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.
Thank you for your commentary regarding false expectations. It is obvious that we are all searching for the best and least expensive solution to an existing problem. In our field, there is always some one, who has found a lens or a prism combination which is superior to vision therapy or any other therapy. The key to this dilemma is for the patient and/or parent to have specific goals and expectations before pursuing any intervention. A lens/prism prescription should have an immediate positive impact on a patient’s visual performance. A plus lens should magnify the print, increase the patient’s reading distance, improve their reading comfort level and make a noticeable difference to the patient. On the other hand, a plus lens, which has minimal value or creates a emotional dilemma for a patient is probably not the treatment of choice. In the area of vision therapy, there should be clear objectives and an appropriate time frame. A child/patient should be aware of positive changes within a reasonable period of time. In my experience, the presenting complaints of blurred vision, eye strain/fatigue, loss of place and headaches will begin to disappear within one to two weeks after implementing therapy and the patient’s visual abilities will continue to improve throughout the course of therapy. The patient’s improvement in academic tasks will be an important by product of the doctor’s vision therapy program. In my opinion, vision therapy is not a substitute for special education but it is an important adjunct intervention.
Thank you again for addressing a common problem facing patients/parents when seeking a simple solution for a complex problem(s). Parents/patients, who are desperate for results, will often fall victim to an unscrupulous person/authority. In the world of finance, Bernie Madoff defrauded billions from investors, who should have known better. Each treatment plan/strategy should have specific goals and expectations. If a recommended program is not meeting those predicted expectations, it is probaby time to reassess the specific intervention and reassess options/priorities. There will always be bumps in the road to success but there must be documented positive changes in a patient’s overall visual performance in a reasonable amount of time in order for any therapy to continue according to plan.
You’re welcome, Richard, and thanks for taking the tend to share your insights.
In regard to (micro)prism therapy, could someone PLEASE direct me to research or studies which show:
2. how it is prescribed
In the clinics where I work, everyday people are talking about “prism glasses” from various doctors in this country and in London. Some are reporting “miracles” of how their child can now read much better where he could not stand reading before. Also better attention span and concentration. Some say the patient failed with vision therapy and improved with “prism glasses”. Since some succeeded, it seems as if everyone now wants the “magic bullet”.
I have seen a couple of these patients and frankly am unable to understand either the reason for the prism or even the rationale for it. For example, a patient with a significant convergence excess given 1^ Base Out in each eye. The bifocal part of the Rx makes obvious sense to me. How does the base out prism improve things? Forces them to learn divergence?
Another one–with exotropia/hypertropia and an overactive inferior oblique muscle. Given an undercorrected myopic correction and a bifocal with 1^Base In OU not even addressing the lack of binocular vision or the vertical deviation which was reported on in the examination. The Rx ignored that.
So, if someone can point me in the direction of literature on this topic, I would be much obliged. Did not find anything of significance on either the OEP or COVD websites.
Truth is, I am skeptical, but I really have an open mind on this. If it really helps, I would be more than happy to provide this service to my patients.
Thank you for your help on this matter.
Hi Joel – there are no published studies on “microprism” that I am aware of. I blogged about the prism mystique previously here: https://visionhelp.wordpress.com/2012/06/28/are-glasses-a-substitute-for-vision-therapy/
I agree with you that prism is being overprescribed in some quarters as a “miracle cure” for Orthodox Jewish children with learning difficulties. That being said, I as well am interested in better differential diagnosis in identifying who the prism is likely to help, and for whom it is at best a placebo. I will Rx low BI prism when there is CI or BO for CE and an add in either case if there is an accommodative basis for nearpoint stress. Certainly yoked prism, or traditional vertical prism can be used when there is non-comitant phoria or strabismus. We are doing more now with probing binocular responses on VEP, and use the Readalyzer or Visagraph to look at eye movement factors related to reading.