Vision

Smoking

Age Related Macular Degeneration (ARMD) is a leading cause of blindness. It is 6 times more common in smokers than non-smokers and we really are not sure why, but it may be related to an increase in free radicals, Free radicals are organic atoms that have lost an electron. They are very unstable, short-lived, and highly reactive. As they steal an electron from another atom they start a chain reaction that alters molecules damaging tissues. Antioxidants, are molecules that prevent free radicals from harming healthy tissue. Vitamin E, beta-carotene (a pre-cursor to vitamin A), and vitamin C are the most common antioxidants.

Vitamin A is an essential vitamin which is necessary to maintain good health. Vitamin A is essential for good vision, but has a number of other important functions as well. Vitamin A is necessary for the growth of healthy bones and teeth, normal immune system function and reproductive function. It also helps maintain the health of the lining of the eyes, respiratory function and digestion. It is required for normal embryonic development.

Vitamin A precursors such as beta-carotene and other carotenoids are powerful antioxidants. Other antioxidants include zinc, selenium, manganese, and copper. They neutralize free radicals which can damage DNA and contribute to age-related eye disease (macular degeneration), heart disease (coronary artery disease) and cancer. The antioxidant properties of beta-carotene and other carotenoids are highest when obtained from foods. There seems to be a significant is less evidence for antioxidant benefit from high dose beta-carotene as a dietary supplement. This difference between foods and dietary supplements actually may be due to the presence of other compounds in fresh fruits and vegetables called phytochemicals.

One study showed that 20,000 IU supplemental beta-carotene and other antioxidants in a dose typical of a good diet decreased the incidence of cancer by 31% and reduced death rates from all causes by 37%. Other studies suggest beta-carotene from food may be safer than synthetic beta-carotene found in dietary supplements. Contrary to prior beliefs that high dose beta-carotene and vitamin A supplementation guard against some types of cancer and heart disease, recent studies suggess potential harmful effects. The Beta-carotene and Retinol Efficacy Trial (CARET) performed by the National Cancer Institute (NCI) showed that 30 mg (100,000 IU) of beta-carotene and 25,000 IU vitamin A failed to decrease the risk of cancer or heart disease.

The study was stopped 21 months early because the beta-carotene/vitamin A takers who were smokers, ex-smokers or asbestos workers had a 28% increase of lung cancer and a 17% more likely chance of dying.

Another study in 1994 showed that smokers taking 20 mg beta-carotene per day had an 18% higher risk of lung cancer and an 8% higher risk of dying from lung cancer or heart disease. A 12-year Physicians’ Health Study taking 50 mg (166,667 IU) of beta-carotene every other day in 22,000 non-smoking men showed no benefit or risk.

Almost all multi-vitamins (Centrum, Centrum Silver, etc.) contain Vitamin A. I would suggest that all smokers, ex-smokers and second-hand-smokers should reconsider their use of these products.

Eye Nutrition

We have always thought that nutrition is a factor in maintaining good eye health. As early as 400 B.C. sailors who stayed out to sea for a long were noted to develop illnesses that today we call scurvey. Its cause is lack of vitamin C. One manifestation of the condition is dry eyes. Most animals can produce their own Vitamin C, but primates including us cannot.

Vitamin A is required for the chemical reactions that take place in the retinal photo-receptors that lead to vision. Vitamin A deficiency can lead to night blindness and in severe cases total blindness. It is rare in this country but is thought to occur in up to one third of children under 5 years of age around the world.

In the year 1999 the AREDS report demonstrated that nutritional supplements could significantly slow the progression of macular degeneration. The AREDS report was based on 4,000 subjects followed over a minimum of five years. The study participants took supplements of Beta Carotene, Zinc, Vitamin C and Vitamin E and they had 25% better outcome than those not taking the supplements. Since then these supplements have been frequently used in the management of ARMD.

In the last ten years since AREDS several studies have impacted the use of the AREDS supplements. Beta Carotene has been shown to increase the risk of lung cancer in smokers. Zinc supplements can cause genitourinary problems. Vitamins C and E are strong antioxidants and are still recommended.

Other studies now point to other supplements that might be effective. Omega-3 fatty acids are fatty acids, which have anti-inflammatory properties. Omega-6 fatty acids have the opposite effect and promote inflammation. Omega-3 is commonly found in cold-water fish (salmon, sardines and tuna) and nuts. The appropriate supplement level is thought to be 1g to 3g/day. This powerful antioxident appears helpful in macular degeneration and dry eyes as well as cardiovascular disease.

Age and Vision

Over our lifetime our eyes change in many ways.

Babies eyes

Our eye color is determined by how many melanocyte pigment cells are present on our iris. If we have many our eyes appear brown. If their are fewer pigment cells the irises may appear blue, green or grey. Hazel eyes are an indeterminate color - maybe dark in some areas and light in other areas.

Our babies eyes may change color. Many baby's irises are gray at birth, and they may stay that color or they may darken over the first six to nine months of life. So gray or blue eyes can turn brown, green, or hazel, but brown eyes won't lighten and become blue.

The gene for blue eyes is recessive, meaning it does not produce a blue eye unless it's matching gene from the other parent is also for blue eyes. So even if both parents have brown eyes, they may both have a recessive blue gene and have a 25% chance of having a baby with blue eyes. If both parents have blue eyes their is a 0% chance of having a blue eyed baby.

Color Vision, Color Blindness, & Color Deficiency

The human retina (the light sensing tissue inside the eye) has two types of light sensing cells. The "rods" supply our night time vision and are very sensitive to even very weak light. They do not see in color and the resolution is not real good so at night we see large details in black, white and grey. We do not see the fine details. The "cones" are our daytime color sensing cells which are capable of very fine resolution. In daylight we see very clearly and in color.

The genes that direct how the retina forms before birth are located on the "X" chromosome. A female develops into a female before birth because she has two "X" chromosomes. A male fetus develops into a male because he has an "X" chromosome matched with a "Y" chromosome. If the males "X" chromosome is defective he does not have a second "X" to take its place and the "cone" receptors do not develop normally resulting in abnormal color perception. Thats why color vision defects are much more common in males (5% of all males) than females (very rare). This is called Inherited Color Deficiency and can be to different degrees. In most cases the person has difficulty distinguishing between red and green. They see color, but some colors appear the same.

A female with one bad "X" chromosome is considered a carrier. Her female children have a 50% chance of getting the bad "X", so 50% would be normals and 50% would be carriers. Her male children also have a 50% chance of getting the bad "X" so 50% would be normal and 50% would be color deficient.

Some retinal and optic nerve disease can also color deficiencies. This is called Acquired Color Deficiency and it most often effects yellow-blue vision instead of red-green vision.

Eye Safety

safety glasses Safety Glasses

Our office provides industrial prescription safety glasses manufactured by the best optrical company in the world. We have plans offering special reduced costs on safety glasses to industries in the area. Wearing safety glasses reduces injuries and saves money for the employer.

Eye First Aid

Eye injuries do occur. Knowing how to deal with them can mean the difference between minor eye damage and permanent injury, or even blindness.