SOLUTION SWITCH

Moving From One Care System to MPDS: A Study

By Kenneth Lebow, OD
April 2000

Patients using a variety of care systems switch to a new multi-purpose disinfecting system.

Patients continue to not comply with one or more steps of lens care regimens. One of the more important steps toward proper lens disinfection is daily cleaning, but unfortunately, this aspect of lens care is also the least likely to be appropriately completed. Digital cleaning has been shown to significantly reduce the microbial load that can be transferred from the contact lens onto the eye, as well as reduce lens deposits.

While other steps in the contact lens care regimen have not been demonstrated to replace an active cleaning step, clinicians and manufacturers search for new multi-purpose soft contact lens products that possess higher levels of disinfection ability as a means of minimizing the risk of microbial keratitis brought about by inadequate compliance. Only solutions with this higher level of disinfection activity can be labeled as "disinfecting solutions."

Alcon's new formulation of Opti-Free Express Multi-Purpose Disinfecting Solution, introduced in June, 1999, was the first to receive this labeling. This product incorporates a second antimicrobial agent, Aldox (myristamidopropyl dimethylamine), in addition to the Polyquad antimicrobial found in the previously marketed formulation of Opti-Free Express. This investigation looks at patient acceptance of Opti-Free Express Multi-Purpose Disinfecting Solution under normal use conditions. Investigators switched patients from their current care systems to Opti-Free Express Multi-Purpose Disinfecting Solution.

Investigators were interested in knowing if a one-bottle solution with enhanced disinfection could provide the ocular safety and comfort for the soft lens patients typically encountered in practice.

Methods

A total of 212 subjects, all previously adapted soft contact lens wearers, were enrolled by 10 investigators. There were no restrictions regarding patient age, sex, occupation or reason for using contact lenses. All subjects were seen at baseline, and for follow-up evaluation after one and three months of wear. At the preliminary visit, after providing informed consent and undergoing slit lamp examination, each subject completed a questionnaire regarding their symptoms of burning or stinging, lens dryness and lens awareness with their pre-study lenses. The rating scale used for these subjective ratings was 0 = no symptoms, 1 = trace, 2 = mild, 3 = moderate and 4 = severe.

Patients then received a new pair of contact lenses of the same type and parameters as their pre-study contact lenses, along with Opti-Free Express Multi-Purpose Disinfecting Solution. Each subject was instructed to use the product in accordance with manufacturer's guidelines, exclusive of any separate surfactant cleaner or enzyme removal product.

At both the one-month and three-month follow-up visits, after recording average wear time and visual acuity, the investigator performed a slit lamp examination, including visual quantification of lens deposits, using a modified Rudko scale. Slit lamp findings for edema, injection, staining, neovascularization and tarsal abnormalities were recorded using a 0 to 4 scale (0 = none, 1 = trace, 2 = mild, 3 = moderate, 4 = severe).

Each subject was asked to complete a questionnaire reporting subjective symptoms of burning or stinging, lens dryness and lens awareness with their study lenses, using the same 0 to 4 scale outlined above. Additionally, each participant completed a questionnaire on contact lens comfort and satisfaction with contact lens wearing time, using a 1 to 10 scale, where 1 = extremely dissatisfied, and 10 = extremely satisfied.

Results

Of the 212 subjects enrolled, 197 (98 percent) completed this three-month evaluation. See Table 1 for the prior lens care system for the 197 completing subjects. Of the 15 discontinued patients, 11 were lost to follow-up, three terminated their involvement due to subjective symptoms reported at the one-month visit and one discontinued after four days of wear due to a solution-related sensitivity reaction rated as grade 2 (mild).

The average reported wear time was 14.1 hours per day at the one-month visit, and 14.0 hours per day at the three-month visit, showing little difference from the 13.7 hours reported at baseline. Slit lamp findings for the baseline, one-month and three-month follow-up visits for the 197 subjects completing all three visits are summarized in Figure 1. All findings were low and did not differ from baseline. Contact lens deposits were visually graded as none or minimal for 98 percent of subjects at both the one- and three-month follow-up visits.

Self-reported symptoms of burning or stinging, contact lens dryness and contact lens awareness (averaged for right and left eyes), both pre-study and after one and three months of use of the new solution, is summarized in Figure 2. The average pre-study response on the subject questionnaire regarding contact lens comfort and satisfaction with contact lens wear time was 8.56 and 8.68 respectively, using the previously described 1 to 10 scale. By comparison, the average comfort ratings were 8.56 and 8.62 at the one- and three-month follow-up visits. Satisfaction with contact lens wearing time was, on average, 8.67 at the one-month visit and 8.59 at the three-month visit, essentially unchanged from baseline values.

Discussion

While enhanced disinfection is an extremely desirable feature when developing a new soft contact lens care product, any improvement in antimicrobial effectiveness cannot be at the expense of patient comfort or solution biocompatibility. This three-month investigation was intended to discover the patient acceptance of Opti-Free Express Multi-Purpose Disinfecting Solution. The patients used the product with the normal instructions given to patients in the office, rather than the stricter controls used in formal clinical studies. Over the period of this study, only one of the initially enrolled 212 subjects was discontinued due to a solution-related sensitivity reaction, and only three (1.4 percent) elected to terminate their involvement because of subjective symptoms.

Slit lamp findings remained, on average, at baseline values throughout the study, with well over 95 percent of all findings being graded 0 (none) or 1 (trace). Of potentially even greater significance, subjectively-reported symptoms of burning or stinging, lens dryness and lens awareness with the Opti-Free Express Multi-Purpose Disinfecting Solution did not differ significantly from those experienced with prior multi-purpose or peroxide-based systems, despite its advanced level of disinfection ability.

The overall patient acceptance of this new product is also evidenced by the high subjective ratings for overall contact lens comfort (8.62 on a scale of 1 to 10), as well as satisfaction with contact lens wear time (8.59 on a scale of 1 to 10) at the three-month follow-up visit. By separately considering contact lens wear time, this investigation sought to ensure the ability of participants to maintain a full day of contact lens wear, averaging over 14 hours, without the development of significant subjective symptoms. When asked at the study termination to judge on a 1 to 10 scale, with 10 = definitely yes and 1 = definitely no, their likelihood of purchasing Opti-Free Express Multi-Purpose Disinfecting Solution, 82 percent of participants gave a response of eight or greater, suggesting a strong overall desire to continue with this new care system.

Based on the high level of patient acceptance and minimal evidence of solution-related sensitivity reactions, the enhanced disinfection of Opti-Free Express Multi-Purpose Disinfecting Solution does not affect overall patient contact lens comfort or overall contact lens wear time.

This study was sponsored by Alcon Laboratories.

Investigators: Joseph Barr, O.D., M.S.; Bobby Christensen, O.D.; Michael DePaolis, O.D.; Burt Dubow, O.D.; Arthur Epstein, O.D.; Julie Eilers-Jackson, O.D.; Kenneth Lebow, O.D.; Brian Pall, O.D.; John Schachet, O.D.; Joseph Shovlin, O.D. and Walter West, O.D.