Comfort Differences Between Multi-purpose Solutions
Patients assessed contact lens comfort while using one of two multi-purpose solutions.
Steve Larsen, OD, Craig Smith, MD, James Mathis, OD, Philip B. Smith, OD, Cheryl Bronner, OD, Robert Maynard, OD, Frank Fontana, OD, and Rex Ghormley, OD
Multi-purpose solutions now represent over 90 percent of contact lens disinfecting solutions sold. Although there are many care product choices, clinicians appear to have strong preferences. Ninety percent of the starter kits dispensed to new contact lens patients are either No Rub Opti-Free Express Multi-Purpose Disinfecting Solution (Alcon Laboratories, Inc.) or ReNu MultiPlus Multi-Purpose Solution (Bausch & Lomb, Inc.).
Because comfort issues concern both clinician and patient, it is important to understand what, if any, differences exist between products. Specifically, which of these two leading multi-purpose care products offers better comfort overall and which of the two performs better for patients who expressly complain of lens-related dryness? An improvement in lens comfort should translate into greater patient satisfaction, decreased contact lens dropout and greater patient retention.
We recently completed a study involving 195 patients. This study was initially designed to demonstrate to the FDA that Opti-Free Express provides good cleaning and clinical performance when the post-soak rinse is eliminated. Renu MultiPlus was the comparison product. In this study, our results confirmed that No Rub Opti-Free Express significantly out-cleaned ReNu MultiPlus, even though MultiPlus was used with a rub, rinse and soak while Opti-Free Express was used with a rinse and soak only.
More interesting to the authors, the results of this study demonstrated a marked comfort advantage for No Rub Opti-Free Express when compared to ReNu MultiPlus. Increased comfort with Opti-Free Express was sustained for the overall patient group as well as for patients who described their eyes as "dry" when entering the study. We had believed, as we suspect many contact lens fitters believe, that all multi-purpose solutions perform about the same in terms of comfort. Our results proved this to be untrue.
This 30-day study was randomized and double-masked, with the identity of the products dispensed kept from both investigators and patients. The authors enrolled patients successfully wearing soft contact lenses on a daily-wear schedule at eight clinical sites. Four sites fit patients with new Group I lenses (Optima FW polymacon, 38.6 percent water, Bausch & Lomb), and four sites fit patients with new Group IV lenses (Surevue, etafilcon A, 58 percent water, Vistakon). Test lenses were worn on a daily-wear basis for at least eight hours per day for the duration of the study without scheduled replacement (lenses were replaced only as needed due to loss, damage or as deemed necessary by the investigator). The pre-study lens care regimen generally represented the U.S. marketplace with the majority of patients previously using either Opti-Free Express or ReNu MultiPlus.
Patients at each site were randomly assigned to two test groups: No Rub Opti-Free Express (N=96) or ReNu MultiPlus (N=99). All patients used their assigned MPS for daily care of lenses following the test regimen (Table 1) and received appropriate rewetting drops to use as needed or desired. All products were delivered in white "study" labeling to mask the product identity from the patient.
During the initial study visit, patients completed a questionnaire to assess comfort and vision with their pre-study regimen. Subjects used the same questionnaire to describe the performance of their assigned study regimen on Days 14 and 30. These questionnaires used a five-point Likert scale where 1=strongly disagree, 2=disagree, 3=undecided, 4=agree and 5= strongly agree (Table 2).
Visual acuity and lens wearing time were recorded and slit lamp examinations were performed at each visit (Days 0, 14 and 30). At Day 30, to evaluate cleaning, all Group IV lenses were collected and analyzed by high performance liquid chromatography (HPLC), a test to quantify residual lens lysozyme. All Alcon laboratory personnel were masked as to the treatment regimens used with the lenses.
When completing the Likert questionnaire after 14 and 30 days of MPS use, most patients described their lenses as comfortable to wear. However, questionnaire results showed the No Rub Opti-Free regimen was superior to ReNu MultiPlus in providing greater lens comfort. By the end of the study, patients assigned to the Opti-Free Express group regardless of lens polymer had higher agreement with the statements "this solution gives my lenses long-lasting comfort," "my lenses feel comfortable at the end of the lens wearing day," and "my lenses stay comfortable longer during the day" (p< 0.05, Fisher's Exact Test).
The comfort differences were especially evident with patients wearing Group IV high water lenses (Table 3). Upon lens insertion, both regimens performed well, with over 89 percent of patients in each lens care group reporting that lenses "felt clean when I put them on in the morning" throughout the study. However, agreement with the statement "my lenses feel comfortable at the end of the lens wearing day" increased with the Opti-Free Express regimen (+6.5 percent to 71.7 percent) as the study progressed but noticeably decreased among patients assigned to ReNu MultiPlus (-12.1 percent to 45.9 percent). This is of clinical importance because comfort typically decreases as the wearing day goes on and is a common reason patients drop out of contact lens wear.
Patients who described themselves as having dry eyes represented 29 percent of patients in the study a proportion similar to most studies of lens wearers in the United States. Regardless of the lens brand they were wearing, the self-diagnosed dry eye patients derived a substantially greater benefit when assigned use of Opti-Free Express. More of the patients using Opti-Free Express agreed or strongly agreed with the statements "This solution gives my lenses long-lasting comfort," "Lens comfort lasts all day with this solution," and "My lenses feel clean all day long when I use this solution" compared to MultiPlus (p < 0.05; see Figure 1).
