Age-related macular degeneration (AMD) is a chronic disease leading to progressive central vision loss. The symptom of central vision loss is due to the fact that the damaged macula is in the center of the retina. Patients with AMD may be unable to recognise faces, read, or drive a vehicle.
AMD is the most common cause of sight loss in people over the age of 50 in Ireland and it’s estimated that 7% of Irish people over 50 years of age are living with AMD. On account of our ageing population, the number of people in Ireland affected by this condition is expected to increase.
Symptoms of AMD include decreased central vision, central scotoma, and metamorphopsia. Scotoma is an area of partially diminished vision surrounded by a field of normal or well-preserved vision. Metamorphopsia is a visual defect that causes people to see objects in a distorted manner; straight objects appear wavy or curvy. Patients will complain of distorted vision, lack of bright colours, or blurred vision.
There are 2 types of macular degeneration: dry and wet. Dry macular degeneration, also known as the nonexudative form, is more common and found in approximately 90% of AMD patients. The onset of dry AMD is subacute. Management of dry AMD includes attempts to prevent progression to and frequent monitoring for the development of wet macular degeneration.
Wet (also known as exudative or neovascular) macular degeneration occurs in about 10% of AMD patients. It is the more acute form and more likely to cause vision loss. Wet age-related macular degeneration develops when abnormal blood vessels grow into the macula. These leak blood or fluid which leads to scarring of the macula and rapid loss of central vision. Wet AMD can develop very suddenly but it can now be treated if caught quickly.
What are the symptoms?
• Gaps or dark spots (like a smudge on glasses) may appear in their vision, especially first thing in the morning. Objects in front of them might change shape, size or colour or seem to move or disappear.
• Colours can fade.
• Sufferers may find bright light glaring and uncomfortable or find it difficult to adapt when moving from dark to light environments.
• Words might disappear when they are reading.
• Straight lines such as door frames and lampposts may appear distorted or bent.
The exact cause of AMD is unknown. However, extensive research efforts over the last decade are playing an important role in uncovering some of the clues as to what may be causing the disease.
Researchers know that certain genes can cause AMD, but they don’t know what triggers the gene. While AMD can be inherited, many lifestyle choices can make progression of the disease worse.
Some risk factors that are believed to increase the chances of developing AMD include being over the age of 50 and having a family history of AMD. Having high blood pressure, a poor diet or being overweight are also thought to be risk factors for this condition.
Because the exact causes of AMD are not yet known, some people may develop AMD even in the absence of these risk factors.
Age-Related Studies (AREDS1 and AREDS2) have shown that a combination of vitamins and antioxidants may help reduce the risk of progression of Early AMD to late-stage AMD. The recommendations include supplements containing vitamins C and E, zinc, copper, lutein and zeaxanthin.
Treatment for Wet AMD is most often through a series of injections into the eye using a drug called anti-VEGF (anti-vascular endothelial growth factor). This treatment works by reducing the growth of new blood vessels.
Response to this treatment is usually better in the early stages of Wet AMD, although even later stages can be stabilised. In some cases, individuals may notice improvements in their vision.
Role of the Pharmacist
It is important to remind patients at risk for AMD to have regular eye exams, even when they are symptom-free. Patients complaining of a recent or chronic loss or change of vision should be urged to see an ophthalmologist immediately. A healthy lifestyle may help prevent AMD. This includes not smoking, eating a healthy diet, and being physically active. Following the recommended guidelines and the use of appropriate pharmacologic agents may help patients with AMD slow vision loss progression, increase visual acuity, and experience a greater quality of life.