Preventive Medicine in Ophthalmology
Preventive Medicine in Ophthalmology
To truly combat eye disease, help patients avoid it in the first place. Here's how.
BY BRIAN WILL, MD
The United States is grappling with some significant problems — slow economic growth, high unemployment, dependence on foreign energy sources and growing federal budget deficits — and the high cost of medical care is one of the most vexing. It's bemoaned by politicians and businessmen alike. Amongst the many proposed solutions, one commonly voiced by medical professionals, policy-makers and the press is the potential for disease prevention and the likely economic benefit to society. Ben Franklin famously said, “An ounce of prevention is worth a pound of cure.” While it's undeniably true that it is generally better to try to avoid problems in the first place rather than try to fix them once they arise, there are some hitches to implementing that philosophy in the real-life practice of medicine. Like many things in life, good ideas are easy to generate, while “the devil is in the details” and the actual execution.
Preventive medicine concepts are not novel to ophthalmology. Unfortunately, though, disease prevention has frequently been confused with “early disease detection” rather than aimed at principles and programs for genuine disease prevention. As a consequence, true preventive measures receive little attention and even less implementation in our specialty.
To fairly address this issue, we need answers to some rather basic questions that I will address here:
(1) What is the evidence that suggests that degenerative diseases such as cataract, glaucoma, macular degeneration, diabetes, cancer and vascular occlusive disease can be prevented?
(2) How do we change the way we practice ophthalmology in order to assist our patients in pursuing lifestyle changes that can enable them to reduce their risk for developing these chronic illnesses?
(3) Do we have an ethical and professional obligation to not just impart these principles to our patients but to adopt strategies that can improve compliance and really make a difference in the incidence of morbidity and cost associated with chronic eye disease and vision loss?
Laying Out the Evidence
Let's begin by considering the evidence showing that preventive efforts can influence the natural history of many of the most common eye diseases.
• Cataracts. Certainly the preponderance of the ophthalmic literature focuses on refining the best method of cataract removal and visual rehabilitation of the patient. Magnificent advancements have been made in these arenas. In contrast, the notion that cataracts might be prevented by lifestyle choices remains virtually absent from major ophthalmic meetings and mainstream ophthalmic publications.
However, the Oxford arm of the European Prospective Investigation into Cancer and Nutrition1 demonstrated a significant association between diet and the incidence of cataract. In their study of 27,670 participants, after adjusting for age, smoking, ethnicity, hypertension, long-term medical treatment and hormone replacement therapy, cataract risk was stratified by dietary preference, with vegetarians and vegans demonstrating 30% and 40% reduction respectively when compared to meat eaters.
A study of 1,609 participants in the Melbourne Visual Impairment Project showed that cortical cataract was significantly associated with total carbohydrate intake2 while in another study of 3,654 participants, dietary glycemic index (GI) was similarly associated with cortical cataract after adjustment for age, gender and diabetes.3 In the latter, each standard deviation increase in dietary GI was associated with a 19% increase in cataract incidence, and people with the highest GI diet were 77% more likely to have cataract than those with the lowest GI diet. Although none of these studies identify a causal factor between dietary preference and cataract, they suggest an association with dietary oxidative load and lenticular opacification.
For women enrolled in the Carotenoids in Age-Related Eye Disease Study (CAREDS), an ancillary study of the Women's Health Initiative, after correcting for age, smoking and other factors, those women who ate diets highest in fruits and vegetables and lowest in fat demonstrated 37% fewer cataracts than those with diets low in fruits and vegetables and high in dietary fat. “Diet was the strongest risk factor related to reduced risk of nuclear cataract in this sample of postmenopausal women,” the authors noted. “Lifestyle improvements that include healthy diets, smoking cessation and avoiding obesity may substantively lower the need for and economic burden of cataract surgery in aging American women.”4
Similarly, in the Beaver Dam Eye Study, participants that consumed the most dietary lutein (kale, spinach, Swiss chard, etc.) demonstrated nearly 50% less cataract compared to those who ate the least. Subjects who ate the most spinach demonstrated 40% decreased incidence of cataract.5 Tobacco users also demonstrate a 72% increased incidence of cataract likely related to elevate serum cadmium that inactivates super oxide dismutase, thereby enabling oxidation of the crystalline lens.6
These and similar studies appear to demonstrate a strong association of lifestyle preferences with the incidence of cataract, and these factors appear to have a very significant clinical effect.
