Chorioretinal folds are undulations involving the choroid and the overlying retina, two layers forming the back wall of the eye. The choroid is a network of blood vessels that nourishes the retina, which is the light-sensitive tissue sending visual information to the brain. These folds are not a disease but a clinical sign of an underlying process. Their appearance on an eye exam signals that further investigation is needed to determine the cause.
Associated Symptoms and Visual Changes
The visual experience of a person with chorioretinal folds can vary. Many individuals are asymptomatic, with the folds discovered incidentally during a routine eye exam. This often occurs when folds are located in the peripheral retina, away from the central line of sight.
When symptoms occur, they involve changes to central, detailed vision. A common complaint is metamorphopsia, a visual distortion where straight lines appear wavy or bent. This occurs because the folds disrupt the smooth surface of the retina, causing the photoreceptor cells to be misaligned. Patients may also report blurred vision or a decrease in visual acuity, making tasks like reading more difficult.
Underlying Causes of Chorioretinal Folds
Chorioretinal folds are caused by mechanical stress that compresses the back of the eye, leading to a buckling of the choroid and retina. These forces originate from various sources, which are broadly grouped into ocular, orbital, and idiopathic categories.
Issues originating within the eye itself are a frequent cause. A condition known as hypotony, or very low intraocular pressure, can lead to the collapse and folding of the eye’s structures after surgery or an injury. Choroidal tumors, which are growths within the choroid layer, can also push on surrounding tissue and create folds. Inflammatory conditions like posterior scleritis cause the sclera to thicken and contract, compressing the choroid and retina.
Problems located in the orbit, the bony socket that contains the eye, can also exert pressure from behind. Orbital tumors or other masses can push the eye forward, causing the posterior wall to indent and form folds. Thyroid eye disease, an autoimmune condition, can cause the muscles and fatty tissues in the orbit to swell, leading to similar compression.
When a thorough investigation fails to uncover a cause, the folds are classified as idiopathic. This diagnosis is made after all known ocular and orbital conditions have been ruled out. Patients with idiopathic folds are often older and may have a history of hyperopia (farsightedness). It is thought that subtle, long-term structural changes in the sclera may be responsible.
The Diagnostic Process
The investigation begins with a comprehensive dilated eye examination. An ophthalmologist uses a slit lamp and special lenses to view the back of the eye, where folds appear as alternating light and dark streaks. The pattern of the folds—whether horizontal, vertical, radial, or irregular—can provide clues about the underlying cause.
To visualize the folds in greater detail, specific imaging tests are used. Fundus photography takes a picture of the retina, documenting the appearance of the folds for future comparison. A more advanced technique, optical coherence tomography (OCT), provides a high-resolution, cross-sectional view of the retina and choroid. OCT allows a doctor to see the undulations and confirm that the folds involve both layers.
If an orbital cause is suspected, further imaging is required to look at structures behind the eye. B-scan ultrasonography uses sound waves to create an image of the orbit, helping to detect tumors or scleral thickening. In cases where more detail is needed, a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be ordered. These scans provide a clear view of orbital tissues, useful for diagnosing conditions like thyroid eye disease.
Managing Chorioretinal Folds
The management of chorioretinal folds is directed at the underlying cause, not the folds themselves. This approach is tailored to the specific condition responsible for the mechanical stress on the eye. Successfully addressing the root problem can lead to the resolution of the folds and an improvement in vision.
For folds caused by ocular conditions, treatment varies. If hypotony is the cause, the focus is on restoring normal intraocular pressure, which might involve surgical repair or adjusting medications. In the case of a choroidal tumor, management could range from observation to radiation or surgery. Inflammatory conditions like posterior scleritis are treated with anti-inflammatory medications, such as corticosteroids, to reduce swelling.
When an orbital issue is identified, treatment extends beyond the eye. An orbital tumor may require surgical removal. For patients with thyroid eye disease, management might involve medications to control the thyroid condition, steroids to reduce orbital inflammation, or surgery to decompress the orbit.
In situations where no cause is found and the diagnosis is idiopathic chorioretinal folds, the standard approach is observation. If the patient has no symptoms and their vision is stable, an ophthalmologist will recommend regular follow-up appointments to monitor the folds for any changes over time.