letters to the editor
Commenting on GP Peripheral Staining
I read with interest the October 2007 Treatment Plan column "Peripheral Staining in GP Lens Wearers," by William L. Miller, OD, PhD, FAAO. I agree with a number of his points, but emphasize that movement of the GP lens is critical to avoiding 3 o'clock to 9 o'clock staining. In my experience, excessive edge clearance does not produce 3 o'clock to 9 o'clock staining nearly as much as a tight lens does, usually a small diameter. It has been my philosophy over the years to fit a larger, lid-attachment type of design to assure lens movement over the surface of the cornea in a controlled manner.
As in the past, the emphasis is to promote a normal blink pattern. The lens design is critical to achieving this.
I wrote an article in the March 1977 Journal of the American Optometric Association titled, "Incidence of central edema and peripheral staining as a function of contact lens fitting philosophy," and although the article dates back to 1977, the retroactive study I did showed that, at least in my hands, a smaller, tighter-fitting contact lens caused more problems with 3 o'clock to 9 o'clock staining as well as with central corneal clouding. Therefore, fitting a larger, freely moving lens worked better in my hands. I use this principle today and, as Dr. Miller has suggested, GP lenses can be larger than previous PMMA lenses and meet our requirements for optical and physiological success.
Using tear supplements as lubricating agents provides only temporary relief and does not solve the previously noted problems. The use of plasma treatment on GP lenses has become standard in my practice. It has allowed previous GP lens wearers to increase their wearing time or maintain a full day with far less dehydration. Cleaning is still the key, and we must instruct patients to use proper cleaning solutions or all of our efforts are wasted.
Richard D. Brannen, OD
Dr. Miller's Response:
I want to thank Dr. Brannen for his remarks and suggestions on how to manage 3 o'clock to 9 o'clock staining. He makes several great points concerning causes for this peripheral desiccation.
There has been some debate as to whether 3 o'clock to 9 o'clock staining is due to an increased or decreased edge lift. Many reports in the literature associate a reduced edge lift with a higher level of 3 o'clock to 9 o'clock staining (Korb, 1970; Williams, 1979; Lebow, 1990; Andrasko, 1990). However, at least one report shows that an increased edge lift produces a larger degree of staining (Bennett, 1985).
Additional published papers suggest that the edge of the lens creates a lid-lens gap that exacerbates drying in the interpalpebral 3 o'clock to 9 o'clock position (Barabas and Fontana, 1967; Graham, 1968). Schnider et al (1997) interestingly showed that a reduced edge lift was related to an increase in 3 o'clock to 9 o'clock staining only in subjects who had staining at baseline. In GP wearers who did not exhibit staining at baseline, lens design issues such as diameter, edge lift, vertical centration and lens movement were not associated with 3 o'clock to 9 o'clock staining during the course of their study. A previous study by the same group (1996) noted specific patient and lens factors associated with predicting the appearance of 3 o'clock to 9 o'clock staining.
As practitioners, we all strive for the ideal edge lift for each GP lens patient. I avoid both minimal and excessive edge lift GP fitting relationships. Staining aside, other issues related to both excesses ultimately affect GP lens comfort.
Again, I appreciate Dr. Brannen's comments and I agree that plasma treatment and proper cleaning play important roles in making our GP patients comfortable throughout the day. Modifying design features in GP lenses to solve patient signs and symptoms is becoming a forgotten art form. It's refreshing to re-visit many of these issues as Dr. Brannen has done.
Continuing the Omega-3 Discussion
I would like to respond to statements made by Dr. Thomas P. Kislan in his letter "More Comments About Omega-3s" from the March issue. As a natural healing professional, I've been studying therapeutic nutrition and nutritional biochemistry for 36 years. I've lectured widely and served as a scientific editor for journals in natural medicine. I've been a medical science consultant in the nutriceutical industry for 20 years. I also remain up-to-date in the scientific literature. Thus, I am a serious student of this subject.
Dr. Kislan states, "There are two problems with flaxseed oil. First, it's converted to EPA and DHA at only 1 percent, as is any GLA or ALA molecule."
A number of studies in the literature have demonstrated conversion rates much higher than that stated by Dr. Kislan. These studies indicate that women of reproductive years can convert 21 percent of ingested ALA into EPA and 9 percent of ALA into DHA. Men have more difficulty, converting perhaps 8 percent of ALA to EPA and up to 4 percent to DHA. But at the recommended daily dosage for flaxseed oil, their rate of conversion will still take men to levels that are protective.
Dr. Kislan further states, "Second, flaxseed oil has been linked to increasing the risk of prostate cancer."
Flaxseed oil itself has never been linked to prostate cancer. A few papers attempted to link ALA to prostate cancer. However, after following almost 30,000 men for more than five years, the National Cancer Institute of NIH concluded that no dietary source of ALA could be linked to any kind of abnormal prostate growth, benign or malignant.
With respect to fish oil, Dr. Kislan states, "…the EE [ethyl ester] form is 300 percent less absorbable than the TG [triglyceride] form…"
Although some initial studies suggested an advantage of the triglyceride form over the ethyl ester form, subsequent more detailed investigations revealed the flaw in the initial studies. Many complex biochemical steps are by-passed by ethyl esters, which can easily pass through the intestinal mucosal membrane. In addition, the ethyl ester form has clinical advantages for persons suffering with malabsorption difficulties and bile insufficiency. As a result of its absorption efficiency, ethyl esters have proven to be extremely effective.