• Age-Related Macular Degeneration. AMD remains the leading cause of irreversible sight loss in the western world, and its prevalence is on the rise. Similar to cataract removal, methodologies for treating AMD have significantly advanced in recent years. Moreover, several high-tech early disease detection techniques have emerged. Despite these amazing success stories, as ophthalmologists we have consistently confused early disease detection with disease prevention and subsequently have done little towards actually encouraging preventive practices that might allow prospective patients to avoid or markedly postpone the onset of AMD.
CAREDS demonstrated a significant association between early AMD and diet, exercise and overall healthy habits. Those women with diets highest in fruits and vegetables showed a 46% reduction in odds for AMD, and those who exercised the most demonstrated a twofold decrease in risk. Nonsmokers who ate the healthiest diets and were the most active reduced their risk for AMD by 71%.7 The authors suggest that “adopting these healthy habits may markedly lower the prevalence of early AMD, the number of people who develop advanced AMD in their lifetime, and healthcare costs associated with treatment of this condition.”
In another large study, after controlling for age, sex, education level, body mass index, alcohol consumption and other variables, researchers found that the higher the dietary glycemic index (dGI), the more likely a person was to have macular degeneration. Those in the highest one-fifth of the dGI had more than a 40% increased risk of significant macular degeneration than those in the lowest one-fifth. The amount of carbohydrates consumed was not correlated with disease, suggesting that it is only carbohydrates with a high glycemic index that cause the effect.8
Similarly, twin studies of lifestyle changes such as consumption of vitamin D, betaine (grains and spinach) and methionine, as well as avoiding smoking, suggest that environmental and even epigenetic mechanisms are involved in AMD.9 Lead author Seddon, a specialist in AMD, concludes, “Eat a healthy diet with lots of fruits and vegetables, and that can make a difference — even if you have a genetic susceptibility to macular degeneration.”
Other studies indicate that individuals who are overweight face double the risk of developing AMD compared to those with normal body weight, and those who performed vigorous physical activities at least three times a week reduce their chances of developing AMD compared to those with a sedentary lifestyle.10 Unfortunately, with the obesity epidemic in America, the vast majority of Americans (and their physicians) do not even realize they are clinically overweight and at greater risk for AMD.
Hypertension has also been linked to AMD.11 Recently published data shows that persons with previously controlled hypertension (blood pressure less than 160/95) were approximately twice as likely, and persons with uncontrolled hypertension (blood pressure more than 160/95) were approximately three times as likely, to develop wet macular degeneration than persons with normal blood pressure.12 AREDS found that persons with hypertension were 1.5 times as likely to have wet macular degeneration compared with persons without hypertension.
In addition, high dietary fat intake is associated with an increased risk of macular degeneration in both women and men. Foods such as flaxseed that are high in omega-3 fatty acids are associated with decreased macular degeneration risk, but only among individuals with a lower intake of Omega-6 fatty acids.13-16
Atherosclerosis, associated with high-cholesterol western diets and a risk factor for heart disease and stroke, has been suspected of being involved in the development of macular degeneration for several decades. Vingerling found that people who had atherosclerotic plaques in their carotid arteries were more likely to have AMD.17
Researchers have also shown an inverse relationship between choroidal blood flow (as well as volume) and drusen extent, suggesting macular ischemia as a factor in why patients with drusen are prone to advanced disease.18
Individuals who are overweight face double the risk of developing AMD.
