Dr. Grossman’s Blog

Long-term heavy smokers have a 2.5 to 3.5 times greater risk of losing vision from age-related macular degeneration, according to medical geneticist John R.W. Yates, Ph.D., of the University of Cambridge.

A study in the British Journal of Ophthalmology shows a strong link between smoking and age-related macular degeneration.  The study also shows the risks associated with exposure to second-hand smoke.

Researchers conducted a case-control study in four British counties to determine the relationship between smoking and either of the two forms of end-stage age-related macular degeneration — geographic atrophy and choroidal neovascularization.

Between 2001 and 2003, 435 participants with age-related macular degeneration were compared with 280 controls.  Of the 435 cases, 261 had choroidal neovascularization, 106 had geographical atrophy, and 68 had a mixed phenotype.   Smoking status was assessed by a questionnaire; smokers were defined as those who smoked at least one cigarette a day for a year.

Scientists found a statistically significant association between age-related macular degeneration and pack-years of smoking. Pack-years were defined as the number of packs smoked a day multiplied by the number of years smoked.

Specifically, for 40 or more pack-years:

• The risk was almost triple, compared with non-smokers, for age-related macular degeneration
• For choroidal neovascularization, the risk was more than double
• For geographic atrophy, the risk was more than triple.

Compared with non-smokers who weren’t exposed to second-hand smoke, the non-smokers who had such exposure had nearly twice the risk of having any form of age-related macular degeneration.

Learn more about macular degeneration including recommended self-help and nutrition to reduce your risk of blindness

Source:  “Smoking and age related macular degeneration: the number of pack years of cigarette smoking is a major determinant of risk for both geographic atrophy and choroidal neovascularization,” Khan, et al,  Br J Ophthalmol 2006;90:75-80.

In glaucoma, cells in the optic nerve die, preventing the brain from understanding what patients see.

Scientists have long believed that there is a link between a gene named WDR36 and glaucoma, but have been unable to determine what the gene does and why some people with variations of the gene get glaucoma while others don’t.

University of Alberta geneticist, Dr. Michael Walter, has published results of a new study which help to explain this link. 

“Our results suggest that glaucoma is polygenetic, which means there have to be changes in several different genes in order for WDR36 to cause the disease,” said Walter, a professor and chair of the Department of Medical Genetics in the Faculty of Medicine & Dentistry.  This finding helps explain why only some people who have WDR36 gene variations get glaucoma.

“Only 10 per cent of glaucoma cases are caused by known genes, so the genes involved in this polygenetic interaction may help to explain the other 90 per cent,” said Walter, who is also a professor in the Department of Ophthalmology.

The WDR36 gene normally helps make ribosomes, specialized molecules that make the proteins necessary to keep the cell functioning.  Dr. Walter suspects that changes to WDR36 will affect ribosome production, and in turn affect the cell’s ability to function.

In addition to this mutation, changes also have to happen to the STI1 gene, which normally packages the proteins produced by WDR36′s ribosomes.  Glaucoma occurs when WDR36 isn’t producing ribosomes properly and STI1 isn’t packaging those proteins properly.  Both mutations must be present to cause the disease.

This DNA detective work may have a tangible impact on preventing and treating glaucoma, as it may help doctors learn to treat the disease rather than just the symptoms.

Learn more about glaucoma

SOURCE:  “Genetic Sleuth Solves Glaucoma Mystery”, University of Alberta Express News, March 20, 2009, http://www.expressnews.ualberta.ca/article.cfm?id=10052.

A recent study done at the Catholic University of Korea showed that using eyedrops containing retinal palmitate daily for 4 weeks can effectively relieve the symptoms of dry eyes and improve tear film production. 

Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea

Accepted 11 August 2008. published online 09 October 2008. Inquiries to Choun-Ki Joo, Department of Ophthalmology, KangNam St Mary’s Hospital, #505 Ban-Po Dong, Seocho-Ku, Seoul 137-040, Korea

For more information on dry eyes and eyedrops containing retinal palmitate, see the dry eye section at http://www.naturaleyecare.com/

A study published in the American Journal of Epidemiology suggests a diet heavy in red meat may increase the risk of age-related macular degeneration, a leading cause of blindness.

Researchers at the University of Melbourne in Australia evaluated associations between red meat and chicken intake and AMD, in a cohort study of 6,734 people aged 58 to 69.  Meat intake was estimated from a food frequency questionnaire; bilateral digital macular photographs were taken and evaluated for AMD.  Of the group, 1,680 participants had cases of early AMD and 77 had cases of late AMD.

It was discovered that participants who ate 10 or more portions of red meat each week were nearly 50 percent more likely to experience deterioration of the retina.  Participants who consumed chicken at least three times a week reduced the risk by more than 50 percent.

Study authors suggested that “different meats may differently affect AMD risk and may be a target for lifestyle modification.”

