Thank you and good afternoon.
I'm a private practice optometrist with a specialty in neuro-optometry. I received my doctoral degree from the University of California at Berkeley.
My interest in the brain and vision began early in my career. After receiving my optometry degree, I spent 22 years doing part-time visually evoked potential research, measuring brain responses to visual stimuli, as co-director of the vision laboratory at the California State University in Bakersfield.
In my private practice I have been practising, writing and lecturing in the field of neuro-optometry for nearly 25 years. My co-editor Dr. Lisa Harvey and I published what is considered the most comprehensive text reference book to date on vision rehabilitation following brain injury. We worked hard to include both the basic science and clinical science involved in visual dysfunction and visual rehabilitation following brain injury.
Neuro-optometrists are interested in testing and treating visual function, including eye movements, eye coordination, visual perception of objects and visual perception of space and motion, as well as how we integrate those visual percepts with the other senses and the motor system so that we can move through space and act on objects. Visual processing is so distributed throughout the brain that it is difficult to injure the brain without some visual consequence.
I am here today not as an expert in mefloquine toxicity and the visual system, although I am happy to share what I know on the subject. I'm not sure that we have experts on the visual system and mefloquine toxicity at this point. However, I am here as a neuro-optometrist who has diagnosed hundreds of patients who have subtle vision deficits resulting from acquired brain stem injury that can mimic or exacerbate the symptoms of post-traumatic stress disorder—PTSD—or other psychological diagnoses.
Quinolones have been shown to cause brain stem lesions. I am here because just like the patients I see with subtle vision dysfunction resulting from other acquired brain stem injury, patients with mefloquine toxicity are at risk of being diagnosed with PTSD or other stress- or anxiety-related disorders when they actually suffer from neurologic vision deficits. I am here to tell you that every patient who suffers mefloquine toxicity and has PTSD-like symptoms, or difficulty reading, or photophobia, or difficulty with balance or dizziness, or feelings of disorientation or anxiety, needs a neuro-optometric workup. Neuro-optometrists and neuro-otologists can test for biological markers of brain injury that other professionals simply do not.
Ordinarily, our visual system and our vestibular system work together to create the perception of a stable physical world around us so that we can move through it with confidence. However, imagine suddenly living in a physical environment that moves and shifts just a little as you move your eyes—not enough for you to be able to say, “Oh, the floor just dropped three inches when I looked to the right”, but just enough to make you feel a little uneasy or queasy, or startled or disoriented, or where the space around you shifts, expanding on one side and contracting on the other.
When you walk toward an object that is straight ahead of you, you find that you're always veering to one side because your visual perception of straight ahead has been shifted from the reality of the physical straight ahead. All of these visual symptoms are common following acquired brain stem injury. They cause difficulty with balance and feelings of disorientation and anxiety because the physical world that we depend on to stay stable under our feet, in our hands and in our visual perception is no longer reliable.
If you have a visual problem that destabilizes the perception of the physical world around you, as I have described, the vestibular system will attempt to keep you upright. If you look to the right side and your visual system says, “Oh, something shifted,” and you get startled, your vestibular system will say, “It's okay. I know where upright is. I know where gravity is,” and it will rescue you. If you have a vestibular problem, the visual system can help stabilize you.
Some of you may remember having drunk enough alcohol to have closed your eyes and have the world start spinning, and then you opened your eyes to make it stop. That is your visual system rescuing you from your vestibular system. If, however, you have both a vestibular and a destabilizing visual deficit, then you suddenly live in an amusement park funhouse.
I want you to think for just a moment, if you were to wake up in a world that was that distorted, how you would try to explain that to your doctor to get help. What words would you use? What would you say? You don't have that spinning dizziness that you get with severe vestibular vertigo. Do you think that once you tried to explain it to them you would be sent to a neuro-optometrist to diagnose your subtle visual deficits creating this instability or exacerbating this instability, or do you think you would be sent to counselling, psychology or psychiatry?
Most of you have probably never heard of neuro-optometry before these meetings, and the same is true for your physicians. This is a common problem for many patients with mild acquired brain injury who can go for years or for a lifetime without ever getting diagnosed. It is certainly possible to have PTSD concurrently with subtle brain stem injury-related visual and/or vestibular deficits, but the treatment is very different for these diagnoses, and patients with mefloquine toxicity deserve accurate diagnosis and treatment with neuro-optometry and neuro-otology.
That's really what I wanted to come talk to you about today. Thank you for the opportunity.