Developmental optometrists examine children and we conveniently label different functions and tests as if there were a firm divide. But often there is not. Take the example of nearpoint retinoscopy. I recall reading a very nice insight from Rob Lewis, O.D. in OEP Curriculum News a few years ago, in which he quoted one of his mentors, John Streff, O.D. Streff said that in retinoscopy (and the rest of the exam as well) the examiner brings his or her visual system to bear on the visual system of the patient. For example:
1) Does the patient remain engaged with the task or let it go (fight or flight)?
2) Where does the patient place identification to deal with the target?
3) What is the symmetry and stability of the visual response?
The appropriate lens power can be a very potent tool in deriving a prescription for a young patient who might otherwise be told that everything is fine because visual targets are seen clearly. But there’s a tremendous amount of information processing that is occurring at the level of the retina that participates in what we see. We know that vision is a collaboration between the eyes and the rest of the visual brain. There is a trend in brain science to look at imaging studies to infer activity in different areas of the brain through changes in blood flow. Conceptualized in these terms, a retinoscope is the substrate of image processing at the retinal level. The direction of the light reflex might be a direct measure of accommodation, or the change in power of the crystalline lens. But the change in brightness or color of the retinoscopic reflex is due to blood flow changes in the retina. A lens that provides optimal processing will provide the optimal retinal reflex. Stated otherwise, the retinoscope used in this manner is a low tech device allowing you to probe cognitive brain imaging at the retinal level.
While doing near retinoscopy I like to engage young children in banter about the target to drive their cognitive function. This part has less to do with any lens in place, and more at the child’s pure thought processes. It has also taken me deeper into the minds of “out of the box” kids (OTB-ers). Take a look at the picture at the bottom. What’s it a picture of? The OTB-ers might tell you it’s a hat, rather than a cake. If we can agree that it’s a cake, I’ll ask what flavor the cake is. More importantly, I’ll ask if there’s anything missing from the cake.
The common answer would be that there’s a piece missing. But the OTB-ers answer that candles are missing. At first I thought this was a carry-over from previous testing that we had done. It might be that I used a picture of a cake with candles for distance or near fixation.
But I’ve found that even when I ask this question without previously having used any cake targets, the OTB-ers tell me that it’s the candles that are missing from the cake, rather than a piece of cake that’s missing. Though these children may have trouble with conformity, they have the type of brain that is increasingly valued in our age. I wouldn’t be surprised if it’s the way Steve Jobs would have answered the question as a young child. It’s also a subtle reminder of the beauty of clinical probes that don’t dwell on standardized testing with percentile ranks, or high tech devices. Not to denigrate such measures, only to point out that a composite picture of the out-of-the-box child emerges from the type of interaction that Dr. Rob Lewis modelled from his mentor Dr. John Streff.
– Leonard J. Press, O.D., FCOVD, FAAO