Objectively, the rinse/soak No Rub Opti-Free Express regimen was statistically superior to the rub/rinse/soak ReNu MultiPlus regimen in maintaining lens cleanliness as measured by residual lens lysozyme on Group IV lenses (average 700 micrograms with Opti-Free Express vs. 1120 micrograms with ReNu MultiPlus (see Figure 2).
No clinically relevant slit-lamp findings were observed in either treatment group during the study and there were no serious adverse events. Measures of visual acuity and lens wearing time were clinically acceptable and comparable for both the No Rub Opti-Free Express and ReNu MultiPlus groups.
In the vision care community, perceptions about MPS products have sometimes obscured reality. One reason is the lack of adequate clinically relevant studies. Common care product misperceptions are:
- All MPS perform the same and offer the same patient benefits.
- MPS use exacerbates lens dryness, potentially leading to increased patient discomfort.
Certainly, not all MPS are formulated in the same way. No Rub Opti-Free Express incorporates Polyquad (polyquaternium 1) and Aldox (myristamidopropyl dimethylamine) as antimicrobial agents and citrate, Tetronic 1304 and AMP-95 as cleaners. ReNu MultiPlus incorporates polyaminopropyl biguanide (PHMB) as an anti-microbial agent and poloxamine and Hydranate as cleaners. With formulations that are very different, there is no reason to assume that clinical performance would not be different.
In the present study, the two leading brands of MPS were compared directly. The products tested were masked to prevent identification by both patients and investigators. The study design randomly assigned experienced lens wearers to these two popular systems. To further ensure study integrity, a parallel group design was used instead of a contralateral eye design because comfort associated with a lens or solution for one eye can be easily confused with the contralateral eye.
While both regimens were acceptable and no significant ocular slit lamp findings or adverse events occurred, many substantial differences were observed. The most striking findings involved patient perception of comfort. More contact lens wearers using No Rub Opti-Free than those using ReNu agreed that the regimen provided greater:
- Sustained comfort
- End of the day comfort
This is the major finding of the study and has implications for practitioners seeking optimal lens performance. Recently a correlation has been suggested between all MPS use and lens dryness. The present study challenges this overly broad assertion, demonstrating that use of Opti-Free Express does not promote lens dryness.
There are several likely explanations for why Opti-Free promotes patient comfort more effectively than ReNu MultiPlus. First, Tetronic 1304 in the Opti-Free Express formula acts as a surface-active wetting agent as well as a surfactant, helping to attract and hold moisture to the hydrophobic sites on the lens surface. Alcon studies have shown Tetronic 1304 to persist on the lens throughout the lens wearing day for as long as 24 hours.
A clean lens is also a more comfortable lens. The Opti-Free Express formula offers better cleaning for Group IV lenses, and even after 30 days, patients can tell the difference. Group IV lenses have been shown to collect lysozyme deposits more than other types of lenses. Significantly less residual lysozyme was detected on Group IV lenses of patients using No Rub Opti-Free compared to lenses of patients in the ReNu MultiPlus group over a 36 percent difference.
Finally, the original objective of the study was accomplished: the results demonstrated that No Rub Opti-Free Express cleans, disinfects and provides safe and comfortable lens wear when both the rub and after soaking rinse were eliminated.
Although patients often appear to be satisfied with whatever care solution they purchase, this study showed that not all multi-purpose solutions perform equally in providing patient comfort.
Patients preferred No Rub Opti-Free Express to ReNu MultiPlus with respect to comfort throughout the day and at the end of the day. This was true for the overall patient population and, particularly, for patients who describe their eyes as dry. Opti-Free Express also removed more protein from lenses that did ReNu MultiPlus even when ReNu MultiPlus was used with a pre-soaking rubbing step and Opti-Free Express was not.
These results demonstrate that Opti-Free Express provides greater lens wearing comfort than ReNu MultiPlus, especially later in the day. An improvement in lens comfort should translate into greater patient satisfaction, decreased contact lens dropout and greater patient retention.
The authors wish to express their appreciation to Renee Garofalo, Tolgar Bayraktaroglu, Jackie Barry, Leslie Napier, Sue Faro, Patricia Meuse and Jerry Stein of Alcon Laboratories for their technical assistance.
To receive references via fax, call (800) 239-4684 and request document #88. (Have a fax number ready.)
Dr. Larsen has two private practices in the San Diego area, is an active board member at Pacific Laser Eye Center in La Jolla, and has been an investigator in over 20 research projects.
Dr. Craig Smith, a general ophthalmologist, specializes in treating anterior segment pathology in Dallas. He conducts clinical studies and has over twenty years of experience in fitting contact lenses.
Dr. Mathis is in private practice in Forth Worth, TX, and serves as a consultant to Alcon Laboratories.
Dr. Philip Smith is in practice in San Diego, a past president of the San Diego Optometric Association and the California Optometric Association.
Dr. Bronner is in a small group practice in Highlands Ranch, CO.
Dr. Maynard is in private practice in Arizona, a past president of the Arizona Optometric Association and a charter member of the Contact Lens Section of the AOA.
Dr. Fontanta specialized in contact lenses in St. Louis, an adjunt assistant instructor of ophthalmology at Washington University School of Medicine and a co-founder of the AOA Contact Lens Section.
Dr. Ghormley is in private practice in St. Louis, MO. He is a past president of the American Academy of Optometry and a Diplomate of its Cornea & Contact Lens Section. He is also the team optometrist for the St. Louis Rams (NFL) and the St. Louis Blues (NHL).