocular diplopia is not high on the radar of most eye professionals. In fact, it is so rarely encountered that any skills and equipment that they may have had must be pulled out of deep storage to be used. There is a perception that a routine screening for the condition would stretch out the length of the appointment too much. However, I would suggest that without the dusting-off and instructional steps, it would not take that long. And, considering that Nancy had to make a really serendipitous self-diagnosis in order to get the condition addressed, it just may be that this is a really common condition that is grossly undiagnosed and that is causing a degradation in the quality of life in, literally, millions of people - perhaps without their even being aware of it!
Binocular diplopia caused by a nerve palsy is not a condition that can be improved by muscle strengthening exercises or forcing the eye to make "natural" accomodation. Failing to correct it fully only leads to eyestrain and the loss of clarity when fatigued.
Bearing in mind the fragility of the 4th Cranial Nerve and its long tortuous path from the back of the brainstem to the eye, how many injuries to it are sustained, especially by athletes and by people in, say, automobile accidents?
Often you will hear a baseball player get on a hot streak and say in an interview, "Well, I'm really seeing the ball well right now?" How often could that be due to his being particularly well-rested at that time, so that the eye is better able to "naturally" accommodate to a binocular diplopia problem?
What Needs to Happen?
- Binocular diplopia screening should become a part of every routine eye exam.
- When binocular diplopia is discovered, an effort must be made to determine the cause. Especially in gradual-onset cases, it could be an early warning of a more systemic problem, such as metastasized tumors.
- Sports organizations should routinely screen their players for binocular diplopia, especially as part of concussion protocols. And some of the streakiness of some athletes, especially hitters, could be improved.