Depending on the material used to make a lens, between 4-16% of light striking the lens surface is ordinarily reflected back or "lost" by the lens. A multi-layer coating of metal oxides, just a few microns thick can significantly increase the amount of light transmitted through the lens by decreasing the percentage of light lost to reflection.

This multi-layer coating is called an anti-reflective or "AR" coating. AR coatings are placed on microscopes and camera lenses to increase light transmission and maximize image quality. AR coatings can sometimes have a faint green or purple color. This color effect can be adjusted when necessary to create a pleasing cosmetic tint, as is often done for spectacle lenses.

AR coating for glasses

Cosmetic advantage - Eye contact is an important part of human interaction. If you glance at someone wearing glasses with ordinary clear lenses, it’s sometimes hard to see their eyes. Even though the lenses are clear, their eyes are obscured by light reflected back toward you from both the front and back surfaces of the lenses.

Some light is actually being reflected from the back lens surfaces and bouncing back and forth inside the lens (between front and back surfaces), until it escapes. These "internal" reflections appear as a series of concentric reflections or rings. Thick lens edges, found in corrections for high degrees of myopia (nearsightedness), often produce rings which create a "coke bottle" look. Modern AR coatings can virtually eliminate these unsightly rings and make the lenses nearly invisible.

Nighttime advantage - Driving

When there are many light sources present, "ghost" images can be a real problem for glasses wearers; the main example of this is driving a car at night. Headlights from other vehicles and streetlights can create distracting double images that make seeing difficult and contribute to eyestrain and fatigue. AR Coatings not only reduce the ghost images but actually increase the amount of light transmitted through the lenses to the eyes. There is an overall reduction in glare and halos around lights - a welcome addition to nighttime vision.

Daytime advantage - Sunglasses

Reflections from back lens surfaces can also be annoying. This is most noticeable with sunglasses because a dark lens acts like a mirror. Under certain conditions, the wearer can actually see their own eyes reflected from the backs of the lenses. To see the effect a back-surface AR coating can have on your vision with sunglasses, cup both hands alongside your lenses, so that all light coming from behind you is blocked…the improvement may surprise you.

Improved technology

Lenses with antireflective (AR) coatings used to be hard to clean but no longer. Fingerprints and smudges have been a challenge for previous anti-reflective lenses but many lenses now incorporate advanced surface treatments that make cleaning much easier. AR coatings are also more scratch-resistant than in the past.

The next time you order glasses, be sure to ask about what’s new in lens coatings and materials…a lot has changed! If you have a strong prescription, think about requesting an AR coating in conjunction with high-index lenses to make your glasses look and feel as thin as possible. You’ll not only look better but see better too!

Vision and Health Newsletter courtesy of:

Dr. Gordon Wong

Gordon G. Wong, O.D.
Wildon C. Wong, O.D.

7825 Fay Ave.
Suite 140
La Jolla, CA 92037

858-454-4699

We would like to thank you for your patronage and for allowing our office to provide your eye care needs.

As the end of the year is quickly approaching, we want to remind you to make an appointment if you need to use money from your Flexible Spending or Health Savings account by December 31.

For your convenience we will be open Friday December 26, the day after Christmas and Saturday December 27 for appointments. Our appointments fill up quickly, so please call soon.

We look forward to seeing you and providing you with the highest quality eye care possible.

Dr. Gordon Wong
Gordon G. Wong
Wildon C. Wong

Chronic Dry Eye - A New Treatment

Millions of Americans suffer from chronic dry eye disease, a condition in which the eye does not produce adequate quantity or quality of tears. While the condition occurs in both men and women, it is much more common in women. Over 3 million women in the United States alone — or 1 in 12 — over the age of 50 suffer from chronic dry eye. Risk factors for this condition include hormonal changes, autoimmune diseases such as arthritis, lupus and Sjögren’s (”SHOW-grins”) syndrome.

Dry-Eye Symptoms

• Itching
• Burning
• Irritation
• Redness
• Blurred vision that improves with blinking
• Discomfort after reading, watching TV or working on a computer
• Excessive tearing

Excessive tearing may seem to be an unusual symptom for chronic dry eye syndrome but these irritant tears, produced as a reflex reaction to the syndrome, contain more water than normal tears, which have a balance of water, fat and mucus. The excess tears just run off the eyes and cannot lubricate them as healthy tears do.

What Causes Dry Eyes?

Chronic dry eye is most common in post-menopausal women because of the hormonal changes associated with aging. Testosterone plays a critical role in maintaining the tear-making lacrimal gland. As women grow older, their production of testosterone declines, making the lacrimal gland more susceptible to inflammation. If the lacrimal gland becomes inflamed, reduced tear production may result.

