Polypoidal Choroidal Vasculopathy

Polypoidal choroidal vasculopathy is a disease affecting the blood vessel layer beneath the retina, causing fluid leakage and bleeding that can lead to vision loss if left untreated. While it shares features with age-related macular degeneration, this condition requires specialized diagnosis and treatment approaches.

Table of contents

• What is Polypoidal Choroidal Vasculopathy?
• Causes and Risk Factors
• Who is Most Affected?
• Signs and Symptoms
• Diagnostic Testing
• Treatment Options
• What to Expect

What is Polypoidal Choroidal Vasculopathy?

Polypoidal choroidal vasculopathy (PCV) is a disease that primarily affects a vascular layer of blood vessels called the choroid, which lies beneath the retina. The retina is the light-sensitive tissue at the back of the eye where photoreceptor cells (specialized cells responsible for vision) are located. When the choroid develops problems, the overlying retina can become damaged, affecting your ability to see^[1].

PCV is characterized by abnormally shaped blood vessels in the choroid. These vessels have multiple, small, polyp-shaped bulges that look like tiny balloons or grapes. These abnormal structures form due to defects in the blood vessel lining, with thinned out cells lining the vessels and fewer support cells compared to normal blood vessels^[2]. The disease is considered a variant of choroidal neovascularization (abnormal blood vessel growth) and shares some clinical features with wet age-related macular degeneration^[1].

The condition causes vision loss when these abnormal vessels leak fluid or blood into or under the retina. The polyp-like structures are particularly prone to leakage and rupture. Over time, PCV may also cause scarring or loss of retinal tissue, which doctors sometimes call atrophy^[1].

The disease was first identified and reported by researchers at an annual meeting of the American Academy of Ophthalmology in 1982. It was initially termed idiopathic polypoidal choroidal vasculopathy. In 1984, other researchers described a similar presentation in middle-aged Black women and named it posterior uveal bleeding syndrome. Later research established that PCV exists across genders, various age groups, and races^[2].

Causes and Risk Factors

The precise causes of polypoidal choroidal vasculopathy remain a mystery, but researchers have identified several factors associated with the disease. The fundamental problem appears to be abnormalities in the inner choroidal blood vessels^[2].

One suggested mechanism for how these polypoidal lesions develop involves small veins forming polyp-like protrusions when compressed by a hardened small artery at a crossing point where an artery and vein meet. The resulting slowed blood flow in the vein leads to tissue breakdown and fragility. Over time, this degeneration can lead to the formation of polyp-shaped structures that tend to leak and rupture^[2].

Several conditions have been associated with an increased risk of developing PCV. High blood pressure appears to be linked to the disease. Increased blood thickness (raised plasma viscosity) and low platelet counts (thrombocytopenia) have also been associated with PCV^[2]. However, more research is needed to fully understand these connections.

• Choroid
• Retina
• Macula
• Retinal pigment epithelium

Who is Most Affected?

Polypoidal choroidal vasculopathy is relatively uncommon in the general population. One study estimated that its prevalence in Europe is only 0.04% of the entire population^[2]. However, the disease shows striking differences in how it affects various ethnic groups.

The prevalence is significantly higher in Asian populations compared to white individuals. Studies have found that among patients with the clinical appearance of neovascular age-related macular degeneration, PCV was found in 7.8% of white individuals, 23% to 54% in Japanese populations, 22.3% in Chinese populations, and 24.6% in Korean populations^[2]. In fact, PCV is reported to be prevalent in 20% to 50% of Asian patients with presumed neovascular age-related macular degeneration^[8].

The disease tends to occur in individuals over the age of 60, although it may occur in much younger people^[1]. The condition is often diagnosed in people between 50 to 65 years old, and it tends to appear later in life for Caucasians than for Asians^[2].

PCV affects those of Asian and African descent more than Caucasians^[1]. While earlier studies suggested that middle-aged Black women were more frequently diagnosed, recent research shows that PCV occurs in both men and women across diverse ethnic groups^[3].

The clinical presentation of PCV can vary among ethnic populations. In Asian populations, PCV more commonly presents in one eye and in the macula (the central part of the retina), typically in men. In contrast, it is more characteristically found in areas near the optic nerve in white and Black women, often affecting both eyes^[4].

Signs and Symptoms

Patients with polypoidal choroidal vasculopathy often experience blurred vision or a blind spot in or near the center of their vision in one or both eyes. These symptoms may appear suddenly and tend not to vary throughout the day^[1].

Other early signs can include distorted vision, where straight lines may appear wavy or bent, and seeing floaters or small specks. People who report these symptoms within three months of onset usually have clearer vision initially^[6].

In some cases, your retina specialist may diagnose PCV early before it has caused any noticeable symptoms^[1]. This is one reason why regular eye examinations are important, especially for people over age 50 or those in higher-risk groups.

During an eye examination, doctors may observe subretinal fluid and bleeding under the retina, or hemorrhagic detachments of the retinal pigment epithelium. In chronic cases, signs like fatty deposits (lipid exudation) or fluid-filled spaces within the retina (intraretinal cysts) may be present^[6].

Interestingly, people with PCV usually have better vision when they first discover the condition than those with typical age-related macular degeneration. This could be because the affected area is sometimes located outside the center of the retina^[6].

