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Minimum effective dose: A prescription for success

Reaching a goal in the treatment of dry eye syndrome can be similar to reaching a fitness goal.

Issue: January 25, 2015

ByDarrell E. White, MD

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When I ask my patients, “What do you do?” they invariably answer by telling me what their job is. This is pretty much standard fare everywhere in the U.S. except California. If you ask a Californian what it is that he or she does, you will get the same sort of reply as I receive from my follow-up question to my patients in Ohio: “What do you do for fun?” Those of you who know me a little better than others know that my answer to question No. 2 — and to No. 1, if I happen to be visiting California — is, “I do CrossFit.” For 9 years or so, CrossFit has been my fitness and health program, as well as my hobby.

What does this have to do with dry eye syndrome (DES)? While doing some fun reading in my CrossFit world, I came across a rather famous proponent of the Paleo lifestyle, Mark Sisson, and a blog post in which he discusses the “minimum effective dose” of all the elements in his life approach. Paleo is a partly philosophical/partly actionable way of living and eating that attempts to bring some of the aspects of prehistoric life to the activities and diets of modern men and women. It is quite popular with a certain segment of CrossFitters. Indeed, we tend to talk about exercise and nutrition in rather med-tech fashion. We do our workouts “as Rx’d,” as prescribed, and we talk about following the “CrossFit prescription” in our diet.

Sisson discussed applying his very CrossFitty life principles in terms of meeting defined goals as efficiently as possible. Specifically, he was talking about what to eat and how much, as well as how to exercise and how much, in order to achieve a defined health and well-being outcome. I immediately saw the parallel between what I do for work and what I “do” in the concept of minimum effective dose (MED). Let’s explore that a bit as it relates to treating DES and associated problems.

In the seminal essay “What is fitness?” Greg Glassman establishes as his overarching goal a type of general physical fitness he defines as “broad and inclusive.” Sisson is both less and more specific in his goal setting, acknowledging the power of a general goal like Glassman’s while at the same time recognizing that some people will have much more specific endpoints in mind. For us as doctors treating DES, the critical concept is that we consciously set a goal, an outcome that we will pursue with our treatment. It sounds trite, but the power of explicitly defining what constitutes success cannot be overstated whether we are discussing DES or dress sizes.

Measuring an outcome

In order to articulate a goal, we must be able to measure an outcome. In CrossFit, one measures fitness, which is defined as “work capacity across broad time and modal domains.” How much can you move, how far and how fast? “Mark’s Daily Apple,” the so-called “life hacking” site dedicated to health and self-improvement, is quite comfortable with seeking this type of general physical preparedness, but Sisson is also clear that his approach can be applied in the pursuit of something as specific as fitting into a wedding dress or preparing for a 100-mile bike race. Both men, and by extension both approaches, begin with choosing a definable metric and then using that metric to plot progress toward a specific goal. We have any number of things we can plot in DES, many of which we have discussed in past columns. Patient symptoms are the primary integers in my protocols, but other easily measured items, such as tear break-up time, tear osmolarity, MMP-9 levels and inferior corneal staining, are also relevant. Once an outcome is defined, it is possible to begin the process of evaluating the effectiveness of the prescription written to achieve it.

Both the treatment of DES and the pursuit of fitness involve basic sets of treatment principles. For one to get strong, it is necessary to lift heavy things. The treatment of an inflammatory disease requires the use of medications that reduce or eliminate inflammation. The concept of MED is both simple and elegant: Use the smallest dose of treatment possible that allows you to achieve your desired outcome. It seems almost silly to write or read this until we look at some of the treatment regimens of DES patients or the training programs of recreational athletes in which it appears the “more is more” strategy is only improved by adding … more.

Why is this? Indeed, we have all been taught this from day 1. The glaucoma model wherein we set a target IOP and treat to achieve it is an excellent example. The first key point is to set the goal, then use the MED to achieve the goal. The pursuit of the MED to “secure your goal” is ongoing, and this is the last of Sisson’s lesson. Perhaps it is “mission creep” — the goal keeps moving — that creates a prescription that exceeds the MED, but I think the problem is more one of prematurely declaring “mission accomplished” and standing pat. Much like losing weight or gaining strength, while treating DES, in many cases it takes a smaller prescription to maintain success than it required to achieve that success.

‘Tweaking’ the MED

Ocular surface disease in general, and DES in particular, lends itself nicely to the concept of a continuously evaluated and “tweaked” MED to achieve specific, measureable outcomes. Sisson talks about utilizing a constant process of consciously fine-tuning nutrition and physical training to maximize some fitness, health or life outcome, all the time seeking the smallest amount of fuel ingested and exercise time invested in the effort. Once we have reduced any of our DES measures — symptoms, osmolarity, inferior corneal staining, etc. — and achieved our goal, we may find that less medicine and fewer visits may suffice. Likewise, some event, a wedding or ragweed season, may prompt us to re-evaluate our prescription in light of a new goal of challenge.

The concept of the minimum effective dose in treating DES is foundational for everything I do, especially if you ask me about that in California at the American Society of Cataract and Refractive Surgery meeting in San Diego in April.