Any condition that damages the lacrimal gland can decrease tear production. Sjögren’s syndrome is a chronic disease in which white blood cells attack the moisture-producing glands. The classic symptoms are dry eyes and dry mouth, but it is a systemic disease, affecting many of the body’s organs. It is one of the most prevalent autoimmune disorders. It is important to realize that environmental, occupational, and lifestyle factors, such as smoke, dry air, dust, the wearing of contact lenses for extended periods of time, and prolonged computer use, can all intensify the symptoms of chronic dry eye disease.

Reducing The Symptoms of Dry Eye

Dry eye syndrome is an ongoing condition that cannot be cured, but the accompanying dryness, scratching and burning can be managed. Ultraviolet (UV) blocking sunglasses can help reduce irritation from sun exposure and help shield your eyes from the effects of wind and blowing dust. Artificial tears can help lubricate chronically dry eyes but they do not help increase tear production. Avoid frequent use of products that whiten the eyes – they can actually make a dry eye problem worse. Adding a humidifier can help offset the drying effects of many heating and air conditioning systems.

New Prescription Therapy For Dry Eyes - Restasis®

In 2003, Allergan introduced a new FDA-approved eye drop called Restasis® that actually helps increase natural tear production, in patients with dry eye disease. The effect of Restasis® is not seen immediately, but after a period of regular use, many patients experience a significant improvement in natural tear production and a reduction in their symptoms.

Your eye doctor will normally prescribe Restasis® drops to be used once or twice per day. There can be some local irritation upon instillation but the drops are well tolerated by the majority of patients. Some patients may require the addition of lubricant eye drops along with their Restasis therapy but this becomes less necessary as the ability to produce natural tears increases. If your eye doctor determines that Restasis therapy is indicated, many major health insurance companies now provide coverage. Consult your particular carrier for the most up-to-date information.

A Word Of Caution - Severe dry-eye cases, if left untreated, can lead to scarring or even ulceration of the cornea and loss of vision. If you have persistently dry eyes, it is wise to seek the advice of your eye doctor. Never change or discontinue medications without checking with your doctor. If you are considering LASER vision correction, it is important that you first seek treatment for any dry eye symptoms.

Sources:

1. Allergan, Inc.
2. American Optometric Association
3. St. Luke’s Eye Institute

Calcium - The "Supernutrient"

Calcium is the first nutrient approved by the FDA for the prevention of a specific disease. The “supernutrient” status of calcium stems from its potential to reduce the risk of osteoporosis, hypertension, colon cancer and other diseases.

Calcium is essential to life. Not only is it the principal mineral in bones and teeth, but calcium is also involved in blood clotting and muscle contraction, among other functions. All of these processes require maintenance of a constant level of blood calcium. Bone is the body’s calcium reserve. When dietary calcium intake is low, skeletal reserves of calcium are drawn upon. Any depletion of bone calcium results in a corresponding reduction in bone’s mechanical strength and eventually increased fracture risk.

High Blood Pressure (hypertension)

Since the mid-1980s, there has been accumulating evidence that a dietary pattern low in fat and rich in low-fat dairy foods, fruits and vegetables reduces blood pressure. A blood pressure reduction occurs often within two weeks that is comparable to that achieved with drugs. In addition, the blood pressure-lowering effect of a low-fat diet is often independent of sodium intake and changes in body weight. Researchers estimate that if the general population were to adopt such a diet, the decrease in blood pressure alone would reduce stroke by 27% and coronary heart disease by 15%.

Osteoporosis

It is important to understand that bone is not a hard and lifeless structure; it is, in fact, complex, living tissue. Our bones provide structural support for muscles, protect vital organs and store the calcium essential for bone density and strength. Because bones are constantly changing, they can heal and may be affected by diet and exercise. Until the age of about 30, you build and store bone efficiently. Then, as part of the natural aging process, your bones begin to break down faster than new bone can be formed. In women, bone loss accelerates after menopause, when your ovaries stop producing estrogen - the hormone that protects against bone loss. Think of your bones as a savings account. There is only as much bone mass in your account as you deposit. The critical years for building bone mass are from prior to adolescence to about age 30. Some experts believe that young women can increase their bone mass by as much as 20 percent - a critical factor in protecting against osteoporosis. A balanced diet rich in calcium and vitamin D, combined with weight-bearing exercise is highly recommended.

Colon Cancer

A protective role for calcium against colon cancer is demonstrated in several different types of scientific studies. Extensive data indicate that calcium reduces abnormal cell proliferation in the colon. A recent investigation of over 800 adults at risk for colon cancer because of removal of adenomatous polyps (i.e., precursors of colon cancer) from the colon found that adding 1200mg calcium per day to their diet reduced colon polyp adenomas by 19 to 24%.When patients at risk of colon cancer consumed an additional 800mg calcium per day from lowfat dairy foods (i.e., a total dietary intake of 1500mg calcium per day), several early markers of colon cancer were reduced. This beneficial effect was greater than expected from the level of calcium provided. The researchers speculated that other components in dairy foods may work together with calcium to produce these positive effects.

