What Causes Subretinal Fluid In The Eye? Root Causes

Subretinal fluid is a buildup of fluid in the space between the retina and the layer of tissue beneath it. That space does not exist in a healthy eye. The retina normally sits flat against the retinal pigment epithelium, held in place by a gentle suction-like force. Fluid collects there only when something disrupts that normal attachment. The causes fall into a few broad groups, and identifying which one is at work determines what happens next.

What Causes Subretinal Fluid In The Eye?

Fluid accumulates under the retina through three main routes: a leak from damaged or abnormal blood vessels, a breakdown of the retinal pigment epithelium barrier, or a problem with the retina’s own pumping mechanism that normally keeps the space dry.

The retinal pigment epithelium (RPE) is a single layer of cells under the retina. It works like a sump pump, actively moving fluid out of the subretinal space and back into the bloodstream. When the RPE is damaged, overwhelmed, or the retina is pulled away from it, fluid builds up faster than it can be cleared.

What causes this to happen varies widely. The most common underlying conditions include:

• Central serous chorioretinopathy (CSC), where fluid leaks from the choroid through a defect in the RPE
• Age-related macular degeneration (AMD), particularly the wet form, where abnormal blood vessels leak fluid
• Inflammatory or autoimmune conditions affecting the choroid and RPE
• Retinal detachment, where a tear or hole allows fluid to enter the subretinal space
• Complications from eye surgery or certain medications
• Choroidal tumors or other growths that disrupt normal fluid regulation

In many cases, the fluid is a symptom rather than a disease itself. The underlying condition is what needs to be identified and managed.

How Does Central Serous Chorioretinopathy Cause Subretinal Fluid?

Central serous chorioretinopathy is one of the most common causes of subretinal fluid in otherwise healthy adults under 60. It occurs when fluid leaks from the choroid — the vascular layer beneath the retina — through a defect in the retinal pigment epithelium. The fluid pools under the retina and causes a localized detachment.

The condition is strongly associated with high levels of cortisol, whether from stress, corticosteroid use, or endogenous overproduction. Some studies suggest that people with Type A personality traits and high stress levels are more prone to CSC, though the relationship is not fully understood.

Symptoms typically include a central blurry spot, distorted vision (metamorphopsia), and sometimes a slight dimming of colors. Many cases resolve on their own within a few months without treatment. However, some people experience recurrent episodes or persistent fluid that can lead to permanent vision changes.

Treatment options for CSC are limited. Observation is common for first episodes. For persistent cases, some clinicians use laser photocoagulation or photodynamic therapy, but evidence for these approaches is mixed. No medication has been approved specifically for CSC.

What Role Does Age-Related Macular Degeneration Play?

In wet age-related macular degeneration, abnormal blood vessels grow beneath the retina — a process called choroidal neovascularization. These new vessels are fragile and leak fluid and blood into the subretinal space. This is different from dry AMD, where no fluid leakage occurs.

Wet AMD is the less common form of the disease but accounts for most severe vision loss. The fluid from leaking vessels causes rapid distortion and blurring. Without treatment, it can lead to permanent scarring and central vision loss.

Anti-VEGF injections are the standard treatment for wet AMD. These drugs block vascular endothelial growth factor, a protein that drives abnormal vessel growth and leakage. Research consistently shows that anti-VEGF therapy can reduce fluid and stabilize vision in many people, though outcomes vary. Treatment usually requires regular injections over an extended period.

It’s worth noting that not all subretinal fluid in older adults comes from wet AMD. Other conditions, including polypoidal choroidal vasculopathy and retinal angiomatous proliferation, can produce similar findings. Distinguishing between them often requires imaging tests like optical coherence tomography (OCT) and fluorescein angiography.

Can Retinal Detachment Cause Fluid Under The Retina?

Yes. In rhegmatogenous retinal detachment — the most common type — a tear or hole in the retina allows vitreous fluid to seep into the subretinal space. The fluid separates the retina from the RPE. This is a medical emergency. Without prompt treatment, the retina can lose its blood supply and become permanently damaged.

Symptoms of retinal detachment include a sudden increase in floaters, flashes of light, and a dark curtain or shadow moving across the field of vision. If you experience these symptoms, seek immediate medical attention.

