Macular Degeneration

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What is Age-Related Macular Degeneration?

Macular degeneration is a progressive condition, which can lead to central vision loss amongst people age 50 and over. The macula at the small central portion of the retina consist of light sensing cells that enables the retina to turn light into electrical signals to the brain, which provides sharp central vision. In Age-Related Macular Degeneration (ARMD), the macula deteriorates due to the presence of major abnormalities in its four functionally interrelated tissues.1

It is estimated that 48% of blindness cases among adults aged 50 years and over in New Zealand were due to ARMD. As a result, this contributed to 400-500 new blindness cases per year. ARMD is more common in people aged 50 or more.

 

Risk factors for ARMD include

                a positive family history,

                smoking

                diabetes

                high dietary fat intake

                obesity (particularly in men)

The influence of genetics is strong. If you have brothers or sisters who have developed ARMD your risk is between 3 and 6 times greater than the general population. To put this risk in to context; in the US population about 0.4% of people between 50 and 60 have the disease, while it occurs in 0.7% of people 60 to 70, 2.3% of those 70 to 80, and nearly 12% of people over 80 years old.

 

On the up side; studies have shown that there was no significant relation between the risk of ARMD and people with high blood pressure, elevated cholesterol, or elevated triglyceride levels. Environmental factors such as UV light exposure and diet can also contribute to this disease.4

What happens in ARMD?

There are three different stages of Age-Related Macular Degeneration, which can be classified as early, intermediate, and the late stage of the disease. The size of yellow fatty deposits called drusen, and the presence of retinal pigmentation changes, determine the stages of disease.

 

Early stage of the disease is defined by the presence of medium-sized drusen in one or both eyes. Intermediate stage of ARMD is diagnosed by the presence of large drusen or changes in the colour of the retina. The early and intermediate stage of the disease are also known as the Dry Form of ARMD. People in the early stage typically do not have vision problems but the larger size of drusen may lead to the distortion of vision as the disease progresses.

 

Interestingly the presence of drusen in the eye does not automatically mean that ARMD will occur.

 

There are two forms of late stage ARDM:

geography atrophy (also known as advanced dry) and

neovascular (also known as wet). Just FYI Neo means new, and vascular means vessel (usually blood vessel) so neovascular means new vessel..

 

Geography atrophy is the gradual thinning of light sensitive layers in the macula leads to vision loss. The majority of people with late stage Macular Degeneration suffer from geography atrophy.

 

Neovascular macular degeneration is characterized by the growth of abnormal blood vessels underneath the retina. There is a leakage of blood and fluid into the retina which causes damage to the macula and eventually leads to permanent vision loss. 1,5

What can I do?

Early changes in ARMD can be detected in regular eye examinations by an optometrist. It is recommended that adults at the age of 45 to have a general eye check up by an optometrist once every five years until the age 60 years, followed by every three years thereafter.6

 

People with early ARMD typically do not suffer from any symptoms. The hallmark symptom of late age-related macular degeneration is a loss or distortion of the central visual field. However, the symptoms may be unrecognized until it progresses or affects both eyes. The symptoms are defined by the how the disease progress in different types of ARMD.

 

The symptoms include:

Dim, blurry spot in the middle of your vision. (A dark area appears in the center of vision, which may resolve in the presence of lower level of light.)

Loss of visual acuity (clarity of vision)

Loss of vision

The alarming symptom of age-related macular degeneration is a sudden onset distortion or loss of vision and they should be urgently referred to an ophthalmologist. This could be due to a hemorrhage caused by neovascular degeneration or other eye conditions. A delay in treatment may result in a poorer treatment outcome.7

Prevention of Age-Related Macular Degeneration

There is no treatment for the early stage of this disease but there are steps that patient can take to reduce their risk and prevent it. The risks can be reduced by avoiding smoking, wearing UV-blocking sunglasses and including fruit, vegetables, fish in their diet.1 A meta-analysis of studies suggests that a higher consumption of lutein and zeaxanthin reduces the risk of people developing macular degeneration by 26% when compared to people with low lutein intake.8

 

It is believed that lutein and zeaxanthin in the macula blocks blue light from reaching the underlying structures of the retina, thereby reducing the risk of light-induced oxidative damage that could lead to macular degeneration. Dietary sources of lutein and zeaxanthin include egg yolk, corn, kiwifruit, dark green leafy vegetables such as spinach, lettuce and kale, and various colored vegetables such as green and orange peppers (capsicum), red grapes, pumpkin, broccoli, green beans, zucchini (courgette), honeydew melon, apples and oranges.

