HEALTHY LENS WEAR
What's the Best Prescription for Healthy Contact Lens Wear?
Three experts square off on leading lens modalities.
By Judith Lee
Contact Lens Spectrum asked three expert contact lens practitioners -- Loretta
Szczotka-Flynn, OD, MS, FAAO; Keith Ames, OD; and Gary Gerber, OD -- to each speak as an advocate for one of today's leading contact lens modalities. Dr.
Szczotka-Flynn, who recently received a five-year grant from the National Eye Institute to study the long-term effects of silicone hydrogel continuous contact lens wear, will advocate silicone hydrogel lenses. Dr. Ames will speak for GP lens wear. Dr. Gerber will defend his modality of choice: daily disposable lenses.
Our experts answered 10 questions based on how each issue related to their advocated modality.
1 What do you think is the greatest risk that contact lens wear poses to the public?
Dr. Szczotka-Flynn: The greatest acute risk is microbial keratitis (MK), which is a concern with the resurgence of extended wear
(EW). The FDA is closely monitoring its incidence with that modality.
But the incidence of MK with silicone hydrogel lenses is so low (only 57 cases worldwide) that it shouldn't limit the option of
EW, although we should appropriately screen patients before fitting them with this modality.
The long-term, chronic risk of low oxygen to the cornea may be a more important and somewhat hidden public risk. We know from a subclinical standpoint that low oxygen is associated with complications, including:
- Increased epithelial permeability
- Increased bacterial adherence
- Increased microcysts, corneal edema, limbal injection and endothelial polymegethism
- Potential increase in myopia (that "slow myopic creep" over the years)
Dr. Ames: Contact lens wear in general is extremely safe; no serious risks exist. The only remaining risk is microbial keratitis (MK), which remains because patients want to sleep in their contact lenses, resulting in a small but measurable risk of MK. Because of this, EW poses the greatest risk. We rarely see MK with daily wear of soft or rigid lenses.
Dr. Gerber: The greatest risk is serious (blinding) corneal infections. Fortunately, most contact lens complications are relatively benign and often self-limiting, but vision loss is always a possibility.
How does your lens of choice help reduce contact lens risk?
Dr. Szczotka-Flynn: Increased oxygen transmissibility helps reduce every one of the complications associated with
low-Dk lenses. Research confirms this. When you resolve all the subclinical complications collectively, MK decreases because the eye's ability to resist infection improves.
Of course, we should warn all EW patients about high risk situations and tell them not to sleep with lenses after swimming or when they're ill. Additionally, smokers or those who have a history of previous contact lens-induced red eye aren't the best candidates because their risk increases. Lastly, we should educate patients that they should remove their lenses if their eyes are irritated, clean the lenses with clean hands and, if irritation persists, leave the lenses out or call their practitioner immediately.
Dr. Ames: Before silicone hydrogel lenses, I was reluctant to fit EW because of the problems associated with it. I then allowed EW for only my GP lens patients. Now I do allow patients to wear silicone hydrogel lenses for
EW, but GP lenses are still my first EW choice for GP tolerant patients.
Dr. Gerber: The safest option is to not wear lenses at all. The next safest is to wear the lens type that stays cleanest. In my opinion, that's daily disposables. With daily disposable lenses, if patients remember to throw the lenses away at the end of the day, then they'll have clean lenses. Daily disposable lenses eliminate most of the barriers to non-compliance and give patients the highest probability of wearing clean and safe lenses. This modality requires little effort on the patient's part to obtain the benefits.
Of course, beyond serious infections, cleaner lenses also reduce the chances of minor eye irritations and annoyances. And because daily disposable lenses require no maintenance, they eliminate solution reactions.
Why do you feel your lens of choice is safer than the other two modes of correction being discussed in this article?
Dr. Szczotka-Flynn: Daily disposables don't have high oxygen permeability. Only silicone hydrogels provide higher oxygen in a soft lens modality.
