MPS COMPARISON
A
Comparison of Two Lens Care Formulations
This
study shows that a newer solution may improve comfort, wear time and visual
acuity for some patients.
By Robert P. Wooldridge, OD, Howard I. Schenker,
MD, Lee E. Rigel, OD, Kenji Hamada, OD, and S. Barry Eiden, OD
|
|
|
Figure 1. Group I and Group IV lens wearers
using Opti-Free Replenish had consistently fewer eyes with grade 2 or higher corneal
staining.
|
The
next generation of lens care solutions has the goal of enhancing patient comfort
and safety. Manufacturers are designing new solutions that condition lenses and
keep them clean and comfortable longer.
Latest Arrival
The newest solution to incorporate an integrated
conditioning system is Alcon Laboratories' Opti-Free Replenish Multi-Purpose Disinfecting
Solution (MPDS), which incorporates the same patented disinfecting system —
Polyquad 0.001% and Aldox 0.0005% — as the company's Opti-Free Express formula.
Replenish also continues to use citrate as a cleaning agent.
TearGlyde, the new proprietary conditioning
system in Opti-Free Replenish, is composed of the surface active agents Tetronic
1304 and C9-ED3A (nonanoyl ethylenediaminetriacetic acid). According to Alcon, this
new system reconditions the lens surface during each overnight soak, positively
affecting wettability (the attraction between the lens surface and the tears). Increasing
the affinity of tears to lens surfaces should improve comfort, increase visual performance
and increase overall patient satisfaction. C9-ED3A also helps to prevent calcium
build-up on lenses and to enhance cleaning, replacing EDTA in the formulation. Opti-Free
Replenish also incorporates propylene glycol, a demulcent, to enhance wetting, lubrication
and comfort. Propylene glycol helps bind water inside the lens and is commonly used
in artificial tear products.
To be useful, new products must offer
improvements upon currently available products. The purpose of this 90-day clinical
study was to evaluate the safety and efficacy of Opti-Free Replenish MPDS compared
to ReNu MultiPlus MPS No Rub Formula.
|
 |
|
Figure 2. Group IV wearers showed better tarsal
conjunctival scores by day 90 with Opti-Free Replenish. |
Statistical Methods
We used analysis of variance to test for differences
between treatment regimens in mean residual lens lysozyme deposits on Group IV lenses
worn by subjects. We used a repeated measures analysis of variance to compare regimen
differences for continuous variables (Likert questionnaire items and average/uncomfortable
lens wearing time). To assess differences between regimens by lens group for categorical
variables (Rudko and lens replacement incidence), we performed a Chi-Square test
of independence. To assess differences in distribution of the corrected visual acuity
and the tarsal conjunctiva slit lamp findings, we used a Cochran-Mantel-Haenzel
rank score test, and we performed a two-sample t-test on residual lens lysozyme
levels from Group I lenses.
Study Methods
Twelve optometry and ophthalmology practices evaluated
Opti-Free Replenish MPDS in a three-month, double-masked, IRB approved clinical
study. Before participating in the study, investigators obtained consent and then
fit experienced soft contact lens wearers who had normal eyes with either Optima
38 lenses (Bausch & Lomb — Group I, low-water, non-ionic material) or Hydrasoft
EW lenses (CooperVision — Group IV, high-water, ionic material). Patients who
could not successfully adapt to the new lenses after seven days were not enrolled
in the study. Investigators enrolled all other patients (day 0) and fit them with
a new pair of Optima 38 or Hydrasoft EW lenses to be worn without replacement for
the next three months. Study participants were representative of the general lens
wearing population in age and gender.
