What is Epiretinal Membrane?
The retina is a thin, light-sensitive layer of tissue at the back of the eye. Its central part, the macula, is responsible for our clear, straight-ahead vision, used for tasks like reading and recognizing faces. An epiretinal membrane forms on the surface of the retina and, as it contracts, can cause the macula to wrinkle or swell. This wrinkling can distort vision and, in more severe cases, lead to macular edema (swelling of the macula) and a loss of central vision.
Symptoms of Epiretinal Membrane
Many people with a mild ERM experience no symptoms at all. When symptoms do occur, they are typically gradual and may include:
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Blurred or wavy vision: Straight lines may appear crooked or wavy.
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Distorted vision: Objects may appear larger, smaller, or a different shape than they are.
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Difficulty reading or seeing fine details: Central vision is most affected.
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Double vision in the affected eye: This can occur in more advanced cases.
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A blind spot or gray area in the center of your vision.
Causes of Epiretinal Membrane
The exact cause of ERM is often unknown, but it is typically related to a natural age-related change in the eye called Posterior Vitreous Detachment (PVD). The vitreous is a gel-like substance that fills the eye. As we age, the vitreous can shrink and pull away from the retina. In some cases, as the vitreous pulls away, it can cause microscopic damage to the retina, leading to the formation of scar tissue or an epiretinal membrane. Other causes may include:
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Retinal detachment
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Past Intraocular surgery
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Diabetes or other vascular diseases of the eye
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Eye trauma
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Inflammatory conditions inside the eye (uveitis)
How Common is Epiretinal Membrane?
ERM is a relatively common condition, especially in older adults. It is estimated to affect around 2 to 5% of the population over age 50 and about 20% of the population over age 75. Most of these cases are mild and do not progress to a point where they affect vision significantly.
When is Treatment Needed?
For most individuals with a mild ERM, no treatment is required, as the condition does not progress or does not affect vision significantly. Regular monitoring with an ophthalmologist is typically sufficient. Treatment is usually recommended when the ERM begins to cause noticeable vision loss or distortion that interferes with daily activities like reading, driving, or recognizing faces.
Diagnosis of Epiretinal Membrane
An ophthalmologist can diagnose an ERM during a comprehensive eye examination. The diagnosis typically involves:
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A dilated eye exam: The doctor will use special instruments to view the retina and macula.
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Optical Coherence Tomography (OCT): This is the most important diagnostic tool. An OCT scan provides a detailed cross-sectional image of the retina, allowing the doctor to see the membrane, measure any retinal swelling (macular edema), and determine the extent of retinal distortion.
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Visual Acuity Test: To measure the patient's vision and assess the severity of the vision loss.
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Metamorphopsia testing: This test, often performed using an Amsler grid or a M-chart, helps to detect subtle distortions or waviness in a patient's central vision, which is a key symptom of ERM.
Treatments of Epiretinal Membrane
The only effective treatment for a visually significant epiretinal membrane is surgery.
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Vitrectomy
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Vitrectomy is the surgical procedure used to treat an ERM. It is typically performed on an outpatient basis. The surgeon uses tiny instruments to enter the eye and carefully remove the vitreous gel. The surgeon then meticulously peels the epiretinal membrane from the surface of the retina. This relieves the traction on the macula, allowing it to flatten and return to its normal position.
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