Friday, 31 January 2014

Age-related macular degeneration (AMD)

Robert Glass Blog - January 2014

Research has shown that antioxidants in the diet can slow the progression of age-related macular degeneration (AMD). The largest trials which have looked at this relationship are the Age-Related Eye Disease Study’s (AREDS 1 and 2). AREDS 1 (2001) found that people with the intermediate stage of dry AMD reduced their risk of developing advanced AMD (wet AMD) by 25% with a supplement which contained antioxidant vitamins. The AREDS 2 trial has now confirmed an improved version of this formula.

Visiting the optometrist can help identify the early and intermediate changes to your macula allowing you to make early treatment choices. Your visit may require drops to dilate your pupils so please make arrangement not to drive when attending and for approximately three hours afterwards.

Antioxidants are mainly found in fruits and vegetables and protect the body against damaging molecules known as free radicals. 
Free radicals are produced in the body when oxygen reacts with other molecules. They are known to damage or destroy cells, altering their function and preventing them from regenerating.

They may be formed in the retina (the light sensitive area at the back of the eye which contains the macula) due to its high demand for oxygen. Long term exposure may cause damage of the light sensing cells responsible for vision. Due to their potential to combat free radicals, diets rich in antioxidants have become of popular interest in the protection of AMD.

In the AREDS 1 study, research on antioxidants and eye health has mainly been focused on the vitamins A, C, E and zinc. The supplement in AREDS 1 contained: zinc – 80mg, vitamin C – 500mg, vitamin E – 400IU, copper – 2mg and beta-carotene – 15mg. A small amount of copper was added to the supplement as high doses of zinc can reduce the level of copper in the body.

Safety of AREDS 1 components
AREDS 1 showed that 7.5% of patients had an increased risk of hospital admission due to bladder/kidney complications from the high doses of zinc. Other research has found that smokers who take high doses of beta-carotene, as found in the AREDS 1 supplement, may be at an increased risk of developing lung cancer. In people with heart disease or diabetes taking high dose vitamin E supplements may increase their risk of heart failure.

The AREDS 2 trial (2008 – 2013) tested omega-3 as well as lutein and zeaxanthin as additional ingredients to the earlier AREDS formula. It also tested whether reducing the amount of zinc or taking out beta-carotene would reduce the numbers of reported side effects and still have the same benefits of reducing the risk of progression to advanced AMD.
It found that overall, there was no additional benefit of adding omega-3 fatty acids or lutein and zeaxanthin to the original formula, however, participants who took a version of the AREDS formula which contained lutein and zeaxanthin instead of beta-carotene, had their risk of progression to advanced AMD reduced by 18%.
Participants who had a low dietary intake of lutein and zeaxanthin at the start of the study who took a version of the AREDS formula with lutein and zeaxanthin instead of beta-carotene were also 25% less likely to develop advanced AMD.

Lowering the amount of zinc from 80 mg to 25mg and removing beta carotene from the original formula did not reduce the effectiveness of the supplements in protecting against the development of advanced AMD.
Beta-carotene appeared to increase the risk of lung cancer in previous smokers so it is likely to be safer for anybody who has ever smoked not to take supplements that contain beta-carotene. The lowered amount of zinc is also very likely to result in fewer stomach upsets in people taking the supplement.

The investigators now suggest that beta-carotene should be removed from the original AREDS formula and replaced with lutein and zeaxanthin. The recommended doses for this formula based on AREDS 1 and 2 are: Vitamin C 500mg, Vitamin E 400IU, Lutein 10mg, Zeaxanthin 2mg, Zinc 25mg, Copper 2mg.
Other trials which have investigated antioxidants in the progression of AMD have found similar results to AREDS 1 and 2 but are of lower quality and reliability.
AREDS 1 and 2 do not provide enough evidence to show that taking the supplement will prevent the onset of AMD.

Thanks to the Macular society for providing this information.

