Age Related Macular Degeneration, AMD or ARMD, is one of the most common causes of irreversible blindness in the elderly, usually above 50 years of age.
AMD is caused by a deterioration of the macula, which is the small central area of the retina of the eye that is responsible for sharp central vision. It may be classified as either dry AMD (due to aging and thinning of macular tissues, and deposition of pigment in the macula) or wet AMD (neovascular or with formation of new blood vessels). Very often, we presume that the decreased vision in the elderly is either due to cataract, or the “normal ageing process”, when AMD may also cause significant vision loss in this age group. Timely diagnosis and treatment of Age Related Macular Degeneration can, therefore, prevent significant loss of vision from the disease.
What is Age Related Macular Degeneration?
The retina is the light sensitive part at the back of the eye, where images are formed, enabling us to see. The macula is the central part of the retina which is responsible for precise central vision and perception of details. When the macula is diseased, vision gradually becomes hazy, and finer details become blurred. If left untreated, this can even result in blindness.
In Age Related Macular Degeneration, two kinds of macular degenerations may take place:
- Ageing and thinning of macular tissues, and deposition of pigment in the macula
- Neovascularization or formation of new blood vessels which are fragile and leak blood
What are the symptoms of AMD?
Your eye doctor can pick up early signs of Age Related Macular Degeneration during your routine eye examination, even before symptoms begin. Therefore, you must go for an annual comprehensive eye examination, even if you have no symptoms.
The usual symptoms of AMD include:
- Blurred vision
- Difficulty in recognizing faces, especially facial details
- Dark areas or distortion in central vision, distortion of lines which may appear wavy or broken
- Shadowy areas in vision
- Patients often complain of difficulty in reading: missing alphabets or words during reading
- Loss of central vision.
What are the types of AMD?
Age Related Macular Degeneration is of two types:
- Dry AMD: In this, the vision loss is more gradual, and the changes are due to ageing and thinning of macular tissues, and deposition of pigment in the macula. There is no definite cure for dry AMD.
- Wet AMD: Wet AMD is the more severe form of disease, which may cause a more rapid deterioration of vision. In this, abnormally fragile blood vessels grow underneath the macula, and may leak fluid or blood. This process is called choroidal neovascularization. This causes blurring, distortion and eventual loss of vision. An early diagnosis and treatment of Wet AMD can help prevent these bleeding and leakages, thus preventing blindness.
Ten percent of patients of AMD have wet AMD, and sometimes dry AMD patients can also convert to wet AMD, therefore regular eye evaluations are a must.
What is the diagnosis and treatment of AMD?
AMD diagnosis and treatment requires a detailed, dilated eye evaluation by your eye doctor, along with special tests. The tests performed include:
Dilated slit lamp biomicroscopy
In this, your doctor will put dilating drops in your eyes, and then examine your retina with a 90/78D lens. Besides this, the doctor may also take fundus photos, or pictures of your retina. thereafter, your doctor will schedule any further tests, if required.
Amsler Grid charting
Your doctor will assess your vision by asking you to view an Amsler Grid. This is a chart of black lines arranged in a graph pattern and can detect distortions of vision. This is a comparatively simple test, and you can therefore do it at home also. (See https://www.macular.org/wp-content/uploads/2016/05/amslerchart.pdf)
How you use the Amsler Grid:
- Wear your prescribed reading glasses, and hold the grid 12 to 15 inches away from your face in good light.
- Cover one eye.
- Focus on the central dot, and look at the grid pattern. If you see any broken or wavy lines, or areas of shadows or missing boxes, please contact your doctor.
- Thereafter, repeat the process with the other eye.
Macular Optical Coherence Tomography, OCT
Macular Optical Coherence Tomography is a high resolution imaging of the macula. Your doctor can see the details of the structure of the macula, and consequently, its abnormalities.
Fundus Flourescien Angiography, FFA
During FFA, the doctor will inject a small amount of dye in your forearm, and examine your retina. The dye passes through the retinal blood vessels, which are then seen in greater detail by your doctor. Any new or leaking blood vessels can therefore be identified and photographed.
Indocyanine Green Angiography, ICG
Your doctor may sometimes perform an Indocyanine Green Angiography. The ICG angiography can help your doctor evaluate the blood circulation in the choroid, the layer of the eye, below the retina.
It is noteworthy that the treatment of AMD will depend not only on the results of these diagnostic tests, but also your visual acuity.
What is the treatment for Age Related Macular Degeneration?
Dry AMD
As mentioned before, there is no definitive cure for dry AMD. Some doctors believe that high doses of eye specific vitamins and micronutrients may decrease the risk of visual loss.
The Age-Related Eye Disease Study (AREDS; 2001) and its follow-up study, called AREDS2 (2013) are large population based clinical trials on AMD. These have suggested that nutritional supplements containing antioxidants, multivitamins, lutein and zeaxanthin may reduce the risk of dry AMD progressing to sight-threatening wet AMD. Your doctor, thus, may prescribe some oral vitamin supplements to help delay the disease process. However, there is no conclusive evidence that this arrests the development or progression of AMD.
Wet AMD
Wet AMD can be treated effectively if diagnosed early. The treatment of AMD focuses on arresting the growth of new blood vessels, and on decreasing the leakage of blood and protein from the existing abnormal vessels. This can be achieved by either laser or injections. Some patients, however, may require a surgical intervention.
Treatment modalities include:
- Trans pupillary thermotherapy(TTT)
- Photodynamic therapy(PDT)
- Vitrectomy
- Intravitreal injections of anti- VEGF agents like Lucentis, Avastin, Accentrix
