Evaluating and Alleviating Contact Lens-related
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.
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
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.
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.
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.