What is the difference between dry AMD and wet AMD? 

Age related macular degeneration (AMD) is a common condition that affects the middle part of your vision, usually appearing in people in their 50s, 60s, and 70s. While all forms of AMD involve the breakdown of the macula, the small part of the retina responsible for sharp central sight, the condition is clinically divided into two distinct types: dry and wet. The primary difference lies in how the damage occurs and how quickly the vision is affected. In the United Kingdom, identifying which type a patient has is the first step in determining the appropriate management plan, as the urgency and treatment options for each vary significantly. 

What We’ll Discuss in This Article 

• The biological mechanisms that distinguish dry AMD from wet AMD. 

• The typical speed of vision loss associated with each type. 

• How the accumulation of waste products versus blood vessel growth impacts the eye. 

• The prevalence of each condition within the UK population. 

• Available treatment pathways for both dry and wet manifestations. 

• Key symptoms that may indicate a transition from dry to wet AMD. 

The nature and progression of dry AMD 

Dry AMD is the most frequent form of the condition, affecting roughly nine out of ten people diagnosed with macular degeneration. It is a chronic, progressive disease that occurs when the light sensitive cells in the macula slowly break down as part of the ageing process. This thinning of the macula is often accompanied by the development of drusen, which are small, yellow deposits of fatty proteins and metabolic waste that build up under the retina. 

The progression of dry AMD is typically very slow, often taking several years or even decades to significantly impact daily life. In the early stages, many people do not notice any changes to their sight. As it advances, central vision may become slightly blurred, or you might find that you need brighter light for tasks like reading or sewing. Because there is currently no medical treatment to “fix” dry AMD, management in the UK focuses on lifestyle changes, such as smoking cessation and nutritional support, alongside the use of low vision aids to maximise remaining sight. 

The urgent characteristics of wet AMD 

Wet AMD is much less common than the dry form, accounting for about 10% of cases, but it is responsible for most severe vision loss. It is called “wet” because it involves the growth of abnormal, fragile blood vessels underneath the macula, a process known as neovascularisation. These new vessels are unstable and prone to leaking fluid, proteins, or blood into the layers of the retina. This leakage causes the macula to lift from its normal position at the back of the eye, leading to rapid damage. 

The onset of wet AMD is often sudden. While dry AMD is measured in years, wet AMD can cause significant visual distortion or a blind spot in the central vision within a matter of weeks or even days. One of the most characteristic signs of wet AMD is visual distortion, where straight lines appear wavy or objects look the wrong size. Because this type of AMD can lead to permanent scarring of the macula very quickly, it is treated as a medical priority in UK eye clinics. You can find detailed descriptions of these sudden changes on the NHS website regarding AMD. 

Comparing physical changes in the eye 

To understand the difference between the two types, it is helpful to look at what is happening physically within the eye. In dry AMD, the problem is essentially one of “wear and tear.” The retinal pigment epithelium, which provides nutrients to the macula, stops working efficiently, leading to the death of the overlying photoreceptor cells. This is a degenerative process similar to the thinning of skin as we age. 

In contrast, wet AMD is an active, inflammatory response. The body attempts to compensate for a lack of oxygen or nutrients in the retina by growing new blood vessels. However, these vessels are poorly formed and “leaky.” The resulting fluid buildup causes swelling (oedema) and can lead to the formation of scar tissue. Once scar tissue forms in the macula, the vision loss is usually permanent. This is why early intervention to stop the leakage is the primary goal for ophthalmologists. 

Key Differences At A Glance 

Feature	Dry AMD	Wet AMD
Main Cause	Thinning of the macula and drusen buildup	Abnormal, leaking blood vessels
Speed of Change	Gradual, occurs over many years	Sudden, can change in days or weeks
Common Signs	Mild blurring, need for more light	Wavy lines, sudden central blind spot
UK Prevalence	90% of cases	10% of cases
Urgency	Routine monitoring	Urgent medical assessment required
Treatment	Visual aids and lifestyle adjustments	Injections (anti VEGF) or laser

Can dry AMD turn into wet AMD? 

It is important to understand that dry AMD and wet AMD are not always entirely separate conditions. In fact, almost everyone who develops the wet form of the disease had the dry form first, even if it was never diagnosed. The presence of significant drusen in dry AMD is a known risk factor for the eventual development of wet AMD. 

UK clinicians often advise patients with dry AMD to monitor their vision daily using an Amsler grid, which is a simple square grid of straight lines. If a patient with dry AMD suddenly notices that the lines on the grid have become wavy or that a part of the grid has disappeared, it may indicate that the condition has transitioned to the wet form. This transition requires immediate referral to a specialist to begin treatments that can suppress the growth of the leaking vessels. Guidance on this transition and what to look for is provided by The Royal College of Ophthalmologists. 

Treatment and management pathways in the UK 

The treatment pathways for the two types of AMD are very different. For dry AMD, the focus is on supporting the patient to live well with reduced central vision. This often involves a referral to a Low Vision Clinic, where specialists provide high powered magnifiers, electronic readers, and advice on lighting. There is also some evidence that specific combinations of high dose vitamins and minerals can slow progression in some people with intermediate dry AMD. 

For wet AMD, the standard treatment in the UK involves injections into the eye of a medication called an anti VEGF (vascular endothelial growth factor). These drugs block the chemical signal that tells the body to grow the abnormal blood vessels, effectively “drying up” the leakage and preventing further scarring. Many patients require these injections every few months to keep the condition under control. National standards for these treatments are set by NICE, ensuring that patients across the country have access to these sight saving therapies. 

Conclusion 

The fundamental difference between dry and wet AMD is the presence of leaking blood vessels. Dry AMD is a slow, degenerative thinning of the macula that occurs over years, while wet AMD is a sudden and more severe complication caused by fluid leakage. While dry AMD is more common, wet AMD poses a much higher risk of rapid sight loss. Understanding these differences allows patients to recognise when a routine eye change becomes an urgent medical matter. If you experience severe, sudden, or worsening symptoms, call 999 immediately. 

Authority Snapshot 

This article clarifies the clinical distinctions between the two main types of age-related macular degeneration. It was written by the Medical Content Team and reviewed by Dr. Rebecca Fernandez, a UK trained physician with experience in internal medicine and acute care. The content is strictly aligned with the diagnostic and treatment protocols established by the NHS and the National Institute for Health and Care Excellence (NICE) to ensure accurate and safe patient information.