Treatment typically involves surgery to reattach the retina. Options include pneumatic retinopexy, scleral buckle, and vitrectomy. The choice depends on the location and extent of the detachment. Success rates are generally high when treatment is prompt, but outcomes depend on how much of the macula was involved and how long the detachment lasted.

Other types of detachment — tractional and exudative — can also cause subretinal fluid. Tractional detachment occurs when scar tissue pulls the retina away. Exudative detachment happens when fluid leaks from vessels without a tear. Each has different causes and treatments.

What Inflammatory And Infectious Conditions Lead To Subretinal Fluid?

Inflammation in the choroid or RPE can disrupt the barrier that keeps fluid out of the subretinal space. Several conditions can cause this.

Uveitis — inflammation of the uvea — can involve the choroid and lead to fluid accumulation. Conditions like Vogt-Koyanagi-Harada disease, sympathetic ophthalmia, and posterior scleritis are known to cause subretinal fluid. These are relatively rare but serious.

Infectious causes include:

• Syphilis, which can cause chorioretinitis and fluid leakage
• Toxoplasmosis, a parasitic infection that can scar the retina and cause fluid buildup
• Cytomegalovirus (CMV) retinitis, usually in people with weakened immune systems
• Tuberculosis, which can affect the choroid
• Fungal infections, though these are uncommon in the eye

Diagnosis often requires blood tests, imaging, and sometimes a sample of fluid from the eye. Treatment targets the underlying infection or inflammation. Corticosteroids are sometimes used for inflammatory causes, but they can worsen infectious ones, so accurate diagnosis matters.

Can Medications Or Surgery Cause Subretinal Fluid?

Yes. Certain medications and surgical procedures can lead to fluid under the retina.

Corticosteroids are a well-known trigger for central serous chorioretinopathy. This includes oral, topical, inhaled, and injected forms. The risk appears to increase with higher doses and longer use, though some people develop CSC after short courses.

Other medications linked to subretinal fluid include:

• Some chemotherapy agents
• Certain blood pressure medications
• Drugs used to treat erectile dysfunction (rare)
• Interferon therapy

Surgery-related causes include complications from cataract surgery, glaucoma surgery, or retinal detachment repair. In some cases, fluid accumulates as part of the normal healing process and resolves on its own. In others, it indicates a problem that needs further intervention.

If you are taking a medication and notice vision changes, talk to your doctor. Do not stop any prescribed medication without medical guidance.

How Is Subretinal Fluid Diagnosed And What Does It Mean For Vision?

Diagnosis usually starts with a dilated eye exam. An eye doctor can see fluid under the retina as a subtle elevation or blister. Imaging tests confirm the finding and help identify the cause.

Optical coherence tomography (OCT) is the most common imaging test. It uses light waves to create cross-sectional images of the retina and can show fluid with high detail. Fluorescein angiography and indocyanine green angiography can show leaking vessels. Ultrasound may be used if the view is blocked.

The impact on vision depends on where the fluid is and how long it lasts. Fluid under the macula — the central part of the retina responsible for sharp vision — is more likely to cause noticeable symptoms. Fluid in the periphery may not affect vision at all.

Short-term fluid often causes distortion or blurring that improves when the fluid resolves. Long-term or recurrent fluid can lead to permanent damage to the photoreceptors and RPE. This is why identifying and treating the underlying cause matters.

Not all subretinal fluid requires immediate treatment. Some cases, like mild CSC, often resolve without intervention. Others, like wet AMD or retinal detachment, need prompt care. The key is accurate diagnosis.

What Should You Do If You Notice Vision Changes?

Any sudden change in vision — blurriness, distortion, flashes, floaters, or a shadow — warrants a prompt eye exam. Subretinal fluid is not something you can see or diagnose on your own. Only an eye care professional can determine whether fluid is present and what is causing it.

If you have a known condition like AMD or diabetes, regular eye exams are important even if your vision seems fine. Fluid can accumulate before symptoms appear.

There is no home remedy or lifestyle change that reliably prevents or treats subretinal fluid. Managing underlying conditions — controlling blood pressure, managing diabetes, and avoiding unnecessary corticosteroid use — may reduce risk in some cases, but the evidence for specific preventive measures is limited.

The most important step is getting an accurate diagnosis. The cause determines the treatment, and the treatment determines the outcome.