Chorioretinal Folds: Causes, Symptoms, and Care
Understanding Chorioretinal Folds
Chorioretinal folds are wave-like undulations that develop in the tissue layers at the back of the eye. When viewed during a dilated eye exam, they appear as alternating dark and light bands or striations across the retina. The folds specifically involve Bruch's membrane, the inner choroid, the retinal pigment epithelium (RPE), and in many cases the overlying neurosensory retina.
Chorioretinal folds were first described in 1884 by Nettleship. He identified them in a patient with optic nerve swelling caused by a brain lesion. Since that time, researchers have identified many different conditions that can produce these characteristic folds.
Any condition that compresses or changes the shape of the inner sclera (the white outer wall of the eye) can push the choroid, Bruch's membrane, RPE, and retina into folds. Think of it like pressing on the underside of a thin, flexible sheet. The layers above buckle and form ridges.
Researchers have proposed several specific mechanisms. Swelling or expansion of the choroid can force Bruch's membrane to fold. Strain between the sclera and the choroid, caused by scleral thickening or shrinkage, creates a buckling force. In 1989, researcher Friberg proposed that this stress-and-strain relationship is the primary driver of fold formation.
Folds can be classified based on which layers are involved. Choroidal folds affect only the choroid and Bruch's membrane. Chorioretinal folds extend into the retina as well. The distinction matters because deeper retinal involvement may carry a greater risk of vision changes over time.
Folds may appear in one eye or both eyes. The pattern of involvement helps a retina specialist narrow down the possible cause.
Who Is Affected and Risk Factors
When chorioretinal folds appear in both eyes, the cause is often a systemic or widespread condition. In a retrospective comparison study, bilateral folds were attributed to the following causes (Retina Today, 2023):
- Age-related macular degeneration, or AMD (29%)
- Hyperopia, or farsightedness, due to a shorter-than-normal eye (25%)
- Idiopathic, meaning no identifiable cause (21%)
- Hypotony, or abnormally low eye pressure (a moderate percentage)
- Scleritis, or inflammation of the sclera (4%)
- Thyroid eye disease (4%)
- Uveitis, or inflammation inside the eye (4%)
- Choroiditis, or inflammation of the choroid (4%)
When folds are present in only one eye, the cause is more likely to be a localized condition. The same retrospective study identified the most frequent causes of unilateral folds as (Retina Today, 2023):
- Scleritis (17%)
- Hypotony (13%)
- Retinal vascular occlusion, or blockage of a retinal blood vessel (13%)
- Intraocular tumors (13%)
- Age-related macular degeneration (10%)
- Optic nerve edema, or swelling of the optic nerve (7%)
- Retinal detachment (7%)
Many other conditions have been linked to chorioretinal folds. These include orbital tumors (growths behind the eye), infections, immunologic disorders, uveal effusion syndrome (fluid buildup beneath the retina), and trauma. Intracranial hypertension (increased pressure around the brain) is a well-known cause. Folds typically occur in patients with papilledema (swelling of the optic disc).
The most common causes overall are idiopathic folds, with a prevalence estimated between 10% and 20%, and progressive hyperopia due to shortened eye length, at 15% to 25% (Retina Today, 2023).
A newer recognized cause is spaceflight-associated neuro-ocular syndrome, or SANS. Astronauts on long-duration missions can develop choroidal thickening and optic disc swelling due to fluid shifts in microgravity. Research documented the incidence and progression of chorioretinal folds during long-duration spaceflight (JAMA Ophthalmology, 2023). While this cause is rare, it has expanded scientific understanding of how folds develop.
Signs and Symptoms
Some patients with chorioretinal folds have no symptoms at all. The folds may be discovered during a routine dilated eye examination. When symptoms do occur, the two most common complaints are blurred vision and metamorphopsia. Metamorphopsia is a distortion of vision in which straight lines appear wavy or bent.
Patients may also notice a gradual shift toward farsightedness. This happens because the folds can subtly change the shape of the retina and affect how light is focused inside the eye.
When chorioretinal folds persist over a long period, they can lead to damage in the affected tissue layers. Long-lasting folds may cause atrophy (thinning) of the RPE, breaks or damage to Bruch's membrane, and eventually choroidal neovascularization, or CNV. CNV is the growth of abnormal new blood vessels beneath the retina. CNV can cause further vision loss if not identified and treated promptly.