Investigational
site staff members responsible for dispensing the solutions and instructions randomized
125 study participants to Opti-Free Replenish MPDS and 127 participants to the control,
ReNu MultiPlus MPS. To mask their identity, the staff members packaged the solutions
in plain white bottles with non-branded, "investigational use only" labels. The
evaluating doctors remained unaware throughout the study of which product each patient
had received. Investigators provided rewetting drops, either Opti-Free Express Rewetting
Drops or ReNu Rewetting Drops, also in masked bottles, for use at the patients'
option. At day 0, patients completed a self-administered Likert-style questionnaire
that used a five-point scale (strongly disagree to strongly agree) to describe their
baseline comfort. Investigators performed baseline slit lamp and visual acuity measurements.
|
|
|
Figure 3. Significantly fewer lenses required
replacement for patients using Opti-Free Replenish.
|
At follow-up visits on days
14, 30, 60 and 90, patients completed a questionnaire using a five-point Likert-style
scale to describe comfort over the respective previous three days. Investigators
scheduled follow-up visits at approximately the same time of day and instructed
patients to wear their lenses from two to four hours before the examination. This
stipulation decreases variability in signs and symptoms that occur over the course
of the lens wearing day and maximizes the ability to detect corneal staining with
some lens/solution combinations.
The investigating doctors asked the
patients about wear time and compliance with the test regimen; evaluated corrected
visual acuity; conducted a slit lamp examination that included corneal staining,
edema, neovascularization, injection and infiltrates; and classified the tarsal
conjunctiva using the Lofstrom-Kruse scale. They graded corneal staining using a
0-4 scale where 0 = none, 1= trace, 2 = mild, 3 = moderate and 4 = severe. Investigators
also evaluated lens cleanliness (modified Rudko) at each visit.
When patients exited the study, investigators
placed their study lenses in new screw-top cases and shipped them overnight to the
sponsor for high performance liquid chromatography (HPLC) analysis to determine
the amount of lysozyme in the lenses. We masked the laboratory workers testing the
lenses as to which solutions had been used with the lenses.
Results
|
 |
|
Figure 4. Differences in uncomfortable wear
time favoring Opti-Free Replenish became significant at day 30 and showed numerical
differences at day 60 and day 90. |
Safety Safety results for Opti-Free
Replenish MPDS were consistent with results historically seen in studies with Opti-Free
Express. Both Opti-Free Replenish and ReNu MultiPlus were safe and well-tolerated.
Two patients (1.6 percent) using Opti-Free Replenish and eight (6.3 percent) using
ReNu MultiPlus experienced ocular complications related to the solutions, primarily
discomfort. Five patients using ReNu MultiPlus were discontinued from the study
for reasons relating to the test solutions (ocular discomfort, dry eye, hyperemia,
conjunctival papillae and corneal staining). None of the patients using Opti-Free
Replenish were discontinued for solution-related reasons.
Injection
and corneal staining were the only slit lamp findings reported as clinically significant
complications during the study and were observed in two (1.6 percent) patients using
Opti-Free Replenish and five (3.9 percent) patients using ReNu MultiPlus. In addition,
Group I and Group IV lens wearers using Opti-Free Replenish had consistently fewer
eyes with grade 2 or higher corneal staining compared to ReNu MultiPlus users at
all follow up visits (Figure 1). Group IV lens wearers showed better tarsal conjunctival
scores by day 90 with Opti-Free Replenish than with ReNu MultiPlus (Figure 2). At
day 90, 88.1 percent of Group IV lens wearers using Opti-Free Replenish had tarsal
grades of 2 or lower compared with 68.9 percent of those using ReNu MultiPlus. Investigators
observed no other clinically relevant differences in slit lamp findings between
regimens during the study.
Lens Replacements
We selected Hydrasoft EW and Optima 38 contact lenses for this study because they
can more likely withstand the FDA's requirement of daily handling for 90 days without
replacement. In this regard, 84 percent of the lens wearers using Opti-Free Replenish
and 73 percent of the lens wearers using ReNu MultiPlus completed the study with
both original contact lenses intact. As Figure 3 shows, significantly fewer lenses
required replacement for patients using Opti-Free Replenish MPDS (16 percent) than
for patients using ReNu MultiPlus (26.8 percent), p=0.037. Significantly fewer Optima
38 lenses (Group I) required replacement when subjects used Opti-Free Replenish
(8.3 percent) than when patients used ReNu MultiPlus (25 percent), p=0.01. There
were no significant differences between solutions for Group IV contact lens replacements.
|
|
|
Figure 5. Group IV lenses cleaned with Opti-Free
Replenish had significantly less lysozyme.
|
Wearing Time and Comfort
At each visit, investigators asked study patients on average how many hours they
had worn their contact lenses each day and how many hours the lenses had been uncomfortable.