Read more about food sources for nutrients that can help prevent macular degeneration

SOURCE:  “Red Meat and Chicken Consumption and Its Association With Age-related Macular Degeneration”, Chong, et al, American Journal of Epidemiology 2009 169(7):867-876.

Researchers in the Department of Ophthalmology and Visual Sciences at the University of Wisconsin have found that risk factors for cardiovascular disease such as smoking and higher body mass index are also risk factors for age-related macular degeneration (AMD).
 
The subjects in this study were 4,288 women age 63 years and older who were participating in the Women’s Health Initiative Sight Examination (WHISE).  Using a standardized questionnaire and examinations, researchers obtained information from the women on cardiovascular disease and its risk factors.  

919 of the women in the study were diagnosed with AMD (determined by standardized grading of fundus photographs).

The results were straightforward:  women who were identified as having four important risk factors for cardiovascular disease were also significantly more likely to have AMD.  These risk factors were:

• smoking
• use of calcium channel blockers
• diabetes, and
• greater body mass index.

Learn more about macular degeneration

Read other studies about macular degeneration research and prevention

SOURCE:  Cardiovascular disease, its risk factors and treatment, and age-related macular degeneration: Women’s Health Initiative Sight Exam ancillary study, Klein, et al, Am J Ophthalmol. 2007 Mar;143(3):473-83. Epub 2007 Jan 10.

Lutein May Help Visual Contrast Sensitivity for Computer Users

Lutein is known to be an essential nutrient in helping prevent the onset of macular degeneration. Researchers now believe that lutein may also help protect against the detrimental effects of long-term computer display light exposure.

A study published in the British Journal of Nutrition indicates that improvements in the eye’s sensitivity to contrast on a computer screen were observed following 12 weeks of supplementation with lutein.

Scientists at the Peking University in China studied 37 healthy individuals aged 22 to 30 who had long-term computer display light exposure. Participants were randomly assigned to one of three groups: one group was given placebos, one group was given 6 milligrams of lutein daily, and one group was given 12 milligrams of lutein daily.

Levels of serum lutein and visual performance indices such as visual acuity, contrast sensitivity and glare sensitivity were measured at the beginning of the study and again at 12 weeks.

After 12 weeks researchers found an increase in blood levels of lutein in both lutein groups. The study authors noted: “Visual function in healthy subjects who received the lutein supplement improved, especially in contrast sensitivity, suggesting that a higher intake of lutein may have beneficial effects on the visual performance.”

Lutein can be found in green leafy vegetables and egg yolks. Learn about food sources for nutrients important to good eye health, including lutein.

Read other studies about the benefits of lutein for good eye health

SOURCE: “A 12-week lutein supplementation improves visual function in Chinese people with long-term computer display light exposure”, Ma, et al, British Journal of Nutrition, Published online by Cambridge University Press 19 Feb 2009 doi:10.1017/S0007114508163000.

The 73-year-old, known only as Ron, had the experimental surgery seven months ago at London’s Moorfields Eye Hospital and is now able to see flashes of light, follow white lines on the road, and sort grey and black socks.

The eye known as the Argus II, which was developed by US company Second Sight, uses a miniature camera mounted on glasses to transmit images to the back of the eye.

An “artificial retina” consisting of an array of electrodes sends messages along the optic nerve to the brain.

So far 18 patients around the world have undergone the surgery as part of trials and Ron, who lost his sight in his forties due to the hereditary eye disorder retinitis pigmentosa, was one of three patients to have the device fitted at the London hospital.

As he starts to get use to the device his life will be transformed even more as he gradually learns how to use the artificial eye.

He said: ‘For 30 years I’ve seen absolutely nothing at all, it’s all been black – but now light is coming through.

‘It gives me grades of bright light to black and anything in between. I can actually sort out white socks, grey socks and black socks.’

Consumption of lutein has been linked to a reduced risk of developing age-related macular degeneration (AMD).  (read studies showing the benefits of lutein for eye health ).

In order to consume the levels of lutein recommended for good eye health many people take lutein supplements.  Results from a study published in the Journal of the American Dietetic Association suggest that it may be beneficial to take supplements of lutein along with vitamin C.

Researchers from the University of Wisconsin gave young healthy men and women supplements of lutein alone, or supplements of lutein combined with vitamins C or E.  It was noted that absorption of lutein varied greatly among individuals, regardless of whether they had taken lutein alone or with vitamins C or E.  However, it was determined that lutein was absorbed significantly faster when given simultaneously with vitamin C.

Learn about lutein and vitamin C supplements, as well as food sources for nutrients essential to good eye health

SOURCE:  “Lutein absorption is facilitated with co-supplementation of ascorbic acid in young adults”, Tanumihardjo, et al, J Am Dietetic Assoc 105:114-18, 2005.