Difference Between Wet and Dry Macular Degeneration

The key difference between wet and dry macular degeneration is that wet macular degeneration is due to abnormal blood vessels growth under the retina towards the macula, whereas dry macular degeneration is due to small white or yellowish deposits which form on the retina beneath the macula.

Age-related macular degeneration (AMD) is an eye disease that may get worse over time. It can lead to severe permanent vision loss in people over age 60 years. It happens when the small central part of the retina called the “macula” degenerates. The retina is the light-sensing nerve tissue located in the back of the eye. This usually takes place when people get older, so often it is referred to as age-related macular degeneration. There are two types of age-related macular degeneration: wet and dry macular degeneration.

CONTENTS

1. Overview and Key Difference
2. What is Wet Macular Degeneration
3.  What is Dry Macular Degeneration
4. Similarities – Wet and Dry Macular Degeneration
5. Wet vs Dry Macular Degeneration in Tabular Form
6. Summary – Wet vs Dry Macular Degeneration

What is Wet Macular Degeneration?

Wet macular degeneration is a type of age-related macular degeneration where abnormal blood vessels under the retina begin to grow towards the macula. This growth degenerates the macula. It is also known as neovascular or exudative macular degeneration. It affects 10-15% of individuals with age-related macular degeneration. But it accounts for approximately 90% of all cases of severe vision loss from this disease.

The proliferation of new abnormal blood vessels is stimulated by vascular endothelial growth factor (VEGF). These abnormal blood vessels are more fragile than typical blood vessels. Therefore, blood and proteins leak from these blood vessels below the macula. Bleeding, leaking, and scarring from these blood vessels eventually cause irreversible damage to the photoreceptors in the retina. This leads to permanent loss of central vision. Preferential hyperacuity perimetry and angiography are two advanced diagnosing techniques for wet macular degeneration.

Ranibizumab, aflibercept, brolucizumab, and bevacizumab are approved VEGF inhibitors for the treatment of wet macular degeneration. Other than that laser coagulation therapy, photodynamic therapy, and cataract surgery could also improve visual outcomes from this condition.

What is Dry Macular Degeneration?

Dry macular degeneration is a type of age-related macular degeneration where small white or yellowish deposits form on the retina beneath the macula that degenerates the macula. It is also called atrophic macular degeneration. Dry macular degeneration affects approximately 80-90% of individuals with age-related macular degeneration. The cause is not known. This condition tends to progress very slowly than wet macular degeneration. Dry macular degeneration encompasses all forms of age-related macular degeneration that are not neovascular in nature. The more advanced form of dry macular degeneration is called geographic atrophy. In geographic atrophy, the multiple layers (choriocapillaris, retinal pigment epithelium, and overlying photoreceptors) that make up the retina undergo atrophy.

Patients with dry macular degeneration have minimal symptoms in the earlier stages. The visual function loss occurs more frequently if the condition advances to the geographic atrophy stage. In 10-20% of people, dry macular degeneration progresses to the wet type. In contrast to sensitivity test, Amsler grid, Snellen chart, electroretinogram, Farnsworth-Munsell 100 hue test, and optical coherence tomography can be used to diagnose dry macular degeneration. There is no cure for this condition. But complement inhibitors are used currently to treat ophthalmic inflammation. In age-related macular degeneration trials, a factor called anti-factor D agent (lampalizumab) is presently tested for the geographic atrophy stage. Moreover, high specific doses of antioxidants and zinc may also improve eye conditions.

What are the Similarities Between Wet and Dry Macular Degeneration?

• These are types of age-related macular degeneration.
• Both types degenerate macular of the retina.
• They occur in people over age 60 years.
• Both types can cause vision loss.

What is the Difference Between Wet and Dry Macular Degeneration?

Wet macular degeneration is a type of age-related macular degeneration where abnormal blood vessels under the retina begin to grow towards the macula. On the other hand, dry macular degeneration is a type of age-related macular degeneration where small white or yellowish deposits form on the retina beneath the macula. So, this is the key difference between wet and dry macular degeneration. Furthermore, wet macular degeneration usually leads to legal blindness. In contrast, dry macular degeneration rarely leads to legal blindness.

The following infographic compiles the differences between wet and dry macular degeneration in tabular form.

Summary – Wet vs Dry Macular Degeneration

Macular degeneration, also known as age-related macular degeneration, is an eye disease that affects people older than 60 years. It is a medical condition that results in blurred or no vision in the center of the visual field. There are two types of age-related macular degeneration as wet and dry macular degeneration. Wet macular degeneration is due to abnormal blood vessels growth under the retina towards the macula. Dry macular degeneration is due to small white or yellowish deposits which form on the retina beneath the macula. Thus, this is the key difference between wet and dry macular degeneration.

Reference:

1.“Macular Degeneration (AMD): Symptoms, Causes, Treatment, Prevention.” WebMD.
2. “A Guide to Age-Related Macular Degeneration.” All About Vision, All About Vision, 5 Mar. 2021.

Image Courtesy:

1. “Age-related macular degeneration ‘Dry Type’” By Community Eye Health (CC BY-NC 2.0) via Flickr
2. “This colour slide shows a choroidal neovascular membrane under the fovea” By Community Eye Health (CC BY-NC 2.0) via Flickr