Epiretinal Membrane
Definition
An epiretinal membrane (ERM) is a thin layer of fibrous scar-like tissue that forms on the surface of the retina, usually over the macula, the area responsible for sharp central vision. ERMs are also commonly called macular puckers, cellophane maculopathy, or surface-wrinkling retinopathy. As the membrane contracts, it can wrinkle or distort the retina, leading to visual symptoms.
Most ERMs are mild and cause little or no vision problems, but some can significantly affect central vision.
Causes and Risk Factors
Causes
The most common cause of ERM is posterior vitreous detachment (PVD), an age-related process in which the vitreous gel separates from the retina. During this process, microscopic defects can develop on the retinal surface, allowing cells to grow and form a membrane.
Other causes include:
- Retinal tears or retinal detachment
- Diabetic retinopathy
- Retinal vein occlusion
- Eye trauma or injury
- Prior eye surgery (including cataract surgery)
- Eye inflammation (uveitis)
Risk Factors
Individuals are at higher risk if they:
- Are over age 50, particularly over age 60
- Have experienced posterior vitreous detachment (PVD)
- Have diabetes or diabetic retinopathy
- Have had retinal tears, retinal detachment, or retinal vascular diseases
- Have undergone previous eye surgery
Symptoms
Many ERMs cause no symptoms and are discovered during routine eye examinations.
Common Symptoms
- Blurred central vision
- Distorted vision (metamorphopsia)
- Straight lines appearing wavy or crooked
- Difficulty reading fine print
- Trouble recognizing faces or performing detailed tasks
Less Common Symptoms
- Double vision in one eye (monocular diplopia)
- Light sensitivity
- Objects appearing larger or smaller than normal
- Progressive loss of central vision in severe cases
Symptoms Typically Not Seen
- No pain
- No significant loss of peripheral vision
Diagnosis
Dilated Eye Examination
An ophthalmologist can often identify an ERM during a comprehensive dilated retinal exam.
Optical Coherence Tomography (OCT)
OCT is the primary diagnostic test because it provides detailed cross-sectional images of the retina and shows:
- Presence of the membrane
- Retinal thickening
- Macular distortion
- Severity of traction on the retina
Treatment
Treatment depends on the severity of symptoms and the effect on vision.
Observation
For mild cases with minimal symptoms:
- Regular monitoring is often sufficient.
- Many ERMs remain stable and never require treatment.
Vitrectomy with Membrane Peel
For significant visual symptoms or progressive vision loss:
- A vitrectomy is performed to remove the vitreous gel.
- The surgeon carefully peels the epiretinal membrane from the retinal surface.
- This relieves retinal traction and allows the macula to flatten.
Expected Outcomes
- Most patients experience improved vision and reduced distortion after surgery.
- Improvement may occur gradually over several months.
- Vision may not completely return to normal, especially if the membrane has been present for a long time.
Prevention
Most ERMs cannot be prevented because they are frequently related to normal aging changes within the eye. However, risk may be reduced by:
- Regular comprehensive eye examinations after age 50
- Proper management of diabetes and retinal vascular disease
- Prompt treatment of retinal tears and retinal detachments
- Protecting the eyes from injury
Summary
An epiretinal membrane (ERM) is a thin layer of scar tissue that forms on the surface of the retina, usually over the macula. It most commonly develops after age-related vitreous changes and may cause blurred or distorted central vision, making straight lines appear wavy. Diagnosis is typically made with a dilated eye exam and OCT imaging. Mild cases may simply be monitored, while more advanced cases can be successfully treated with vitrectomy and membrane peel surgery to improve vision and reduce distortion.