Pachychoroid is an eye condition characterized by structural changes in the choroid, a vascular layer beneath the retina. It is an important factor in the development of several vision-threatening diseases.
Understanding Pachychoroid
The choroid is a network of blood vessels situated between the retina and the sclera, the white outer layer of the eye. Its function involves supplying oxygen and nutrients to the outer layers of the retina, particularly the photoreceptor cells.
In pachychoroid, the choroid exhibits abnormal thickening, often significantly thicker than normal, due to the dilation of large choroidal vessels, known as pachyvessels. These dilated vessels can also lead to increased hydrostatic pressure within the choroid.
The structural alterations in pachychoroid also include a thinning of the choriocapillaris, the innermost layer of the choroid responsible for direct nutrient exchange with the retinal pigment epithelium (RPE). Areas of RPE atrophy or detachment may occur, impacting retinal health.
Recognizing Pachychoroid
Individuals with pachychoroid may experience visual symptoms, though it can be asymptomatic in early stages. Common complaints include blurred vision, particularly in the central field, distorted vision, or a central blind spot. Light sensitivity can also be a symptom. The severity of symptoms often depends on fluid leakage or other complications.
Eye care professionals use specific diagnostic methods to identify pachychoroid. Optical Coherence Tomography (OCT) provides high-resolution views of the retina and choroid, allowing measurement of choroidal thickness and visualization of dilated pachyvessels. OCT can also detect fluid accumulation. Fluorescein angiography and indocyanine green angiography (ICGA) evaluate choroidal blood flow, with ICGA providing detailed images of choroidal vasculature.
Conditions Linked to Pachychoroid
Pachychoroid is an underlying factor for a spectrum of related eye conditions. Central serous chorioretinopathy (CSC) is a prominent example, characterized by fluid accumulation under the retina, leading to distorted or blurred vision. Pachychoroid contributes to CSC due to impaired choroidal drainage and increased hydrostatic pressure, causing fluid to leak through a compromised retinal pigment epithelium.
Pachychoroid pigment epitheliopathy (PPE) represents a milder form, where RPE dysfunction or atrophy occurs without significant fluid detachment. This condition often precedes more severe manifestations like CSC. The RPE changes are thought to result from chronic circulatory disturbances within the thickened choroid.
Pachychoroid neovasculopathy (PNV) involves the growth of abnormal new blood vessels from the choroid into the subretinal space. These fragile vessels can leak fluid or blood, causing severe vision loss. PNV is considered a complication of chronic choroidal dysfunction and RPE damage associated with pachychoroid.
Polypoidal choroidal vasculopathy (PCV) is another condition strongly linked to pachychoroid, characterized by a network of abnormal, branching choroidal vessels with polyp-like dilations. PCV lesions are prone to leakage and hemorrhage, resulting in sudden vision loss. The dilated choroidal vessels in pachychoroid are thought to provide an environment for these polypoidal structures.
Managing Pachychoroid
Management strategies primarily focus on addressing associated complications, as there is no direct treatment for choroidal thickening. Regular monitoring is a fundamental aspect of care to detect changes early, often involving periodic OCT scans to track choroidal thickness, fluid accumulation, and RPE health.
For conditions like central serous chorioretinopathy (CSC), treatment aims to resolve fluid and prevent recurrence. This may include laser photocoagulation to seal leaking points, or photodynamic therapy (PDT), which uses a light-activated drug to close abnormal choroidal vessels.
In cases of pachychoroid neovasculopathy (PNV) or polypoidal choroidal vasculopathy (PCV), anti-VEGF injections are a common treatment. These medications block vascular endothelial growth factor, a protein that promotes abnormal blood vessel growth and leakage. Multiple injections are typically required to stabilize vision and reduce leakage.
Treatment plans are individualized, depending on the specific condition, its severity, and the patient’s overall eye health. The goal is to preserve vision by controlling fluid leakage, preventing abnormal vessel growth, and mitigating further retinal damage.