GP materials are also available with high oxygen permeability, but GP lenses still suffer from comfort issues, no matter how hard we try (and I routinely advocate GPs). It's also simple to fit a GP drop-out with silicone
Dr. Ames: I'm not recommending GP lenses for all patients. If a patient is interested in
EW, I only recommend either silicone hydrogels or GP lenses. Both modalities are effective and much safer for EW because of their higher Dk.
Two problems associated with EW are corneal hypoxia and entrapment of metabolic debris and waste behind the contact lens. Silicone hydrogels solve hypoxia problems, but not debris entrapment. GP lenses solve both problems and are ideal in my opinion. Both modalities adequately oxygenate the cornea, but GP lens movement flushes out debris.
Daily disposable lenses are an excellent alternative for people who have no desire to sleep in their contact lenses. However, GP lenses offer the same advantages at a lower cost (see my answer to question 6 below). GPs present no lens spoilage issues and no need to replace lenses often. GPs offer the advantages of clean lenses without higher cost.
Dr. Gerber: GP lenses require some maintenance that we hope patients accomplish correctly. If not, then they'll have dirty lenses.
Also, in my experience, even a text book perfect GP fit isn't as comfortable as a fresh, clean, soft daily disposable lens. Patients might attempt to push through their GP discomfort and develop complications that you just don't see with daily disposables.
Comparing the safety of daily disposable lenses to silicone hydrogel lenses is a bit more challenging. This puts the superb cleanliness of daily disposables against the higher Dk of silicone
hydrogels. I think that the two tie or come close to it, and overall I think the jury is still out. But if we had a daily disposable silicone hydrogel lens available, then I think it would be, by far, the absolute safest modality.
What patient characteristics do you consider when deciding on the healthiest lens modality?
Dr. Szczotka-Flynn: I always ask, "How often will you wear your lenses? Part time or full time (7 days a week)?" If a patient will wear the lenses only part time, then oxygen isn't as big a concern. For full-time wear, oxygen is a critical concern.
Age is also a factor. If a patient is young and will wear lenses for many years, then I prefer to prescribe a lens with high oxygen permeability.
As far as ocular physiology goes, I don't put a patient in contact lenses if he doesn't exhibit good physiology. The same applies for personal hygiene. If a patient doesn't have good hygiene, then he may not be a good candidate for any kind of contact lens.
Dr. Ames: Occupation and lifestyle come into play. GP lenses don't make sense for patients who work in a blue-collar job that has a dirty or dusty heavy manufacturing setting. Such patients will do better in a frequent replacement soft lens.
Compliance is another issue. If a patient won't replace lenses as often as I request, then I'll steer him toward GP lenses. Daily disposables may not be a proper option when cost is an issue. I've found that patients will follow certain replacement cycles, such as monthly replacement. If you ask patients to replace their lenses more frequently than that, then compliance goes down. I find that many patients don't comply with a two-week replacement schedule.
Some patients are more sensitive to corneal hypoxia. While I have patients who do quite well in
EW, even with conventional products, others need higher technology to succeed. You can't predict this until a patient wears the lenses. Currently I fit only silicone hydrogel or GP lenses for
EW. I also consider tear film composition and volume. If it's healthy, then the patient will do well in any modality. With inadequate tear film or volume, the patient may have better success in daily wear with low-water soft lenses or GP lenses.
Dr. Gerber: I don't consider any patient characteristics. I offer daily disposable lenses to all my patients, parameters allowing, of course. Why would I discriminate delivering a great modality on the basis of age -- or anything else for that matter? If it's available in a patient's parameters, then I recommend it as my modality of choice for that patient.
What advantages does your lens of choice offer to patients other than safety?
Dr. Szczotka-Flynn: A 30-day silicone hydrogel lens is the ultimate in convenience. Also, with LASIK increasing, patients are always looking for alternatives to not "hassle" with their eyes.
Dr. Ames: Some patients have better vision with GP lenses. In spite of today's technology, patients who have significant astigmatism have no soft lens choice that offers the level of oxygen permeability required to allow
EW. GP lenses are the best choice, providing better vision and safety. Practitioners who shy away from GPs and fit such patients with silicone hydrogel lenses achieve marginal vision. Also, I don't advise EW with current soft toric contact lenses.