The mean reported wearing time for each lens type and solution group was maintained
at 13 to 14 hours throughout the study. The average uncomfortable wearing time at
the baseline examination ranged from 1 to 1.4 hours. Opti-Free Replenish was more
successful than was ReNu MultiPlus in keeping average uncomfortable lens wearing
time stable with baseline for Group I lens wearers. Differences in uncomfortable
wear time favoring Opti-Free Replenish became significant at day 30 (p= 0.03) and
showed numerical differences at day 60 and day 90 (Figure 4). We found no significant
difference in average uncomfortable wear time with Group IV lenses.
A
review of the Likert questionnaires that patients used to describe their ocular
comfort at each visit showed that comfort and satisfaction remained at high levels
throughout the study with both solutions. We found the most consistent difference
with the statement "This solution is gentle on my eyes," for which patients wearing
Group IV lenses rated Opti-Free Replenish significantly higher than ReNu MultiPlus
overall (p<0.01) and at days 60 (p<0.03) and 90 (p<0.01).
Responses to the statement "When
I use this solution my lenses feel moist" were significantly more favorable overall
with the Opti-Free Replenish regimen compared to the ReNu MultiPlus regimen (p=0.03)
and at day 60 (p<0.01) among Group IV lens wearers. When we combined Group I
and Group IV contact lenses across all visits, mean responses by patients using
Opti-Free Replenish were significantly more favorable for the statements "When I
use this solution my lenses feel moist" (p=0.04) and "This solution is gentle on
my eyes" (p=0.04). Responses to all other Likert statements showed no significant
difference between solutions.
Visual Acuity and Lens Cleanliness
Opti-Free Replenish and ReNu MultiPlus successfully maintained corrected visual
acuity with baseline values throughout the 90-day study. We found no differences
between Opti-Free Replenish and ReNu MultiPlus with Group I lenses. With Group IV
lenses, we observed a greater prevalence of worsening in visual acuity from baseline
for ReNu MultiPlus at day 14 (p=0.02), with numerical differences noted at days
30, 60 and 90.
Like its predecessor Opti-Free Express,
Opti-Free Replenish was highly effective at keeping lenses clean throughout the
90-day study as measured by both objective HPLC measurement of protein in the lenses
at day 90 and subjective Rudko evaluations conducted by the investigators. HPLC
analysis measures the amount of lysozyme, the primary protein in tears, in a contact
lens. Opti-Free Replenish proved to be an effective cleaning solution with significantly
less residual lysozyme compared to ReNu MultiPlus (Figure 5). After 90 days, we
found 47 percent less residual lysozyme in the Group IV lenses treated with Opti-Free
Replenish (mean = 564.5μg) compared to lenses treated with ReNu MultiPlus (mean
= 1062.8μg, p<0.0001). We saw no significant difference in residual lysozyme
with Group I lenses, which absorb much less protein.
|
 |
|
Figure 6. The mean percent area of crystalline
deposits on Group IV lenses was significantly less for the Opti-Free Replenish MPDS
regimen at day 60 and day 90. |
Visual
examination of the contact lenses, conducted at each study visit, paralleled the
HPLC results. Investigators classified lens deposits according to the modified Rudko
scale. They found no significant differences with Group I lenses. The percentage
of patients with Group IV lenses that investigators classified as microscopically
clean (Rudko Type 1) was significantly higher (p=0.02) for the Opti-Free Replenish
group at day 90 compared to the ReNu MultiPlus group. Investigators noted no significant
differences in lens area with film deposits among the treatment regimens at any
visit for either lens type. The mean percent area of crystalline deposits (Rudko
Type 2-4) on Group IV lenses was significantly less for the Opti-Free Replenish
MPDS regimen at day 60 (p=0.01) and day 90 (p=0.03) (Figure 6).
