Pigment epithelial detachment (PED) is a condition where the retinal pigment epithelium (RPE), a layer of cells in the eye, separates from underlying tissue. The RPE is a single layer of cells beneath the retina, containing light-sensing photoreceptor cells. It provides nourishment to the retina and removes waste products from photoreceptors. When detached, it creates a blister-like elevation, disrupting this support system.
Causes and Associated Conditions
Pigment epithelial detachment often arises from age-related macular degeneration (AMD), particularly its “wet” or neovascular form. In wet AMD, abnormal new blood vessels (choroidal neovascularization) grow from the choroid beneath the retina. These new vessels often leak fluid or blood, accumulating beneath the RPE, causing it to lift and detach. This leakage impairs RPE function.
Another common cause of PED is central serous retinopathy (CSR), where fluid accumulates under the RPE without the growth of new blood vessels. In CSR, fluid leaks from the choroid, the vascular layer, seeping through a compromised RPE barrier. This condition is often associated with stress, corticosteroid use, or certain systemic conditions. The fluid buildup elevates the RPE, leading to visual disturbances.
Other less common conditions can also contribute to PED formation, including inflammatory conditions affecting the eye or polypoidal choroidal vasculopathy (PCV). PCV involves an abnormal branching vascular network in the choroid with characteristic polyp-like dilations that can leak fluid and blood, causing RPE detachment. These causes highlight the varied mechanisms by which the RPE can separate from its supportive membrane.
Symptoms and Visual Changes
Individuals experiencing a pigment epithelial detachment often notice changes in their central vision. These changes are painless and can manifest as blurriness or haziness in the direct line of sight. The central visual field, responsible for sharp, detailed vision, is most affected due to the RPE’s macular location.
A hallmark symptom is metamorphopsia, where straight lines appear distorted, wavy, or bent. This occurs because the detached RPE surface becomes uneven, causing the light-sensing cells above it to be displaced and perceive straight lines as curved. Another common visual change is a scotoma, a dark, gray, or blurry spot in the central field of vision. This blind spot results from the impaired function or damage to the photoreceptors overlying the detached RPE.
Some patients may also experience micropsia, where objects appear smaller, or macropsia, where objects appear larger. These perceptual distortions arise from the altered spacing and arrangement of the photoreceptors due to the RPE elevation. The specific visual changes experienced can vary depending on the size, location, and type of fluid or material accumulating beneath the RPE.
The Diagnostic Process
Diagnosing a pigment epithelial detachment begins with a dilated eye exam. During this exam, the doctor can often observe the elevated RPE layer, particularly if the detachment is large or involves specific features. However, detailed imaging is necessary to confirm the diagnosis and determine the underlying cause.
Optical Coherence Tomography (OCT) is the primary imaging tool for diagnosing and monitoring PEDs. This non-invasive scan uses light waves to create high-resolution, cross-sectional images of the retina and its underlying layers. OCT clearly visualizes the RPE separation from Bruch’s membrane and identifies material (fluid, blood, drusen) accumulating in the sub-RPE space. It provides precise measurements of the detachment’s height and width, important for tracking changes over time.
Fluorescein Angiography (FA) is another important diagnostic test, especially for suspected choroidal neovascularization (CNV). A dye is injected into an arm vein, and rapid photographs are taken as it circulates through retinal and choroidal blood vessels. FA helps identify leaking blood vessels, differentiating between wet AMD-related PEDs and other types, like those caused by CSR. In specific cases, Indocyanine Green Angiography (ICGA) may complement FA, offering better visualization of choroidal circulation and helping identify conditions like polypoidal choroidal vasculopathy.
Treatment and Management Strategies
Treatment for pigment epithelial detachment is tailored to its underlying cause, to stabilize vision and prevent further damage. For PEDs caused by wet age-related macular degeneration (AMD), anti-vascular endothelial growth factor (anti-VEGF) injections are the standard of care. These medications are injected into the eye, blocking the protein responsible for abnormal blood vessel growth and leakage. By reducing fluid and blood leakage, anti-VEGF therapy allows the RPE to flatten, restoring its normal function and improving vision.
Photodynamic therapy (PDT) is another laser treatment used, often with anti-VEGF injections, for specific PED types, such as those associated with polypoidal choroidal vasculopathy or certain central serous retinopathy cases. This procedure involves injecting a light-sensitive drug into the bloodstream, activated by a non-thermal laser applied to the affected area. The activated drug selectively targets and closes abnormal blood vessels, reducing leakage and flattening the PED.
Focal laser photocoagulation may be considered for specific, well-defined leaking spots, particularly in central serous retinopathy cases where leakage is not directly under the central macula. This treatment uses a precise laser to seal leaking blood vessels. For certain PED types, such as small, stable drusenoid PEDs or some serous PEDs associated with CSR, observation without active treatment may be the initial approach. These detachments can sometimes resolve or may not significantly impact vision, allowing for careful monitoring by an ophthalmologist.