Additionally, high dietary intake of red meat is associated with increased risk for AMD. The likelihood of developing AMD was 47% higher in persons who consumed red meat 10 times per week or more compared to those who ate red meat 4.5 times per week or less — even after accounting for smoking and obesity. Lead author Chong suggests an increase in oxidative stress to the macula as the cause of this association.19
Yet another common lifestyle issue implicated in AMD is sunlight exposure. The risk profile appears dependent upon the individual's level of dietary derived serum antioxidant levels. People with low serum levels of vitamin C and E, zinc and zeaxanthin are at higher risk of developing AMD than those with high serum antioxidant levels.20 Those who stay outdoors in the summer sun for more than five hours a day in their early years of life have a twofold greater likelihood of developing early macular degeneration changes (soft drusen or increased retinal pigment). In these individuals, the likelihood of developing early AMD is reduced by wearing hats or sunglasses at least half of the time when outside in the summer sun.21
Smoking is the most consistently established modifiable risk factor for macular degeneration. The risk of AMD is two to three times higher in current-smokers compared with never-smokers.22 Quitting smoking can mitigate the likelihood of AMD by 6.7%. After another five years of not smoking, the risk is further reduced by another 5%; after yet another five years of no-smoking, the risk drops by an extra 4.2%.23
In AREDS, individuals with moderate or advanced AMD who received 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta carotene and 80 mg of zinc oxide (and 2 mg cupric oxide to prevent copper deficiency) had significantly reduced progression of their disease, compared with subjects receiving a placebo.24 Caution is advised, however, given evidence that beta-carotene supplementation may increase lung cancer risk among smokers, and that daily doses of vitamin E 400 IU and greater may increase cardiovascular and all-cause mortality.25
• Glaucoma. A number of studies suggest that, compared to other eye diseases, the relationship between glaucoma and lifestyle appears to be more complex.
Confounding factors include a simplistic focus on intraocular pressure rather than on health of the optic nerve as a metric of success. Clearly, in 2012 the data on IOP variability as an independent risk factor for glaucoma progression is inconclusive. Despite these limitations, generally, the conclusion of these studies is that a healthy lifestyle does decrease the risk of blindness from glaucoma.
In the Blue Mountain Eye Study, open-angle glaucoma patients who consumed coffee regularly had higher IOP than their counterparts who abstained from coffee consumption.26 Results from a large prospective, population-based sample of health professionals suggests that consuming five or more cups of caffeinated coffee per day was associated with a 1.6-fold increased risk of primary open angle glaucoma (POAG) in patients with a family history of glaucoma.27 In a longitudinal study of the role of caffeine in pseudoexfoliation glaucoma, the risk of pseudoexfoliation was significantly elevated by 63% in caffeinated coffee drinkers compared to non-drinkers.28
A recent study at the University of Michigan Kellogg Eye Center linked diabetes and hypertension, both modifiable risk factors, with an increased risk of developing POAG. People with diabetes alone had a 35% increased risk of developing POAG, those with hypertension alone had a 17% greater risk and those with both diabetes and hypertension had a 48% increased risk of developing POAG. Given the epidemic of obesity, type II diabetes and hypertension in America, these findings are staggering.
New studies also call into question the advisability of the often ill-conceived notion of ingesting dietary supplements. People who took greater than 800 mg/day of calcium were 2.4-fold more likely to report glaucoma than those getting lower amounts. For iron supplementation, people ingesting more than 18 mg/day were 3.8-fold more likely to report glaucoma. For those consuming high levels of both nutrients, the risk was 7.2-fold higher.28 The implications of these recent studies are truly sobering. Unfortunately, vitamin manufacturers appear to have convinced our society that true health comes in the form of daily vitamin supplementation; as medical professionals, we have frequently succumbed to that paradigm without fully considering the adverse physiologic consequences of such simplistic and reductionistic thinking. A diet rich in fruits and vegetables or adhering to guidance from well-controlled trials like AREDS will be of greater value than a scattershot approach to dietary supplementation.
• The Diabetes Epidemic. In America, diabetes is destined to financially swamp the US medical care system, with one in three Americans exhibiting diabetes or prediabetes in 2012.29 As if that's not alarming enough, projections are that diabetes rates will double or triple by 2050.30 Diabetes is clearly linked to the epidemic of obesity in this country where two thirds of Americans are overweight or obese. As ophthalmologists, we are familiar with the devastating effects this disease can have on vision, quality of life and workplace productivity.
The overwhelming majority of diabetes is due to excess body fat reserves interfering with insulin and thereby elevating serum blood sugar levels. Although the cause of obesity is frequently obscured by medical jargon, in America its predominant drivers are the excessive consumption of calorie-dense, nutrient-poor refined foods, excessive consumption of animal products (meat and dairy) and a sedentary lifestyle. Perhaps no other health problem receives more attention from the purveyors of quick fixes in the form of fad diets, pills, potions, lipo-cosmetic procedures and magic pharmaceutical agents than obesity. There is a lot of money to be made by telling people that they can't maintain a healthy weight on their own through simple lifestyle change and hawking a solution for $19.99 plus shipping and handling!
