I’ve blogged previously about the use of lens and/or prism prescriptions as either a panacea for a wide array of performance problems, or as an indispensable adjunct to, if not a substitution for office-based vision therapy. The ad that just came across my desk for a seminar in the UK for a Diploma in School Vision Practice is another example of this. Let me reiterate my position. As I wrote many years ago – in this review of Lenses and Behavior that is part of the core reading material for candidates taking Board Certification examinations in Vision Development and Therapy – the appropriate lens or prism prescription can have a profound influence on visual performance. But that is a far cry from claiming that every patient can benefit from a lens or prism prescription, and that one of our professional responsiblities is to determine the ideal prescription for every individual. That sounds as counterintuitive as claiming that every patient can benefit from auditory modification, and the key is to find the ideal hearing aid that provides the best binaural balance. If something sounds too good to be true, it usually is. Let me be equally clear, however, that I don’t subscribe to the “lens bashing” undertaken by pediatric ophthalmologists who claim that 35% of the prescriptions issued by optometrists for children are unnecessary. That’s simply willful or unintended misrepresentation wrapped in a medical degree.
In considering why some of my optometric colleagues feel so passionate about prescribing the “correct” lens, several possiblities stand out:
1) The prescribing of lenses and prisms are unique tools in optometric practice. One therefore tends to be enamored with tools in one’s toolbox. This isn’t much different than the outook of some pediatric ophthalmologists, who tend to be aggressive about recommending eye muscle surgery, which is their bread and butter.
2) To the extent that a lens or prism prescription might address performance issues, it would be very attractive to have a magic bullet that requires no weekly office visits and little if any home therapy. It is a less costly alternative in terms of money and time.
3) There is no confounding factor of expecting insurance reimbursement. The recommendation of a special lens prescription, particularly if it involves prisms or tints, can be presented as a non-conventional prescription that requires direct payment on the part of the patient.
There are two broad classes of lenses applied to potential therapy populations, presented much as medication might be Rxed for children with ADHD, as a singular magic bullet. One is prism lenses, usually in yoked form, but sometimes as base-in prism. The yoked form is more commonly used for children on the autistic spectrum, and the base-in for children with dyslexia or similar reading issues. The other class is the tinted lens, sometimes used in conjunction with syntonics, marketed most recently by companies promoting prodcuts such as the Intuitive Colorimeter or proprietary lenses such as Chromagen, again targeting dyslexia and similar conditions.
My impression of magic bullets, be they surgical, pharmacologic, or optical, is that if something has a good track record there is likely truth behind it. And if we pretend that nothing in medicine is administered “off label” without scientific studies being done before pediatricians or ophthalmologists prescribe it, then we’re being terribly naive. So if a particular lens or prism Rx or tint has a particularly benefical effect, wonderful! But what if the patient tries the magic bullet, and there is little if any effect? Or, if there is a placebo effect at the outset, that wears off quickly. Then what? This is where we run the risk of concluding that there must not have been a vision problem underlying the performance problem, because the magic bullet didn’t work. We seem to be encountering a wave of patients whose parents have taken them for the magic bullet, often overseas to the UK, only to return with a sense of disillusionment relative to their expectations. For many of the cases that we deal with, there simply are no shortcuts to office-based therapy, as alluring as the promise might be of an optical panacea.
One takes certain risks in using quotations, but I’ll cite one from Thoreau that was used freqently by one of my mentors, Dr. Donald Getz. “The flexibility of your adaptability is a measure of your intelligence”. Here, to my way of thinking, is the strongest argument against the expectation that a singular lens prescription will be a magic bullet for the populations we’re dealing with. Above all, the notion that the patient’s visual system is so finely tuned that all one might need to optimally calibrate function is to tweak the system by a tiny bit of lens, prism, or tint lacks an intuitive base. For the patient who is helped in a way that is disproportionate to the range of power or wavelength adjustment we’re considering, that can’t be the ideal outcome. Why? Because if the patient can’t function adequately without being tethered to that relatively small power, the ranges or degrees of freedom of his visual system are narrow. By definition, we have limited flexibility and limited adaptability. That, I would argue, is what Dr. Getz had in mind in terms of the power and range of what active vision therapy with visual motor planning, movement, visual cogntion and so forth can accomplish. In that regard, the lens or prism or filter is simply a tool. A crucial tool, in some cases, but not an all-purpose Rx to which the patient is tethered.