11_04 CLS_AMO SUPPLEMENT
Evaluating and Alleviating Contact Lens-related
Dry Eye
Switching lens
materials or multipurpose solutions may make a big difference in comfort to contact
lens patients.
By Glenda B. Secor, OD,
FAAO
Silicone hydrogel
contact lenses alleviate many problems associated with traditional hydrogel lenses,
such as hypoxia, ocular redness and end-of-day dryness, but patients continue to
have difficulties with discomfort and microbial keratitis.1
To overcome these issues, practitioners must
know how to evaluate dry eye symptoms and offer the best lens materials and care
solutions to relieve patients' discomfort.
LOW-DK AND HIGH-DK CONTACT
LENSES
In 2001, the FDA approved
two high-Dk silicone hydrogel contact lenses: Lotrafilcon A (Night & Day) and
balafilcon A (PureVision). These lenses, which can be worn continuously for up to
30 days, have Dk levels four to six times higher than those of low-Dk hydrogel lenses.
In addition to high oxygen transmissibility, high-Dk silicone hydrogel lenses provide
good comfort and help retain moisture on the ocular surface.
Over the past 3 years, my colleagues
and I have evaluated the effect of high-Dk lotrafilcon A lenses on patients who
previously wore extended and daily wear low-Dk contact lenses successfully.2
This ongoing study includes 140 patients using daily wear lotrafilcon A lenses and
140 patients using
extended wear lotrafilcon A lenses.
To qualify for this study, patients
had to tolerate low-Dk lenses for 24-hour extended wear, a criterion to remember
when evaluating our findings and conclusions. Our primary variables of interest
were biomicroscopic corneal changes and subjective symptoms. Of the 280 enrolled
subjects, 237 completed the 12-month protocol.
Baseline evaluation of patients who
formerly used low-DK lenses for
extended wear showed more conjunctival staining
and epithelial microcysts, which are manifestations of extended wear-lens induced
hypoxia, than patients who used low-Dk lenses for daily wear. However, more severe
dry eye occurred more frequently in the low-Dk daily wear group than in the low-Dk
extended-wear group.
After switching to lotrafilcon A lenses,
clinical signs of conjunctival staining, incidence of epithelial microcysts and
frequency and severity of the ocular surface symptoms were reduced in both groups.
These improvements were maintained through the first 12 months of the study.
Patients who switched from low-Dk extended
and daily wear lenses to lotrafilcon A lenses had a lower incidence of epithelial
microcysts (shown above) and other hypoxia-related symptoms. Photo courtesy of
David W. Hansen, OD, FAAO.
These
results suggest contact lens materials influence ocular dryness, but other factors,
such as the choice of lens care products, also may contribute to discomfort associated
with silicone hydrogel materials. However, before we can identify specific factors
and develop treatments to alleviate dry eye discomfort in contact lens patients,
we need an effective way to evaluate and quantify their symptoms.
SURVEYING SYMPTOMS
Over the years, several
questionnaires have been developed to assess dry eye, but most of them are designed
to identify patients with severe disease.
The Ocular Surface Disease Index (OSDI),
developed by the Outcomes Research Group at Allergan Inc., is a reliable 12-question
survey
designed to measure the severity of dry eye symptoms and evaluate how
they affect vision-related functioning. This instrument elicits responses on three
subscales: Vision-related function (watching TV, reading), ocular symptoms (grittiness,
blurred vision) and environmental triggers (low humidity, high wind).3
In addition to effectively discriminating among normal, mild to moderate and severe
dry eye disease with good to excellent reliability, OSDI results are quantitative
and suitable for statistical analysis. See "Quantifying Dry Eye" for details about
the OSDI.
Recently, my colleagues and I used
the OSDI to determine if certain multipurpose lens care products effectively relieved
dry eye symptoms in
contact lens patients.
SWITCHING SOLUTIONS
The goal of our study was
to evaluate the efficacy of Complete MoisturePlus multipurpose solution for relieving
dry eye symptoms in contact lens wearers with clinically documented symptoms of
dryness or discomfort. The primary endpoint was the mean change in OSDI scores from
baseline to day 7 and day 30. Secondary endpoints were mean change from baseline
in overall lens comfort and end-of-day comfort.
To qualify for enrollment, patients
had to wear daily wear hydrogel contact lenses for a minimum of 8 hours a day for
at least 3 months before the study. These patients also had to use a multipurpose
solution or a hydrogen peroxide-based system for at least 1 month before enrollment.
We enrolled 24 patients
in the study. Their mean age was 34.9 years, ranging from 19 to 63 years. Of these
patients:
• Ten (42%) used ReNu Multi-Plus multipurpose solution
• Eleven (46%) used Opti-Free Express multipurpose
solution
• Three (13%) used Clear Care disinfecting
solution.
All participants switched to Complete MoisturePlus
multipurpose solution for the duration of the 30-day study.
The mean OSDI scores for all participants
were 16.5 at baseline, 8.0 at day 7 and 11.5 at day 30. On day 7, 75% of participants
reported decreased dry eye symptoms, 12.5% stayed the same and 12.5% had increased
symptoms. At day 30, 82.6% reported decreased symptoms, none remained the same and
17.4% had increased symptoms. Overall and end-of-day comfort scores improved
from baseline scores as the study progressed.
After using Complete MoisturePlus multipurpose solution for 30 days, most participants felt they could wear their lenses longer
and more comfortably than with their pre-study solution. Almost 64% of the participants
stated the study solution was better than their pre-study solution and almost 73%
said they would continue to use Complete MoisturePlus multipurpose solution on a
regular basis.
These results suggest that switching
to Complete MoisturePlus multipurpose solution relieved mild to moderate dry eye
symptoms in patients wearing traditional hydrogel contact lenses. We propose a follow-up
study that includes a control solution to determine if our current results are influenced
by the placebo effect.
CLINICAL APPLICATION
This pilot study suggests
that OSDI scores may be useful for assessing dry-eye related discomfort in contact
lens wearers. When used as an adjunct to objective Schirmer testing, subjective
OSDI scores can help practitioners evaluate the severity of and identify possible
causes of dry eye symptoms. We also believe this same testing regimen can help us
evaluate ocular changes associated with contact lens materials and care solutions.
CLS
Quantifying Dry Eye
The Ocular Surface Disease
Index (OSDI) rates dry eye severity on a scale of 0 to 100. For each question, patients
choose a number between 0 and 4 to describe their symptoms, where 0 indicates none
of the time, 1 some of the time, 2 half of the time, 3 most of the time and 4 all
of the time. If a patient chose 2 for all the questions, his OSDI score would be
50. The lower a patient's score, the fewer dry eye symptoms and vice versa.
Contact Lens Spectrum, Issue: November 2005