Article Date: 9/1/2009

Evaluating a Silicone Hydrogel Daily Disposable Contact Lens
SIHY DAILY DISPOSABLE

Evaluating a Silicone Hydrogel Daily Disposable Contact Lens

A new lens combines the higher Dk/t of silicone hydrogel with the convenience of daily disposability

By Kurt Moody, OD, FAAO, & Robin L. Chalmers, OD, FAAO



Dr. Moody is the associate director of New Product Clinical Research at Vistakon in Jacksonville, Fla. He is also a Diplomate in the Cornea and Contact Lens Section of the American Academy of Optometry, a Fellow of the BCLA, and a member of the AOA.


Dr. Chalmers is an independent clinical trial consultant and an adjunct professor at Indiana University School of Optometry. Since 1985, she has conducted clinical trials studying contact lens complications, dry eye, and the measurement of ocular surface symptoms. She is a consultant or advisor to Alcon, CIBA, and Vistakon and an advisor to Bausch & Lomb.

Unlike some fields in health care, contact lens practice is a constantly changing endeavor. With the invention and development of new contact lens materials and a need for a deeper understanding of their effect on the ocular surface, contact lens practitioners must dedicate themselves to keeping pace with improvements in the field.

Even in these pressing economic times, patients will benefit from your well-considered advice and guidance on their choice of contact lenses. In fact, with pressure from other sources of lens supply, you as a contact lens practitioner should think of this advice and guidance as a “value added” portion of the eye exam that patients cannot source elsewhere. They come to your office for contact lens advice, so you should be ready to give your patients your best.

As veteran members of the contact lens research community, we are proud to report that the past decade has delivered a solid lineup of new and innovative products that improve contact lens wear for a wide range of patients. Some patients want overnight wear, others want less lens care, while some struggle with lens wear due to late-day symptoms. In an efficient practice setting, clinicians need a decision framework to help them determine which patients may benefit from new lens offerings.

Following are our thoughts on how to consider upgrading your patients to newer lens materials and how a new contact lens option that offers higher oxygen delivery and daily disposability can meet the contact lens needs for many of your patients.

Matching Needs to Lens Types

For patients who wear their lenses for many hours throughout the day, you now have many silicone hydrogel lens materials from which to choose that you can fit without feeling guilty about depriving their eyes of oxygen. This array of silicone hydrogel materials offers a wide range of fitting options and refractive corrections; you can now fit patients who have high refractive error as well as toric, multifocal, or unusual prescriptions with high-oxygen-transmissibility lenses. Refractive error now poses little barrier to choosing silicone hydrogel lens materials for current hydrogel lens wearers who could benefit from higher oxygen transmissibility.

For symptomatic soft lens wearers, practitioners now have a wide range of lenses that have performed well in comparative clinical trials with regard to reducing particular symptoms. Some of these lenses are designed to hold or slowly release wetting agents. Other lens types, including most of the silicone hydrogels, have been associated with reduced dryness symptoms perhaps because they have lower water content. Whatever the mechanism, if you ask about and discover dryness symptoms, you have many lens options that could help such patients.

Patients who want to avoid lens care can be fit with a range of daily disposable lenses. Most companies now offer some daily disposable option, and many daily disposable lens materials have been improved to maximize their wearing comfort.

The one segment in the daily disposable category that had been lacking until recently was a silicone hydrogel material lens. Thus, clinicians had faced a dilemma when considering the combination of material and modality.

Evaluating a New Option

The newest addition to the daily disposable lens family addresses all of these issues. Vistakon has recently introduced new 1-Day Acuvue TruEye Brand daily disposable silicone hydrogel lenses in the United Kingdom. With this option, practitioners no longer need to segregate their patients based on those who need the benefits associated with the newest lens material type and those who want the convenience of daily disposable wear.

Before launching 1-Day Acuvue TruEye daily disposable silicone hydrogel lenses, we conducted a number of clinical studies to test their performance. Here is an overview of one such study conducted in the United States.