Chronic folds involving the macula (the central part of the retina responsible for sharp vision) may result in chorioretinal folds-related maculopathy. This condition reflects lasting structural changes to the macular tissue.
In addition to the folds themselves, a retina specialist may observe other findings during the examination. These can include retinal hemorrhages (bleeding), particularly near the optic nerve. Other associated findings include subretinal edema (fluid beneath the retina), macular edema (swelling in the macula), macular exudates (deposits of fluid and protein), and disorganization of retinal inner layers.
Diagnosis and Testing
The first step in identifying chorioretinal folds is a thorough dilated eye examination. A retina specialist uses specialized lenses and lights to view the back of the eye. The folds appear as alternating light and dark bands on the retinal surface. The pattern, location, and number of folds provide initial clues about the underlying cause.
A detailed medical history is also important. Information about thyroid disease, recent eye surgery, headaches, and medications can help narrow the list of possible causes.
Optical coherence tomography, or OCT, creates detailed cross-sectional images of the retina and choroid. OCT can clearly show the undulations in Bruch's membrane, the RPE, and the retinal layers. It can also detect subretinal fluid, macular edema, or changes in choroidal thickness. This test is quick, noninvasive, and essential for monitoring folds over time.
Fluorescein angiography is a test in which a fluorescent dye is injected into a vein in the arm. The dye travels to the blood vessels in the eye, and a special camera captures images as the dye passes through. In patients with chorioretinal folds, the angiogram shows alternating bright and dark bands that correspond to the peaks and valleys of the folds.
Additional imaging may be needed depending on the suspected cause. B-scan ultrasonography can evaluate the sclera and tissue behind the eye. MRI of the brain and orbits may be ordered if intracranial hypertension or an orbital tumor is suspected.
Because hyperopia from a short eye is a common cause of chorioretinal folds, measuring the axial length with a biometer can be helpful. A change in refraction toward farsightedness, especially if new or progressive, may prompt closer evaluation. Comparing measurements between the two eyes can reveal asymmetry that points to a specific diagnosis.
Treatment Options
Chorioretinal folds themselves typically do not require direct treatment. The focus of care is on identifying and managing the condition responsible for the folds. Because the causes range widely, treatment must be individualized based on the specific diagnosis.
For example, if posterior scleritis is the cause, anti-inflammatory or immunosuppressive medications may be prescribed. If hypotony following eye surgery is responsible, restoring normal eye pressure is the priority. If a tumor is identified, oncologic evaluation and treatment are necessary.
When chorioretinal folds are caused by intracranial hypertension, treatment may include acetazolamide. This medication reduces cerebrospinal fluid production. Results from the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) showed that at six months, eyes treated with acetazolamide had fewer folds compared to placebo, with a 57% reduction in retinal fold frequency (IOVS, 2016). Choroidal folds were observed in 13 eyes, representing 10% of study eyes (IOVS, 2015).
The research also found that some folds persisted even after marked improvement in optic nerve head swelling. This suggests that long-standing folds may cause lasting changes in the affected retinal tissues.
If long-standing chorioretinal folds lead to choroidal neovascularization, treatment with anti-VEGF injections may be recommended. Anti-VEGF medications block vascular endothelial growth factor to stop abnormal vessel growth. Common agents used for CNV include Eylea (aflibercept), Lucentis (ranibizumab), and Avastin (bevacizumab), which is used off-label for eye conditions. A retina specialist will determine the most appropriate medication and schedule.
In cases where the chorioretinal folds are mild, stable, and not causing vision problems, a retina specialist may recommend regular monitoring. This is common in idiopathic cases or mild folds associated with hyperopia. Periodic eye exams and OCT imaging allow the specialist to track changes and intervene if complications develop.
What to Expect
The evaluation for chorioretinal folds may take one or more visits. A retina specialist will perform a dilated exam, obtain OCT images, and may order fluorescein angiography, B-scan ultrasound, or MRI. Finding the underlying cause can sometimes take time, especially if the folds are bilateral or idiopathic.
Patients should be prepared to share a complete medical history. Details about thyroid disease, headaches, recent surgeries, or eye trauma are critical for guiding the workup.
