Epiretinal membrane: symptoms, diagnosis and management

An epiretinal membrane (ERM) is a thin scar tissue that forms on the surface of the macula and, as it contracts, distorts central vision. It mainly affects patients over 60 and presents as straight lines perceived as wavy (metamorphopsia) together with a progressive decline in visual acuity.

UNDERSTANDING

What is an epiretinal membrane?

The macula is the central area of the retina, responsible for fine vision (reading, recognising faces, driving). An epiretinal membrane, abbreviated ERM, is a thin layer of fibroglial cells that develops on the surface of the macula, just above the inner limiting membrane of the retina.

This membrane is avascular and translucent in its early stages. Over time, it contracts and puckers the underlying retina, like a thin sheet of cellophane shrinking onto a piece of paper. It is these folds and this tangential traction that impair visual function.

It is also referred to as:

• Cellophane maculopathy (early translucent form)
• Macular pucker (advanced form with marked contraction)
• Premacular membrane

SYMPTOMS

What are the symptoms?

The symptoms often appear insidiously, over several months, and typically affect a single eye at first.

Metamorphopsia (straight lines that look wavy)

This is the most telling sign. Patients describe straight lines that appear curved or wavy: door frames, lines of text, roof tiles, tile grout. The Amsler grid test, which you can perform at home by covering each eye in turn, easily reveals this distortion.

Progressive decline in visual acuity

Visual acuity declines slowly. Many patients seek advice when it has dropped from 20/20 to 20/30 or 20/35. The difficulty shows up with reading, sewing and driving at night.

Micropsia (objects appear smaller)

Traction from the membrane on the macula spreads the photoreceptors apart: an object projected onto the retina then occupies a larger area than in the healthy eye. The brain interprets the image as smaller. This micropsia is responsible for aniseikonia (a difference in image size between the two eyes) which can considerably disturb binocular vision.

Mild central scotoma

Less commonly, some patients describe a slightly blurred area in the centre, without a distinct dark spot. A marked central scotoma should prompt consideration of another diagnosis, in particular an associated macular hole.

Self-assessment at home — the Amsler grid is a square of straight lines with a central dot. You fix your gaze on the dot, one eye at a time, at 30 cm. If any lines appear wavy, missing or distorted, make an appointment for a retinal examination.

WHO IS AFFECTED

Who is affected?

Risk factors

ERM is above all a condition linked to ageing of the vitreous and its posterior detachment:

• Age: prevalence is around 7% between 60 and 69 years and exceeds 11 to 12% after age 70 in several population-based studies Mitchell 1997
• Posterior vitreous detachment (PVD): the main triggering mechanism
• Diabetes: diabetic retinopathy promotes fibroglial proliferation (see our page on diabetes and the retina)
• History of retinal tear, photocoagulation, venous occlusion
• Intraocular inflammation (uveitis)
• Recent cataract surgery
• High myopia

Idiopathic vs secondary ERM

In about two thirds of cases, the ERM is described as idiopathic: it arises in an otherwise healthy eye, simply as a consequence of posterior vitreous detachment. In the remaining third, it is secondary to an identified condition (diabetes, post-surgical, post-inflammatory). This distinction guides the additional work-up and sometimes the prognosis.

DIAGNOSIS

Diagnosis: macular OCT is essential

The clinical fundus examination is enough to suspect an ERM (shiny cellophane reflex, retinal folds, tortuous vessels). But the definitive diagnosis rests on macular optical coherence tomography (OCT).

Spectral domain OCT produces a high-resolution cross-section of the retina. It directly visualises the membrane as a hyperreflective line above the inner limiting membrane, measures macular thickness, and looks for oedema, a pseudo-hole or an associated macular hole.

The Govetto OCT classification Govetto 2017 distinguishes 4 stages according to the preservation of the retinal layers and the shape of the fovea:

• Stage 1: foveal depression preserved, retinal layers clear
• Stage 2: loss of the foveal depression, layers preserved
• Stage 3: ectopic inner retinal layers visible, depression absent
• Stage 4: diffuse disorganisation of the layers, thickened membrane

This classification is useful because it correlates with pre-operative visual acuity and functional prognosis.

At my Paris 13 office, I have a spectral domain OCT that makes it possible to establish the diagnosis in a few minutes and to monitor progression over time without dilating the pupil at every visit.

TREATMENT

Is surgery always necessary?

No. An ERM does not always progress and does not call for immediate surgery. The decision takes into account the functional impact, the rate of progression and which eye is involved.

Simple monitoring

An ERM with few symptoms, preserved acuity (≥ 20/30–20/25) and slight metamorphopsia warrants simple monitoring. The usual schedule is:

• A check-up at 3–6 months, then yearly if stable
• Routine macular OCT
• Self-monitoring with an Amsler grid at home

Indications for surgery

Surgery is offered when the ERM significantly impairs quality of life:

• Visual acuity < 20/40 or 20/30 in the affected eye
• Disabling metamorphopsia for reading, driving or work
• Aniseikonia interfering with binocular vision
• Documented progression on two successive OCT scans (macular thickening, falling acuity)
• Associated symptomatic lamellar hole or pseudo-hole

TREATMENT

The surgery: vitrectomy and peeling

How it proceeds

The procedure takes place in the operating theatre at the Clinique Sainte-Geneviève, as day surgery, under local peribulbar anaesthesia. It lasts 30 to 45 minutes.

