As physicians quickly find out, when evaluating a patient, one factor or measurement isn’t the be-all and end-all, and could actually lead one down a wrong path. However, one measurement can, in many instances, be a good starting point to direct you toward other factors to evaluate, and, taken together, give you a more complete picture of a particular patient's condition.
Take the body-mass index, for example. It’s an easy-to-calculate, inexpensive indicator of someone’s fitness, at least as far as their weight is concerned: It has standardized cuttoff points that can point toward an underweight, normal or obese condition.1 But, though it’s a handy, objective measurement, it’s not perfect.
For instance, an athletic patient could have a high BMI, but a lot of their weight is actually muscle.2 While, on the other end of the scale, someone could have a normal BMI—maybe a little on the high side. However, when you look at their waist size, it turns out it’s more than 40 inches. Studies have shown that carrying most of one’s fat in the abdomen area is actually a risk factor for problems such as heart disease, high blood pressure, type 2 diabetes and stroke.3
Also, BMI indexes may need to be broken down by sex and race, as Asians tend to have more body fat than white patients.1
Despite such limitations, though, BMI is a good quick jumping-off point in a series of exams and measurements that can characterize the patient’s condition fully. The BMI can be followed by more intensive measurements, such as bioelectric impedance and/or underwater weighing.1
Similarly, surgeons interviewed for this month's cover story on selecting the right laser refractive surgery for a particular patient discuss how just one or two measurements or exams might be useful to a point, but it's when all of the patient's data are taken together that you can make a decision on a procedure. For example, a patient's refractive error may be well within LASIK's zone of efficacy and predictability, but when you look at the cornea, an irregularity might rule out the patient. Similarly, the patient may have an acceptable refraction, corneal topography/tomography and pachymetry, but when you inquire about his hobbies, it turns out he likes to box (a risk for a displaced flap)—so you instead might lean toward surface ablation.
We hope that this deep dive into the key factors involved in laser refractive surgery will help you best align your patient with the right procedure.
— Walter Bethke
Editor in Chief
1. Harvard T.H. Chan School of Public Health. Measuring obesity. https://www.hsph.harvard.edu/obesity-prevention-source/obesity-definition/how-to-measure-body-fatness/. Accessed June 23, 2023.
2.Centers for Disease Control and Prevention. Body mass index: Considerations for practitioners. https://www.cdc.gov/obesity/downloads/bmiforpactitioners.pdf. Accessed June 26, 2023.
3. National Heart, Lung and Blood Institute. Assessing your weight and health risk. https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm. Accessed June 26, 2023.