An epiretinal membrane (ERM) is a thin layer of scar tissue that develops on the surface of the retina, specifically the macula. This tissue can contract, causing the macula to wrinkle or pucker, which then distorts vision. When this distortion significantly impairs daily activities, surgical intervention is recommended to remove the membrane and improve vision.
Understanding Epiretinal Membrane
The macula is the central part of the retina responsible for sharp, detailed vision, allowing for tasks like reading and recognizing faces. Many epiretinal membranes are idiopathic, meaning they develop without a clear underlying cause and are often age-related. As people age, the vitreous gel, the clear, jelly-like substance filling the eye, naturally begins to separate from the retina. This separation process can sometimes release cells that multiply and form the membrane. Secondary causes for ERM development include previous retinal detachment, eye injuries, intraocular inflammation, diabetic retinopathy, or retinal vein occlusions.
Individuals with an ERM commonly experience blurred central vision, making it difficult to see fine details or read small print. Distorted vision, known as metamorphopsia, is also a frequent symptom, causing straight lines to appear wavy or bent. Some people may also notice double vision in one eye (monocular diplopia) or a gray area in their central field of vision. The severity and progression of these symptoms vary among individuals.
Diagnosis of an epiretinal membrane involves a dilated eye examination by an ophthalmologist. Optical coherence tomography (OCT) imaging is a primary diagnostic tool, providing high-resolution, cross-sectional views of the retina. OCT scans clearly show the presence of the membrane and reveal how it is affecting the macula, such as causing swelling or wrinkling.
The Surgical Procedure
Surgery for an epiretinal membrane is considered when visual symptoms, such as blurring or distortion, interfere with daily life. The goal is to improve vision and reduce distortion.
The primary surgical procedure for an ERM is a pars plana vitrectomy. This microsurgical technique involves making several tiny incisions, typically less than one millimeter, in the white part of the eye. Through these small openings, micro-instruments are inserted to remove the vitreous gel, allowing the surgeon direct access to the retinal surface.
Following vitreous removal, the core of the procedure, known as a membrane peel, is performed. Using fine micro-forceps, the surgeon grasps and peels the thin epiretinal membrane away from the retinal surface. In some cases, an additional layer called the internal limiting membrane (ILM) may also be peeled. This additional step can help reduce the chances of the ERM recurring.
Epiretinal membrane surgery is performed under local anesthesia, where the eye is numbed, and the patient receives sedation. General anesthesia is also an option depending on patient preference and medical history. The procedure takes approximately 30 to 60 minutes to complete.
After the membrane is peeled, the eye is filled with either a saline solution, a gas bubble, or silicone oil. A gas bubble or silicone oil helps to flatten the retina and provide internal support as the eye heals, acting as a temporary internal bandage. If a gas bubble is used, it gradually dissipates and is replaced by the eye’s natural fluid over several weeks. Silicone oil may require a second surgical procedure for its removal at a later date.
Post-Operative Recovery
Immediately following epiretinal membrane surgery, the eye may be covered with an eye patch, which is removed the next day. Patients are given prescriptions for eye drops, which include antibiotics to prevent infection and anti-inflammatory drops to reduce swelling and discomfort. These drops are important for healing and are used for several weeks, typically three to four weeks.
If a gas bubble was placed in the eye during surgery, specific head positioning instructions will be provided. This involves maintaining a face-down position for one to five days, to ensure the gas bubble presses against the macula to support proper retinal reattachment and healing.
Patients should anticipate some temporary activity restrictions during the initial recovery period. Avoid heavy lifting, strenuous physical activity, bending over, and rubbing the operated eye. While bathing and showering are permitted, care should be taken to prevent water from entering the eye. Swimming should be avoided until the eye drops have been completed and the surgeon approves.
Regular follow-up appointments with the ophthalmologist are scheduled to monitor healing progress and assess visual improvement. The first follow-up is within 7 to 10 days after surgery, with subsequent visits arranged over the following months. These visits allow the doctor to check for any complications and adjust the treatment plan as needed.
Initial vision after surgery may be more blurred, particularly if a gas bubble was used, as the bubble can obscure vision until it is absorbed. Vision gradually improves as the eye and retina heal, with noticeable changes occurring over several weeks. While initial recovery takes a few weeks, the full visual improvement can continue for three to six months, and sometimes up to a year after surgery.
Expected Visual Improvement and Risks
Many patients experience an improvement in vision after epiretinal membrane surgery, with an average of 50% improvement in visual acuity reported. While significant reduction in distortion is common, vision may not return to its pre-ERM state or achieve 20/20 acuity, especially if the membrane was present for an extended period or caused substantial retinal damage.
Several factors can influence the final visual outcome, including the duration the epiretinal membrane was present before surgery and the extent of damage to the macula. The severity of the retinal wrinkling and the presence of any other underlying eye conditions play a role in how much vision can be recovered. Even with successful surgery, a small percentage of patients may not experience improved distortion.
As with any surgical procedure, there are risks associated with epiretinal membrane surgery. One of the most common side effects is the accelerated progression of cataracts, which occurs in 70-90% of patients within the first year after surgery. If a cataract significantly impacts vision, a separate cataract surgery may be necessary. Temporary increases in intraocular pressure can occur in about 10% of patients, which can be managed with eye drops. Mild discomfort, redness, or a gritty sensation in the eye are common and resolve within one to two weeks.
Less common but more serious complications include retinal tears or detachment, which occur in about 4-5% of cases. While the surgery can sometimes treat detachment, it remains a risk of the vitrectomy procedure. Infection (endophthalmitis) is a rare but serious complication, occurring in 1 in 1000 cases, and bleeding in or around the eye is also a rare risk.
Be aware of warning signs that require immediate medical attention. Patients should contact their ophthalmologist if they experience sudden severe pain, a sudden loss of vision, new or increasing flashing lights, a sudden increase in floaters, or increasing redness or discharge from the eye. These symptoms indicate a serious complication requiring urgent evaluation.