Early results promising for 30-day extended wear contact lenses

Issue: September 1999

As practitioners in the United States are prescribing contact lenses that can be worn continuously for up to 7 days, their European counterparts have already begun limited prescribing of the same lenses for 30-day wear. Their impressions have been favorable — encouraging news as U.S. Food and Drug Administration (FDA) clinical investigations begin for 30-day wear.

Bausch & Lomb (Rochester, N.Y.) and CIBA Vision (Duluth, Ga.) have developed materials that are variations on the traditional hydrogels. The properties of these materials allow more oxygen to reach the cornea, which the companies believe will answer concerns about trauma caused by hypoxia. Less clear is how the cornea will respond to 30 days of continuous wear, with no cleaning to remove deposits from the lenses.

Bausch & Lomb’s PureVision lenses have received FDA approval for extended wear up to 7 days, and the company has reached an agreement with the agency on the protocols for clinical trials for 30-day wear. CIBA’s Focus Night & Day is currently in trials for both 6- and 30-day wear.

European responses

Juan J. Rubio, OD, in private practice in Madrid, Spain, has been involved in the European study of the Focus Night & Day lenses and has been impressed with the lenses’ performance during the 6 months he has been prescribing them for 30-day extended wear. He currently has eight patients in the study and another 12 in his practice wearing the lens.

Patients have responded well to the CIBA Vision lens, which has offered good stability, comfort and visual acuity, Dr. Rubio said in an interview with Primary Care Optometry News. Of the 85 patients originally involved in the current study, only two have left due to lens-related problems, he said. An additional eight patients left due to subjective responses to the comfort of the lens, he said.

“We have found no important external deposits on the lenses,” Dr. Rubio said. “There have been no problems with dryness on the external surface of the lens, and we have found debris under the lens in very few patients. The debris has mostly consisted of mucin balls and trapped air bubbles and has occurred in only a small percentage of patients. The trapped debris has had no impact on comfort or vision.”

The lens has been surprisingly stable and easy to fit, despite having only one base curve, Dr. Rubio said. “The lens has only one geometry, and even if you think from a conceptual viewpoint that the lens is too tight because of a steep base curve, it gives fairly good feeling even in flat corneas. It’s a surprising finding,” Dr. Rubio said.

Explaining the lens to patients

One challenge to the practitioner has been educating patients about the unique wear schedule, Dr. Rubio said.

“We had to re-educate patients in the sense that they don’t have to worry about wearing the lens continuously for 1 month. You can keep the lens in your eye as long as your eye looks good, your vision is good and you feel comfortable,” he said.

Practitioners should keep in mind that the limits of the new technology have not been determined, so they should exercise caution before recommending this wear pattern, he said.

“We don’t have to try to fit every single patient we have in our office on this kind of schedule,” Dr. Rubio said. “This is a very specialized lens that needs more follow-up than regular extended-wear contact lenses, at least for the first few months after starting this schedule.”

In selecting patients, Dr. Rubio looks for those seeking a particular lifestyle, who want to be rid of glasses and may be considering refractive surgery. Patients with corneal, conjunctival or scleral abnormalities or who have initial pathologies are not fitted. Dr. Rubio has begun experimenting with some dry eye patients, and the lens has performed well.

A new generation of extended wear

One of the more important things to stress to patients is that the new extended wear lens materials are very different from those in the past, Urs Businger, OD, FAAO, in private practice in Luzern, Switzerland, told Primary Care Optometry News.

Dr. Businger has been involved in clinical trials for 30-day wear of the PureVision lenses since 1997. Initially, the PureVision lens was worn continuously for 30 days while the control lens, Vistakon’s Acuvue, was worn continuously for 7 days, removed and cleaned, worn for another 7 days and discarded, he said. After 1 year, only one of the 23 patients had left the study, the reason being a loss of interest in the wearing modality. In the second year, which is nearing its conclusion, 18 of those patients were invited to continue with the study. The patients had to pay professional fees and wear the PureVision lenses in both eyes.

Conservative approach

Dr. Businger is conservative in prescribing the PureVision lenses, which are now commercially available in Switzerland. He prescribes the lenses for daily wear first, then at the first progress check, if there are no positive slit lamp findings, Dr. Businger allows the patient to wear the lenses overnight. After 1 week of overnight wear, if there are no problems, the patient can then begin 30-day continuous wear.

Patients with anterior segment problems, thyroid problems and systemic diseases such as diabetes are not good candidates for the lens because they start with a higher risk, Dr. Businger said. He also does not prescribe them for marginal dry eye patients, as their tear defense is already compromised.

During the 2-year clinical trial, there were no infection problems, but Dr. Businger added that he had a small number of patients, and because the lens wear was part of a study, both patients and practitioners are more careful.

“So the final question — do we have less infection with the new generation of soft lens materials — can only be honestly answered after thousands of lenses have been fitted,” Dr. Businger said.

Some of his patients do not plan on wearing the lenses on the 30-day schedule, but want the convenience and safety for times when they want to wear the lenses for several nights. Dr. Businger said the surface characteristics allow the lens to be worn as a daily wear lens that can be cleaned and manipulated every day without losing its wettability.

Increased oxygen

The most obvious obstacle to overcome in developing an extended wear lens is ensuring that the oxygen transmissibility of the material will be sufficient to avoid hypoxia-related complications, such as corneal swelling. PureVision lenses are made of balafilcon A, which incorporates oxygen-transmissible silicone into a standard hydrogel, allowing for a Dk/t of 110 in –3 D lenses. Focus Night & Day lenses are made of lotrafilcon A, a biphasic material with microsized channels of fluorosiloxane, which transmits oxygen, and hydrogel, which transmits water and ions. As a result, Focus Night & Day has a Dk/t of 175.