Perhaps more tragic than the devastating effects of diabetes on vision is the fact that with appropriate lifestyle modification, 50 to75% of Type II diabetics on insulin and 80 to 90% of those on oral hypoglycemic agents will normalize their blood sugar and be free of medication within weeks.31 Despite these known facts, ophthalmologists treating diabetics for cataracts, retinopathy and glaucoma rarely act as interventionalists in attacking the cause of the disease and effecting a cure. Instead, we blithely and efficiently treat the symptoms through surgery and laser therapy.
If as medical professionals we wish to truly fulfill our role as healers, it is time that we take strides to fix the “poisoned well” rather than manufacture and sell the antidote. Rather than chronicling the lifestyle factors that contribute to causing diabetes here, I recommend the book by Neal Barnard MD, Reversing Diabetes. It is a must-read for anyone serious about preventive ophthalmology.
What to Tell Our Patients?
Recognizing that lifestyle choices can profoundly affect our patients' risk of devastating vision problems is only the first step towards making a difference. As physicians, we need to understand these principles and communicate them effectively to patients. After all, in general, the same types of lifestyle choices that can improve eye health and protect against chronic eye disease are the same choices that improve heart health, reduce risk of dementia and vascular disease, and assist with weight loss.
A sedentary lifestyle contributes to obesity — and, thus, diabetes. Encourage routine exercise.
To be effective in communicating these principles, it is imperative that the physician — and not just the primary-care physician — becomes proactive in engaging patients on these topics. As a LASIK surgeon, I am shocked how many young patients I see who are on antihypertensive agents, oral hypoglycemics, statins and antidepressants. Many are in the overweight or obese category as well. Perhaps the most challenging issue is that many of these patients have never been told by their primary care physician that they can likely eliminate the need for these medications by changing their lifestyle. A subset is aware of these therapeutic options but don't really understand how to implement lifestyle changes. As a result, they remain on the pharmaceutical path that treats the symptoms rather than the cause; they lack direction, not will.
A quick look at a magazine stand at the local supermarket or a search on the Internet will expose most people to a lot of confusing, contradictory and frequently incorrect information promulgated by advertisers. In the sidebar on page 30, I've summarized several important principles that appear to be consistent with the scientific research from well-constructed health trials and that have stood the test of time and rigorous debate. To impart these to patients, feel free to photocopy this and hand it out, or adapt it as you see fit.
It's All in the Execution
The greatest business plan in the world is of no value without good execution. The same is true for implementing lifestyle modification objectives into your medical practice. You wouldn't expect compliance from a glaucoma patient if you simply gave him a glossy color brochure about the disease, prescribed some eye drops and sent him on this way. Changing human behavior takes a lot more than information.
Get Educated: The first step to success is to become educated yourself and start becoming a healthy person. Don't expect to find much on this topic at AAO or other specialty meetings, as it is generally ignored. Begin with some broad, well-documented and scientifically based information that will provide a good platform for change. Here are some books that fit the bill:
|What You Can Do to Improve Your Ocular Health|
Advice for patients from Brian Will, MD, ophthalmologist and wellness instructor, Loma Linda, Calif.
|1. Stop smoking. Nicotine is even more addictive than heroin or crack cocaine. Many people who try to quit just become dependent upon nicotine substitutes in the form of gums and patches. Go to a reputable stop-smoking program in your community or hospital for true success.
2. Eat more fruits and vegetables. Ideally, five to nine servings of fruits and vegetables every day. The phytochemicals and antioxidants will protect against cataracts, AMD and even cancer.
3. Reduce or eliminate meat and dairy products. They are loaded with cholesterol, fat and known cancer-inducing agents. Further, they are totally fiber deficient. And, by the way, chicken has as much or more cholesterol per serving as red meat!
4. Avoid refined foods. Most people consume way too much refined food in the form of cakes, pastries, ice cream, etc. This applies pretty much to anything in a “crinkly bag” or a can. These foods are calorie dense and nutrient poor as well as being chock full of salt. The mantra is: Eat whole foods! Eat foods as grown!
5. Omega-3 fatty acids are helpful. Most doctors recommend fish oil capsules or ingesting fish. However, virtually no fish products are mercury free. Mercury is toxic to the macula. Instead, consume flaxseed oil or, even better, eat flaxseed meal or chia seeds and get the extra phytochemicals present in the natural product.