Although PCV may appear to affect only one eye initially, it often goes on to affect both eyes over time. This makes frequent monitoring important to catch changes in the second eye early^[1].

Diagnostic Testing

The most important test used to diagnose polypoidal choroidal vasculopathy is a careful dilated eye examination by a retina specialist^[1]. However, several specialized imaging tests are essential for confirming the diagnosis and planning treatment.

Indocyanine green angiography (ICGA) is the essential test for diagnosing PCV. This imaging technique is able to create detailed images of the choroidal blood vessels beneath the retina. The test requires a special dye to be injected into a vein, usually in the arm or hand, before photographs of the retina are taken^[1]. On ICGA, PCV appears as abnormal blood vessel complexes, often with a branching vascular network and polyp-like dilations appearing as nodular bright spots, often with a dark halo around them^[4].

Fluorescein angiography is another dye-based imaging test that may be useful in evaluating PCV. Like ICGA, it requires a special dye to be injected into a vein before retinal photographs are taken. This test helps your retina specialist identify important abnormalities in the retinal blood vessels^[1].

Optical coherence tomography (OCT) scanning of the retina is routinely used to aid in diagnosis of PCV. OCT is a non-invasive imaging technique that creates detailed cross-sectional images of the retina. On OCT, the polyps appear as focal, highly peaked elevations of the retinal pigment epithelium, shaped like an inverted U. There are often associated fluid collections beneath the retina, and the branching vascular network has a characteristic appearance^[4].

Some specialized variations of OCT, such as en face OCT, can provide additional views of PCV structures. This technique allows doctors to view the abnormal vessels from above, where they appear as dilated vascular structures. OCT angiography is another advanced technique that can help visualize blood flow in these abnormal vessels^[4].

Treatment Options

Early diagnosis and treatment may restore vision and prevent further vision loss in some patients with polypoidal choroidal vasculopathy. The most common treatments are injections of anti-VEGF medication into the eye and photodynamic therapy^[1].

Anti-VEGF therapy involves injections of medication directly into the eye. Vascular endothelial growth factor (VEGF) is a molecule generated by the body that causes the abnormal vessels in PCV to leak fluid and bleed into and under the retina. Anti-VEGF drugs block the activity of VEGF and often result in a decrease in the fluid or blood caused by the abnormal vessels^[1].

Successful treatment with anti-VEGF medication often requires repeat dosing as frequently as every 4 to 6 weeks to prevent increased leakage or bleeding. Previous studies have shown that anti-VEGF therapy may reduce leakage in PCV, although it has been less effective at causing the polyps themselves to completely disappear. In one major study, complete regression of polyps was achieved by only 30% of patients receiving anti-VEGF treatment alone. However, visual improvement was still noted at 6 months despite persistence of polyps, possibly due to the medication’s strong effect against leakage^[8].

Photodynamic therapy (PDT) is another treatment option. In this procedure, a special light-sensitive medication called verteporfin is injected into a vein over 10 minutes, making the eye more sensitive to light. Then a special “cold” laser is applied to the retina and choroid to damage or destroy the abnormal blood vessels found in PCV^[1]. Many reports have demonstrated excellent short-term effectiveness of PDT for treating PCV, with complete polyp regression achieved in 80% to 95% of cases at the 1-year follow-up^[8].

Combination therapy using both anti-VEGF injections and photodynamic therapy has been investigated. Combining these two approaches may lead to better results, as PDT has effects that close off abnormal blood vessels while anti-VEGF therapy reduces leakage and prevents new vessel growth. Recent studies have suggested that combination therapy has some advantages over either treatment alone, including reduced need for repeated PDT treatments, faster absorption of fluid, and fewer bleeding events^[8].

A meta-analysis of multiple studies found that combined therapy involving anti-VEGF agents and PDT may be more effective in improving long-term outcomes for patients with PCV than single-treatment approaches^[11].

On rare occasions, surgical removal of the eye’s gel-like substance (a procedure called vitrectomy) may be used to remove or move aside a large hemorrhage caused by PCV^[1].

What to Expect

The outlook for polypoidal choroidal vasculopathy varies from person to person. Without treatment, progression to severe visual loss occurs in about 50% of patients due to repeated episodes of fluid leakage, bleeding, and scarring^[4].

Unfortunately, some patients with PCV experience irreversible central vision loss in one or both eyes. However, early diagnosis and treatment may restore vision and prevent further vision loss in many patients^[1].

The course of PCV can be unpredictable. It might remain quiet for long periods and then suddenly become active with bleeding or fluid leakage. Some patients experience slow, steady worsening, while others have episodes of rapid change followed by stable periods. This variability makes regular monitoring essential to catch changes before major damage occurs^[14].

It is generally accepted that PCV has a better visual outlook than typical neovascular age-related macular degeneration when treated appropriately, as progression is often slower and severe scarring is less common. However, the visual outcome is variable and depends on many factors^[8].

Factors that may favor better visual outcomes include smaller vascular lesions, better initial vision, less bleeding, and polyps that are not located directly under the center of the macula^[8].

The treatment burden can be significant, as patients may require frequent follow-up visits and repeated treatments over months to years. Effective treatments that can prolong the intervals between injections while maintaining vision gains remain an important area of ongoing research^[7].