Hybrid Lenses and Lens Care Systems
This study examined hybrid lens wearers' preferences and compatibility with different lens care systems.
By Robert Davis, OD, FAAO, & S. Barry Eiden, OD, FAAO
Dr. Davis is co-founder of Eye-Vis Eye and Vision Research Institute. He practices in a suburb outside Chicago. He is an advisor or consultant to CooperVision and SynergEyes, has received research funds from CooperVision and B+L, and has a proprietary interest in SpecialEyes and Alternative Vision Solutions
Dr. Eiden, co-founder of Eye-Vis Eye and Vision Research Institute, is president of a private group practice in Illinois. He has a financial interest in Alternative Vision Solutions, LLC, is a consultant or advisor to Ciba Vision, CooperVision, SynergEyes, Alcon, and SpecialEyes, and has received research funds from Vistakon, CooperVision, and B+L.
A successful contact lens fit requires the appropriate selection of lens material, design, and lens care system. Inappropriate selection of lens care system can result in numerous undesirable objective and subjective consequences as documented by Weissman (2004) including, among others: hyperemia, papillary hypertrophy, corneal staining, corneal infiltrates, symptoms of dryness and burning, and other indicators of poor lens wearing comfort.
The SynergEyes (SynergEyes, Inc.) hybrid contact lens received FDA approval in 2005. It is comprised of a GP center fabricated from Paragon HDS (Paragon Vision Sciences) material along with a hydrogel soft skirt fabricated from a 27-percent water content polyHEMA material. The goal of hybrid lens fitting is to achieve visual performance similar to that of a GP lens while providing comfort closer to that of a soft lens. Compatibility of the SynergEyes hybrid lens with an associated lens care system is critical to overall success with SynergEyes lens wear.
This study was developed to establish a family of lens care systems that could optimally be used with the SynergEyes hybrid lens. The purpose of this clinical study was to evaluate the clinical performance of the SynergEyes A lens design when used for prolonged periods of time with various lens care systems.
We performed a multicenter clinical trial at five sites in accordance with the tenets provided by the Declaration of Helsinki and in adherence to the guidelines of the IRB reviewing this investigational protocol. Each investigator obtained informed consent from patients before entering into the investigation. The study design was an investigator-masked, randomized, two-week crossover investigation. Thirty-one subjects were enrolled in the study. All subjects were adapted SynergEyes A hybrid lens wearers.
We evaluated four lens care systems: Clear Care (Ciba Vision), ReNu MultiPlus (Bausch + Lomb), Complete (Abbott Medical Optics), and Aquify (Ciba). Subjects were randomly assigned to one of the four lens care systems in random succession and were dispensed a new pair of SynergEyes A lenses with each change in lens care system. Subjects would wear the lenses and use the specified lens care system for two weeks. Each subject was entered into the clinical protocol after they satisfied the inclusion/ exclusion criteria. Only subjects who were current wearers of SynergEyes A lenses on a daily wear schedule were selected to enter the investigation. Subjects were required to have a refractive astigmatism of 6.00D and be older than 18. Subjects had to be willing to undergo refitting with new SynergEyes A contact lenses provided by SynergEyes, to wear only the study lenses during the study comparison trial period, and to maintain a wearing schedule of a minimum of six hours, at least six days a week.
Subjects had normal healthy eyes with no evidence of severe tear insufficiency, lid infection, or structural abnormality; a conjunctiva free of infection; a cornea clear and free of edema, scars, staining, vascularization, infiltrates, or opacities when examined by slit lamp biomicroscopy; and no evidence of iritis or uveitis. Subjects were in good general health with no active internal or external disease as well as no history of allergies that would contraindicate solution use and/or "normal" lens wear. Subjects were not taking or anticipating taking drugs that might alter normal ocular physiology (eye drops containing ephedrine, phenylephrine, etc.), thereby affecting or interfering with successful lens wear.