Thursday, 14 November 2013

One of the main causes of sight loss in the world is Age Related Macular Degeneration (AMD). There are two types of macular degeneration, wet and dry. Wet progresses more rapidly than dry and can be treated using certain drugs.  For many years scientists have searched for a cure to dry AMD but without much success. The following information may help to explain the current thinking on prevention.
George Torrey, Ph.D., a graduate of Brown (‘61), Harvard (‘62) and the Univ. of Connecticut (‘68), writes for the AMDF Newsletter and the AMDF Web site. Both his parents suffered from macular degeneration.
Consumption of fruits and vegetables containing two carotenoid pigments may be linked to a reduced risk for age-related macular degeneration, the leading cause of vision loss in people over the age of 55. According to research, lutein and zeaxanthin comprise a component of the central region of the retina and may play a role in some aspects of visual acuity. Increasing the concentration of these pigments in the eye may prevent the devastating vision loss caused by age-related macular degeneration.
Increasing macular pigment density may slow, or possibly even reverse, the progression of age-related macular degeneration.
Carotenoids are phytochemicals (chemicals found in plants) commonly found in certain fruits and vegetables that provide the red, orange and yellow colours of these foods. Lutein and zeaxanthin are found primarly in broccoli, corn, squash and dark green leafy vegetables like spinach and kale.
Lutein and zeaxanthin are concentrated in the fovea, the central region of the retina, in a spot known as the macula lutea, or yellow spot. The macula helps produce the sharp central vision needed for activities like reading, sewing and driving.
For the vast majority of those with age-related macular degeneration (AMD), there is no known cure or treatment. Symptoms of AMD include blurred or fuzzy vision; the illusion that straight lines, such as sentences on a page, are wavy; and the appearance of a dark or empty area in the center of vision. Risk factors for the disease include cigarette smoking and family history of AMD. Exposure to sunlight/UV, having light coloured irises, and even being a woman appear to be additional risk factors.
According to an article in The British Journal of Ophthalmology(2.) eating green leafy vegetables, which are rich in lutein and zeaxanthin, may decrease the risk for age-related macular degeneration. The goal of this study was to analyse various fruits and vegetables to establish which ones contain lutein and/or zeaxanthin and can serve as possible dietary supplements for these carotenoids.
Egg yolk and yellow corn contain the highest mole percentage (% of total) of lutein and zeaxanthin (more than 85% of the total carotenoids). Yellow corn was the vegetable with the highest quantity of lutein (60% of total) and orange pepper was the vegetable with the highest amount of zeaxanthin (37% of total). Substantial amounts of lutein and zeaxanthin (30-50%) were also present in kiwi fruit, grapes, spinach, orange juice, courgette, and different kinds of squash. The results show that there are fruits and vegetables of various colours with a relatively high content of lutein and zeaxanthin.
Most of the dark green leafy vegetables, previously recommended for a higher intake of lutein and zeaxanthin, have a 15-47% of lutein, but a very low content (0-3%) of zeaxanthin. This study shows that fruits and vegetables of various colours can be consumed to increase dietary intake of lutein and zeaxanthin.
Dr. Johanna M. Seddon and her associates at Harvard University(3.) found that 6 mg per day of lutein lead to a 43 percent lower risk for macular degeneration. Half a cup of cooked kale contains 10.3 mg of lutein while half of a cup of cooked spinach provides 6.3 mg.
The Schepens Eye Research Institute 1998 study concluded that vision loss associated with aging maybe preventable - even reversible - through improved nutrition. Although visual sensitivity decreases with age, this process need not be inevitable.

Thursday, 26 September 2013

Hello and welcome to my first post in my first Blog.
The first question to answer is, why am I blogging?
The fact is that I am only doing it because I feel as if I am missing out on a  way to share some of my thoughts with whomever wants to read them. Naturally, since I am an optician I plan to write a lot of about my profession.
Please pop back soon to see what I have come up with.