Discussion
Results indicate that Opti-Free Replenish MPDS
offers an advance over the compared multipurpose solution. We believe the addition
of TearGlyde enhances comfortable wear and reconditions the lens surface to retain
moisture. Use of Opti-Free Replenish was associated with excellent comfort, lens
cleanliness, visual acuity and patient satisfaction. Corneal and tarsal findings
with Opti-Free Replenish were consistent with or better than baseline and the control
solution, ReNu MultiPlus MPS.
We believe Opti-Free Replenish MPDS offers
clear advantages over ReNu MultiPlus, especially for the 70 percent of traditional
soft contact lens wearers who wear Group IV lenses. Opti-Free Replenish maintained
visual acuity more consistent with that observed with new lenses. Microscopic deposits
were fewer, and at the end of the study we recovered 47 percent less protein from
the contact lenses cared for with Opti-Free Replenish. Study patients consistently
rated Opti-Free Replenish as "gentle on my eyes." Group IV lens wearers also trended
toward more agreement with the statement "with this solution my lenses feel moist"
with Opti-Free Replenish.
Patients who suffer dryness and discomfort
are more likely to become dissatisfied and to drop out of contact lens wear. TearGlyde
in Opti-Free Replenish is designed to recondition the lens surface during every
overnight soak so that patients may achieve a high level of lens surface moisture
for all-day comfortable lens wear. Recent studies have shown that Opti-Free Replenish
maintains lens surface wettability for 14 hours after 30 days of lens wear.
As
the lenses aged over the course of the study, total wearing time did not change
— but uncomfortable wearing time remained more consistent with baseline with
Opti-Free Replenish. This was especially evident with Group I lens wearers at day
30, where average uncomfortable lens wearing time was statistically significantly
lower for Opti-Free Replenish than for ReNu MultiPlus.
Potter et al (2005) have shown
that Opti-Free Replenish MPDS with TearGlyde increases comfort for wearers of the
most common soft contact lens material who experience discomfort. Our study showed
that the solution provides substantial benefits with asymptomatic lens wearers compared
to ReNu MultiPlus. The solution is also designed to provide safe and effective cleaning,
storage and enhanced disinfection, yet is gentle enough for sensitive eyes.
Alcon Laboratories sponsored this
study. All authors served as principal investigators for this study.
To obtain references for this article,
please visit http://www.clspectrum.com/references.asp and click on document #132.
Dr. Wooldridge is the Director of The Eye Foundation
of Utah, an optometric co-management center in Salt Lake City, Utah, and is an adjunct
clinical professor at several schools and colleges of optometry.
Dr. Schenker is an associate clinical professor at the University
of Rochester. He is a fellowship trained glaucoma specialist, and his areas of research
include glaucoma, contact lenses, dry eye and allergy.
Dr. Rigel is located in E. Lansing, Mich., where he practices
in a three doctor office specializing in contact lenses. He also participates in
clinical investigational studies for several contact lens manufacturers and pharmaceutical
laboratories.
Dr. Hamada is co-founder of a group practice located in Grants
Pass & Cave Junction, Oregon. He has been a clinical investigator and consultant
and served on numerous contact lens and pharmaceutical panels.
Dr. Eiden is president of North Suburban Vision Consultants, Ltd.,
a private group practice specializing in primary eye care, contact lens management,
treatment of eye diseases and refractive surgery. He is also an assistant clinical
professor at the University of Illinois at Chicago Medical Center in the Department
of Ophthalmology, Cornea and Contact Lens Service.
Contact Lens Spectrum, Issue: November 2006