Subjects had to attend all scheduled office visits. No subjects who were pregnant, anticipating pregnancy, or lactating were entered into the clinical investigation. Subjects using any topical ocular medication such as steroids, anti-infectives, or autonomic drugs, or who were taking any systemic medications that the investigator believed would interfere with the study, were not entered into the study.
Each investigator collected demographic information and performed a baseline slit lamp evaluation as well as routine baseline evaluation procedures for each subject. At the dispensing visit, each subject applied the study lenses and was evaluated for movement, push-up test, position, lag, pre-lens tear film (PLTF) quality, and Snellen visual acuity. Subjects were asked to report on lens handling, lens comfort, and visual clarity. Subsequent measurements were taken at the initial visit and after two hours of lens wear at the exit visit for all four lens care systems. After lens removal, investigators performed an ocular examination of the anterior segment using the slit lamp biomicroscope.
Subjects who experienced an adverse reaction to a lens care system were required to have slit lamp findings returned to baseline in what we defined as a washout procedure before continuing to the next care system. New lenses were dispensed so as not to bias the next care system data.
A number of statistical tests were performed to detect any significant differences in average clinical performance measured among the care systems. Statistical hypothesis tests were conducted on subsets of the study data; clinical and subjective measures were recorded at the initial visit and after two hours of lens wear at the exit visit. All statistical hypothesis tests were conducted at a 95-percent confidence level. We used the paired t-test to detect any statistically significant differences in the average lens movement, position, lag, PLTF, ease of handling, and comfort ratings. For those measures not meeting the assumptions of the paired t-test, the Wilcoxon matched-pairs signed-ranks test was performed. The Wilcoxon test was also used to test for significant differences in slit lamp findings after lenses were removed. We used the McNemar test for related samples to detect statistically significant differences in the acceptability of comfort and handling.
At the end of the study, subjects were asked to make a forced-choice decision in terms of their preferred lens care system for comfort, visual clarity, lens handling, and the best solution regimen.
Outcomes from the subjective "comfort questionnaire" (Table 1) indicated no significant differences among the solutions tested with the exception of "overall physical comfort" and symptoms of "eye feeling itchy." Specifically, while using the ReNu MultiPlus system, subjects found lenses to be significantly less comfortable than while using Clear Care (p=0.005) or while using Complete (p=0.03). Also, while using ReNu MultiPlus, subjects reported that symptoms of their eyes feeling itchy were significantly more likely than while using Complete (p=0.03).
Results from the subjective "vision questionnaire" explored responses to specific questions relating to the subject's visual performance while wearing SynergEyes A lenses with the care systems evaluated. Table 2 shows that there were no significant differences among the tested lens care systems for any questions in the vision questionnaire (criteria p=0.05 or greater).
A series of four subjective "scales" were given to subjects following the use of the SynergEyes A lenses along with each of the tested lens care systems (Table 3). The scales allowed subjects to rate subjective symptoms and performance on a 1 to 10 response scale. Areas evaluated in the subjective scales were comfort rating, visual clarity, lens handling rating, and dryness rating. The comfort rating scale showed a significant difference overall among lens care systems tested (p=0.04). Specifically, Clear Care was rated as significantly more comfortable compared to ReNu MultiPlus (right eye p=0.006, left eye p=0.002) and Complete was rated as significantly more comfortable compared to ReNu MultiPlus (left eye only p=0.02). The vision clarity rating scale showed a significant difference overall among lens care systems tested (p=0.04). Specifically, Clear Care was associated with significantly better visual clarity of all solutions tested (ReNu MultiPlus p=0.008, Aquify p=0.01, and Complete p=0.02). There was no significant difference among the care systems tested in regard to the handling or dryness rating scales.
Subjects were asked to determine the acceptability of comfort and handling with each of the care systems tested (Table 4). Clear Care was the only lens care system that had a 100-percent handling and comfort acceptability. Aquify had a 100-percent handling acceptability.
