Have you ever wondered about vision loss and how it can occur? Age-related macular degeneration (AMD) is an eye disease that effects many people over the age of 50. It can develop undetected over time and is often only diagnosed once a person notices a change in their vision and goes to an eye doctor If left untreated it may cause severe and often permanent vision loss. It happens when the macular pigment protecting the macula, wears down allowing blue light and oxidative stress to damage the light-sensitive cells in the macula. However, thanks to numerous scientific studies at Waterford Institute of Technology1,2 we know what causes it and how to help prevent it.
There are two types of the disease commonly called dry and wet AMD. Whilst the dry form is the most common and is a slowly deteriorating condition, the wet form is not as prevalent but needs urgent treatment over years.
What is Dry AMD?
Dry macular degeneration causes the cells in your macula to slowly stop working normally. It may begin in one or both eyes, then spread to the other.
Dry AMD tends to progress slowly in stages, becoming increasingly worse over time with vision loss occuring in the middle to late stages. In the early stages, dry AMD can develop in one eye first with no noticeable effects on your vision, as the second, good eye, compensates. Often, it is only when the second eye develops symptoms that a problem becomes apparent. This could be too late to treat the first eye. That is why, if you are over 50, it is crucial that you have a full eye exam every year.
What is Wet AMD?
Wet AMD is a more advanced type of the disease in which abnormal blood vessels grow and leak in the eye, causing vision loss. It is less common than dry AMD but it can cause more rapid loss of vision.
If your optometrist feels you have wet AMD, you will be referred to an ophthalmologist at a hospital for a full assessment and diagnosis.
If found early enough, wet AMD can be treated, using regular Anti-VEGF injections into the eye. One of the contributing factors for wet AMD is a protein called vascular endothelial growth factor (VEGF-A). VEGF-A causes the new weak blood vessels to grow and leak within the eye, damaging central vision. Anti-VEGF therapies stop further damage to the eye and can even sometimes repair some of the damage that has occurred. Multiple injections will be administered over a number of months.
After that, the patient will be evaluated to see if more injections are needed.
What symptoms should we look out for?
Getting a full eye examination every year is the best way to ensure you look after your eye health. Dry AMD often develops with no noticeable changes to a person’s vision. Being aware of even the tiniest of changes in your vision may help you catch the disease early enough to prevent vision loss. Both dry and wet AMD can present with very similar symptoms, here are the changes in your vision to look out for:
- Your vision may be a little more blurred than normal.
- Words may vanish, when you’re reading.
- Objects in front of you may change shape, size, and colour, as well as appear to move or disappear
- The vividity of colours might fade over time
- You might find bright light blinding and unsettling, or you might find transitioning from dark to light situations challenging
- Gaps or dark patches in your eyesight, similar to a smudge on glasses, may become noticeable, especially first thing in the morning
- Straight lines such as door frames, lines on the road or lamp posts may appear deformed or bowed
If you notice any changes in your vision, no matter how small, make an appointment with your optometrist as soon as possible. Your optometrist can test your vision with an OCT machine, which will scan and provide cross-sectional images of your retina. This will detect even the earliest signs of macular degeneration, often referred to as drusen. These are small yellow deposits seen at the back of the eye, that become bigger as the disease progresses. There is currently no cure for dry AMD, however that doesn’t mean nothing can be done to prevent it from getting worse.
What causes Age-related Macular Degeneration?
The risk factors for AMD can be split into modifiable and non-modifiable risks.
The non-modifiable risk factors are things we cannot change or influence such as genetics, age (aged 50+) and family history of the disease.
The risk factors within our control are:
- Smoking – being a current smoker quadruples the risk of progression to late AMD3. Current smokers develop late wet AMD at an average of 5.5 years younger than those who never smoked and 4.4. years younger than past smokers4,5. However, if you give up smoking the risk of AMD goes back to that of a non-smoker within 10 years of quitting6.
- Body Mass Index – There is a direct association with a higher body mass index (BMI) (>30) leading to higher risk of AMD and progression to advanced AMD7.
- Nutrition – A diet low in omega-3 and -6 fatty acids, antioxidant vitamins, carotenoids and minerals are a risk factors for AMD. The macular pigment which protects the eye, needs to be nourished with carotenoids from our diet every day. Otherwise the macular pigment breaks down allowing damage to the macula. .
1. Enrichment of Macular Pigment Enhances Contrast Sensitivity in Subjects Free of Retina Disease: Central Retinal Enrichment Supplementation Trials – Report 1, Nolan et al, IOVS, 2016.
2. The Impact of Supplemental Antioxidants on Visual Function in Nonadvanced Age-Related Macular Degeneration: A Head-to-Head Randomized Clinical Trial” Akuffo, et al IOVS, 2017.
3. Bertram, K.M., et al., Molecular regulation of cigarette smoke induced-oxidative stress in human retinal pigment epithelial cells: implications for age-related macular degeneration. Am J Physiol Cell Physiol, 2009. 297(5): p. C1200-10.
4. Tan, J.S., et al., Smoking and the long-term incidence of age-related macular degeneration: the Blue Mountains Eye Study. Arch Ophthalmol, 2007. 125(8): p. 1089-95.
5. Detaram, H.D., et al., Smoking and treatment outcomes of neovascular age-related macular degeneration over 12 months. Br J Ophthalmol, 2019.
6. Evans, J.R., A.E. Fletcher, and R.P. Wormald, 28,000 Cases of age related macular degeneration causing visual loss in people aged 75 years and above in the United Kingdom may be attributable to smoking. Br J Ophthalmol, 2005. 89(5): p. 550-3.
7. Seddon, J.M., et al., Progression of age-related macular degeneration: association with body mass index, waist circumference, and waist-hip ratio. Arch Ophthalmol, 2003. 121(6): p. 785-92.
