The Science of Stress, subtitled “Living Under Pressure”, is a gorgeous volume from the University of Chicago Press that I’ve had on my desk for the past year, fully underlined and highlighted. My favorite passage is on page 49, under the heading “The Performance Edge”: Managing stress is to the brain what building muscle through exercise is to the body. Of course finding the right balance between pumping too much or too little weight and running too little or too much is key. So it is with stress: not enough stress leads to boredom and lethargy; too much stress leads to reduced performance and damage.
Stress is implicated in just about everytying these days and Elliott Forrest’s seminal book on Stress and Vision was, in many ways ahead of its time. What the U. of Chicago book emphasizes in rather artsy fashion, without mentioning vision specifically, is the confluence of bottom/up and top/down interactions. This mind/body flow is something we all too often pay lip service, but ignoring its implications can result in excessive wear and tear in any of our physiological or psychological systems. Forrest addressed this wear and tear in terms of allostatic load, the outcome of crossing the boundary between eustress (positive stress, or a healthy cognitive load) and distress (counterproductive overload).
Heavily influenced by Hans Selye, Forrest masterfully addressed the eustress/distress continuum as it relates to accommodative/convergence interaction with a spring analogy. Along with his colleague, Marty Birnbaum, Forrest postulated that most visual disorders have their origin in nearpoint stress and specifically in the disruption between sympathetic and parasympathetic responses at near. This results in secondary adaptive responses in the vergence system that can be expressed at any distance and at a variety of levels. This dovetails nicely with more mechanistic models of visual system balance.
Before Forrest & Birnbaum, and Hung & Ciuffreda, modelling of stress in the visual system was done by Leo Manas in his classic work on Visual Analysis. It was a book I discovered serendipitously as a student hanging around in the PCO library, and it changed my entire outlook on vision and on life. Manas depicted visual demand and performance as the inverted “U” curve, setting the stage for what is now commonly known as the Yerkes-Dodson Human Performance and Stress Curve.
While we have plenty of references in the literature on how Yerkes-Dodson applies to patients, we need occasional reminders of how this continuum helps us as providers to stay centered. For more on this, I’ll direct you to a recent blog by one of my favorite vision therapists, Robert Nurisio.