“Keep ’em in the green and they’ll keep you in the green” is an old expression that was commonplace in teaching clinics when I was cutting my teeth in Optometry. This refers to the practice of making sure that patients, particularly those who are nearsighted, have a distance prescription that leaves them slightly favoring the ease of seeing black letters in a green background in contrast to black letters in a red background. My purpose here is not to debate the merits of this practice, but to point out an entirely different aspect of vision – one that is rarely addressed by eye doctors in the course of examination.
That aspect involves movement. Invariably every aspect of vision assessment during an “eye examination” involves stationary targets, with a sedentary patient. Even if one could make the argument that increasingly our days are occupied by sitting in front of a computer screen scanning print (what are you doing now?), a considerable amount of time is still spent getting from place to place. Think of walking or driving for adults, at the very least, yet alone the visual world of the developing child. We need better tools with which to assess patients during an examination that reflects visual demands in the natural environment.
My argument here is that we need a new construct for keeping patients in the green, and that green does not represent clarity of distance sight, but efficiency of visual ecology. Ecology is the study of our interaction with the environment, and in that sense our traditional way of assessing visual function isn’t very eco-friendly. Perhaps the closest we come to recognizing this is in the development of test procedures to assess the athlete in “Sports Vision” evaluations. But why not broaden this thinking to every patient for, after all, we each have needs involving either dynamic visual scenes and/our own own movements as we use our eyes and visual systems. The psychologist J.J. Gibson can be credited for championing this approach, and his most comprehensive treatment of the subject was in his book on The Ecological Approach to Visual Perception. It is a book, as Gibson notes in his introduction, about how we see in our natural environment. His notion of what he terms an ambient optic array displaces the more narrow idea of vision as based on a retinal image. Gibson first used the term, Ecological Optics in an article in Vision Research way back in 1961 to convey this idea.
By the way, when Gibson mentions the ambient optic array that may ring a chord with the distinction made between ambient and focal vision. Although this concept is often credited to Trevarthen, it was really Gibson’s work on ecological optics and perception that set the stage for Trevarthen’s work. I can see that I’m going to need a few more parts to this blog to adequately elaborate, but let me leave you with this thought. We’ve reviewed many times before than vision is a collaboration between the eyes and the brain. Gibson goes further. He writes: “We are told that vision depends on the eye, which is connected to the brain. I shall suggest that natural vision depends on the eyes in the head on a body supported by the ground, the brain being only the central organ of a complete visual system. When no constraints are put on the visual system, we look around, walk up to something interesting and move around it so as to see it from all sides …” To Gibson, ambient vision involves looking around, and ambulatory vision involves active exploration. He finishes his introduction by noting that the examination procedures in ophthalmology and optometry require the patient to hold his eye fixed like a camera, obtaining good facts used in determining eye health and prescribing “corrective spectacles”. He argues the case compellingly that there is so much more. How is it that Gibson has been overlooked for so long?
This question was posed to me by Sue Barry, whose idea it was to re-visit Gibson’s work, apply it to her personal experiences, and use it as the framework for our upcoming presentation. She is the catalyst for many of the ideas that we’ll be visiting through eco-optics.