Age-Related Macular Degeneration – An Overview
Age-Related Macular Degeneration (AMD — formerly ARMD) is a condition of the macula, part of the retina that is responsible for the central vision needed to read, write, and drive.
The retina is made of specialized cells called photoreceptors that convert light into electrical impulses that stimulate the brain. The macula, a 1/8 inch area near the center of the retina, is dense with cone-type photoreceptors, resulting in a density of electrical signals. These signals translate into the perception of focused, central vision, as well as color vision.
As people age and circulation to the retina decreases, the macula degenerates and the capacity for direct central vision is lost. The ability to see fine details is lost: patients see edges of images, but not what is in the middle. Eventually a blank or dark spot – called a scotoma – forms in the center of the visual field, colors become less vivid, blurriness and wavy lines may appear, and in some cases, the patient becomes legally blind (legally defined as having vision of 20/200 or less with best correction).
Wet AMD
In Neovascular, or Wet Macular Degeneration, blood vessels in the retina become abnormal and prone to leaking. Leakage of the vessel may cause a sudden loss of vision, sometimes in a matter of days. Wet AMD is often treated with lasers or injections that stop or slow vascular growth (see Existing Treatments, below, for more detail). The Santa Fe Eye Protocol is the only documented treatment that can improve the vision of patients with Wet AMD, and without the use of lasers or injections.
Dry AMD
Non-neovascular or Dry Macular Degeneration is more common than Wet AMD and affects 90% of patients. Dry AMD is characterized by a loss of pigment in the retina and small deposits of drusen – a waste product – in the layer of membrane behind the retina. Outside of the Santa Fe Eye Protocol, the only proven treatment for this condition is high doses of antioxidant vitamins plus Lutein, Zeaxanthin and Zinc Richer, Stuart et al; Veterans Lutein Antioxidant Supplementation Trial (LAST); Optometry; April 2004; 75:216-30 and Richer, Stuart et al; LAST II; Optometry; May 2007; 78 213-219 The Santa Fe Eye Protocol significantly improves vision even in those persons who already are supplementing and we encourage people to supplement if they are not already.
Existing Treatments for Wet AMD
Thermal Laser:
The first proven treatment to stop bleeding in the retina was thermal laser treatment, which uses a laser beam to cauterize the leaking blood vessels. Unfortunately, this procedure involves an immediate loss of three lines of vision, though it does prevent further – and possibly more severe – vision loss in cases of Wet AMD.
Photodynamic Therapy:
Next was introduced Photodynamic Therapy in which the medicine Verteporfin is administered by injection into a blood vessel, and a laser light is then directed at the back of the eye. Verteporfin, when activated by the light of the laser, destroys rapidly growing blood vessel cells in that area. Unfortunately, only 40% of Wet macular degeneration patients qualify, and most people continue to lose vision.
Macugen (pegaptanib):
In early 2005, the drug Macugen was approved to treat Wet AMD. It is an anti-angiogenic medicine, meaning that it discourages the abnormal growth of blood vessels that are leaking and damaging the back of the retina. Typically, an ophthalmologist will numb the eye and inject the Macugen directly into the eyeball every six weeks. Macugen can be used in 100% of people with wet AMD, and it stops bleeding in 60% of them. A small percentage of patients gain vision, but when questioned, the manufacturer reported that overall, most patients lost vision.
Avastin (bevacizumab):
Avastin is another anti-angiogenic medicine that operates on more sites than Macugen to block growth of abnormal blood vessels. It is approved by the FDA for cancer therapy and is being used off-label for wet AMD.
Lucentis (ranibumab):
Lucentis is a derivative of Avastin and was approved for treatment of wet AMD by the FDA in July 2006. The October 5, 2006 issue of the New England Journal of Medicine reported on trials on 716 patients with wet AMD. They were treated with eye injections monthly for two years. Those treated with Lucentis improved vision 7 letters on average. Those who had sham medicine lost an average of 10 letters.
Avastin vs Lucentis: The National Eye Institute reported in July 2011 that compared side by side, Avastin was just as effective as the much more expensive Lucentis. Most retina doctors are now using Avastin rather than Lucentis.
Further Reading
In Dr. Lundgren’s opinion, the best and most understandable explanation of the mechanism of AMD comes from the first part of the Caltech Alumni Magazine, “Engineering and Science”, No 3, 2006. Click here to access the pdf (2.1 MB).
The October 5, 2006 issue of The New England Journal of Medicine, pages 1474-1485 published a Review Article titled “Age Related Macular Degeneration” by T. V. M. de Jong. Click here to read the abstract.
With kind permission of Stuart Richer, OD, PhD, text of his articles may be accessed below.
Double masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the veterans LAST study (Lutein Antioxidant Supplementation Trial)
LAST II: Differential Temporal responses of macular pigment density in patients with atrophic age-related macular degeneration to dietary supplementation with xanthophylls.
Updated: 21 December 2013