Age related macular degeneration (ARMD)
ARMD is the leading cause of blindness in all age groups in the United States. It can be divided into two general stages:
- Dry ARMD - there is progressive deterioration of several retinal layers that typically results in difficulty with reading. Usually it progresses slowly and very rarely causes blindness.
- Wet ARMD - There is fast loss of central vision associated to bleeding and/or fluid accumulation in the central part of the retina. This requires prompt diagnosis and treatment.
ARMD is diagnosed by inspection of the retina with a dilated fundus exam. Occasionally, as part of proper diagnosis, special tests can be ordered. These may include:
- Optical Coherence Tomography (OCT)- This non-invasive test provides an exquisite microscopic view of the retinal tissues. No injections are necessary for this test.
- Fluorescein Angiography (FA)- A special yellow dye is injected in a vein in the arm and as it circulates through the retina, images can be obtained that demonstrate the microcirculation on the superficial retinal layers. This test helps in deciding the most appropriate treatment for ARMD.
- Indocyanine Green Angiography (ICG)- a special green dye is injected and images are taken to demonstrate the circulation of the deeper layers of the retina. This test helps in accurately diagnosing certain variants of wet ARMD.
In the dry form of ARMD, treatment is aimed at decreasing the rate of progression and severity. Genetics certainly are important in the development of ARMD, but certain lifestyles will increase the odds for trouble. Cigarette smoking greatly increases the risk for wet ARMD as well as uncontrolled blood pressure and cholesterol. Vitamin supplements following the Age Related Eye Disease Study (AREDS) recommendations may decrease the risk for progression and severity. Recent studies also suggest that supplementation of Omega-3 Fatty Acids as well as supplemental Vitamin D may help. Smoking is the most important risk factor and cessation of it is advised. A word to smokers: do not use regular AREDS formula since high doses of Beta-carotene increase the risk of lung cancer, use the AREDS-2 formula that replaces this with other carotenoids (Lutein and Zeaxanthin).
The wet form of ARMD can be treated in several ways. In all of these, the aim is at stopping the growth of abnormal new vessels.
Regular thermal lasers may work for small lesions peripherally but they can leave blind areas in the vision; this modality is seldom used presently.
Non-thermal photodynamic therapy with Visudyne (Verteporphin) can stabilize vision but does not tend to improve it; it is used for selected cases.
Intravitreal injections of compounds that shrink abnormal vessels include the FDA approved Macugen (Pegaptanib), Lucentis (Ranibizumab), Eylea (Aflibercept) or the off-label Avastin (Bevacizumab). Usually the decision of which compound is used is based on very specific circumstances. These have the best outcomes and are the preferred treatments at present. Several other compounds are being evaluated and may become available in a near future. These injections are done in the office under topical anesthesia on an outpatient basis.