Between Monday 23 and Sunday 29 September it is National Eye Health Week. To mark this, Porterhouse Medical Group is raising awareness for age-related macular degeneration (AMD), one of the most common causes of vision loss in adults.
AMD is a condition that affects the macula, a small structure at the back of the eye. The macula is responsible for our central vision, most of our colour vision and the resolution of fine details . AMD usually affects people in their fifties and sixties, with 1 in 200 suffering from the condition by the age of 60. In the UK, more than 600,000 people are affected by AMD, and with an increasingly ageing population it is anticipated that its prevalence will continue to rise [1–3].
There are two types of AMD: dry and wet. The dry form is the most common, accounting for about 90% of cases . Dry AMD causes progressive vision loss due to inflammation and death of photoreceptors (specialised cells in the eyes that are responsible for the perception of colour and night vision) [4, 5]. Unfortunately, there is currently no treatment for dry AMD. Wet AMD is a less common but more aggressive type of the disease and is associated with rapid progression to severe vision loss, sometimes within days [2, 6]. Up to 20% of people with dry AMD will go on to develop wet AMD . Although wet AMD causes a more rapid deterioration of vision than the dry form of the disease, there are treatment options available. The standard treatment for wet AMD is intravitreal injections of anti-VEGF agents. This is because the pathology of wet AMD is mediated, in part, by a chemical called vascular endothelial growth factor (VEGF), which causes aberrant development of new blood vessels at the back of the eye [5, 6]. These vessels can bleed and leak fluid, thus causing loss of central vision. Anti-VEGF agents work by inhibiting the formation of these new blood vessels .
Living with AMD
AMD does not cause total blindness, as it doesn’t affect peripheral vision . However, loss of central vision heavily affects a person’s ability to engage in everyday and work-related activities, such as reading, cooking and driving. Along with functional decrease, AMD may also cause emotional distress, as those affected lose the ability to see faces clearly, become increasingly dependent on help for everyday tasks and may experience visual hallucinations . Such hallucinations are believed to be caused by the brain continuing to process visual information in the absence of actual visual input from the photoreceptors, comparable to ‘phantom limb syndrome’ in which amputees continue to feel sensation from an amputated limb .
Common symptoms of AMD are [1, 8]:
- Gaps or dark spots appearing in central vision
- Objects seeming to change shape, size or colour
- Colours fading
- Bright light becoming uncomfortable and glaring
- Words disappearing while reading
- Straight lines, such as doorframes, appearing distorted or bent
Taking care of your eyes
Family history of AMD is a strong risk factor for developing the condition and there is of course little that can be done regarding a genetic predisposition . However, there are steps that everyone can take to maintain good eye health and lower their chance of developing AMD (and other eye conditions).
- Get regular check-ups
As a general rule, most people, even those with perfectly healthy eyes, should attend an eye test every couple of years . AMD, like many conditions affecting the eyes, does not cause pain or discomfort, and by having regular check-ups an optician can detect early signs of disease, even before symptoms of altered vision are evident to the patient . Early detection also increases the chances of receiving effective, vision-saving treatment .
- Protect your eyes
Just like your skin, UV rays from the sun can cause damage to your eyes . It is therefore important to remember to protect your eyes by wearing sunglasses with appropriate UV protection. Sunglasses that provide the appropriate level of UV protection comply with the British Standard BS EN ISO 12312-1:2013 and carry the CE marking .
- Stop smoking
For smokers, the risk of developing AMD is up to 4 times that of non-smokers; for smokers with a genetic predisposition to the condition the risk increases to 20 times that of a non-smoker [1, 3].
- Maintain a healthy diet
Certain essential substances required for macular function are not produced by the body and must be obtained from the diet. These substances are called yellow plant pigments and they give certain foods their colour . They can, unsurprisingly, be found in yellow and orange fruits and vegetables, as well as in leafy greens and eggs .
You can learn more about AMD, and how to live with and manage the condition, by visiting the Macular Society web page: https://www.macularsociety.org/.
- Macular Society. Your guide to age-related macular degeneration. Available at: https://www.macularsociety.org/sites/default/files/resource/Macular%20Society%20Guide%20to%20AMD%20accessible%20pdf%20MS002%20JUN17.pdf. Accessed September 2019.
- Al-Zamil WM and Yassin SA. Recent developments in age-related macular degeneration: A review. Clin Interv Aging 2017; 12: 1313–1330.
- García-Layana A, Cabrera-López F, García-Arumí J et al. Early and intermediate age-related macular degeneration: Update and clinical review. Clin Interv Aging 2017; 12: 1579–1587.
- American Academy of Ophthalmology. Photoreceptors. Available at: https://www.aao.org/eye-health/anatomy/photoreceptors. Accessed September 2019.
- Hernández-Zimbrón LF, Zamora-Alvarado R, Ochoa-De la Paz L et al. Age-related macular degeneration: New paradigms for treatment and management of AMD. Oxid Med Cell Longev 2018; 2018: 8374647.
- National Health Service. Treatments: Age-related macular degeneration (AMD). Available at: https://www.nhs.uk/conditions/age-related-macular-degeneration-amd/treatment/. Accessed September 2019.
- VisionAware™. Charles Bonnet syndrome: Why am I having these visual hallucinations? Available at: https://www.visionaware.org/info/your-eye-condition/guide-to-eye-conditions/charles-bonnet-syndrome/124. Accessed September 2019.
- National Health Service. Symptoms: Age-related macular degeneration (AMD). Available at: https://www.nhs.uk/conditions/age-related-macular-degeneration-amd/symptoms/. Accessed September 2019.
- National Health Service. Look after your eyes: Healthy body. Available at: https://www.nhs.uk/live-well/healthy-body/look-after-your-eyes/. Accessed September 2019.
- Macular Society. Nutrition and eye health. Available at: https://www.macularsociety.org/sites/default/files/downloads/Accessible%20Nutrition%20JAN17.pdf. Accessed September 2019.