 

Regular consumption of fish and omega-3 fatty acids found in fish is also believed to lower the incidence of age-related macular degeneration. It has been shown in a systematic review and meta-analysis that people with high consumption of omega-3 fatty acid have a reduction in their risk of late age-related macular degeneration by 38% and reduction by 33% among people with high intake of fish twice per week.9

Multivitamin and mineral supplementation

The studies carried out by researchers at the National Eye Institute indicated that a combination of certain vitamins and minerals reduced the risk of macular degeneration among people who have intermediate and late stage Macular Degeneration. According to the first randomized trial (known as the AREDS trial), there was a risk-reduction of 25% of macular degeneration for people taking a supplement combination of vitamin C, vitamin E, beta-carotene, zinc, and copper.10 The second trial (AREDS2) found that the replacement of beta-carotene with a 5-to-1 mixture of lutein and zeaxanthin reduce the risk of disease progression in late stage Macular Degeneration. Beta-carotene has also been shown to increase the risk of lung cancer in non-smokers, so patients are recommended to avoid taking beta-carotene as a supplement. 11

Charles Bonnet syndrome (Visual Hallucinations)

People with impaired vision sometimes can experience visual hallucinations, known as Charles Bonnet syndrome. They may see simple patterns of lines, shapes, detailed pictures of people, or buildings. It is stated that the occurrence of visual hallucinations in patients with age-related macular degeneration is about 5-40%.14

Charles Bonnet syndrome is not a mental illness, and experiencing these visual hallucinations is a relatively common occurrence. There is limited evidence on the treatment of Charles Bonnet syndrome. It can be resolved in some cases with specialised treatment where an improvement can be seen in the visual acuity. In the meantime, there are ways that can be done to reduce hallucinations. As hallucinations occur more commonly in dim light, a brighter environment might help by turning on lights or televisions. Blinking and closing eyes again to keep concentrating on a real object might be helpful as well.1

 

1. https://nei.nih.gov/health/maculardegen/armd_facts 

2. National Health Committee. Age-related macular degeneration, Tier 2 assessment consultation submissions. Wellington, New Zealand: National Health Committee, 2015. Available from: http://nhc.health.govt.nz (Accessed May, 2016). 

3. Access Economics. Clear focus - the economic impact of vision loss in New Zealand in 2009. A report for Vision 2020 Australia in support of the Vision 2020 New Zealand Trust. Australia: Access Economics Pty Limited, 2010. Available from: http://blindfoundation.org.nz/learn/blindness/clear-focus (Accessed May, 2016) 

4. Chakravarthy U, Wong TY, Fletcher A, et al. Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis. BMC Ophthalmol 2010;10:31.

5. Chakravarthy U, Wong TY, Fletcher A, et al. Clinical risk factors for age-related macular degeneration: a systematic review and meta-analysis. BMC Ophthalmol 2010;10:31.

6. Glaucoma NZ. Glaucoma screening. Available from: www.glaucoma.org.nz/About-Glaucoma/Investigations/Glaucoma- Screening.asp (Accessed May, 2016)

7. Royal College of Ophthalmologists. Age-related macular degeneration: guidelines for management. London: Royal College of Ophthalmologists, 2013. Available from: www.rcophth.ac.uk (Accessed May, 2016).

8. Ma L, Dou H-L, Wu Y-Q, et al. Lutein and zeaxanthin intake and the risk of age-related macular degeneration: a systematic review and meta-analysis. Br J Nutr 2012;107:350–9. </span></p>

 

 

9. Chong EW-T, Kreis AJ, Wong TY, et al. Dietary omega-3 fatty acid and fish intake in the primary prevention of age-related macular degeneration: a systematic review and meta-analysis. Arch Ophthalmol 2008;126:826–33. <

10. Age-Related Eye Disease Study Research Group. 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;119:1417–36.

11. The Age-Related Eye Disease Study 2 (AREDS2) Research Group. Secondary analyses of the effects of lutein/zeaxanthin on age-related macular degeneration progression: Areds2 report no. 3. JAMA Ophthalmol 2014;132:142–9.

12. National Health Committee. Age-related macular degeneration. Wellington, New Zealand: National Health Committee, 2015. Available from: http://nhc.health.govt.nz/ (Accessed May, 2016).

13. Schmucker C, Ehlken C, Agostini HT, et al. A safety review and meta-analyses of bevacizumab and ranibizumab: off-label versus goldstandard. PLoS ONE 2012;7:e42701.

14. Schadlu AP, Schadlu R, Shepherd JB. Charles Bonnet syndrome: a review. Curr Opin Ophthalmol 2009;20:219–22. 

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