Methods Table 1 lists the five U.S. clinical sites that participated in this study between April 2007 and October 2007. Each clinical site enrolled current spherical soft lens wearers who had good ocular health and wore corrections between −1.00DS and −6.00DS (no monovision allowed). After completing IRB approved informed consent documents, the participants were randomized to either 1-Day Acuvue TruEye or 1-Day Acuvue (Vistakon) lenses to use on a daily disposable basis with no overnight wear. Both participants and clinical investigators were masked to the lens type and remained masked through the study. Table 2 shows the study lens parameters.



After receiving their daily disposable lenses, subjects returned for follow up after one, two, four, and eight weeks and after three months. At each follow-up visit, subjects answered questions about their subjective experience with wearing the lenses and underwent a complete contact lens examination.

Results

Study Participants Table 3 shows the demographics of each group. As shown in Figure 1, most of the subjects entered the study wearing silicone hydrogel frequent replacement lenses. Table 4 lists the habitual lens brands.



Figure 1. Habitual lens type worn among patients in the study.

Slit Lamp Examination and Visual Acuity Both lens types were associated with less than 10-percent frequency of any slit lamp signs at all visits, with no significant differences between lens types for any visit. Visual acuity remained within one Snellen line for all subjects during this trial in both lens types.

Symptoms A steady improvement in symptoms during the first month of wear occurred after refitting with the daily disposable lenses. The rate of participant symptom reporting for 1-Day Acuvue improved from 38 percent at one week to approximately 24 percent at the four-week visit. For the new 1-Day Acuvue TruEye lenses, 30 percent of subjects had some complaint at the one-week visit, which diminished to 17 percent at the four-week visit.

In particular, the symptom of dryness was reported by more than twice as many 1-Day Acuvue patients compared to 1-Day Acuvue TruEye subjects (23 percent versus 11 percent, p=0.001). Lens awareness (Figure 2) was noted less frequently among the subjects wearing the new 1-Day Acuvue TruEye lens (8 percent versus 2 percent, p=0.001).

Figure 2. Percentage of subjects experiencing symptoms of dryness or lens awareness.

Average Wearing Time Figure 3 shows the average wearing time for subjects in each lens type through the first month of the study. Wearing time increased slightly during the first month of the study, with more subjects who wore the 1-Day Acuvue TruEye lens reporting increased wearing time during that month.

Figure 3. Average wearing time for subjects in each lens type through the first month of the study.

Study Success Rate Ninety-five percent of the participants who were assigned to the silicone hydrogel daily disposable lens, 1-Day Acuvue TruEye, completed the study (Table 5). Only two participants discontinued the study due to noncompliance with the protocol. Seven control participants discontinued the study for reasons including loss to follow-up (4), noncompliance (1), discomfort (1), and pregnancy (1). Note that most of the discontinuations were not contact lens-related, as deemed by the clinicians.

Conclusions

In this randomized clinical study, a new silicone hy-drogel daily disposable lens, 1-Day Acuvue TruEye, performed well compared to the control 1-Day Acuvue daily disposable lens. Patients who wore the 1-Day Acuvue TruEye lens reported less dryness and lens awareness compared to the 1-Day Acuvue wearers. Average wearing time for each lens type was more than 12 hours per day for three-quarters of the participants in each lens type.

It is important to note that 60 percent of the participants in this study had already been wearing silicone hydrogel contact lenses that were replaced either every two weeks or monthly. Switching to a silicone hydrogel daily disposable lens provides an option to patients who want the benefits of higher oxygen delivery without the steps involved in contact lens care.

We believe that prescribing 1-Day Acuvue Tru-Eye lenses gives eyecare practitioners another tool to meet some patient requirements — simultaneous needs for lens comfort and daily disposability as well as Class I UV protection. We feel that this lens will be a valuable addition to the stable of lenses currently available for modern contact lens wearers. CLS



Contact Lens Spectrum, Issue: September 2009