Progressive contact lens practitioners have embraced the idea that a fresher lens is better, as evidenced by the recent growth of the daily disposable market.1 These practitioners recognize that fresh lenses have fewer subjective complaints and less deposits as well as tend to have a lower overall complication rate as compared to their older counterparts. While daily disposables are a great option, practitioners find lens parameters limited––particularly in the toric and multifocal segment. Some patients are reluctant to move into a daily lens modality due to issues associated with cost, end of the day comfort, lens tearing, perceived wastefulness or other factors. When a daily disposable isn’t an appropriate option, how does a contact lens practitioner decide between a one-month and a two-week lens?

Two-Week Wear Schedule
Patient compliance is probably the topic that gets the most attention in any discussion of two-week and one-month contact lenses. While some studies suggest two-week contact lenses have a slight compliance edge, all research suggests that both groups have a high non-compliance rate.2 Do we really think if patients are provided proper instructions, that a non-compliant two-week wearer will be more compliant with a one-month lens?

The biggest issue with studies that show a slight compliance advantage of one-month contact lenses is the tendency to use a short and absolute definition for non-compliance. A 2009 study by Kathy Dumbleton, O.D., M.Sc., and colleagues, found non-compliance for two-week contact lenses at 17 days and one-month lenses at 31 days.2 When you account for those patients who might overwear their lenses by a few days, the results may not be so conclusive in suggesting that a one-month replacement schedule inspires better compliance than a two-week replacement schedule. While we prefer a patient to be 100% compliant with a prescribed replacement date, the common practice of over-wearing contact lenses a couple of days is probably inconsequential in the grand scheme of the contact lens wearing experience.

1. Patients reporting wearing contact
lenses eight weeks or longer.

Extreme Non-Compliance
If we cannot achieve 100% compliance, would we rather have a non-compliant two-week wearer or a one-month wearer?

A recent study was conducted by surveying patients over the Internet about their behaviors with contact lens care and thus, eliminated the doctor/exam room bias.3 The study showed that 23% of one-month contact lens patients wore their contact lenses for eight weeks or more compared to just 4% of two-week contact lens patients (see figure 1).3

Contact lens practitioners should be concerned about the issues associated with such extreme overwear. These are the patients most at risk for visual and ocular complications, which could ultimately lead to contact lens drop out or even permanent visual impairment. With such a large percentage of one-month contact lens patients engaging in extreme overwear, doesn’t this make a two-week more compliant than one-month contact lens wearer?

While the authors didn’t consider this point, a study by Sheila Hickson-Curran, B.Sc., M.C.Optom., and colleagues showed that 89% of two-week wearers replaced their contact lenses within one-month compared to just 37% of one-month wearers.3 This comparison not only holds one-month wearers to a rigid 100% compliance standard, but also suggests that patients would be 89% compliant with a monthly replacement goal if told to replace their contact lenses every two weeks. This statistic would be in line with the compliance rate of one-day disposables, which is reported to be as high as 93%.4

Furthermore, Dr. Dumbleton’s 2010 study shows that 19% of two-week wearers and 13% of one-month wearers rarely replace their lenses as recommended.4 This data does give one-month lens wearers a slight edge—but if compliance is our primary goal, it is reasonable to suggest that one-month lens wearers would be more compliant if told to replace lenses every two-weeks. 

If compliance is our ultimate goal, should we consider telling our one-month wearers to replace their lenses every two weeks? This unconventional thinking certainly puts an interesting new spin on the compliance debate.

FDA Approval
It is important to dispel a myth among many clinicians that daily wear contact lenses are FDA approved for two-week or monthly daily wear replacement intervals. The FDA recognizes both of these lens types in the single medical device category: soft contact lenses—frequent replacement. The manufacturer is responsible for setting a recommended replacement interval for a lens material. The manufacturer conducts studies of these lenses in accordance with the interval selected. Because the FDA does not differentiate between one-month and two-week replacement schedules of daily wear contact lenses, is there really a difference between the two modalities?