Dr. Gerber: Daily disposables represent the most convenient way to wear lenses. Additionally, because the lenses are always clean, comfort and vision are great. Spare lenses are never an issue as they're in abundant supply. And, of course, daily disposables are maintenance-free.
Do economics affect your recommended lens option for given patients?
Dr. Szczotka-Flynn: No. We've finally learned to recommend what's best for the patient, no matter what economic range the patient is in. I can't tell patients what to do with their pocketbooks. I've seen many patients who have the financial means reject a lens for cost, while other patients who seems price-sensitive will accept a costlier modality. Patients will make their own decisions after they hear your recommendations. Going by my experience, if you recommend what you feel is best 100 percent of the time, then you'll get about 85 percent to 90 percent acceptance.
Dr. Ames: I practice in a blue-collar, middle-income community, so cost is an issue. We try to find the least expensive, correct alternative for patients. I've found that GP lenses are the least costly lens option. In ballpark figures, GP patients purchase lenses every two to three year, with a $100 to $200 material cost. Daily disposable patients will spend $300 to $400 on materials each year, and silicone hydrogel patients will spend $200 to $300 each year.
Dr. Gerber: Never. While economics might affect whether patients accept my recommendation, it's not my job to determine how much the patient wants to spend. My only job is to deliver the best option -- every time -- to every patient.
How much consideration do you give to a patient's request for a specific form of contact lens correction? What if it's not your modality of choice?
Dr. Szczotka-Flynn: I always listen to the patient's thoughts. I always ask, "Why are you requesting this?" I consider what about the particular modality appeals to him. Then I present options based on his perceived benefits of the modality he's requesting. If it was the free trial lenses that appealed to the patient, then I say, "I'll give you a 'free trial' of any disposable lens that fits your needs. But what is it about that modality that brought you here? Is it because you want to sleep in the lens?" If the answer is yes, then I tell him that silicone hydrogels are the best option. Sometimes patients comply, sometimes they don't; it depends on their particular reason for wanting a particular modality.
Dr. Ames: I take the request into consideration, but it's not my primary decision-making factor. I approach the patient objectively and determine the best vision correction for him based on objective testing and lifestyle considerations. I make a recommendation to the patient, and it may go against what he's requesting. Patients don't always accept my recommendation, but most will.
I try the option that a patient wants to try, as long as he's made an informed decision and the choice is a clinical possibility. I don't just tell the patient what he wants to hear. My job is to tell him what he needs to hear. I'm not afraid to make a recommendation.
Dr. Gerber: It depends on the case. I believe our job is to fit the best available lenses for each patient. While most patients succeed with daily disposables, a small percentage can't wear them, principally because of the somewhat limited parameters. As I said before, if a patient can wear daily disposables, then I'll recommend them regardless of what he requests.
If he can't wear daily disposables, then I'd consider a second alternative, provided it's now the best alternative. I'm not saying that I don't allow patients to voice their opinions and desires, but the bottom line when the dust settles is that I know more about contact lenses then they do. And as I've said before, my job is to give every patient the absolute best care and products that I can.
8 What is your approach to continuous wear?
Dr. Szczotka-Flynn: I ask any patient who shows any interest in sleeping in lenses to consider silicone hydrogel lenses or
hyper-Dk GPs. Whether for seven-day or 30-day wear, the patient needs the high oxygen component for safe
EW. That's my mandatory requirement. If a patient who wears a low-Dk lens wants to continue in overnight wear, I review the risks of low oxygen with him and document it in his chart. Few will remain in
low-Dk lenses once they hear the whole story about oxygen.
Similarly, when I started practicing 12 years ago and patients insisted on reordering PMMA lenses, I required them to sign a waiver stating that they understood their risks. We knew PMMA lenses were harmful to their eyes. I don't take it to this extreme with
low-Dk and high-Dk soft lenses, but it's a similar analogy.
