By Eyecare NGTypes | Risk Factors | Symptoms | Diagnosis | Treatment | How to Monitor | Management of Vision Loss
Age-related macular degeneration is the gradual deterioration of the sharpest point of vision on the retina (macula) leading to progressive loss of central vision; the part of vision that is required for performing many daily tasks such as reading, writing, watching television, recognizing faces and more. It usually shows up from age 50 years and above. People are often not aware that they have the condition until vision gets very blurry. This is because the condition causes a painless loss of vision which in most cases occurs gradually. Regular eye examination is important for the early diagnosis and management of age related macular degeneration.
Dry age related macular degeneration (Dry ARMD): This is the most common type of age related macular degeneration. In this type of ARMD, tiny collections of proteins called drusen accumulate under the macula causing it to deteriorate and thin out. Loss of central vision is gradual.
Wet age related macular degeneration (Wet ARMD): This accounts for about 10% of all cases of ARMD. In this type, new abnormal blood vessels grow on the retina around the macula area. These abnormal vessels tend to break and leak blood and other fluids under the macula, causing it to pull away from connective tissue below. Loss of central vision in the wet type is faster than in the dry type.
The risk factors for the development of age related macular degeneration include:
- Old age (over 50 years)
- Diet high in saturated fats.
- Overweight and obesity
- Family history of ARMD
- Race (white people tend to be more affected than other races)
- Heart disease
- High cholesterol
Age and smoking seem to be the greatest risk factors for age related macular degeneration.
- Painless loss of central vision
- Shadows or patches in some areas of central vision
- Distorted vision (lines may appear wavy)
- Missing parts in central vision
Diagnosis is made during an eye examination that includes the following:
- Case history – to obtain chief complaints, medical history, ocular history and more
- Visual acuity test – to measure central vision.
- Amsler’s grid test – to check for blank spots, blur or distortion in the central field of vision.
- Dilated examination of the retina to check for drusen (protein deposits on the retina), new blood vessels, haemorrhages and swelling.
- Fluorescein angiography, a test that involves injecting fluorescein dye into the blood stream to highlight the blood vessels in the back of the eye, so that a clear and distinct picture of the retina can be taken. This is used to check for leaky blood vessels.
- Ocular coherence tomography (OCT), an imaging test that works like ultrasound and captures the image of the retinal tissues beyond what is visible to the naked eye. Macular thickness, swelling and scarring can be revealed by OCT.
There is presently no treatment for dry ARMD. However, people with a lot of drusen or those who have serious vision loss might benefit from taking certain combination of nutritional supplements.
Based on the outcome of the Age Related Eye Disease Study 2 (AREDS 2), a combination of the following vitamins and minerals when taken daily may help slow down the progression of dry ARMD:
- Vitamin C (500mg)
- Vitamin E (400 IU)
- Lutein (10mg)
- Zeaxanthin (2mg)
- Zinc (80mg)
- Copper (2mg)
Treatment for wet ARMD may include one or a combination of the following treatment options:
- Anti-VEGF drugs: Wet ARMD can be treated with drugs such as Lucentis and Avantis. These are injected into the vitreous to help reduce the growth of abnormal blood vessels in the retina and stop them from leaking blood and other fluids.
- Laser surgery: Laser can be used to burn abnormal new blood vessels around the macula, thereby destroying them. This slows down or stops the abnormal blood vessels from leaking blood.
Monitoring age related macular degeneration
Age related macular degeneration can be monitored using the Amsler grid. The Amsler grid is a tool made up of horizontal and vertical lines with a dot at the centre. It used to monitor a person’s central visual field.
If you are at risk of age-related macular degeneration, you can use it to monitor your central vision at home. To ensure you do it regularly, it is advisable to place the Amsler grid chart in a place where you can see it every day, like on your wardrobe or bathroom door.
To perform the test,
- Ensure the room lighting is good.
- Look at the grid from a distance of about 12 to 15 inches with your glasses on (if you wear one).
- Cover one eye and focus directly on the dot in the centre of the grid with the uncovered eye.
- Observe the lines on the Amsler grid to see if any is out of shape, bent, wavy, blurry, dim or missing.
- After performing the test on one eye, switch to the other eye.
Management of vision loss
Age related macular degeneration is one of the causes of low vision. This can be managed using the following:
- Hand magnifiers: These can be used to magnify prints and images and enable the individual perform some near tasks like reading.
- Computers and smart phones: These digital devices have special features that can magnify prints and numbers.
- Closed circuit television (CCTV): These can magnify objects and make it easy to view them.
- Peripheral (side) vision: The peripheral vision is not affected in age related macular degeneration so the patient can be trained to make use of his peripheral vision in carrying out some tasks.