Age-related macular degeneration begins with characteristic yellow deposits in the macula (central area of the retina which provides detailed central vision) called drusen between the retinal pigment epithelium and the underlying choroid. Most people with these early changes (referred to as age-related maculopathy) have good vision. People with drusen can go on to develop advanced AMD. The risk is considerably higher when the drusen are large and numerous and associated with disturbance in the pigmented cell layer under the macula. Recent research suggests that large and soft drusen are related to elevated cholesterol deposits and may respond to cholesterol lowering agents or the Rheo Procedure.
Advanced AMD, which is responsible for profound vision loss, has two forms: dry and wet. Central geographic atrophy, the dry form of advanced AMD, results from atrophy to the retinal pigment epithelial layer below the retina, which causes vision loss through loss of photoreceptors (rods and cones) in the central part of the eye. While no treatment is available for this condition, vitamin supplements with high doses of antioxidants, lutein and zeaxanthin, have been demonstrated by the National Eye Institute and others to slow the progression of dry macular degeneration and in some patients, improve visual acuity.
Neovascular or exudative AMD, the wet form of advanced AMD, causes vision loss due to abnormal blood vessel growth in the choriocapillaries, through Bruch's membrane, ultimately leading to blood and protein leakage below the macula. Bleeding, leaking and scarring from these blood vessels eventually cause irreversible damage to the photoreceptors and rapid vision loss if left untreated.
Until recently, no effective treatments were known for wet macular degeneration. However, new drugs, called anti-VEGF (anti-Vascular Endothelial Growth Factor) agents, when injected directly into the vitreous humor of the eye using a small, painless needle, can cause regression of the abnormal blood vessels and improvement of vision. The injections frequently have to be repeated on a monthly or bi-monthly basis. Examples of these agents include Lucentis, Avastin and Macugen. Only Lucentis and Macugen are FDA approved as of April 2007. Macugen has been found to have only minimal benefits in neovascular AMD and is no longer used. Worldwide, Avastin has been used extensively, with excellent results, despite its "off label" status. Genentech, the maker of both Avastin and Lucentis, has been hoping to promote the use of Lucentis due to the potential for much higher revenues. The cost of Lucentis is approximately $2000 US while the cost of Avastin is approximately $50. Fortunately, retinal specialists worldwide have together proven that Avastin is at least as effective and safe as Lucentis, at a fraction of the cost.
'Vision loss' or 'blindness' in macular degeneration refers to the loss of 'central vision' only. The peripheral vision is preserved. Blindness in macular degeneration does not mean 'inability to see light' and even with far advanced macular degeneration, the peripheral retina allows for useful vision.
loss of central vision profoundly affects visual functioning. It is not possible, for example, to read without central vision. Pictures which attempt to depict the central visual loss of macular degeneration with a black spot do not really do justice to the devastating nature of the visual loss. This can be demonstrated by printing letters 6 inches high on a piece of paper and attempting to identify them while looking straight ahead and holding the paper slightly to the side. Most people find this surprisingly difficult to do.
Similar symptoms with a very different etiology and different treatment can be caused by Epiretinal membrane or macular puckeror leaking blood vessels in the eye.
Fluorescein angiography allows for the identification and localization of abnormal vascular processes. Optical coherence tomography is now used by most ophthalmologists in the diagnosis and the followup evaluation of the response to treatment by using either Avastin or Lucentis which are injected into the vitreous of the eye at various intervals.
Anecortave acetate, (Retanne), is an anti-angiogenic drug that is given as an injection behind the eye (avoiding an injection directly into the eye) that is currently being studied as a potential way of reducing the risk of neovascular (or wet) AMD in high-risk patients.
Research started in 2005 has shown that intravitreal injection of Avastatin (bevacizumab) can improve vision and slow down the macular degeneration. This therapy is currently being used in various centers around the world. Avastatin is an immunoligic drug that prevents neovascularization. Hence it may also be effective in diabetic retinopathy. Avastatin was initially used for the treatment of colorectal cancer.
A study by a neuroretinologist in the late 80's suggested that microcurrent stimulation of acupuncture points for the eye had positive effects in slowing and even stopping progression of the disease . This study was based on Ngok Cheng's research on the increased amounts of ATP levels in living tissue after being stimulated with microcurrent. ("The Effects of Electric Currents on ATP Generation, Protein Synthesis, and Membrane Transport in Rat Skin.") Several similar studies are currently being underway.
Recent studies suggest that statins, a family of drugs used for reducing cholesterol levels, may be effective in prevention of AMD, and in slowing its progression.
Studies are underway at Harvard, with the goal of reducing lipofuscin accumulation.
On September 10, 2007, in a 6-year study, researchers, led by John Paul SanGiovanni of the National Eye Institute, Maryland found that Lutein and zeaxanthin (nutrients in eggs, spinach and other green vegetables) protect against blindness (macular degeneration), affecting 1.2 million Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD (journal Archives of Ophthalmology). Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas and Brussels sprouts.