Not Your Mother's Extended
Silicon hydrogel continuous wear
contact lenses are safer than ever.
BY GLENDA SECOR, O.D., Huntington Beach, Calif.
This is a thrilling time for contact lens practitioners. The new silicon hydrogel continuous wear contact lenses have fulfilled the "holy grail" desire for safe, comfortable, extended wear. Patients can now benefit from unparalleled research and study assuring a new paradigm in contact lenses.
It's our job as practitioners to be willing to embrace this concept and to share this new modality with our patients. Whenever we're presented with new challenges professionally, we naturally seek the advice and wisdom of others who have studied and solved the problems. While I don't claim any level of expertise other than having experienced the excitement and enthusiasm of my patients, I'd like to offer you some insight I've gained into their success.
Today's extended wear contact lens materials
reduce the risk of infiltrative keratitis.
Dawn of a new day
Past attempts at extended wear with silicon elastomers were initially promising, but discomfort and hydrophobicity problems frustrated us. What makes us think things will be different this time is the new surface coatings and treatments, which enhance
wettability. The surfaces are also amazingly resistant to bacterial adhesion, which dramatically reduces the lens-related ulcerative keratitis infections so often associated with traditional extended wear.
Although we can't guarantee complete infection-free wear, we can assure patients of a significantly reduced risk of microbial keratitis -- the most sight-threatening infection.
Here are the types of extended wear lenses currently available:
PureVision. Because the Bausch & Lomb PureVision design only comes in one base curve, the choice is easy. You choose the appropriate power and dispense the lens.
Focus Night & Day. CIBA Vision's lens has two base curves. From experience, the 8.4 is my preferred starting point. Too often I find the flatter base curve results in excess edge "fluting," which doesn't diminish with time.
The flatter base curve is associated with a greater incidence of mucin balls -- the annoying yet unthreatening posterior lens surface debris associated only with this lens material. Even the most astute clinician may have difficulty differentiating between nebulous mucin balls and the more severe
microcysts, which are often associated with continuous wear. Remember that microcysts show a reversed illumination effect with a biomicroscopic observation. In contrast, mucin balls are unreversed and you can remove them with cleaning. The significance of mucin balls isn't yet determined.
This photo shows silicon
Tips for success
Here are tips that may help you when fitting these lenses.
Choose initial powers carefully. The initial power I choose is still often based on customary lens power. But at times the final dispensed power may be different than I expected. Often, when I refit a patient into the
high-Dk materials, he experiences a slight hyperopic shift, which may indicate a minor reduction in myopia. The hypothesis is that the slight myopic creep that often accompanies thick hydrogel extended wear may be eliminated with silicon
Choose a return-visit schedule you're comfortable with. In my experience, a 3-week adaptation period seems adequate to determinate lens power needs and discern corneal compatibility with the new modality. I recommend seeing the patient at an initial visit, 1 week later and 2 weeks later before dispensing any
Whether or not you choose a 1-day visit depends on your confidence with the patient and the modality. I routinely choose to not see people the day after dispensing the diagnostic pair.
Like a new shoe, the lens may not be comfortable at Day 1 but feel fine by Day 7. So you may choose to avoid the issue by skipping ahead to Day 7 when patients are more accustomed to the new feel of the more rigid silicon
hydrogels. I've yet to change my fitting plan as a result of any information gathered at the 1-day visit. The only exceptions are "virgin" contact lens patients. I start them with daily wear first.
Here's an example of silicon
hydrogel fluting with fluorescein.
Set an easy replacement schedule. Fortunately, after the 1-month initial lens wear, I've seldom found any problems or reasons to change the lenses. I do see patients at 3 months as a compliance-builder visit to reinforce the monthly replacement schedule. Again to my surprise, most patients are fairly compliant and seem to change their lenses as directed. We try to set replacement cycles close to the first of each month to simplify the memory game of "when did I last change my contacts?"
Consider occasional-wear patients. Not every one of my patients in continuous wear lenses sleeps 30 days in his lenses. Some want only occasional overnight wear and the additional assurance of increased oxygen permeability. I feel there's no reason why you shouldn't offer this alternative. The additional stiffness of the material helps with the handling aspects of the lenses and the additional oxygen permeability offers reduced risk of problems when patients sleep in lenses.
Even though we're confident about the superiority of the new lenses, we practitioners still have some concerns. We can't eliminate all complications from continuous wear lenses. Here are some points to remember.
Peripheral ulcers and keratitis are less of a problem.
Confusion still exists regarding the classification of adverse effects and the difference between contact lens peripheral ulcers and microbial
I've seen a few peripheral ulcers that were mild, annoying and responsive to antibiotic therapy. I assume they're associated with Staphylococcal lid disease. The jury's still out on the effect of extended wear on microbial
keratitis, but it seems that we've reduced incidence worldwide.
The easiest way to avoid problems is to discourage contact lens wear when patients are sick. When they don't feel their best, there's little reason to risk the potential of greater problems. Ocular resistance to infections is reduced and minor situations can domino into problems. I've had a few patients come into the office with red eyes while wearing continuous wear lenses, but history has often indicated a concomitant systemic infection.
Emphasize the safety of the lenses. Many people remember the 1987 Contact Lens Institute extended wear scare and the horror of microbial
keratitis. Now, everyone recognizes the link between sleeping in contact lenses and painful, sight-threatening corneal ulcers. We must clarify that the new silicon hydrogels aren't the same as the old materials. This isn't your mother's extended wear!
Explain that the lenses are six times more oxygen permeable than current disposable lenses and the plastic is deposit resistant. It's so deposit resistant that the bugs that can cause infections can't stick to the surface. We can't guarantee that an infection won't occur, but research indicates the risk is significantly less.
They may be safer than what the patient's currently wearing. The other major issue facing us is the complacent, sometimes-compliant extended wear patient wearing a standard hydrogel lens. These patients have no problems -- or so they think. The challenge is convincing them that the new approach is better, safer and the best way to continue sleeping in lenses. Sometimes the patients aren't the only ones who need convincing.
About those freebies
Offering a free trial pair to let patients experience the new modality is now traditional for many new options, including continuous wear. Just because the first pair of contact lenses may be free doesn't mean the professional services necessary to assure success with this new approach are free. This modality has the potential for great success but astute, confident practitioners are needed to assure the patients of lens safety. Professional fees are justified and reasonable with the expansion of specialized care.
Appeals Court Grants Stay
1, 2002-Last week, a U.S. District Court ruled in
favor of CIBA Vision in a patent infringement lawsuit
against Bausch & Lomb. The court ordered
Bausch & Lomb to discontinue manufacturing and
selling PureVision, B&L's silicone hydrogel
extended wear contact lenses, in the United
States. Bausch & Lomb then filed a motion
with the U.S. Circuit Court of Appeals and on June 28,
the court granted a temporary stay of the injunction
while it considers the appeal.
Management will continue coverage of this story in
the "Pulse" section of upcoming issues.
The secret of continuous wear's success lies in reduced handling. Minimizing the daily hassles of cleaning, disinfecting, inserting and removing lenses is one of the biggest reasons to seek an alternative to traditional contact lens wear. Tell your patients about the health and convenience benefits of this modality, reassure them about past horror stories they may have heard, and take the plunge. You and they will be glad you did.
Dr. Secor is in private practice in California. She's a diplomate in the Cornea & Contact Lens Section of the American Academy of Optometry and is a member of the Southern California College of Optometry Board of Trustees.
Optometric Management, Issue: July 2002