Age-Related Macular Degeneration (AMD)

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Age-Related Macular Degeneration (AMD)

As our nation grows older, more people are being diagnosed with age-related macular degeneration (AMD). This degenerative condition is the leading cause of irreversible vision impairment in those over the age of 50, and by 2050, it will impact an estimated 22 million men and women. AMD targets your retina, a thin, photosensitive tissue layer located on the eye’s back wall.

The retina has the crucial responsibility of enabling sight, as it converts light signals that enter the eye into electrical signals, which then progress to your brain via the optic nerve. Specifically, AMD impacts the macula, the retina’s sensitive, central portion that’s home to cells allowing your eye’s central vision. Over time, your macular tissue weakens and loses its functionality, causing issues with your sharp, straight-ahead, fine vision and related activities, like reading, seeing faces, or perceiving color.

AMD is defined as one of two types, the earlier, much more common “dry” form and the later, rarer “wet” form. Dry, or atrophic AMD, a natural factor of aging, is generally not harmful or painful, and any vision loss often develops slowly and gradually. You may not even realize you have the condition until your ophthalmologist discovers it during an annual dilated eye exam.

If you have a dry AMD diagnosis, it’s imperative to monitor your vision regularly. You must also alert your doctor immediately of any vision changes. Left untreated, dry AMD can turn into wet AMD type, increasing the chances of vision loss. However, combining early detection and regular monitoring gives patients a better chance of preserving their vision.

With wet, or exudative AMD, the much more serious form, any vision loss is much quicker and more noticeable than with dry AMD. Wet AMD’s most tell-tale sign is the development of choroidal neovascularization (CNV), which are irregular, weed-like blood vessels under the retina. Should they break, these new vessels can cause blood and other fluids to leak into the macular area, resulting in swelling, bleeding, central vision blurriness and distortions, and worsening vision loss.

Controllable Risk Factors

AMD is an incurable condition, and no treatments yet exist. Additionally, its main risk factor is being over 50 years old. Nevertheless, there are certain risk factors and lifestyle factors that may increase your chances, including:

• Having a family history
• Having underlying conditions, like diabetes, high blood pressure, or high cholesterol
• Obesity
• Smoking
• Long-term, unprotected exposure to sunlight
• Having irises with a lighter color. The iris, the colored tissue at the front of the eye, helps control pupil size to let light into the eye. Research suggests that lighter-colored eyes are twice as likely to develop AMD, as the iris absorbs less UV light, allowing more to reach the retina and causing damage.

Demographics

Perhaps not surprisingly, seniors are most at risk for age-related macular degeneration, hence the condition’s name. Studies show that up to 10% of individuals over 65 and 35% of individuals over 75 can expect to display some AMD signs. It almost always affects both eyes to some degree, and in most cases, patients will first develop the dry form. Wet AMD affects an estimated 10% of macular degeneration patients. When it comes to AMD risk factors, the most common and uncontrollable ones include being of advanced age and having a genetic tendency.

Clinical Appearance & Symptoms

In many cases, age-related macular degeneration, in its dry, or atrophic form, may have a low-key beginning, with patients possibly experiencing no symptoms. It’s only during your annual, comprehensive, dilated eye exam that you may even become aware that you have this condition.

During this exam, as your ophthalmologist inspects the retina, they may observe changes in the pigmented layer of tissue that nourishes the retina, known as the retinal pigment epithelium (RPE). This represents a significant concern, as the RPE is essential to the retina’s metabolic processes. With dry AMD, one distinguishing feature is the development of drusen, which are small, yellow deposits, similar to cholesterol, that accumulate under the retina. While a few are not a problem, should drusen grow in number and size, this can harm the RPE.

Another concern with dry AMD is dark clumps, known as RPE hyperpigmentation. They target the RPE, causing them to die off, and eventually, RPE atrophy may develop, in which whole retinal pigment epithelium tracts begin to disappear. This is the leading cause of any blindness associated with dry AMD. However, this loss is typically gradual, with patients noticing visual distortion, darkness, or blind spots. Truthfully, many dry AMD patients find that they retain superior visual function for years on end. A potential complication of RPE atrophy, should broad patches develop in the central macula, is becoming legally blind. Fortunately, with early detection and regular monitoring, dry AMD patients have a better chance of preserving their vision.

Wet AMD, the more serious form, is characterized by choroidal neovascularization (CNV), in which fragile, irregular blood vessels grow in the choroid and radiate outward. The choroid is a spongy, pigmented layer of blood vessels and connective tissue connected to the RPE, its responsibilities include:

• Supplying the retina’s outer layers with oxygen and blood
• Retinal temperature regulation
• Helping to control intraocular pressure
• Helping the growth and thickness of the sclera (the white part of the eye)
• Protecting against light toxicity

The term “wet” AMD stems from the effects of CNV and the resulting leakage of the bloodstream’s fluid, blood, fats, and proteins. As new blood vessels form, they can grow within or through the RPE into the space under the retina. Early on, you may see distorted images, and over time, dark or blind spots may occur., as the damaged RPE starts to damage the retina. The RPE is tasked with nourishing and keeping the retina healthy, so any disruption prevents it from doing its job.

