Extended Wear Revisited: Opportunity and Responsibility
BY PETER D. BERGENSKE, OD, FAAO
Twenty years ago the contact lens industry was just beginning to understand oxygen's importance to the cornea. In the late 1970s, Polse and Mandel showed us that there was a critical level of oxygen required at the corneal surface to prevent swelling. Irving Fatt taught us the words "permeability" and "transmissivity," and gave us the unit of Dk/l. Holden and Mertz established the required Dk/l for contact lenses that could be left on the closed eye and result in no more corneal swelling than the closed eye without a contact lens in place. Minimum oxygen tension at the corneal surface was a topic for many researchers long before we realized that we could actually have contact lenses that would meet these demands.
A Brief History
Although soft contact lenses were available 20 years ago, our understanding of the physiological requirements of the cornea was just beginning. The rigid gas permeable contact lens, first known as CAB, then as the Polycon lens, taught all fitters how significant oxygen transmission can be.
The oxygen era also begat our greatest problem child-- extended wear. Holden and Mertz had given us a seemingly unreachable goal for the minimum oxygen tension required at the corneal surface for overnight wear. And perhaps the fact that this goal seemed unreachable is what challenged the industry to go forward with the concept anyway.
The bar had been set for minimum corneal oxygen under closed eye conditions, and this measure had not been met. Nevertheless, fueled with the economic and clinical success of the soft contact lens, as well as the feeling that the Russians were coming (in the form of Radial Keratotomy), contact lenses of mediocre physiological performance were labeled for use as extended wear contact lenses for up to 30 days.
The initial approval of extended wear lenses in this country in 1979 allowed for the fitting of lenses only for aphakia. Later, in 1981, "cosmetic" extended wear lenses gained approval. Optimistic projections figured that extended wear lenses would comprise 50 percent of the industry revenues by the mid 1980s.
One might argue that it is due to the credit of the community of contact lens fitters that the industry was frustrated at the profession's lack of enthusiasm for its "breakthrough" product. This reluctance was perhaps based on respect of science and concern for patients, but was at least in part due to our resistance to accept new concepts.
To Fit or Not to Fit
Many ethical fitters chose to work with extended wear contact lenses with a demand of careful maintenance and monitoring. It's possible that with careful patient selection and control, you'll have very few problems with extended wear, but in time, the rate is clearly not zero. Others chose to take the stand that extended wear lenses were unsafe and chose not to fit patients on an extended wear basis.
Consequently, there were two "high grounds": fit with vigilance or don't fit at all. Unfortunately, this left a lot of open area where there was high interest in extended wear among consumers, a significant fraction of which was not interested in paying for high levels of care. Advertising had created a market. It could not fail that the unscrupulous would take advantage. But that was not the whole story.
More Harm Than Good
It turned out that careful vigilance was not enough to avoid all complications. Inflammatory reactions clearly happened more often with extended wear, and the effect was relatively non-discriminating -- it affected all "classes" of fitters. Patients were not measurably safer by dealing with a certain fitter or by wearing a specific brand of lens. The commonality was overnight wear.
Gradually, we began to take note of the problems that were arising with extended wear. Barry Weissman's now classic epistle in the January 1983 edition of Optometric Monthly, "Danger: EXW," pointed out the fallacy that careful vigilance was enough.
Whatever the reason, be it poor patient care, poor education or just the sheer number of patients put into extended wear lenses, really serious problems started occurring with the extended wear of contact lenses. One effect of this "epidemic" was a series of very negative press on contact lenses. Another was an increase in the rift among the three "O's," as each was willing to blame someone else for the problems that were occurring.
Extended Wear: The Next Generation
Many of the problems and hard feelings have faded since that time, but we are now facing the beginning of a new era of extended wear contact lenses.
Bausch and Lomb recently obtained approval of the PureVision contact lens, and CIBA Vision has launched its Night and Day contact lens in Mexico. These lenses have broken the "oxygen barrier" and talk of a true 30-day lens as common, but as Barry Weissman pointed out over 15 years ago, "Unfortunately, corneal metabolic needs exclusive of oxygen have not been thoroughly explored." Is there more to this than the amount of oxygen that meets the eye?
One might legitimately question, given the flat growth curve of extended wear over the past decade, whether there is still consumer interest in extended wear. The answer is a resounding "yes." Consumers have largely forgotten the extended wear scares of a decade ago.
Both the profession and the consumer will expect new technology to improve the new extended wear contact lens. Refractive surgery, even with its current popularity, continues to have many skeptics. Although refractive surgery is here to stay, it does not fulfill the needs of a high number of patients in the way that a safe, 30-day extended wear contact lens will.
Despite vast improvements, it is likely that the new extended wear will still demand vigilance and patient education to alleviate our greatest concern: safety. I speak of safety for patients, but also for our profession and the contact lens industry. Safety will depend on all involved. The industry will need to provide products that are truly better, not just products that have a marketing edge. The industry must also be responsible for the promotion of these products to both the consumer and the professional. We need to carefully evaluate the literature, not just the promotional materials. We must be honest with both ourselves and our patients, and we must be vigilant.
In the first extended wear trial, we focused all of our attention on the effects of inadequate oxygen - microcysts, striae, polymegathism and vascularization. We tolerated higher levels of these findings in extended wear than we would in daily wear. What are we willing to tolerate this time?
It is my hope that our professional organizations can develop better interprofessional communication, along with the Industry, to make this new extended wear opportunity a successful and safe one for all. We must be willing to work side by side to see that extended wear of contact lenses is done safely.