Age-related macular degeneration (ARMD) is a rather common eye disease. In 2012, World Health Organisation has published a report which pointed out that ARMD was the third cause of blindness in the world.1 In 2010, the Hong Kong Hospital Authority has found that there were about 3,000 new ARMD cases per year and estimated that there were around 500,000 ARMD patients in Hong Kong. With a growing aged population, these figures should definitely increase. The symptoms, causes, types, prevention and treatment of ARMD will be discussed in this blog entry.
Symptoms of ARMD :
Macula is a very important ocular structure in retina, there are millions of retinal sensory neurons being located in this 5mm diameter region. Its function is to transform the lights from the seen objects into electrical signals which are then transmitted to the brain. It is crucial for performing different daily activities such as driving, reading and writing, as it is the key area for providing the sharp central vision. Unfortunately, ARMD is the disease which leads to degeneration in the the macular region, the major symptoms are as follows:
- Blurred vision
- Seeing blind spots in the central vision field
- Seeing straight lines become curved
- Seeing objects with irregular shape
Types and Causes of ARMD :
ARMD can be classified into two types: dry and wet form. Approximately 90% of the ARMD cases are dry form. There are yellowish deposits called drusen being accumulated underneath the retinal sensory cells in patients with dry ARMD. Those drusen are the metabolic wastes produced by the retinal sensory cells. Vision of dry ARMD patients usually will not deteriorate very rapidly, however it could develop to wet form. Approximately 10% of the ARMD cases are wet form. There is retinal neovascularisation in wet ARMD patients, those newly grown blood vessels leak very easily, which ends up causing macular bleeding and scarring. Vision of wet ARMD patients can deteriorate very quickly, therefore it is of paramount importance to consult eye care professionals as soon as possible if there is any acute central vision loss.
The complete cause of ARMD has not yet been fully understood. Some of the risk factors were found to be associated with this ocular disease and they are as follows:
- Ageing. There are approximately 30% of elderly older than 75 years of age having ARMD.
- Smoking
- Long term exposure of ultraviolet (UV) light from the sun to the eyes
- High blood lipid and cholesterol level
- Family history of ARMD
Prevention of ARMD :
Within these 15 years, different research was done to find out if there were any vitamins or nutritional supplements that were able to prevent ARMD. Results shown that patients with intermediate dry ARMD took supplements with a formula known as AREDS 2 would have 25% less risk of developing late or wet ARMD when compared to those who did not take the supplements.2,3 The main ingredients of AREDS 2 forumla are vitamin C and E, lutein, zeaxanthin and zinc, intermediate ARMD patients should consider having it daily. Other preventive measures such as quitting smoking, reducing sunlight exposure and balanced diet especially avoiding food with high fat content can also be taken.
Treatment of ARMD :
While taking AREDS 2 supplements may help the dry ARMD patient from developing wet ARMD rapidly, ways to treat wet ARMD are 1) intraocular Anti-Vascular Endothelial Growth Factor injections, 2) Photodynamic therapy and 3) Laser photocoagulation treatment. The aims of these three treatment methods are to suppress the new retinal blood vessels from growing, and destroy the newly grown retinal blood vessels in a bid to slow down the vision from deteriorating rapidly. Ophthalmologists will decide to choose which treatment options according to the situation of each individual case.
Finally, the chance of having eye disease will increase with age, elderly should have comprehensive eye examination with their optometrists regularly, and take appropriate action for any abnormalities so as to avoid any significant and irreversible vision loss.
By Paco Chan, Registered (Part I) Optometrist
Eyecare information by Swisscoat Vision Centre
Address : G/F Yuen Yick Building, 27-29 Wellington Street, Central, Hong Kong
Appointment :+852 3579 4763
Website : www.swisscoat.com
References:
- Pascolini D, Mariotti SP. Global estimates of visual impairment: 2010. The British journal of ophthalmology 2012; 96(5): 614-8.
- Age-Related Eye Disease Study Research G. 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(10): 1417-36.
- Age-Related Eye Disease Study 2 Research G. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA 2013; 309(19): 2005-15.