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What is Macular Degeneration?

Macular degeneration (AMD) is an age-related disease that affects central vision. It is a gradual death of patches of the central retina responsible for your detailed vision. 90% of cases are known as “dry” or atrophic for which there is currently no effective treatment. 10% of cases are known as “wet” or neovascular. This type causes more rapid and severe vision loss but early treatment can limit the damage.

  • What are the symptoms and causes of macular degeneration?

    The dry form of AMD causes gradual loss of central vision. It firsts manifests with slightly blurry central vision that does not improve with glasses. It occurs due to accumulation of metabolic waste products under the central retina. These plaques or “drusen” cause oxidative damage to the surrounding tissue and lead to patchy central vision loss or increased distortion over time. In later stages, it can cause a complete loss of central vision.

    Large plaques can weaken the underlying tissue to the point where blood from underneath the retina starts to leak into the retina and cause rapid vision loss (wet AMD). This manifests as rapid onset distortion or patches of blur that worsen over the course of a few days. Both forms of AMD are very rare under the age of 50 but the incidence increases exponentially with age.

  • What is the risk of developing macular degeneration?

    Some risks are genetic (non-modifiable) and others are environmental and can be modified.

    Non-modifiable risk factors include being female, having fair skin and light eye color, moderate to high myopia (near-sightedness), and having an immediate family history.

    Environmental factors include smoking, lifetime UV exposure (especially when young) and poor diet and nutrition. These modifiable factors can contribute to progression because they lead to further oxidative stress.

    Modern science has given geneticists insight into the genetic risk “alleles” contained in our DNA. Much of the data being analyzed today is a retrospective analysis from the largest study ever conducted on the efficacy of vitamin supplements and AMD. This was the the AREDS (Age-related eye disease study). It was started when we knew very little about the disease and the protocols and supplements were changed at various points along the way, leading to complex statistical analysis, controversy, and confusion which still exists today.

    During statistical analysis of the AREDS data, it was noted that AMD progressed faster in some patients who were supplementing with zinc. This lead to speculation that certain people were genetically predisposed to this type of progression and should NOT be taking added Zinc. There are now easily administered in-office genetic tests (MaculaRisk® and VitaRisk®) designed to assess both the risk of disease progression, and what combination of supplements would work best. There are conflicting viewpoints on both the validity and implication of these tests, and the results of such tests need very cautious interpretation.

  • What is the treatment for macular degeneration?

    The wet type of AMD requires urgent referral to a retina specialist for treatment to prevent further vision loss. Nowadays, treatment involves periodic injections of a class of drug (anti-VEGF) that stops the blood vessels from leaking. These painless injections are done in office at regular intervals from 4 to 12 weeks apart, depending on severity. The goal of treatments is to prevent further vision loss but in some cases, vision can improve slightly following treatment.

    As noted previously, there is no currently available treatment for the dry type of AMD. At this time, a healthy diet and nutritional supplements (vitamins) are the only means to slow its progression. This too is an area of controversy.

    The AREDS study is still the only evidence based long-term study we have to draw from and the evidence from it only applies to stage 2 (moderate) dry AMD or greater. There is no evidence of the efficacy of vitamin supplementation in prevention of disease or those with mild AMD. The most recent combination of vitamins and nutrients from this study came to be known as the AREDS2 formulation and variants of it can be found in numerous commercially available eye vitamins. There is still much debate on these formulations, especially surrounding the use of zinc (more below).

    The Canadian RDI for Zinc is 9mg/day, and the AREDS study confirmed no difference in efficacy between 25mg and 80mg/day of supplementation. Yet most commercially available AREDS supplements contain 80mg of Zinc per daily dose! Zinc has been implicated in some studies as contributory to heavy metal toxicity and may be associated with a number of diseases, including Alzheimer’s. For this reason, we do not advise taking supplements containing zinc and if you do, we advised no higher than 25mg/day.

    We also know is that nutrition also plays a large role. More on this can be found in our blog article here. Antioxidant and anti-inflammatory nutrients such as Vitamins A, C, E, Zinc and Omega 3 fatty acids play a role in sequestering “free-radicals” which cause oxidative damage. In addition, lutein, zeaxanthin and other carotenoids play a protective role by preventing free-radical formation and oxidative damage. These carotenoids are found in high concentrations in the macula (central area of the retina). We often recommend carotenoid supplements but it is important to take formulations that are in the ideal ratio since they compete with each other for absorption.

    We have an in-office nutritional survey you can fill out to see if you are getting adequate intake of these nutrients, and if supplementation may be of benefit. Based on your risk profile, your optometrist can discuss appropriate preventative strategies. If you have AMD, you may be sent home with a nutrition or supplement plan, along with an “Amsler Grid” to monitor for any changes at home. If you have a family history or are concerned about AMD, book an eye exam so we can assess your risks and go over our findings and recommendations.