Three 0.5 mm micro-incisions (25 or 27 gauge trocars) are made in the sclera, 4 mm from the limbus. They allow the introduction of a light source, an infusion line and the vitrectomy probe. The main steps:

1. Central vitrectomy: removal of the vitreous gel
2. Staining of the membrane with a specific dye (Coomassie Blue, MembraneBlue-Dual or Brilliant Blue G) that makes it visible
3. Forceps peeling: the membrane is grasped at its edge and removed in a single piece
4. Possible peeling of the inner limiting membrane (ILM) under staining
5. Inspection of the peripheral retina to look for tears
6. Tamponade with air, gas or simply BSS depending on the case

Should the inner limiting membrane (ILM) be peeled?

The question of routinely peeling the ILM in addition to peeling the ERM is the subject of several studies. A recent meta-analysis Fung 2017 concludes that ILM peeling reduces the recurrence rate of the epiretinal membrane without significantly altering the final visual acuity gain.

My personal approach is to peel the ILM in cases of a thick, contractile or recurrent ERM, and to leave it intact for thin ERMs with little macular puckering. This decision is discussed on a case-by-case basis.

Anaesthesia and duration

Local peribulbar anaesthesia (an injection near the optic nerve) is comfortable and allows immediate recovery. General anaesthesia is reserved for very anxious patients or particular situations. Admission is on a day-case basis: arrival in the morning, discharge in the early afternoon.

TREATMENT

Post-operative course

Positioning (if gas is used)

If gas was injected at the end of the procedure (rare in simple ERMs without a macular hole), face-down positioning may be required for a few days. You will be unable to fly or go to altitude until the bubble has resorbed (2 to 6 weeks depending on the gas).

Visual recovery timeline

Recovery is gradual over 3 to 6 months. You can expect:

• Week 1: blurred vision, sometimes a swollen eyelid, a foreign-body sensation
• Weeks 2 to 4: improvement of metamorphopsia, beginning of acuity recovery
• Months 1 to 3: progressive acuity gain, marked easing of the wavy lines
• Months 3 to 6: stabilisation, final functional assessment

Post-operative eye drops (anti-inflammatory and antibiotic) are prescribed for 4 to 6 weeks. Driving is usually resumed at 1–2 weeks depending on the acuity of the other eye.

Induced cataract

Vitrectomy accelerates the development of a cataract in phakic patients (those who still have their natural lens). More than 60% of patients over 55 will develop a significant cataract within 1 to 2 years following vitrectomy Cherfan 1991. For this reason, I often propose combined surgery: a single-stage phaco-vitrectomy that removes both the lens (replaced by an implant) and the membrane. This strategy avoids a second operation a few months later.

RESULTS

Expected results

The functional results of ERM peeling are generally favourable, although not guaranteed in every case. Studies Dawson 2014 report:

• A mean gain of 2 lines of visual acuity (equivalent to +0.2 to +0.3 LogMAR) at 6–12 months
• An improvement in metamorphopsia in roughly 70 to 85% of patients who undergo surgery
• A reduction in macular thickness on post-operative OCT

It is worth knowing that:

• Metamorphopsia may persist to a lesser degree, without always disappearing completely
• The acuity gain depends on pre-operative acuity and on how long the membrane has been present
• Early surgery, when acuity is just starting to drop, gives on average a more favourable functional result than late surgery on a severely altered macula

RISKS

Risks and complications

Like any intraocular surgery, vitrectomy carries risks, which remain uncommon:

• Induced cataract (the most frequent, around 60–80% at 2 years in phakic patients)
• Retinal tear and detachment: 1 to 5% depending on the series
• Endophthalmitis (intraocular infection): fewer than 1 in 2,000 cases
• Transient post-operative ocular hypertension
• Post-operative cystoid macular oedema (often resolving with eye drops)
• ERM recurrence: 5 to 15% depending on whether the ILM was peeled or not
• Persistent metamorphopsia: reported by 15 to 30% of patients

The pre-operative examination and detailed information make it possible to discuss these risks in light of the expected benefit.

FAQ

Frequently asked questions

Scientific sources

1. Mitchell P, Smith W, Chey T, Wang JJ, Chang A. Prevalence and associations of epiretinal membranes. The Blue Mountains Eye Study, Australia. Ophthalmology. 1997;104(6):1033-1040. PMID 9186446
2. Govetto A, Lalane RA 3rd, Sarraf D, Figueroa MS, Hubschman JP. Insights Into Epiretinal Membranes: Presence of Ectopic Inner Foveal Layers and a New Optical Coherence Tomography Staging Scheme. Am J Ophthalmol. 2017;175:99-113. PMID 27993592
3. Fung AT, Galvin J, Tran T. Epiretinal membrane: A review. Clin Exp Ophthalmol. 2021;49(3):289-308. PMID 33656784
4. Cherfan GM, Michels RG, de Bustros S, Enger C, Glaser BM. Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker. Am J Ophthalmol. 1991;111(4):434-438. PMID 2012145
5. Dawson SR, Shunmugam M, Williamson TH. Visual acuity outcomes following surgery for idiopathic epiretinal membrane: an analysis of data from 2001 to 2011. Eye (Lond). 2014;28(2):219-224. PMID 24310238

Further reading

• Diabetes and the retina — Paris 13
• Dr Moïse Tourabaly — Ophthalmologist
• Book an appointment at the office

Paris 13 office · Tel. 01 45 47 08 11

Disclaimer

This article is intended for information purposes. A personalised ophthalmological opinion remains essential for any treatment decision.

This article is intended for general information and does not replace a medical consultation. The diagnosis of an epiretinal membrane requires a complete ophthalmological examination with macular OCT. The decision to operate is made on a case-by-case basis, after assessing the expected benefit and providing the patient with detailed information. For any question regarding your vision, consult an ophthalmologist.

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