The timeline for improvement depends on the underlying cause. If the cause can be treated effectively, such as resolving scleritis with anti-inflammatory medication, the folds may flatten over weeks to months. However, folds present for a long time may not fully resolve even after the underlying condition is corrected.
Results from the IIHTT showed that acetazolamide led to measurable fold reduction at six months, though some folds persisted (IOVS, 2016). This underscores the importance of early detection and treatment before lasting tissue changes occur.
Patients with chorioretinal folds generally need ongoing monitoring. Even after the underlying cause is treated, a retina specialist will track the folds to watch for complications such as RPE atrophy or choroidal neovascularization. The frequency of follow-up visits varies based on the cause and severity.
Living with Chorioretinal Folds
Many patients with mild chorioretinal folds experience little or no impact on daily life. If the folds do not involve the macula, central vision may remain unaffected. Patients whose folds involve the macula may notice distorted or blurry central vision, affecting reading, driving, and face recognition.
An Amsler grid (a simple printed grid used to detect central vision changes) can be a helpful self-monitoring tool. If straight lines appear wavy or a new blind spot develops, the patient should contact a retina specialist promptly.
Because chorioretinal folds are most often a sign of another condition, managing overall health is important. Patients with thyroid disease should continue following up with their endocrinologist. Those with intracranial hypertension should adhere to their treatment plan and report new headaches or vision changes. Patients with AMD should follow their retina specialist's recommendations.
Learning about a structural change in the eye can cause anxiety, especially when the cause is unclear. Many cases of chorioretinal folds are stable and manageable. Open communication with a retina specialist about concerns and the monitoring plan can help reduce uncertainty.
When to See a Retina Specialist
A referral to a retina specialist is appropriate whenever chorioretinal folds are detected during an eye exam. The folds can be caused by a wide range of conditions, some of which are serious. A thorough evaluation by a specialist trained in vitreoretinal disease is important. Patients with known risk factors such as hyperopia, thyroid eye disease, or scleritis should have regular dilated exams.
Certain symptoms require prompt evaluation. Patients should see a retina specialist or go to the emergency room immediately if they experience a sudden increase in floaters, flashes of light, a curtain or shadow over their vision, or sudden vision loss in one eye. These symptoms may indicate a serious complication such as retinal detachment or choroidal neovascularization.
New or worsening metamorphopsia (wavy or distorted vision) should also prompt a timely visit. Progressive distortion may indicate worsening folds or a new complication such as CNV.
Questions and Answers
Chorioretinal folds may improve or resolve if the underlying cause is successfully treated. For example, folds caused by posterior scleritis may flatten once inflammation is controlled. However, folds present for a long period may cause lasting changes to Bruch's membrane and the RPE, meaning they may not fully disappear. Research from the IIHTT showed that some folds persisted despite significant improvement in optic nerve swelling (IOVS, 2016).
No. Chorioretinal folds and macular pucker (also called epiretinal membrane) are different conditions. Chorioretinal folds originate from changes in the choroid and Bruch's membrane beneath the retina. Macular pucker involves a thin membrane on the inner surface of the retina. Both can cause visual distortion, but the mechanisms, causes, and treatments are distinct. A retina specialist can differentiate them using OCT imaging.
In many cases, chorioretinal folds do not cause significant lasting vision loss, especially when the underlying cause is identified and managed early. However, chronic folds involving the macula can lead to RPE atrophy, Bruch's membrane damage, and choroidal neovascularization. These complications can result in lasting vision changes. Regular monitoring allows a retina specialist to detect complications early and begin treatment when needed.
Yes. Age-related macular degeneration is one of the more common causes of chorioretinal folds. It accounts for approximately 29% of bilateral cases and 10% of unilateral cases in one retrospective study (Retina Today, 2023). Structural changes in the choroid and Bruch's membrane that occur with AMD can contribute to fold formation. Patients with both conditions may require more frequent monitoring from a retina specialist.
The evaluation typically includes a dilated eye exam, OCT imaging, and often fluorescein angiography. Additional tests may include B-scan ultrasonography, biometry to measure eye length, and MRI of the brain and orbits if a neurological cause is suspected. Blood work for thyroid function or inflammatory markers may also be ordered. The specific tests depend on whether the folds are in one eye or both, the fold pattern, and medical history.