As wet AMD progresses, the abnormal blood vessels under the retina become scarred, leading to severe visual consequences. It’s at this point that most patients become legally blind (vision <20/200), resulting in them being unable to perform fine, close-up activities, such as reading, cooking, or recognizing faces with the affected eye(s). There is some good news, as AMD patients rarely experience a complete lack of vision. This is because the eye’s macula is, in most cases, the only retinal part area impact, while the peripheral vision is almost always safeguarded.

Diagnosis

It’s essential to schedule regular dilated eye exams to detect the earliest signs of AMD. In particular, if you’re between 40 and 54, you should visit our ophthalmologists at least every 2-4 years, depending on your health needs. If you’re over 55, you should schedule an eye exam every 1-2 years. Once you’ve been diagnosed with macular degeneration during your eye exam, your retinal specialist may perform additional testing to evaluate the condition further.

This testing is commonly conducted to identify portions affected by choroidal neovascularization, with the goal of arranging and implementing potential treatment. A diagnostic technique known as fluorescein angiography is often utilized to identify macular degeneration. The general procedure involves a yellow dye being injected into an arm vein, which then journeys to the eye, making its way through the circulatory system. This dye, which has the role of a tracer, is photographed as it moves through the ocular circulation. The locations with leakage can be identified, as they correlate to areas of choroidal neovascularization in wet AMD.

With dry age-related macular degeneration, those regions containing drusen and RPE atrophy are readily identified. In this situation, another diagnostic methodology, optical coherence tomography (OCT), is a go-to option for obtaining high-resolution retinal images, along with any thickening related to fluid leakage due to choroidal neovascularization. On occasion, OCT can be utilized to demonstrate the location of unusual blood vessels. It’s also very valuable when it comes to determining the level of fluid and monitoring any responses to possible treatment options.

Treatment

Above all else, the one aspect of age-related macular degeneration treatment that is most crucial is prevention. When diagnosed in its earliest stages, the chances of delaying and preserving vision loss due to wet AMD increase. Doctors typically employ retinal intervention to prevent vision loss due to CNV. For a more thorough overview of these therapeutic options, you can review the “Treatments” section. In addition, we’ve compiled a “Medications” section, to provide information about the latest pharmaceutical treatments utilized in wet AMD treatment.

Preventative Actions

With age-related macular degeneration, you can take certain preventive measures to slow or prevent its development. These include:

• Getting any underlying conditions that worsen AMD under control
• Staying active and exercising daily
• Avoiding smoking
• Achieving and maintaining a healthy body mass index (BMI)
• Protecting your eyes from harmful UV ray exposure with sunglasses and hats

Research shows that consuming a diet containing foods rich in certain nutrients may promote eye and vision health, such as dark leafy greens, oily fish, citrus fruits, and nuts. You may also consider taking nutritional supplements found to benefit vision. One specific formulation, known as Age-Related Eye Disease Studies (AREDS and AREDS2), includes vitamins C and E, lutein, zeaxanthin, zinc, and copper. If you are interested in pursuing an AREDS blend, you and your healthcare provider can discuss if this supplement holds any benefits for your condition.

One good way to monitor your vision for any changes is for dry AMD by using an Amsler grid. Every day, you just look at this simple paper chart, consisting of horizontal and vertical lines that form a grid pattern, with a dot in the center. With regular use, it can help you detect any visual distortions. However, should you notice any changes or distortions, contact your ophthalmologist immediately.

Non-Surgical Treatment Options

Anti-Vascular Endothelial Growth Factor Agents – It has been shown that the retina itself is responsible for choroidal neovascularization, as it releases chemicals leading to this process. However, a variety of medications have been developed, which are designed to inhibit these chemicals, thereby stopping or slowing new blood vessel growth.

Among these drugs, known as anti-vascular endothelial growth factor (anti-VEGF) agents, are Macugen® (pegaptanib), Avastin® (bevacizumab), Lucentis® (ranibizumab), and Eylea® (aflibercept). Administered via injection directly into the eye, they’ve shown benefits in preserving vision compared to no treatment. The downside is that for the majority of patients, dramatic visual advantages are not likely post-treatment. A definite number of patients can also expect to continually be deprived of their vision, regardless of drug treatment. Most often, you’ll have to undergo retreatment at 4-week to 6-week intervals, although this may be dependent on the specific medication taken.

Surgical Treatment Options

Photodynamic Therapy – With this procedure, a retinal specialist will combine drug and laser treatments. Typically, you will have a photosensitizer, a light-sensitive drug, injected into an arm vein, and via your blood circulation, it will migrate to the retina. Following a 15-minute waiting period, a low-energy laser is used to activate this drug. The laser’s target is the newly formed, fragile blood vessels.

Studies show that the use of photodynamic therapy may impart benefits for slowing or stopping vision loss, as compared to patients not taking any treatment. Similar to anti-VEGF agents, most AMD patients should not expect to achieve noteworthy vision following their treatment. The need for being retreated is most often necessary at 3-month intervals.

Thermal Laser– Occasionally, retinal specialists will use a thermal (hot) laser, with the intent of burning abnormal blood vessels and warding off additional growth and associated visual loss. While the preceding treatment modalities have, for the most part, replaced the need for this procedure, the thermal laser remains a component in wet AMD treatment. Again, you and your healthcare provider can talk about whether or not you’d benefit from thermal laser use or another therapeutic option.