6. Eat a very low-fat diet. Cut your oil, fat and grease intake in half. Animal fats in particular increase the risk of obesity and vascular disease. Fat from all sources increases risk for age-related macular degeneration.
7. Eat a diet that is low in sugar and refined foods containing sugars. A typical container of soda contains 10 to 12 teaspoons of sugar. These drinks spike your serum glucose levels and contribute to chronic disease. Eat unrefined complex carbohydrates, such as whole multigrain bread, whole wheat spaghetti, oatmeal and other cereal grains, beans, brown rice, etc.
8. Avoid caffeine. It can cause a rise in eye pressure that is linked to glaucoma. Drink between 8-10 cups of pure water each day for optimal health.
9. Avoid juices. They are calorie dense, and the healthy plant fiber has been removed, so there's little health benefit to them.
10. Exercise and lose weight. To feel good, get into a routine exercise program on a daily basis. Exercise reduces your risk for hypertension and helps with weight loss. Minimum is 30 minutes three times per week. For weight loss, double that amount. The best exercise? Simple walking — no gym fees, no expensive equipment, no “exerscuses” allowed, as almost everyone can walk. Remember, there is no such thing as bad weather, just bad clothing.
11. Control your cholesterol. The primary source of cholesterol in the American diet is from animal products — meat and dairy. Eliminating those from your diet, combined with getting to a healthy weight (based on BMI metrics) will reverse virtually all cases of hypercholesterolemia and avoid the potential for liver and muscle toxicity of statin medications.
12. Avoid vitamin supplements by eating whole foods. A diet rich in green leafy vegetables and a variety of fruits will deliver all of the needed vitamins and minerals needed for optimal health. Antioxidant supplements can help but are no substitute for a healthy diet.
13. Avoid dairy products. Research has shown that the highest rates of osteoporosis and hip fracture occur in countries with the highest consumption of dairy products. These findings call into question the mantra that dairy is needed for calcium and healthy bones. A balanced whole food, plant-based diet will provide all of the calcium, iron and other micronutrients your body needs.
14. Limit salt intake. Approximately 80% of the salt in our diets comes from eating refined foods and food from restaurants. A half can of canned soup can deliver 50% of the daily allowance of sodium. Canned vegetables can also be extremely high. American food is bathed in salt, but with some simple guidelines you can learn to recognize sodium disguised as food and make intelligent dietary choices.
• Former FDA chief, Dr. David Kessler's The End of Overeating: Taking Control of the Insatiable American Appetite addresses the issue of refined foods.
• Dr. Neal Barnard's Reversing Diabetes is a must read.
• Dr. T. Colin Campbell's The China Study, considered the “Grand Prix” of epidemiology, addresses the role of cholesterol and animal products in chronic disease.
• Peter Singer's The Ethics of What We Eat challenges you to consider what foods are healthy for ourselves and our planet, and explores how American food choices affect world supplies of food, clean water and contribute to deforestation of the rainforests, global warming and America's energy crisis.
• Cleveland Clinic Surgeon, Dr. Caldwell B. Esselstyn's book Prevent and Reverse Heart Disease: The Revolutionary, Scientifically Proven and Nutrition-based Cure is the primary resource that changed former President Clinton from his wayward dietary choices to a whole-food, plant-based diet.
• For those who don't have time to read, consider audio books or even documentaries like “Forks over Knives” or Dr. Sanjay Gupta's “The Last Heart Attack,” which can provide an information base.
If you believe that preventive measures are not part of medicine or represent a fringe science because “real medicine” requires the use of pills and procedures, then you are part of the problem in America, not the solution.
Take Action: “Without vision, the people perish” — this message from the Old Testament still resonates with us today. At a time when our country and our economy need our leadership in finding ways to reduce the cost of medical care and, more importantly, reduce the cost of chronic preventable illness, often we are more of the problem than the solution.
When it comes to affecting lifestyle changes for patients, a glossy brochure combined with an admonition to lose weight or to eat more vegetables is generally drowned out by decades of consuming refined foods, misleading nutritional information in the media promoted by special interest groups, family traditions and cultural eating preferences, “pseudoscience” and other myths promulgated by food industries, the convenience of fast food and human inability to make radical life changes without hands-on intervention.
