Research Review

Contact Lens Noncompliance: It's Only Human

By Eric Papas, PhD, MCOptom, DipCL, FAAO

Are my contact lens patients doing what I tell them to do? This is a question all clinicians must ask themselves, at least occasionally, and getting a reliable answer is far from being a trivial exercise. Indeed, when you think about it, the question itself is not really that straightforward. What we actually want to know is: are our patients aware of, obeying, and successfully carrying out an extensive set of complicated instructions involving personal hygiene, lens wearing schedules, replacement frequencies, handling, cleaning, and disinfection as well as following recently introduced, rigorous lens case hygiene guidelines (Wu et al, 2010)?

Faced with this jungle of activity, it would not be surprising if no one at all was managing to be fully compliant, and research confirms that this is indeed the case. For example, when presented with 15 questions about their contact lens care regimens, none of the participants in a recent study gave satisfactory answers to them all, and 60 percent of respondents failed on at least six (Yung et al, 2007).

Defining Noncompliance

Part of the problem is that patients' perceptions of their own performance do not always correspond with what their practitioner might wish them to be. While 86 percent of survey respondents see themselves as being compliant, only one-third of this number actually rated as being so against the objective scoring model developed for the purpose (Bui et al, 2010). To make matters worse, there is no universal agreement on what the correct instructions should actually be. Do we go by the manufacturers' recommendation? Or, does our clinical expertise and knowledge of our individual patients give us a sufficient foundation on which to base our own advice?

While it is certain that many will hold to the latter view, this does cause problems when seen from the viewpoint of those trying to conduct research in the field. Clinical study designers usually attempt to carefully control the conditions for their investigation, and the existence of multiple criteria within the population of interest makes that very difficult to do effectively. For this reason, many reports in the literature have used the manufacturers' recommended instructions as the defacto standard for measuring compliance.

Taking replacement frequency as an example, noncompliant wearers are usually defined as those who continue with lenses for one or more days beyond the manufacturers' indication for the product. On that basis it seems that each gender behaves just as well (or badly) as each other, with roughly one in three males and females failing to comply (Dumbleton et al, 2009; Yeung et al, 2010). An interesting detail underlying this finding is that men appear to be more enthusiastic noncompliers compared to women, as their mean over-wear time of 48 days considerably exceeds the 28-day average of their female counterparts.

While refractive error does not affect replacement compliance, both replacement frequency (daily, bi-weekly, monthly, quarterly, annually) and care system type (multipurpose versus hydrogen peroxide) appear to do so. Wearers who should replace their lenses every two weeks and users of multipurpose solutions are the worst offenders, with about 40 percent over-wearing in each case (Yeung et al, 2010).

Visual Consequences

What are the consequences of this behavior? Do over-wearers suffer clinical complications as a result of their departure from the recommended pathway? Judged in terms of the number of problems suffered, the answer is a qualified “yes.” Looking across a range of conditions such as contact lens-induced papillary conjunctivitis, conjunctival redness, edema, infiltrates, neovasculariza-tion, corneal staining, superior epithelial arcuate lesions, and “ulcers,” the average annual number of complications seen per eye was higher among noncompliers (0.9 versus 1.3 per eye), but only when compliance was extremely poor. Recommended wearing times had to be exceeded by a factor of more than three times before this excess risk approached statistical significance.

When it comes to the two factors that are perhaps of most immediate concern to the majority of contact lens wearers, namely vision and comfort, the situation is clearer. For indicated replacement frequencies of both two weeks and one month, noncom-pliant wearers appear to fare less well in regard to these key variables. This is true not only when they eventually come around to the view that it was indeed time to change their lenses, but also at the end of the normal wearing day (Dumbleton et al, 2010). Presumably this latter effect becomes increasingly important as the lenses age beyond the recommended wearing period.

Other than lens replacement, disinfection procedures are the main area in which compliance is perceived to have important consequences, and this is not unreasonable given the presumed link between corneal infection and microbial contamination of lenses and cases. When a population of contact lens wearers who had all developed microbial keratitis was evaluated for their care system compliance, again using adherence to manufacturer guidelines as the criterion, 31 percent were deemed to have been so (Najjar et al, 2004). This is significantly fewer than would have been expected by chance, suggesting that, while giving no guarantee of safety, this kind of compliant behavior does confer some benefit.

Who Are The Noncompliant?

These clinically evident problems make it appealing to suppose that if we could identify potentially noncompliant patients “upfront,” we might be in a better position to provide them with more care and attention. The hope being that this would result in an improvement to their contact lens-wearing experience.

Some very recent work that has looked at the relationship between compliance and various patient and practitioner characteristics may help in this direction (Carnt et al, 2010). The bad news for clinicians from this research is that practitioner perception seems to be a poor predictor of compliant behavior. Factors such as age, contact lens-wearing experience, and gender are also not helpful. In fact, the only significant indicator of non-compliance was the propensity for the contact lens wearer to take risks.

Overall, this means that it is probably a waste of practitioner time to try and spot those lens wearers who will be noncompliant on the basis of information gleaned during the course of a conventional clinical interaction. On the other hand, incorporating some kind of risk-taking assessment might be of value, although whether the individuals so identified are susceptible to changing their contact lens habits remains to be seen.

Recent work that attempted to improve compliance by having lens wearers review their care procedures every three months showed that, with the exception of case hygiene, no change took place (Yung et al, 2007). This lack of effectiveness may well be the result of the innateness of risk-taking behavior (and presumably, therefore, noncompliance), which means that these characteristics are likely to persist even when contact lens wearers know that adverse health effects can occur as a consequence.

Room to Improve

Looking ahead, it seems that research into more effective educational strategies would be one area toward which activity could be directed as a means of improving patient cooperation with practitioner instructions. However, as we have been eloquently reminded (Cho and Boost, 2009), the ancient Chinese proverb says, “Rivers and mountains may change but human nature does not,” and our modern research does little to contradict this wisdom. Thus it is likely that pressure will remain on manufacturers to simplify and improve their contact lenses and care products so that they can be used safely and effectively with as little need for compliance as is humanly possible. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #184.

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Associate Professor Papas is executive director of Research & Development and director of Post Graduate Studies, Brien Holden Vision Institute and Vision Cooperative Research Centre, and senior visiting fellow, School of Optometry & Vision Science, University of New South Wales, Sydney, Australia. He has received research funds from Ciba Vision, Alcon, AMO, and Allergan. You can reach him at e.papas@brienholdenvision.org.