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Article Date: 6/1/2010

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Lens Replacement Frequency
Point/Counterpoint

Lens Replacement Frequency

Point: Let Clinical Evidence and Lens Performance Guide Your Decision

BY COLLEEN M. RILEY, OD, MS, FAAO

Clinicians and contact lens manufacturers share a common responsibility: to meet the ocular health and vision needs of the millions of patients who depend on us.

As manufacturers, we must continually provide innovative products, and we have a responsibility to clearly articulate the evidence and clinical experience behind them so that practitioners can prescribe with confidence. From the introduction of the first disposable soft lenses in 1987 (etafilcon A) to the current surge in silicone hydrogels, practitioners have depended on clinical evidence, lens performance, and patient experience to guide their recommendations.

While there is scientific support to suggest that more frequent replacement is better for optical performance, patient comfort, and ocular health, there are advocates for a longer replacement interval who believe that reduced frequency of replacement will improve compliance. If patients are noncompliant with a two-week replacement schedule, do we really believe that they will be more compliant if allowed to wait four weeks to change lenses?

Optimizing Performance

In a masked clinical study, 379 subjects were randomized to wear either one brand of two-week or one brand of monthly silicone hydrogel lens for one cycle of manufacturer-recommended replacement (Data on file, Vistakon, 2010). Those in the two-week lens experienced superior comfort, better vision, and fewer lensrelated problems such as deposits, limbal hyperemia, and symptoms of dryness or lens awareness.

The differences were particularly noticeable at the one- and two-week time points, with significantly more patients (72 percent) expressing satisfaction with the two-week lenses compared to the monthly lenses (60 percent). At the end of their recommended replacement schedules, only 56 percent were satisfied with overall comfort with their monthly replaced lens. More than one-quarter of the monthly lens wearers were dissatisfied with overall comfort (rating their lenses as fair or poor) at the end of the replacement cycle.

Quality of vision also suffered with monthly lenses. Thirteen percent of monthly wearers rated their quality of vision as poor or fair at the end of the replacement cycle. At the two-week time point, this was 8 percent for the monthly lens versus 5 percent for the two-week lens. The two-week lenses in this study offered a much better wearing experience, both throughout the day and across the replacement cycle.

Practitioners may want to consider questioning their monthly replacement lens wearers specifically on whether comfort and vision performance meet their needs in the third and fourth weeks of wear, as this study suggests that for many patients, their monthly lens may not provide consistent comfort and vision over the entire replacement cycle.

Compliance is Important

Compliance is a constant challenge. Lens over wear, sleeping in lenses, and poor case and lens hygiene can lead to significant comfort and health problems.

In a masked survey, perfect compliance with the replacement schedule was noted in 43 percent of two-week wearers and 36 percent of monthly wearers (Hickson-Curran et al, 2009). But 23 percent of monthly wearers extended their contact lens wear to eight weeks or more—more than five times the rate of such extreme over wear by two-week lens wearers (4 percent).

The time interval we recommend can impact frequency of replacement, so it is imperative that we reinforce the importance of compliance and emphasize to patients that longer lens wear impairs performance, patient experience, and ocular health. When noncompliance with reusable lenses is a concern, switching to single-use lenses is a better alternative. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #175.


Dr. Riley is vice president of Professional Development for Vistakon.

Counterpoint: Patients are More Compliant When Replacement is Easy to Remember

BY PETER D. BERGENSKE, OD, FAAO

For many years and until quite recently, the most commonly prescribed soft contact lenses in the United States were the two-week replacement type. They have been so common that we generally have not stopped to ask, "Why two weeks?" This interval may be difficult to remember, and as such it adds a complexity to contact lens wear that may be a barrier to compliance.

Why Two Weeks?

When "disposable" contact lenses were first marketed, they were intended as single-use products to be worn for up to a week and then replaced. It was suggested early on that although overnight wear was perhaps not for everyone, frequent replacement seemed to make a lot of sense; and if the lenses were intended for one week of extended wear, then logically they ought to be good for two weeks of daily wear (Bergenske, 2000).

Over the next decade a good body of evidence developed showing that for HEMA lenses, replacing lenses at daily, twoweek, or monthly intervals provided significant advantages over longer replacement intervals (Poggio and Abelson, 2003; Solomon et al, 1996). Primarily based on issues having to do with deposits and the eye's response to them, for HEMA lenses, shorter was better.

Enter the Silicone Hydrogels

Traditional, HEMA-based contact lenses are known to uptake very high levels of protein from the tear film (Sack et al, 1987; Minno et al, 1991) whereas silicone hydrogel lenses uptake substantially less (Suwala et al, 2007). Arguments in favor of two-week replacement are based either on data that pre-dates silicone hydrogels or on survey responses from HEMA and silicone hydrogel lens wearers combined. Let's make it clear that for this discussion I am referring only to silicone hydrogels.

Of course differences exist among silicone hydrogel lens brands, and some are better suited to two-week replacement than to monthly. Lipid and protein affinities vary, with plasma surface lenses showing the best deposit resistance (Gabriel and Nash, 2009; Boone et al, 2009).

Make Replacement Memorable

Be that as it may, we eventually come to the issue of human nature and what is a reasonable interval for patients to remember for replacing their lenses. There are two ways to approach this.

First is to ask patients what interval they would prefer. In a 2009 survey of nearly 3,000 contact lens patients, 77 percent of respondents indicated that they would prefer either a one-day or a one-month replacement schedule. Furthermore, among responses from current two-week lens wearers, 65 percent preferred a monthly schedule (Data on file, Ciba Vision, 2009).

A second approach is to look at what patients actually do. In the same survey, we found that more patients wearing two-week contact lenses actually replaced them at one month than at two weeks. Dumbleton et al (2009) studied compliance among silicone hydrogel lens wearers and also found that compliance with monthly replacement is significantly better than it is with two-week replacement.

Compliance is not just a matter of behavior, it is also one of design. In the Dumbleton study, when patients were asked the reason for not replacing their contact lenses as recommended, the most common reason was "forget which day to replace." Could it be that two weeks is just a tough interval to work with? Doesn't it make more sense to design contact lenses around a schedule that patients can remember?

There is a reason why our calendars are arranged in months and not in fortnights. With no evidence of a downside to using a monthly replacement silicone hydrogel lens for a month, this is an interval that makes sense and can be remembered. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #175.


Dr. Bergenske is director, Professional Support, Ciba Vision North America.

Contact Lens Spectrum, Issue: June 2010

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