While the increased oxygen transmissibility is a significant advancement, it should not be considered the only factor in improving prospects for extended-wear lenses, Gerald Lowther, OD, dean of the School of Optometry at Indiana University told Primary Care Optometry News. Dr. Lowther was involved in the clinical trials for both the PureVision and Focus Night & Day lenses.

“We know that a lot of the problems that occur with extended wear are due to decreased oxygen supply to the cornea,” Dr. Lowther said. “During sleep, there is very little oxygen reaching the cornea through presently marketed lenses. With the new high Dk materials, a lot more oxygen is reaching the cornea.”

Continued research with more contact lens wearers is needed to determine the exact effect of the increased oxygen reaching the cornea, he said.

“One of the things we’re going to be able to find out is how many of the problems we’ve been seeing are related to oxygen and how many are related to immune reactions and other types of problems,” Dr. Lowther said. “My estimation is that it is considerably safer to have all extended contact lens wearers have more oxygen permeability through the lenses.”

Among the other concerns surrounding an extended-wear schedule are the effect on the risk of infection and the likelihood of deposits forming on lenses that are not being cleaned for 30 days.

In trials, both balafilcon and lotrafilcon performed well in resisting deposit formation, Dr. Lowther said. As for the risk of infection, the higher Dk may actually reduce the likelihood, he said.

“Obviously, no one thinks this is going to eliminate infection problems, but it could significantly decrease infection problems, depending on what’s causing the infection,” Dr. Lowther said. “We know that higher oxygen permeability should decrease edema, and we certainly see patients who don’t have nearly as much redness, injection and so forth as we do with standard lenses we’ve had in the past.” Another benefit should be the decreased likelihood of neovascularization with patients on extended-wear schedules, he added.

Dr. Lowther also cautioned that these lenses would not answer all concerns related to extended wear.

“I think you are still going to have some patients who are going to have build-up of cell debris and mucus to which they’re going to have reactions,” he said. “You still have the potential for infections. It’s not a panacea, but it’s a major step forward in getting more patients who are able to wear lenses on an extended-wear basis.”

Some practitioners are taking a more wary approach. Barry Weissman, OD, PhD, director of contact lens services at the Jules Stein Eye Institute at the University of California at Los Angeles, has no specific doubts about the new extended-wear lenses, but wants more definitive data before he begins prescribing for 7-day wear.

“I’m just concerned that we’ve been down this road before, and I’d hesitate to go down it again until we’re really sure we’ve got a good deal,” Dr. Weissman said. “It is going to take a lot of patients wearing these lenses a lot of years before we are really going to know.”

Dr. Weissman said he would recommend these lenses for daily wear for patients who would benefit from increased oxygen flow to the cornea. “Either product will be very valuable to patients who have hypoxic concerns now. Patients who have blood vessels already growing in their corneas, for example, and, therefore, should only wear rigid gas-permeable lenses, might be fitted with these new high Dk soft lenses with more safety,” he said.

Rocky road

Alan Dozier, corporate vice president and president of Bausch & Lomb North American Vision Care, said that with clinical protocols approved by the FDA, approval for 30-day wear is still likely a few years away. He also cautioned that, although the company is confident about its prospects for developing a 30-day extended-wear lens, there is no guarantee this will come to fruition.

Bausch & Lomb has already hit a few snags in its efforts to begin marketing its PureVision lenses for 7-day wear, which is now being prescribed by about 1,500 practitioners in the United States.

Prior to Bausch & Lomb launching PureVision in March, CIBA Vision filed a patient infringement lawsuit, alleging that Bausch & Lomb’s lens infringes on four patents held by CIBA that relate to the development of an extended-wear contact lens. The companies entered negotiations to reach a settlement at the suggestion of the court. Those negotiations continue, but Mr. Dozier said that if an agreement cannot be reached, litigation could resume.

Then, in April, the FDA issued a warning letter challenging some of Bausch & Lomb’s marketing claims, including the claim that the PureVision lens provided “a new level of ocular health.” The FDA’s concerns were not related to the safety and efficacy of the lens, and after discussions with the agency, new marketing materials that clarify the questions the FDA had raised will be released in the coming months, Mr. Dozier said.

For Your Information:

Juan J. Rubio, OD, can be contacted at Jazmin 18, Madrid 28033, Spain; (34) 913-023-227; fax: (34) 917-660-239; e-mail: juan_jose_rubio@ compuserve.com.

Urs Businger, OD, FAAO, can be contacted at Weggisgasse 3, 6004 Luzern, Switzerland; (41) 41-410 17 83; fax: (41) 41-410 48 63; email: businger@centralnet.ch.

Gerald Lowther, OD, is dean of the School of Optometry at Indiana University. He can be contacted at 800 East Atwater Ave., Bloomington, IN 47405; (812) 855-4440; fax: (812) 855-8664; e-mail: glowther@ indiana.edu. Bausch & Lomb and CIBA Vision have supported studies through the University of Indiana College of Optometry.

Barry Weissman, OD, PhD, can be contacted at Jules Stein Eye Institute, 100 Stein Plaza, UCLA Box 957000 Los Angeles, CA 90095-7000; (310) 825-5000; fax: (310) 825-0841; e-mail: weissman@jsei. ucla.edu. Drs. Rubio, Businger, Lowther and Weissman have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.

Alan Dozier, corporate vice president and vice president of Bausch & Lomb North American Vision Care, can be contacted at One Bausch & Lomb Place, Rochester, NY 14604-2701; (800) 828-9030; fax: (716) 338-6808.