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July 2012: Understanding Age Related Macular Degeneration

01 Jul 2012

Rumya Rao, M.D. is an ophthalmologist at the Retina Institute of Illinois affiliated with Vanguard Weiss Memorial Hospital. She completed her residency training at Northwestern University and fellowship in medical retinal diseases at the University of Miami Bascom Palmer Eye Institute.

Rumya Rao, M.D.
Retina Institute of Illinois
(773) 784-9400 or (847) 297-8900

Identifying the symptoms and risk factors of eye disease
Age Related Macular Degeneration (ARMD) is the leading cause of blindness in adults older than 50 years in developed countries, and a major cause of visual loss worldwide. The retina is the nerve layer lining the wall of our eye, and is responsible for sight. ARMD affects the macula, the portion of the retina responsible for center vision (Figure 1).

 Figure 1

Figure 1: The macula is the center part of the retina, which is the nerve tissue that lines the back of the eye and senses light

As the disease progresses, affected individuals may note decreased center vision, distortion in their vision, difficulty with reading and/or difficulty recognizing faces.

As the name implies, age is the primary risk factor for developing ARMD. Approximately 10 percent of patients 66 to 74 years of age will have findings of macular degeneration. The prevalence increases to 30 percent in patients 75 to 85 years of age. Patients with a family history of ARMD are more likely to develop the disease than those individuals with no family history. Macular degeneration is more likely to be found in Caucasians than in people of African descent. Asians are thought to have similar rates of ARMD as Caucasians.

Classifying ARMD

ARMD is broadly divided into two categories: dry (non-exudative) and wet (exudative). Both dry and wet forms of ARMD can lead to central vision loss.

Dry ARMD is the more common form, affecting about 90 percent of patients with ARMD. In the dry form, cellular debris called drusen accumulates underneath the retina, causing small detachments (Figure 2). Over time, these drusen can disappear and lead to atrophy in the retina. Retinal atrophy in the macula results in central vision loss.
Figure 2

Figure 2: Dry ARMD with drusen (yellow subretinal deposits) in the macula

There is no treatment for dry macular degeneration. The goal of managing this disease is through prevention and monitoring. Smoking, hypertension, obesity and high cholesterol are all risk factors associated with ARMD. Smoking cessation and optimizing known medical risk factors are recommended for individuals with dry ARMD. Large clinical studies have shown micronutrient supplementation (eye vitamins) may benefit some individuals diagnosed with intermediate-level dry ARMD. However, it’s important to note these supplements have not been shown to benefit patients with early ARMD.

Patients who have been diagnosed with dry ARMD should monitor their vision daily with a standardized grid, a diagnostic tool used to detect visual disturbances. Any changes in vision may be suggestive of conversion to wet ARMD.

About 10 percent of patients with dry ARMD will eventually develop new blood vessels that grow into the macula. Those individuals have converted to wet ARMD. Wet ARMD causes vision loss due to abnormal blood vessel growth into the macula (Figure 3). Bleeding, leaking, and scarring from these blood vessels eventually causes irreversible damage to the retinal nerve cells and may cause rapid central vision loss if left untreated.  
Figure 3

Figure 3: Wet ARMD with a subretinal hemorrhage in the macula

Detecting, managing and treating ARMD
Fortunately, there are treatments for wet ARMD. Anti-angiogenic medications have been shown to stabilize or improve vision in most patients with wet ARMD. These medications are injected into the cavity of the eye and cause regression of the abnormal blood vessels seen in wet ARMD. Most patients require treatment on a monthly basis for this condition. Photodynamic therapy, which selectively seals leaking blood vessels using a cold laser is another treatment option for wet ARMD.

The key to managing ARMD is prevention, early diagnosis and treatment. Your eye doctor will perform a comprehensive eye exam to determine if you have ARMD, and whether it is dry or wet. Special tests may be performed, like color pictures, retinal scans or a fluorescein angiogram to evaluate macular degeneration in the eye. Counseling and treatment in the form of lasers or injections in the cavity of the eye may be offered to patients with wet ARMD. Early complications can be detected and treated before resulting in more profound problems and vision loss.

For more information
If you would like more information about Age Related Macular Degeneration or other retinal diseases, or you or a loved one are in need of an eye exam, please call Dr. Rumya Rao for an appointment at (773) 784-9400 or (847) 297-8900.