Age-related macular degeneration – medical news bulletin health news and medical research

Age-related macular degeneration is a progressive and chronic disease of the eye that is the leading cause of central vision loss in patients living in developed countries. 1The disease damages the central part of the retina, which is involved in allowing us to see objects ahead of us. Age-related macular degeneration does not lead to complete loss of vision since only the central vision is affected. Patients with macular degeneration usually retain their peripheral vision. 3

One analysis showed a prevalence of 5.4% among white patients, 4.6% among Chinese patients, 4.2% in Hispanics, and 2.4% in African-Americans. The prevalence of age-related macular degeneration is more important in the western countries; however, due to the westernization of diet and lifestyle, other countries are reporting increases in the rates of the disease.

Considering the overwhelming statistics and the incurable nature of the disease, strong efforts are aimed at preventing age-related macular degeneration. 5 Pathophysiology

The retina is a very important structure of the eye since it is where the light-sensitive cells are located. This structure is found at the back of the eye. The macula is the spot in the centre of the retina with the highest concentration of light-sensitive cells, called rods and cones, which produce the sharpest images. These cells also allow for colour vision. The retinal pigment epithelium contains cells that are located immediately behind the rods and cones to keep them healthy and functioning normally. In age-related macular degeneration, the macula progressively deteriorates. 3 Dry vs. Wet Macular Degeneration

Wet age-related macular degeneration occurs in about 15% of patients. This form of age-related macular degeneration is more severe than the dry form. It results from the development of abnormal new blood cells under the retina. This increased blood flow around the retina causes swelling of the macula. If blood pools into this small area the macula can become raised in the retina and may detach from the retinal pigment epithelium. Scarring may then appear under the retina. 2

Patients with wet age-related macular degeneration will experience a faster progression of the disease. The progression of the disease may be days or weeks. If one of the abnormal blood vessels bleeds the progression may be even quicker. As with the dry form, peripheral vision is usually not affected. Unlike the dry form, in wet age-related macular degeneration, one eye will be affected at a time and patients will experience difficulties watching television and reading. 7 Diagnosis

An eye doctor can examine the eye for signs of age-related macular degeneration. By shining a light into the back of the eye through an ophthalmoscope, eye specialists can detect signs of age-related macular degeneration before any damage causes permanent symptoms. For the wet form of age-related macular degeneration, the doctor will take colour photographs of the eye or will take a closer look at the blood vessels around the retina through another diagnostic test called fluorescein angiography. 7 Stages of Disease

In the early stages, doctors may detect drusen in the eye. Drusen are deposits of lipids under the retina. These deposits do not cause age-related macular degeneration but they increase a patient’s likelihood of developing the disease. As the disease progresses from early, to intermediate, and finally to the advanced stage, the number and size of the deposits increases.

In wet age-related macular degeneration, vascular endothelial growth factor inhibitors can be effective in decreasing the loss of vision. 10 Photodynamic therapy and laser photocoagulation are non-medicinal techniques previously used in the treatment of age-related macular degeneration; however, are no longer considered the first line of treatment. 1 Laser Photocoagulation

Laser photocoagulation was introduced in the 1980s and showed promising results in about 20% of wet age-related macular degeneration cases where the abnormal blood vessels were formed in specific areas of the macula. Due to its limited success and high rates of the disease recurring it is no longer in widespread use for the treatment of wet age-related macular degeneration. 1 Photodynamic Therapy

Photodynamic therapy involves an injection of a photosensitive dye that accumulates in the newly developed blood vessels and is activated by infrared light. The activated dye causes damage to the surrounding blood vessels and this strategy helps to control the development of the abnormal vessels that cause wet age-related macular degeneration. Today this treatment is rarely used. 1 Vascular Endothelial Growth Factor Inhibitors

Vascular endothelial growth factor inhibitors are the standard of care for the treatment of wet age-related macular degeneration. These include ranibizumab, bevacizumab, aflibercept, and pegaptanib. Vascular endothelial growth factors block the development of blood vessels. They also help to reduce the swelling of the macula and restoring the normal structure of the eye. The administration of these agents is through injections into the eye. Local numbing agents are used to lessen the pain associated with the injection. Since the eye is very prone to infections, the doctor administering the treatment will also have the patient use antiseptic drops into the affected eye prior to receiving the needle. If the treatments are effective, patients will receive a dose every two to four weeks. 10

Since age-related macular degeneration is not a treatable disease, prevention must be emphasized. In dry age-related macular degeneration, there is no way to reverse the damage. Certain supplements can help patients with extensive drusen, pigment changes in the macula or signs of atrophy or cell death of the macula reduce the likelihood of developing the advanced form of the disease by about 25 percent. 2

Two large studies on antioxidant formulations for preventing age-related macular degeneration were conducted in 2001 and 2013. 11 In 2001, the age-related eye diseases (AREDS) formulation contained zinc oxide 80mg, copper 2mg, vitamin C 500mg, vitamin E 400 units, and beta-carotene. In 2006, the formulation was modified slightly (AREDS 2) to reduce the amount of zinc oxide to 25 mg and to substitute beta-carotene for zeaxanthin 2mg and lutein 10mg. Both formulations showed a decrease in the risk of vision loss and a decrease in the risk of progression to advanced age-related macular degeneration. Smokers are must avoid the use of the original AREDS formulations with beta-carotene since there is a risk of developing lung cancer in smokers taking beta-carotene supplements. 3

The only two formulations that were studied in depth are the PreserVision Eye Vitamin AREDS Formula and the PreserVision Eye Vitamin AREDS 2 Formula. It is recommended that patients use the exact products that were used in the study since other similar products have different combinations of ingredients and their effectiveness has not been extensively studied. 3 Controlling risk factors

Age-related macular degeneration is a disease usually affecting people of advanced age. With a rising life expectancy in the western world, this disease is expected to be more and more discussed in routine check-ups. Since treatment options are lacking, a focus on quick diagnosis and detection of clinical signs of a progressing disease are necessary. Once a diagnosis is established, doctors and patients must discuss methods for slowing down the progression and preservation of the eyesight. Visual aids and counselling may help patients with advanced loss of vision cope and function with limited sight. Finally, current studies are investigating new treatment options and effective preventative measures, and visual prostheses. These advances will, one day, provide better outcomes for patients with age-related macular degeneration. 1