Clinical Intuition
With so many non-compliant contact lens wearers out there, clinicians have ample opportunity to see non-compliant patients on a daily basis. If brand identifying markings were removed, I think most clinicians would be hard pressed to tell the difference between a two-week and one-month lens at any time interval—between one day and eight weeks of wear. Most clinicians could correctly identify an older lens by the degree of soiling, regardless of whether it is a two-week or one-month contact lens. In order to optimize patient comfort, ocular health and optical performance, we owe it to our patients to do what is best and recommend two-week replacement over one-month. After all, if daily lens replacement is better, how can a monthly contact lens be better than a two-week contact lens?

There are very few independent studies that compare the many aspects of wearing two-week and one-month products beyond the manufacturer suggested replacement schedule. This research would help clinicians better understand the consequences of overwear and help guide the selection of appropriate lens material and replacement schedules. However, until such studies surface, clinical intuition suggests that a fresher lens is better. Hence, two-week replacement lenses are better than their one-month counterparts.

One-Month Wear Schedule
In my practice, I used to fit a lot of two-week replacement lenses until I asked the patients at their follow-up visit how often they actually replaced their lenses. What I learned is that the answer largely depends on how you ask the question. If you ask an open-ended question, you generally get as close to the real answer as possible. What I learned is that most of my patients were stretching their wearing schedule to three to four weeks, and in some cases, it was not completely out of the ordinary to have patients wear these lenses for three months to even one year.

After reviewing the literature and changing my prescribing habits, I found that my patients are more compliant (or at least I like to think so) with one-month replacement vs. a two-week replacement modality.

Corneal infiltrates in contact lens acute red eye (CLARE).
Deriving Patient Compliance
Several studies have recently ordered patient compliance with lens wear and found that patients best adhere to one-day replacement lenses, followed by one-month and lastly, two-week replacement lenses.5,6 In my ideal practice, all soft lens patients would wear daily disposable lenses. However, daily disposable lenses do not come in all parameters—especially for toric and multifocal lenses. Materials and base curves are also limited. At this time, many practitioners are still fitting two-week and monthly replacement contact lenses as their initial lens of choice.

The above-mentioned 2009 study by Dr. Dumbleton is relevant because SH lenses now account for more than 50% of lenses prescribed and are worn worldwide.2,7 In the study, participating practitioners invited 20 patients wearing either daily disposable, two-week or monthly replacement SH lenses to complete an anonymous survey. Questions included lens type, eye care practitioner recommendations for replacement frequency and lens replacement frequency.

The results indicated that patients are most compliant—or least non-compliant—with the recommended replacement frequency when wearing daily disposable lenses, with a 12% non-compliance rate.2 Monthly SH lens wearers were the next compliant group with a 28% non-compliance rate, followed by two-week SH lens wearers as the least compliant group with a 52% non-compliance rate.2

Infiltrative keratitis (IK).
Combating Non-Compliance
When surveyed, the primary reason for non-compliance amongst patients was forgetfulness—forgetting which day to replace their lenses.2 The results suggested that patients wearing two-week replacement lenses were less compliant with the recommended replacement frequency, compared to those patients wearing one-month replacement lenses. Patients find it easier to remember to replace a contact lens once a month than every few weeks.

When finalizing a contact lens fit, I verbally inform patients and document on their written prescription the recommended replacement frequency of their lenses. I also encourage patients to start each month by adding their replacement days to their calendar. Regardless of the recommended lens replacement, eye care practitioners should write out the recommended replacement schedule on the final contact lens prescription. Even if contact lens materials are dispensed to the patient, it is still important for patients to have this information so that it can be easily referenced.

You can also recommend that patients set an alarm on their phone to remind them to replace their lenses on the first of the month. New services, such as Acuminder (, Vistakon), can be set up to send patients a text message or email reminder for lens replacement. This service can be utilized for any lens type with any replacement frequency.

