Health for life

Many people with diabetes wonder if their blurred vision signals the beginning of diabetic retinopathy or perhaps another common cause of vision loss, macular degeneration.

While blurred vision occurs with both conditions, there are distinct differences between diabetic retinopathy and macular degeneration.

First, macular degeneration generally results in central vision loss while diabetic retinopathy results in dispersed areas of vision loss.

Heres a normal view:


Heres that same view through the eyes of someone with macular degeneration:


Heres that same view through the eyes of someone with diabetic retinopathy:


You may be able to turn your head to compensate for central vision loss. Compensation for dispersed loss from retinopathy is more challenging.

Another difference between the two is the age at which they develop.

Where age-related macular degeneration usually occurs in an older age group (60 years and older), diabetic retinopathy can and does strike a younger population.

The ADA states:

"After 20 years of diabetes, nearly all patients with type 1 diabetes and >60% of patients with type 2 diabetes have some degree of retinopathy."
- American Diabetes Association: Diabetic Retinopathy

The average age for diagnosis of type 2 diabetes has shifted from the 40s and 50s in recent years towards a younger population, occurring with troubling frequency in adolescents. Type 1 diabetes can occur in children as young as 2 years old.

Twenty years on from childhood or the teen years places someone with diabetes at risk of losing their eyesight at the height of midlife. The ADA says:

"Diabetic retinopathy is estimated to be the most frequent cause of new cases of blindness among adults aged 20–74 years."

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Photos of vision loss from NIH National Eye Institute via Wikipedia.

A large-scale National Eye Institute study has shown fish oil supplements containing omega-3 fatty acids do not alter the progression of age-related macular degeneration, says a national team of researchers including David M. Brown, M.D., an retina specialist at The Methodist Hospital who ran Houstons part of the study.

Another key finding of the Age-Related Eye Disease Study 2, or AREDS 2, is that lutein and zeaxanthin may be safer than beta-carotene in reducing risk of disease progression.

"If you look at all the analysis performed in the AREDS 2 study, it looks like lutein taken with zeaxanthin is at least as effective and may be better than beta-carotene," Brown said. "If you also consider that beta-carotene was associated with increased lung cancer rates in all former smokers, I no longer recommend any formulations containing beta-carotene."

Researchers saw a modest decrease in the development of age-related macular degeneration (AMD) among those who took high amounts of zinc, but that result was not statistically significant.

"Millions of older Americans take nutritional supplements to protect their sight without clear guidance regarding benefit and risk," said NEI director Paul A. Sieving, M.D., Ph.D. "This study clarifies the role of supplements in helping prevent advanced AMD, an incurable, common, and devastating disease that robs older people of their sight and independence."

Like beta-carotene, lutein and zeaxanthin can be converted to vitamin A in humans and can collect at the retina, where they probably limit chemical damage caused by light. Lutein is found in foods like egg yolk and animal fat deposits. Zeaxanthin is found in some berries, corn, and paprika.

AREDS 2s results agree with past studies that have shown an association between beta-carotene consumption and the development of lung cancer in current or former smokers. About half of AREDS 2 participants reported having been smokers at some point in their lives.

Macular degeneration is a disease in which retina damage causes a loss of visual acuity in the center of the eye, called the macula. AMD is a major cause of blindness in the elderly, and currently affects about 11 million Americans. National Eye Institute experts believe that number will double by 2050.

About 12 years ago, the National Eye Institute began funding studies to look at how diet and dietary supplements affect the progression of the disease. AREDS showed a 25 percent decreased risk of AMD when study participants took vitamin C, beta-carotene (a precursor to vitamin A), vitamin E, zinc, and copper (called the AREDS Formulation).

The five-year AREDS 2, which began in 2006, was a national study of more than 4,200 people. It suggests fish oil supplements probably do not need to be added to the formulation, and that lutein with zeaxanthin might replace beta-carotene in the AREDS Formulation, since lutein is not associated with increased risk for lung cancer.

"The first AREDS study showed us that vitamins really make a difference in decreasing the complications of AMD," Brown said. "Now with the AREDS 2, we have solid data on what to recommend to our patients. Based on the AREDS 2 data, I now recommend that my patients no longer take beta-carotene but look for a vitamin with 10 mg Lutein, 2 mg zeaxanthin, 80mg zinc, 2mg copper, 500mg vitamin C, and 400 IU vitamin E."