First, become an expert yourself. In addition to the reading suggested above, stay grounded in the science of peer-reviewed papers to maintain a balanced and rational perspective. Fringe medicine concepts will jeopardize your credibility and marginalize your effectiveness.
Secondly, engage patients with the question, “If there was a way for you to no longer have diabetes (or hypertension, obesity, etc.) would you be interested in getting off or reducing your dependence on medication?” If the answer is affirmative, they may be interested in lifestyle modification.
Here is where you can provide programs that will empower patients to make permanent lifestyle changes. The ideal solution is residential centers that have proven results such as The Pritikin Longevity Center, the Preventive Medicine Research Institute (Dean Ornish), The Dr. McDougall Health and Medical Center and the Weimar Institute. I recognize, however, that these programs also come with big disadvantages for many patients: they entail a high fee, the need to take time off from work and the problem of compliance once the patient returns to their home and old lifestyle habits.
While these residential programs are very effective and scientifically based, you will need other options for your patients. The best solution in my experience has been to refer these patients to a local 40-hour educational Complete Health Improvement Program (CHIP) (www.chiphealth.com). This is a community-based lifestyle program that addresses all aspects of healthful living, provides a peer support network, motivational speakers, uses local expert resources from physicians to hospitals, teaches nutritional and cooking skills and creates an exercise regimen that is sustainable. It's more affordable than the programs listed above, and participants can attend in off-work hours, reducing lost wages. Lifestyle changes are implemented gradually while the patient manages day-to-day modifications of schedules for exercise, food pantry revisions, dealing with family and other challenges in their own work and home environment. They participate in cooking schools to learn how to prepare delicious healthy food, how to read nutritional labeling and how to shop for healthy foods. I personally volunteer as Medical Director for three regional CHIP programs that serve our community of 250,000 people. The cost is nominal.
The nutritionist's mantra: Eat whole foods! Eat foods as grown!
CHIP results have been published in more than 20 peer-reviewed journals. The most recent publication in the American Journal of Cardiology shows that the CHIP program can reduce high cholesterol levels similar to leading statin medications.
It is important to understand that disease reversal will require a greater commitment than disease prevention. However, for those who may be unable to commit to a formal lifestyle management program due to time or financial restraints, I suggest a method called “The Full Plate Diet” (www.fullplatediet.org). Television programs like “The Biggest Loser” are typically designed to be more entertaining than motivating but they can create common ground for doctor-patient discussion.
Popular programs such as “Dr. Oz” raise awareness of healthy lifestyle but they often attempt too little lifestyle change, to placate advertisers and maintain viewership. The fact that obesity and diabetes are escalating out of control despite the “popularity” of these and similar programs, underscores the fact that these programs are ineffective motivators for lifestyle change in our society.
Right now, we are looking for answers to very difficult problems. However, as physicians, it is our responsibility to find a way to help people. If the mechanisms are currently not in place, then we need to invent new methods to change the direction of health in this country.
Time to Act
Most importantly, as professionals we must begin to take our destiny into our own hands. The Titanic was equipped with the most sophisticated telecommunications systems of its day as well as state-of-the-art propulsion, steering and navigation systems. The problem that led to its calamitous demise was that the crew ignored messages warning them of icebergs in their path. Arrogance, blind faith in technology and an unwillingness to take appropriate corrective action when the answers were all too clear drove them headlong to destruction.
We can continue to ignore the fact that current medical practices in America are unsustainable and we can sail the “HMS Medicare” into the looming iceberg. The choice — rather, the lifestyle choice — is ours. OM
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33. Anderson, JW. Dietary Fiber and Associated Phytochemicals in Prevention and Reversal of Diabetes, in Nutraceuticals, Glycemic Health and Type 2 Diabetes (eds V. K. Pasupuleti and J. W. Anderson), 2009, Wiley-Blackwell, Oxford, UK.
||Brian Will, MD, is an adjunct clinical professor of ophthalmology at the Loma Linda University School of Medicine, Loma Linda, Calif., and medical director for Will Vision and Laser Centers in Vancouver, Wash. He is a Wellness Instructor and Medical Director for the Clark County CHIP Association, Clark County, Wash. He is an active sea kayaker, skier and backpacker. Contact him at Drwill@willvision.com.
Ophthamology Management, Volume: 16 , Issue: April 2012, page(s): 24 - 32