What Is Age-Related Macular Degeneration? Dry vs Wet AMD Explained

Age-related macular degeneration (AMD) is a condition that affects the macula and can lead to loss of central vision, especially in adults over 50.

Age-related Macular Degeneration

Age-related macular degeneration (AMD) is the number one cause of legal blindness (vision

less than 20/200) in persons over the age of 50 in the United States. This disease has two

specific presentations: non-exudative or "dry" macular degeneration and exudative or "wet"

macular degeneration. AMD almost never causes complete loss of vision and usually

involves only the central vision, leaving the peripheral vision intact. Although two specific

presentations, wet and dry, are described, they are actually a spectrum of disease. The wet

form usually occurs after the dry form has been present for a long period of time and both

forms can be present in one patient. Eye care specialists ask patients to evaluate themselves

with an Amsler Grid each day and return immediately if any changes occur.

The dry form occurs when there are pigmentary changes and loss of pigmented cells in the

center part of vision along with the hallmark of macular degeneration, drusen. These are

small, white spots under the retina at the level of Bruch’s membrane, and are thought to

indicate problems with the normal function of the retinal pigment epithelium (RPE), the

pigmented cells. 80 to 90% of patients with macular degeneration have the dry form, but

only 10 to 20% of severe visual loss is in the dry form. The wet form, therefore, accounts for

the majority of severe visual loss in this disease.

DRUSEN

Drusen are the hallmark of macular degeneration. These usually precede the formation of wet changes

Understanding Wet Age-Related Macular Degeneration (AMD)

Overview

The wet AMD form is a more aggressive disease causing rapidly progressive vision loss. The

vision loss is due to abnormal blood vessels growing underneath the retina that leak fluid or

bleed. This fluid or blood underneath the retina impairs its ability to function, resulting in vision

changes such as distortion, blurriness, or loss of central vision. If left untreated, a scar develops

resulting in permanent irreversible vision loss.

Current Treatments and Research

At present, there is no cure for age-related macular degeneration despite extensive ongoing

research studies. However, there are treatments that can preserve your vision. Treatments for

dry AMD are presently aimed at slowing the development of drusen. There currently are no FDA

approved drugs for the treatment of dry AMD. However, large studies by the NEI known as

AREDS have demonstrated the benefit of eye vitamins at decreasing the risk of dry AMD

progressing to wet AMD. In addition, studies have shown that smoking and tobacco products

significantly increase the risk of dry AMD converting to wet AMD.

Treatment Options for Wet AMD

In the past, thermal laser treatment was used for treating wet AMD. While the laser would

destroy the abnormal vessels growing underneath the retina, it also creates a scar and often did

not restore the vision lost. Currently, wet AMD can be successfully managed with anti-VEGF

therapies such as Avastin, Lucentis, or Eylea and a newer “cold” laser called photodynamic

therapy (PDT). These drugs inhibit abnormal vessel growth and cause the bleeding or leaking

abnormal vessels to regress. These drugs have revolutionized the management of wet AMD

because they not only eliminate the abnormal vessels without creating a scar such as laser

therapy, but also restore and preserve vision when detected early.

Delivery of Medication

Because the eye is an immunoprivileged site meaning that medications taken by mouth do not

penetrate well into the eye, the medicine has to be delivered by an injection into the eye. All

these medicines simply convert wet AMD which can cause rapid vision loss back to dry AMD.

However, repeated injections are often necessary since the underlying disease process remains

and abnormal vessels may grow back to bleed or leak fluid. There are many different subtypes

of wet AMD. It is important to see your retinal specialist to determine a personalized tailored

therapy in selecting what medication is best for you and your eye.

Disclaimer

The information contained in this document is for informational purposes only. Diagnosis and

therapy should be based on a thorough examination by and recommendations of a qualified eye

care provider.

Symptoms

• Blurry or distorted central vision

• Difficulty reading

• Trouble recognizing faces

Causes and Risk Factors

• Aging

• Family history

• Smoking

• Poor cardiovascular health

Diagnosis and When to See a Doctor

Regular eye exams and retinal imaging help detect AMD early.

Treatment and Management

Dry AMD is often managed with monitoring and lifestyle changes. Wet AMD may require injections or specialist care.

Summary and Next Steps

Early detection is key to preserving vision. Schedule regular eye exams if you are at risk.