In light of the tremendous advances in lens and solution research initiatives over the past few decades, is the rate of complications less and are the associated risks different today? If not, why is that? Let’s go over why these are difficult questions to answer with certainty.

To begin, even the most careful of studies performed by scientists are often imperfect. There can be several reasons for this: inadequate sample sizes, poor study designs, researcher bias, financial interests and faulty statistical analysis can contribute to studies falsely purporting to reveal new truths.^1,2   

Measuring errors and adverse events in health care can be especially foreboding. Eric J. Thomas, M.D., M.P.H., and Laura A. Petersen, M.D., M.P.H., admirably review seven ways to measure errors in medicine and adverse events. They discuss morbidity and mortality conferences, malpractice claims, administrative data analysis, chart review, electronic medical records, observation of patient care and clinical surveillance as effective methods to evaluate and measure errors.3 Unfortunately, most of these methods are expensive; of those that are not, there can be significant potential for bias.

Observation of patient care and clinical surveillance are generally more accurate and precise for detecting adverse events, but are not as good for detecting latent errors.^2,3 Many studies and reports lack contemporary controls that reflect similar practice patterns in recommending lens type and solution care systems.

Consider the challenges in reporting contact lens adverse events. For example, let’s look at infiltrative keratitis (IK) as an adverse event and consider the many impediments/obstacles we face. First, classification schema may impact incidence.^1,4 The overall rate of non-infectious events is also highly dependent upon the diagnostician, as demonstrated by Phillip B. Morgan, B.Sc., Ph.D., and colleagues. In their study of 111 cases, three events were unambiguously diagnosed as microbial keratitis (MK), seven events could be diagnosed as MK or contact lens peripheral ulcer (CLPU) and two cases could be either MK, CLPU or IK.⁵

A further confounder is that, unlike microbial keratitis, many of these non-infectious events are self-limiting and may not present to the eye care practitioner or be captured in any clinical trial design. I also believe geographical location of the patient may affect infiltrative events due to practice patterns and even water source contaminants.

Other investigators cite several challenges they encountered in designing a recent retrospective study looking for risk factors in corneal infiltrative events.6 These include incomplete data from retrospective chart reviews, assuring adequate contemporary controls with information on exposure, “the ever changing mix of products” investigated and obtaining an adequate sample size.⁶

To say that the challenge of reporting and interpreting results in research endeavors is daunting is an understatement. Nevertheless, phenomenal work has been done in reporting device complication rates and revealing their associated risks. Join me in thanking the dedicated researchers who have shed light on this topic. Although we still lack all the information on trends in risk and complication rates, I look forward to new data in years to come. 

1. Ionnidis JP. Why most published research findings are false. Plos Med. 2005 Aug;8(2):124.
2. McDonnell P. Are you skeptical of the latest peer-reviewed results? Ophthalmology Times. 2006 Feb 15;10(2):2.
3. Thomas EJ,Petersen LA. Measuring errors and adverse events in health care. J Gen Intern Med. 2003 Jan;18(1):61-7.
4. Shovlin JP, Efron N. Risk factors for non-infectious contact lens associated corneal infiltrative events: A systematic literature review. Ocular Surface (in press).
5. Morgan PB, Efron N, Brennan NA, et al. Risk factors for the development of corneal infiltrative events associated with contact lens wear. Invest Ophthalmol Vis Sci. 2005 Sept;46(9):3136-434.
6. Chalmers RL, Keay L, McNally J, Kern J. Multicenter case-control study of the role of lens material and care products on the development of corneal infiltrates. Optom and Vis Sci. 2012 Jan 5;89(3):1-9.