Silicone Hydrogel Contact Lenses Can they overcome Practitioner Resistance?

Dr Jim Kerr - O.D
Graduated from the University of Waterloo School of Optometry in 1976. Served as President of the Saskatchewan Association of Optometrist and President of the Canadian Association of Optometrists. Practices in Saskatoon, Saskatchewan, Canada in a large group practice. Has served on many contact lens advisory boards including Ciba Vision, Johnson and Johnson Vision Care, Wesly Jessen and Bausch and Lomb. Currently involved in clinical research in Extended Wear. Serves on the Board of Directors of the Horizon Laser Vision Center. Has spoken extensively on Silicone Hydrogel lenses over the past 3 years.

As I have travailed across North America the past two years extolling the virtues of the new silicone hydrogels I have been amazed and appalled at the incredible practitioner resistance to these lenses. The practitioner bias goes beyond reason to the detriment of the Canadian contact lens wearer and exposes our patients to risks of adverse effects of both current lenses and unnecessary surgery with all its attendant risks.

At the very least these lenses possess properties that could improve contact lens safety and comfort in most daily wear patients.

• Increased oxygen transmission,
  
• decreased tear film component deposition,
  
• decreased dehydration,
  
• decreased limbal injection and
  
• decreased bacterial adherence to the corneal epithelium

are all properties that should make us look at this lens for daily wear. Add to that the documented absence of overnight corneal swelling and the obvious benefit of eliminating the chemical damage to the epithelium from Multipurpose solutions and one has to wonder why we still fear continuous wear with these lenses.

The reason is, of course, the potential for microbial keratitis which occurred in significant numbers with HEMA extended wear. Dwight Cavanagh has clearly addressed this from a scientific perspective and his data should be enough to convince even the most cautious practitioner that the risk that we expose our patients to is very small and very likely similar to or even less than the risk they currently take with daily wear lenses ESPECIALLY when we knowingly allow patients to extend the wear of disposable lenses long past the time when they are likely to remain clean and non toxic to corneal tissues.

Recent research has shown that ALL multipurpose solutions cause increasing superficial punctate keratitis as the lenses approach three weeks of use when worn on a daily wear basis, leaving the cornea in a compromised state. However when worn on an extended wear basis solutions are eliminated and thus so is corneal insult which would reduce the risk of infection.

According to Brien Holden Microbial Keratitis is the ONLY significant adverse event in extended wear with silicone hydrogels. All other adverse events are either treatable or reversible and NONE are sight threatening.

With that preamble let me tell you the addition of silicone hydrogels to our practice has totally revolutionized our practice. Our 5 doctors are all fitting the lenses routinely. Many of our 14 day disposable wearers are changing to theses lenses and it has been rewarding for both patient and practitioner alike. 80% of the patients sleep with the lenses. These tend to be the patients who were overwearing their HEMA lenses and most of these patients enjoy "whiter" eyes and less dryness than the best lenses they wore previously. 20% of our patients wear these lenses on a daily basis finding they dry less and can wear them longer with better vision and comfort.

Incredibly some 800 patients now wear these lenses in our practice - some for 3.5 years now and we have seen precious few complications. In all we have treated fewer than 5 red eyes. No microbial keratitis has been seen to date. The red eyes have been either CLARE or CLPU. They are easily treatable by removal of the lens and treatment with anti-biotics or steroids or combinations. In many cases removal of lenses and artificial tears may be sufficient.

Some clinical pearls:

• The lenses need to be fitted. Loose lenses are quite uncomfortable - resist the urge to fit loose thinking they will tighten up - they wont. To date we have not heard of a lens adhering to the eye even with overnight wear. Keep in mind the lenses are a very low water content and fairly small so excessive movement should be avoided.
  
• Pre-existing eyelid disease is a contra-indication to overnight wear. Clear up these eyelids BEFORE you fit these lenses and you will have fewer problems.
  
• Expect the patients to show "whiter" eyes. The increased oxygen and improved bio-compatibility allows the limbal arcades to drain and you should EXPECT these patients to "look" good with less redness than any previous lenses.
  
• They don't work for every patient. You will have patients who either are not comfortable or whose lenses coat up more than other plastics. These patients may do better with single use lenses as usually the cause is environmental and daily disposal may be the best for them.
  
• We fit these lenses out of stock at the end of a routine exam. We give the patients a free trial period of 1 month. We do NOT see them the next morning ( there is no reason to and some patients take some time for adaptation). We do the first progress check in the morning after 1 week of continuous wear and the second after 4 weeks.
  
• The patients are instructed that they MUST remove the lenses with any redness, discomfort or blurred vision. They use rewetting drops before bed and in the morning and any other time they feel the need.
  
• Cost has not been an issue. Most patients are willing to pay a little more for the added convenience and comfort that these lenses afford.
  
• Compliance has been surprisingly good. The patients love these lenses and don't want to jeopardize their ability to wear them.

With the tremendous advantages these products have brought to our practice and our patients it continues to amaze me that they have had such a slow acceptance with Canadian optometrists. We all have our biases but this goes beyond reason.

There is good scientific evidence that these lenses will not create the problems that we experienced in the 1980's with extended wear of HEMA lenses. We all have many of our patients having laser surgery and we all seem quite comfortable with the attendant risks given the significant advantages - BUT have we really explored all the options available to the patients and really managed the risks properly if we have not allowed them to try these new lenses before surgery?? I think not. The risk of a significant adverse effect with silicone hydrogels is extremely small compared to the risk of loss of best corrected acuity with LASIK. It is time that Canadian optometrists get over the baggage of the 80's and get on with giving their patient the benefit of continuous vision without the risk of surgery.

D. James Kerr O.D.
Atrium Optometric Group
Saskatoon, Saskatchewan
Canada