Age-Related Macular Degeneration (AMD)

by | Feb 17, 2020 | Health Topics

Written by Go Swee Teng, pharmacist.

What is AMD?

AMD is a disease that affects the macula at the back of the eye, [1,2] causing the central part of vision become wavy or blurry.[2] Some of the patients might experience a blind spot in the middle of their vision. Therefore, AMD is considered to be the leading cause of blindness among patients above 65 years old. [2] AMD can progress through 3 stages: early AMD, intermediate AMD and late AMD.[3]

Figure 1: The vision of healthy eye condition, early AMD and late AMD.[4]

Early AMD : Small yellow deposits called drusen are found under the retina.[3] These deposits are formed when the body unable to break down the by-products from very intensive metabolic processes that occurs in the sensory cells of retina.[4,5]

Intermediate AMD : Large drusen found under the retina and pigment changes in the retina.[4] These may lead to some vision loss.

Late AMD : Large drusen are found under the retina and vision loss occurs from damage to the macula.[4,5]

  • Dry AMD – 9 out of 10 cases of AMD are dry AMD, [2] and this occurs due to breakdown of the light-sensitive cells in the macula and the supporting tissue.[5]
  • Wet AMD – Wet AMD often progresses more rapidly than dry.[5] It is due to abnormal, leaky blood vessels grow under the retina and can cause damage and swelling of the macula.[5]

Figure 2: Figure above shows the types of AMD- Dry AMD and Wet AMD. [6]

Risk Factors

  • Age : Risk increases after the age of 60 years.[2,7,8]
  • Smoking : Smokers have 4 times higher risk of AMD compared to non-smokers.[2,5,7,8]
  • Ethnicity : Caucasians is more likely to have AMD than other groups.[2,3,7,8]
  • Family History : Approximately 15 to 20 percent of AMD patients have a close relative with the condition.[2,3,7,8]
  • Obesity : People with BMI 30 and above, together with linked factors such as high blood pressure and high cholesterol levels appear to have higher risk of AMD. [4,7]
  • Heart Disease and High Blood Pressure : People with history of coronary heart disease or high blood pressure increases the risk of AMD. [4,7]

The Symptoms of Dry AMD and Wet AMD [4]

Symptoms of Dry AMD Symptoms of Wet AMD
Ø Text seems blurry Ø Central vision is getting worse
Ø Requiring a brighter light while reading Ø Blind spots appeared in the centre of vision
Ø Struggling to recognise people’s faces Ø Visual distortions – e.g. when a straight line looks crooked or wavy
Ø Colours lose their vibrancy Ø Hallucinations – seeing animals, people or shapes that aren’t there
Ø  Vision appears less defined or hazy  

Macular Degeneration Diagnosis

Treatment 

Treating Dry AMD [3,4,7]
  • Taking diet or vitamin supplements high in lutein, zeaxanthin, and vitamins A, C and E may slow down how quickly dry AMD progresses.
  • Foods that are rich in vitamins A, C and E include oranges, tomatoes, carrots, leafy green vegetables and kiwis. On the other hand, leafy green veggies, sweetcorn, mangoes and peas are also a great source of lutein.
Treating Wet AMD

There are 2 main treatments for wet AMD:

 1.      Anti-VEGF Medication [3,4,7]

  • One of the chemicals responsible for new blood vessels growing in our eyes is Vascular endothelial growth factor (VEGF). In order to prevent these blood vessels from being produced, anti-VEGF drugs can be used.
  • Examples of anti-VEGF medications include ranibizumab (Lucentis), and bevacizumab (Avastin).

2.     Surgery [3,4,7]

  • Photodynamic Therapy
  • A drug called verteporfin (a light-sensitive medicine) is injected into the arm and travels to the new blood vessels.
  • A low-powered laser is then used to activate the drug in the abnormal blood vessels, stopping their growth and the progressive vision loss. This will not affect the normal blood vessels.
  • Laser Photocoagulation
  • A laser is used to burn away sections of retina.
  • This causes the affected area to harden, preventing any abnormal blood vessels from moving further along the macula.
  • This method only suitable if the abnormal blood vessels aren’t growing close to the fovea.

 

Complications [7-8]

  • Adapting to vision loss.
  • AMD can affect a person’s ability to drive.
  • Visual hallucinations start to develop.

References:

  1. Harika J. Prevalence of age Related Macular Degeneration in A Tertiary Care centre. Journal of Clinical Research and Ophthalmology. 2019;:007-010.
  2. February is Age-Related Macular Degeneration Awareness Month [Internet]. Clay Eye Physicians. 2019 [cited 19 November 2019]. Available from: https://www.clayeye.com/2018/02/07/february-age-related-macular-degeneration-low-vision-awareness-month/
  3. Salus Health – What is Age-Related Macular Degeneration? [Internet]. Salusuhealth.com. 2019 [cited 19 November 2019]. Available from: https://www.salusuhealth.com/eye-institute/news/news-stories/what-is-age-related-macular-degeneration.aspx
  4. A Comprehensive Guide to Age-Related Macular Degeneration (AMD) | Laser Eye Surgery Hub [Internet]. Laser Eye Surgery Hub. 2019 [cited 19 November 2019]. Available from: https://www.lasereyesurgeryhub.co.uk/age-related-macular-degeneration-amd-guide/
  5. Overview A. Age-related macular degeneration (AMD): Overview [Internet]. Ncbi.nlm.nih.gov. 2019 [cited 19 November 2019]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK315804/
  6. Jared Knickelbein P. Age-related macular degeneration in 2019 – Allegheny County Medical Society [Internet]. Allegheny County Medical Society. 2020 [cited 8 January 2020]. Available from: https://www.acms.org/2019/03/age-related-macular-degeneration-in-2019/
  7. Age-related macular degeneration (AMD): Symptoms and treatment [Internet]. Medical News Today. 2019 [cited 26 December 2019]. Available from: https://www.medicalnewstoday.com/articles/152105.php#symptoms
  8. Berrow E, Bartlett H, Eperjesi F, Gibson J. Risk Factors for Age-related Macular Degeneration. European Ophthalmic Review. 2011;05(02):143.