The retina is the light-sensitive layer lining the back of the eye that converts light into electrical signals sent to the brain. A retinal cyst is a fluid-filled sac that forms within the layers of this tissue. This development causes the retinal layers to separate, disrupting the eye’s ability to process light accurately. The impact of a retinal cyst on vision is directly related to its size and precise location within the retina.
Categorizing Retinal Cysts
Retinal cysts are categorized primarily by location, which determines the potential severity of visual impairment. Macular cysts form in the macula, the central area responsible for sharp, detailed vision needed for tasks like reading and driving. Even a small cyst here can cause significant visual symptoms.
Peripheral cysts are located in the outer regions of the retina and typically do not affect the central line of sight. They are often less symptomatic and discovered incidentally during routine eye examinations. Cysts are also classified by origin: congenital (present at birth) or acquired (developing later due to inflammation or vascular issues).
Recognizing the Signs
Symptoms depend heavily on whether the cyst affects the macula. A macular cyst often leads to a decrease in central visual acuity, making fine detail work difficult. Patients may report distorted vision, known as metamorphopsia, where straight lines appear wavy or bent. This distortion occurs because the fluid pocket physically warps the light-sensing cells.
Individuals may also observe floaters or a scotoma (a blind spot) in their central visual field. Peripheral retinal cysts are frequently asymptomatic because they spare the macula and are often noticed only during a comprehensive eye exam. Any new or worsening visual symptoms, especially involving the center of vision, warrant immediate evaluation.
Underlying Causes and Risk Factors
Retinal cysts generally develop as a secondary effect of an underlying medical condition that compromises the integrity of the retinal blood vessels. The most common cause is the pooling of fluid, often referred to as edema, resulting from chronic vascular leakage. Diabetic retinopathy, a complication of diabetes, is a major contributor, causing blood vessels to become weakened and leaky. Retinal vein occlusion (RVO), an eye stroke where a vein is blocked, also leads to fluid backup and subsequent swelling.
Chronic inflammation inside the eye, such as from uveitis, can break down the blood-retinal barrier, allowing fluid to accumulate. Ocular trauma or previous eye surgery can also trigger an inflammatory response resulting in fluid leakage. Genetic factors contribute in cases like X-linked retinoschisis, a hereditary disorder that causes the retina to split into two layers. Managing the underlying disease is the primary focus for preventing and treating the cyst.
Definitive Diagnosis and Treatment Approaches
The definitive tool for diagnosing and characterizing a retinal cyst is Optical Coherence Tomography (OCT). This non-invasive imaging technology provides a high-resolution, cross-sectional view of the retina, confirming the presence, size, and depth of the fluid pockets. OCT also differentiates a true cyst from other lesions and monitors treatment effectiveness over time.
Fluorescein angiography (FA) is another diagnostic test involving injecting a dye to highlight areas of active leakage from damaged blood vessels, confirming the source of fluid accumulation. Visual acuity testing is performed to measure the functional impact of the cyst on central vision.
Treatment depends entirely on the cyst’s location, size, and the severity of vision loss. Observation is the primary approach for small, stable, and asymptomatic peripheral cysts that do not threaten the macula. For symptomatic macular cysts, medical management is the standard first-line therapy, particularly those associated with cystoid macular edema (CME).
This management involves intravitreal injections of medications, such as anti-VEGF agents or corticosteroids, delivered directly into the eye. Anti-VEGF drugs target the proteins that promote leaky blood vessels, reducing the fluid buildup and swelling. Corticosteroids work by reducing the chronic inflammation responsible for the leakage.
Surgical intervention, typically a procedure called vitrectomy, is reserved for complex cases. These include when the cyst has progressed to form a full-thickness macular hole or when there is concurrent tractional retinal detachment. In a vitrectomy, the vitreous gel is removed, and tension is relieved from the retinal surface, which helps flatten the retina and resolve the fluid pocket. Laser photocoagulation is sometimes used, but it has largely been supplanted by injection therapy for most cases of macular edema.