In Dr. Dumbleton’s 2009 study, 50% of patients preferred an electronic method, such as a phone alarms, text messages or e-mail reminders.2 Twenty-six percent of respondents preferred the routine of changing their lenses the same day each week or month. Another 22% said they prefer a countdown on the lens case, while just 14% preferred a paper calendar reminder.2 More compliant patients reported using a calendar or another system to replace their lenses (52%), compared with 28% of non-compliant patients.2

The Financial Breakdown
From a cost standpoint, the cost-per-wear of monthly and two-week replacement spherical lenses is almost identical.8 In an Australian study, the cost-per-wear was determined by adding the cost of professional fees, contact lenses and solutions divided by the number of times the lenses are worn per year.8 The cost-per-wear increased for toric and multifocal lenses—multifocal lenses have the highest cost-per-wear of all lenses.8 If cost is an issue, it would be logical to fit patients with monthly-replacement lenses since the cost is almost the same for both types of lenses and compliance with lens replacement is better for one-month replacement lenses.

If daily disposable lenses are not an option and the choice is between two-week and one-month replacement lenses, the one-month replacement option is clearly the better choice.

We both agree that, regardless of contact lens replacement schedule, it is important patients have a pair of glasses with an updated prescription. It was demonstrated that more compliant patients reported having a pair of glasses with a current prescription compared to non-compliant patients.2 Ninety-two percent of compliant patients had an up-to-date spectacle prescription, compared with 86% of non-compliant patients.2 In our practices, we always recommend a pair of glasses in addition to contact lenses. For first time prescriptions, we often advise patients to get glasses prior to the contact lens fitting.

While we may never achieve 100% compliance with either lens replacement modality, we both agree that taking the time to discuss proper lens wear and replacement with patients is important. Give patients reasons why they should comply with the replacement schedule. We both find it effective to discuss the risk of infection, but, more importantly, patients seem to respond to the warning that continued over-wear of lenses eventually leads to contact lens intolerance in the long term. Advising a patient that they may not be able to wear lenses in the future is a powerful tool to make patients want to comply with the wearing schedule.

And with that, the two-week vs. monthly replacement schedule debate continues on... 

Dr. Smiley is the owner of a two-location private practice in Columbus, Ohio. He serves as a clinical assistant professor at The Ohio State University College of Optometry.Dr. Smiley has served as a clinical investigator for Bausch + Lomb and Blanchard Contact Lens, Inc. He has received speaking honoraria from Alcon and Blanchard Contact Lens, Inc. He has no financial interest in the items discussed.

Dr. Barnett is a senior optometrist at the UC Davis Medical Center in Sacramento, where she performs primary and medical eye examinations and fits contact lenses including specialty contact lenses in addition to teaching optics and contact lenses to ophthalmology residents. Dr. Barnett has received speaking honorariums from Alcon and Allergan. She has no financial interest in the items discussed.

1. Nichols JJ. Contact Lenses 2010. CL Spectrum. 2011 Jan;26(1):24-8.
2. Dumbleton K, Woods C, Jones L, et al. Patient and practitioner compliance with silicone hydrogel and daily disposable lens replacement in the United States. Eye Cont Lens. 2009 Jul;35(4):164-71.
3. Hickson-Curran S, Chalmers RL, Riley C. Patient attitudes and behavior regarding hygiene and replacement of soft contact lenses and storage cases. Cont Lens Anterior Eye. 2011 Jan. [epub ahead of print]
4. Dumbleton K, Richter D, Woods C, et al. Compliance with contact lens replacement in Canada and the United States. Optom Vis Sci. 2010 Feb;87:131-9.
5. Jones L, Dumbleton K, Fonn D, et al. Comfort and compliance with frequent replacement soft contact lenses. Optom Vis Sci. 2002;79:259.
6. Morgan P. Contact lens compliance and reducing the risk of keratitis. Optician. 2007;234:20-5.
7. Morgan PB, Woods C, Jones D, et al. International contact lens prescribing in 2007. CL Spectrum. 2008;23:36-41.
 8. Efron N, Efron SE, Morgan PB, et al. A ‘cost-per-wear’ model based on contact lens replacement frequency. Clin Exp Optom. 2010;93(4):253-60.