The research behind graceful eye ageing

In October, 2001, one of the world’s largest clinical eye studies, conducted in America, revealed that high levels of antioxidants and zinc slowed down the progression of AMD by 25% in patients with a high risk of developing advanced AMD[1].

This study was titled, ‘The Age-Related Eye Disease Study (AREDS)’ and it investigated the effects of antioxidants and zinc on macular and lens health to prevent and/or slow down AMD and cataract, respectively. It was sponsored by the National Eye Institute, one of America’s National Institutes of Health.

The macula or macula lutea is the immediate area around the fovea which is located in the centre of your retina. The macula and fovea contain the highest amount of cones which are a type of photoreceptive cell responsible for sharp colour vision during the day. These photoreceptors in the macular degenerate with age, particularly after the age of 65 and this is known as age-related macular degeneration. Its sufferers develop irreversible ‘doughnut’ vision because they lose their central vision and are left with only their peripheral vision. Treatment is currently very limited therefore interest lies in preventing and slowing down the progression of AMD.

Cataract occurs when the elastic fibres in the lens become opaque instead of transparent. The light rays can no longer come through the lens.  Vision can be restored by surgically removing and replacing the lens however, finding ways to prevent and slow down cataract development could lead to more treatment options for patients.

Researches divided this study into two clinical trials, one for AMD and the other for cataract. Both trials generally shared the same patients aged between 55 and 80 years. There were 3,640 people suffering from at least early AMD and 4,629 participants in the cataract trial. Approximately 90% of people were followed for a minimum of 5 years.

Patients were randomly assigned to receive daily, one of four tablets: 1) zinc alone; 2) antioxidants alone; 3) zinc and antioxidants combined; and 4) placebo which had no effect.

The antioxidant and zinc formulations and dosages are displayed in table 1.

Table 1 Formulation and dosages of nutrients

Tablet Ingredients
Antioxidant 500 mg vitamin C
400 IU vitamin E
15 mg of beta-carotene
Zinc 80 mg zinc oxide

The best results were seen in patients with intermediate and severe AMD in one eye taking the combined (antioxidants and zinc) supplement. Patients had a 25% reduced risk of developing advanced AMD and a 19% reduced risk of its associated vision loss. Table 2 shows the results from each group.

No supplement slowed down the progression of patients with early AMD and no effects were seen in the cataract group.

Table 2 Results from all the groups

  Zinc + Antioxidants Zinc alone Antioxidants alone
Reduced risk of developing AMD 25% 21% 17%
Reduced risk of central vision loss

 

19% 11% 10%

These results suggest that people with a moderate to high risk of developing advanced AMD may possibly slow down the progression of their disease by taking a supplement containing zinc and antioxidants.

References

  1. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8.Arch Ophthalmol, 2001.119(10): p. 1417-36.
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