Dr. Kislan then states that the "…EE form can cause liver toxicity…"
What evidence does he have for this statement? The ethyl ester form has been used for clinical studies of EPA and DHA for at least 20 years with an excellent safety record throughout. In fact, there is at least as much laboratory and clinical research on the ethyl ester form compared to triglyceride.
Dr. Kislan then asserts that this alleged liver toxicity and the need for patient monitoring is the reason why "…the EE form of omega-3 is not available over-the-counter in any country other than the United States."
This statement is false. For years ethyl ester fish oil products have been sold to the public all over Europe without prescription. I personally know the owner and the senior UK distributor for the most popular fish oil product in Europe, an ethyl ester product.
Dr. Kislan further declares, "The EE alcohol in most omegas also causes the side effects associated with fish oil supplements such as belching with a fishy taste, GI upset, bloating and fish smell."
Fishy smell and taste in fish products arise from bacterial action on fish components. Fresh fish has no fishy smell or taste. If it occurs in a product, that means that the fish were not fresh enough, undesirable impurities were not removed thoroughly from extracted oil, and/or the product has gone rancid.
Then Dr. Kislan says, "The 4g of absorbable omega-3s recommended for anti-inflammatory effects can not be tolerated when in the EE form."
I have taken daily doses of a tablespoon (14 grams) of liquid ethyl ester fish oil for years with no adverse effects. If people are taking the capsule form, rather than liquid, they may have some digestive upset if they are sensitive to capsule constituents.
I do not wish to attack Dr. Kislan personally in any way. I believe it's possible that he has been misled by others. Nevertheless, the dissemination of misinformation about sources of omega-3s must cease. I believe both triglyceride and ethyl ester forms of omega-3s are useful. We are blessed with a wide range of viable choices for supplementing our diets with omega-3 essential fatty acids. Each has its rightful valued role to play.
Herb Joiner-Bey, ND
Medical Science Consultant
Barlean's Organic Oils
Skip Monovision, Fit Multifocals
I enjoyed the March Prescribing for Presbyopia column from John Mark Jackson, OD, MS, FAAO, titled "New Multifocal Designs: Give Back What Patients Are Missing," except for one part; he states that "Monovision is great but, as we all know, has its issues." I don't agree that monovision is great.
I've been fitting bifocal contacts lenses for 42 years and have never even thought of monovision. We have two eyes and a brain for a good reason. Depth perception is hurt tremendously and confidence is poor with monovision.
Even Benjamin Franklin did not think of having only one bifocal for reading. Contact lens practitioners, have faith in yourself and fit bifocal contact lenses.
Ben T. Balkema, OD
Grand Rapids, MI
Dr. Jackson's Response:
I'd like to thank Dr. Balkema for his interest in my column. Although I try to fit multifocals as often as possible, we cannot deny that monovision has "legs" — that is, large numbers of contact lens patients have used it successfully. There are patients who prefer their vision with monovision over vision with multifocals, primarily due to the lack of crisp vision at each distance that can occur with multifocals. This may change over time as multifocals improve, but because of the intentional aberrations induced to achieve the add power, it will always be an issue.
Monovision is less expensive as well, although I don't believe cost should be a primary factor in lens selection.
I think we owe it to our patients to present all options and recommend for them what we think is best based on our experience.
Upgrading to New Technology
I am writing in response to the May 2008 Contact Lens Case Reports column titled "Upgrade Patients When New Technology Becomes Available," by Patrick Caroline, FAAO, and Mark André, FAAO.
It's important to note that this patient was originally fit more than 18 months ago. At that time, the SynergEyes PS lens was not available in the marketplace and was still undergoing testing to optimize the design and the fitting approach. The SynergEyes PS lens that launched on Jan. 1, 2008 is a different offering than that which was available more than 18 months ago.
I agree that patients should be upgraded as new technology becomes available — upgrading this post-RK patient from uncomfortable GP contact lenses to the SynergEyes PS hybrid lens design has made lens wear possible, clearly improving his vision and quality of life. But the appearance of corneal neovascularization at the incision sites, while not an unexpected consequence of wearing any type of contact lenses in a post-RK patient, is always a concern.
SynergEyes, Inc. makes the following recommendations as part of our certification process for prescribing SynergEyes PS:
• Exercise extreme care when fitting any post-surgical patient in general, and incisional patients in particular.
• Incisional patients need to be monitored every three months, and semi-annual lens replacement is a must.
• Limit daily wearing time of patients with incisions or highly compromised corneas (14 hours/day may not be acceptable for this particular patient).
• Stress open-eye, lens-free time prior to lens application in the morning and after lens removal at the end of the day.
• Clearance across the treatment zone should always be the goal. The fluorescein photo shown in Figure 2 demonstrates excessive bearing in the region of the displaced corneal apex at 6 o'clock to 7 o'clock. The SynergEyes PS fitting guide recommends steepening the base curve, increasing the lift provided by the reverse curve, steepening the skirt curve or some combination of these options to achieve the required apical clearance.
Upgrading to new technology is a hallmark of the leading edge contact lens practice. This includes using the most up-to-date diagnostic sets and fitting recommendations provided by manufacturers.
Garold L. Edwards, OD, FAAO
Vice President, Clinical Affairs
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Contact Lens Spectrum, Issue: July 2008