Biomicroscopic (slit lamp) data was analyzed following the use of the lens care systems tested (Table 5). Lens fitting characteristics and anterior segment physical findings were graded at each visit. Lens movement in primary gaze and upgaze was estimated in millimeters of movement with blink. For primary gaze, there was significantly more movement with blink with lenses used with Clear Care compared to Complete (right eye p=0.001, left eye p=0.0043). There was significantly more movement with blink with ReNu MultiPlus compared to Complete (right eye only p=0.02) and with Aquify compared to Complete (left eye only p=0.003). While using Complete, lenses had significantly less movement with blink in primary gaze compared to the other three lens care systems tested (p=0.004 versus Clear Care, p=0.003 versus Aquify, and p=0.02 versus ReNu MultiPlus). While using Complete, lenses had significantly less movement with blink in upgaze than they did with Clear Care (p=0.0001), Aquify (p=0.009), and ReNu MultiPlus (p=0.02). There were no other significant differences found in biomicroscopic findings among the care systems tested.
At the termination of the study, subjects were asked to make a forced-choice decision of the lens care system that they would prefer to continue using (Figure 1). Aquify was selected as the lens care system of choice significantly more frequently than were all other care systems tested (p=0.01). ReNu MultiPlus was the lens care system of choice significantly less frequently compared to all other care systems tested (p=0.02).
Figure 1. Forced choice for the care system preferred.
Summary and Discussion
This study evaluated the performance of four commonly used lens care systems when utilized with the SynergEyes A hybrid lens. An array of subjective and objective measures were evaluated and compared among the care systems tested. A prior internal study conducted by SynergEyes, Inc. evaluated the performance of two other popular lens care systems (Opti-Free Express and Opti-Free Replenish [Alcon]) when used with the SynergEyes A lens. Those studies rated limited parameters and were evaluated following very limited exposure and wearing times with the SynergEyes A lens. Further clinical investigation needs to be performed to properly evaluate the use of these care systems with SynergEyes lenses. Our current study of lens care system compatibility and preference with the SynergEyes lens evaluated performance following prolonged exposure and use of each of the care systems tested and looked at multiple variables.
These results illustrate the importance of selecting the appropriate lens care system to create the opportunity for the greatest lens comfort, optimal lens movement, acceptable lens handling, and the best vision clarity.
Clear Care was found to be significantly more comfortable in comparison to ReNu MultiPlus and was found to provide better vision clarity compared to the three other contact lens care systems tested. Additionally, Clear Care was found to provide significantly more lens movement with blink compared to Complete in primary gaze and versus Aquify in upgaze. Clear Care was the only system rated by subjects as 100-percent acceptable for both comfort and handling.
ReNu MultiPlus seemed to fare the worst with the SynergEyes contact lens of all four contact lens care systems tested. It was subjectively rated as significantly less comfortable compared to Clear Care and Complete and was rated as significantly more likely to cause eye itching in comparison to Complete. ReNu MultiPlus was also rated last in the forced choice of preferred contact lens care system by subjects at the end of the study (by only 9.7 percent of the subjects).
Aquify was found to be acceptable in handling by 100 percent of subjects. It also was found to be associated with significantly more movement in upgaze versus Complete. Most interestingly, Aquify was selected as the contact lens care system of choice most frequently (41.9 percent of subjects) in the forced choice of preferred contact lens care system at the end of the study. Based upon numerous subjective and objective individual measures in this study in which Clear Care was rated highest, we might have predicted that Clear Care would have been most frequently selected as the contact lens care system of choice. However, other factors not measured by this study (such as convenience of use) may have contributed to Aquify's status as contact lens care system of choice by our subjects at the end of the study.
In summary, based on the outcomes of this study, all four lens care systems tested in this study should be considered acceptable for use with SynergEyes contact lenses. However, both Clear Care and Aquify would be considered as contact lens care systems of choice based on their overall superior performance in this study. Further investigation comparing the performance of Opti-Free Express and Opti-Free Replenish to Clear Care and Aquify would be helpful in determining what available lens care systems are preferred for use with SynergEyes contact lenses.
Based on the outcomes of this study the four available contact lens care systems tested (Clear Care, Aquify, Complete, ReNu MultiPlus) can be considered compatible with SynergEyes contact lenses. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #175.