A protective role for calcium against colon cancer is demonstrated in several different types of scientific studies. Extensive data indicate that calcium reduces abnormal cell proliferation in the colon. A recent investigation of over 800 adults at risk for colon cancer because of removal of adenomatous polyps (i.e., precursors of colon cancer) from the colon found that adding 1200mg calcium per day to their diet reduced colon polyp adenomas by 19 to 24%.When patients at risk of colon cancer consumed an additional 800mg calcium per day from lowfat dairy foods (i.e., a total dietary intake of 1500mg calcium per day), several early markers of colon cancer were reduced. This beneficial effect was greater than expected from the level of calcium provided. The researchers speculated that other components in dairy foods may work together with calcium to produce these positive effects.

A protective role for calcium against colon cancer is demonstrated in several different types of scientific studies. Extensive data indicate that calcium reduces abnormal cell proliferation in the colon. A recent investigation of over 800 adults at risk for colon cancer because of removal of adenomatous polyps (i.e., precursors of colon cancer) from the colon found that adding 1200mg calcium per day to their diet reduced colon polyp adenomas by 19 to 24%.When patients at risk of colon cancer consumed an additional 800mg calcium per day from lowfat dairy foods (i.e., a total dietary intake of 1500mg calcium per day), several early markers of colon cancer were reduced. This beneficial effect was greater than expected from the level of calcium provided. The researchers speculated that other components in dairy foods may work together with calcium to produce these positive effects.

Dietary Calcium Calcium-rich foods include foods from the Milk Group (e.g., milk, yogurt, cheese). Green leafy vegetables, calcium-set tofu, shellfish, crustaceans and a few nuts are other calcium-containing foods. Food sources of calcium are usually good sources of other essential nutrients. This is why diets low in calcium are generally low in several other essential nutrients. For individuals who cannot meet all of their calcium needs from foods naturally containing this nutrient, fortified foods (e.g., breakfast cereals, bread, pasta) calcium supplements are advisable.

Supplement - Calcium Carbonate - There are several different forms of calcium available. Each form has a different degree of solubility and absorption. Older people often have a stomach acid deficit or take drugs such as Prilosec that block stomach acid production. Individuals with insufficient stomach acid output have been shown to absorb only about 4% of calcium carbonate supplements. Even people with normal levels of stomach acid only absorb about 22% of calcium carbonate supplements. Most commercial calcium preparations (including “oyster shell” calcium) and OTC anti-acid products contain lower-cost calcium carbonate.

Supplement - Calcium Citrate Malate - A form of calcium called calcium citrate is more effective at getting into the bloodstream. While people with insufficient stomach acid output absorb only about 4% of calcium carbonate supplements, they can absorb up to 45% of calcium citrate supplements. While calcium citrate is superior to most commercial calcium supplements, there is another form of calcium that has even better solubility and absorption. When the chelating agent malic acid is added to calcium citrate, calcium citrate malate is created, a compound that is 10 times more soluble than calcium citrate.

Recommendations

• The government has established new goals for the daily intake of calcium for men and women. Called AI (Adequate Intake), the figures below supplant the old RDA (Recommended Daily Allowance) and represent the amount of daily calcium that all individuals in the following age groups should try to meet: For men and women ages 50 to 70: 1,200 mg a day. For men and women ages 19 to 50: 1,000 mg a day.
• Your body can’t absorb more than about 500 mg of calcium at a time, so divide a daily dose of 1,000 mg, for example, into two doses of 500 mg and take them at different times of the day.
• In addition, when calculating your dose, make sure to look at the amount of “pure” or “elemental” calcium, not just the weight of each pill. The packaging will usually provide this information. For example, a 600 mg calcium carbonate tablet contains 240 mg of elemental calcium.
• The absorption of zinc, iron, and magnesium may be hindered by calcium, particularly when calcium is taken in high doses. Take a multimineral supplement to ensure balanced absorption of these other nutrients.
• Calcium carbonate may cause gas and constipation in some cases. If this happens, switch to calcium citrate. This should resolve the problem.
• Take calcium with food–it’s best absorbed that way. Orange juice and other foods with calcium citrate mixed right in can now easily be found on grocery store shelves.
• Avoid calcium supplements made from bone meal, oyster shells, or dolomite; they may contain high levels of lead.
• People over age 65 are advised to use calcium citrate because they may not have enough stomach acid to absorb calcium carbonate.
• Don’t consume calcium within one to three hours of taking an antibiotic such as doxycycline, minocycline, or tetracycline. It may decrease the absorption of the drug.
• If you use thiazide diuretics, consult your doctor before taking calcium supplements. When taken together, they can cause dangerously high calcium levels in the body, possibly resulting in kidney failure.

Sources:

1. University of Oregon Health Sciences
2. Columbia University College of Physicians & Surgeons