Dr. Ames: If a patient is interested in
EW, then my view is that two viable options exist: silicone hydrogel or GP lenses. If the patient can't wear either, then I discourage
Dr. Gerber: I'm fine with patients who want continuous vision, and I fit it frequently. I fit only silicone hydrogel lenses for overnight wear and have just about abandoned any other material for continuous wear
(CW). I'm more strict with follow-up schedules for CW patients, and we keep them on a tighter leash than we do daily disposable patients.
If multiple lens materials are available in your lens of choice, then how do you select a material to fit?
Dr. Szczotka-Flynn: This question will become more common as the options in this category expand. We have a daily wear silicone hydrogel lens
(Acuvue Advance, Vistakon), and when PureVision (Bausch & Lomb) was available in the United States we had choices for Dk values, base curves and flexibility compared to the Focus Night & Day
(CIBA Vision) lens for CW.
A general rule with current silicone hydrogels is that when Dk values increase, so does lens stiffness. You need to balance the options of oxygen permeability and lens flexibility for a given patient. If the patient is a candidate for daily wear only, then you can consider either Acuvue Advance or Focus Night & Day based on replacement schedule and lens compatibility during the trial fitting period. If the patient wants
EW, the only option today is Night & Day.
Dr. Ames: I believe it's important for practitioners to simplify product offerings. I try to fit a small number of lens designs that will fit the largest percentage of patients. I don't want 10 to 15 lens designs -- I limit it to three or four designs. I fit silicone hydrogel lenses and monthly replacement soft lenses. For daily wear GP lenses, I choose a
medium-Dk, fluorosilicone acrylate material because it offers a balance of properties to patients. I use a
higher-Dk material for EW, high plus lenses and for special, thicker designs such as prism-ballasted.
Dr. Gerber: I wrap all of those considerations into one and I base my decision on my past experience with what I've already tried.
Where do you see your preferred modality fitting into the contact lens spectrum in 10 years?
Dr. Szczotka-Flynn: I predict that silicone hydrogels will be the only soft lens of choice in 10 years. I think all manufacturers will move to high oxygen lenses, including daily disposables. Based on this prediction, in the future we'll have to decide among lens characteristics such as stiffness, surface treatments and oxygen performance. Here in the United States, we'll return to making these decisions when B&L PureVision returns to the market. International colleagues I've spoken to, particularly in Australia and England, who have the PureVision lens available face these decisions daily.
Dr. Ames: I think GP lenses will remain an important part of contact lens practice. In approaching patients objectively, you should fit 20 percent to 25 percent of them with GP lenses. I don't see GP use increasing as a percentage, but I don't think it will decrease for the foreseeable future. GP lenses have a legitimate place in the market that should remain. I foresee that 10 years from now, most, but not all, patients will wear
higher-Dk lenses, and silicone hydrogel lens technology will predominate.
Dr. Gerber: I believe daily disposables will remain strong and will become the dominant mode of correction. Practitioners have been a bit slow to "buy in" to the concept of daily disposables, but patients haven't. When I offer them to patients, the majority say, "Yes!" Contact lenses are consumer-driven, and eventually this patient demand will sway the currently less-than-enthusiastic practitioners to embrace this modality. After all, if you ask a patient, "Given a choice, would you like to clean your lenses or just throw them away?" how many would opt for the former choice? Practitioners should routinely discuss this option with patients rather than continuing to place them in a niche for part-time wear.
Szczotka-Flynn has been in clinical practice for 12 years with the Department of Ophthalmology, University Hospitals of Cleveland, as director of the Contact Lens Service. She's also an associate professor at Case Western Reserve University and is an FDA clinical investigator.
Dr. Ames has been in private group practice for 13 years. He has previously served on the clinical faculty at the University of Waterloo School of Optometry, Ontario, Canada, as research optometrist and manager of Clinical Evaluation for Bausch & Lomb and as director of Technical Affairs for Polymer Technology Corp.
Dr. Gerber is in private practice and is a well-known speaker. He's president of the Power Practice, a leading optometric consulting company.
Ms. Lee has been reporting on the vision industry since 1979. Along with her work as a researcher and reporter, she operates a communications consulting firm, Judith Lee Associates, in
Atglen, Pa. You can reach her at email@example.com.
Contact Lens Spectrum, Issue: June 2004