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Eye Diseases > Retina

Epiretinal Membrane

Evidence-based assessment and management of epiretinal membrane. Comprehensive guide covering etiology, Gass classification, pathogenesis, diagnosis, and surgical treatment protocols for optometry practice.

Epiretinal membrane(glistening cellophane reflex)Retinal striae(macular pucker)Pseudohole(no true break)Dragged vessels(heterotopic)Optic disc

Epiretinal membrane (ERM): glistening cellophane-like reflex over the macular surface with radial retinal striae (macular pucker). Retinal vessels are dragged toward the centre (heterotopic). A pseudohole is visible centrally — an apparent break with no full-thickness retinal defect.

Epiretinal membrane (ERM) — also known as macular pucker, cellophane maculopathy, or pre-macular fibrosis — is an avascular fibrocellular membrane that forms on the inner surface of the retina at the macula. It is the most common vitreoretinal interface disorder, with a prevalence of ~7% in adults over 50, rising to over 20% after age 75.

The majority (~75%) are idiopathic, arising spontaneously following posterior vitreous detachment (PVD). Secondary causes include retinal tears/detachment, uveitis, diabetic retinopathy, retinal vein occlusion, and prior intraocular surgery.

The hallmark symptom is metamorphopsia (distortion of straight lines). Classification follows the Gass system (stages 0–2) or OCT-based criteria. Surgical treatment — pars plana vitrectomy (PPV) with membrane and ILM peeling — is highly effective and indicated when VA falls or metamorphopsia is functionally significant.

Idiopathic (~75%)

No identifiable precipitating cause; associated with age-related PVD that allows glial cells and hyalocytes to access the inner limiting membrane (ILM) surface. Bilateral in ~20–30% of cases, though rarely symptomatic in both eyes simultaneously.

Secondary Causes (~25%)

  • Posterior vitreous detachment (PVD): Most common precipitant of both idiopathic and secondary ERM; vitreous separation from ILM creates micro-breaks allowing cellular access
  • Retinal tear / retinal detachment: Liberation of RPE cells and glial cells during or after tear formation; post-scleral buckle or post-PPV ERM is common
  • Uveitis: Chronic inflammation → RPE cells and inflammatory cells migrate onto ILM; associated with intermediate and posterior uveitis
  • Diabetic retinopathy: VEGF-driven proliferation; ERM present in up to 20–30% of DR patients; contributes to tractional component of DMO
  • Retinal vein occlusion (BRVO/CRVO): ERM forms in 10–25% of RVO cases; traction worsens macular oedema
  • Post-laser photocoagulation or cryotherapy: Thermal disruption of RPE → cell migration onto ILM
  • Penetrating ocular trauma: Disruption of retinal and RPE barriers; inflammatory response promotes membrane formation
  • Post-vitreoretinal surgery (PPV, scleral buckle): RPE cells liberated during surgery seed the inner retinal surface; ERM is a recognised post-operative complication
  • Intraocular tumours: Choroidal melanoma, retinoblastoma — disruption of retinal architecture; paraneoplastic effects
  1. Cellular seeding of the ILM surface — PVD or micro-breaks in the ILM allow glial cells (Müller cells, astrocytes), RPE cells, myofibroblasts, fibrocytes, and hyalocytes to migrate onto the inner retinal surface. In secondary ERM, inflammatory cells also contribute.
  2. Cellular proliferation and ECM deposition — Seeded cells proliferate and secrete extracellular matrix proteins (collagen types I, II, IV, fibronectin, laminin) → an avascular fibrocellular membrane forms directly on the ILM.
  3. Myofibroblastic transformation and contraction — Key cells differentiate into myofibroblasts expressing α-smooth muscle actin (α-SMA); these cells exert tangential (horizontal) contractile forces on the inner retinal surface → wrinkling, striae, and macular pucker (the defining structural change).
  4. Retinal distortion and thickening — Tangential traction distorts the inner retinal layers → loss of foveal pit, intraretinal cystoid spaces, schisis-like changes, inner nuclear layer disruption; foveal ectopia (displacement from normal position) may occur with severe or eccentric membranes.
  5. Secondary outer retinal disruption — Chronic traction and oedema progressively damage the outer retinal layers; disruption of the ellipsoid zone (EZ) and external limiting membrane (ELM) on OCT indicates photoreceptor damage — the key determinant of visual prognosis.
  6. End-stage complications (rare) — Extreme tangential traction may cause a lamellar macular hole (partial thickness, involving inner layers) or, uncommonly, a full-thickness macular hole when all retinal layers are disrupted.

Gass Classification (Ophthalmoscopic — Classic)

StageNameFeaturesTypical VA
0Cellophane maculopathyTranslucent ERM; no retinal distortion; glistening reflex on retroillumination only; macula appears normal on direct inspection≥6/9 — usually asymptomatic
1Crinkled cellophane maculopathyFine irregular wrinkling of inner retinal surface; mild retinal striae visible; mild metamorphopsia; vessels slightly distorted6/6 – 6/12 — mild symptoms
2Macular puckerOpaque or semiopaque ERM; obvious retinal folds and striae; distorted dilated vessels dragged toward centre; pseudohole may be visible; significant retinal distortion≤6/12 — significant metamorphopsia

OCT-Based Classification (Modern / Preferred)

Supersedes Gass in clinical practice; provides prognostic information:

  • ERM reflectivity: Hyperreflective (opaque/dense) vs hyporeflective (translucent/early)
  • Central subfield thickness (CST): Measured in µm; correlates with severity and surgical urgency
  • Foveal morphology: Intact pit / flattened / pseudohole / lamellar macular hole / full-thickness macular hole
  • Outer retinal integrity: Ellipsoid zone (EZ) and external limiting membrane (ELM) — intact vs disrupted; most important prognostic indicator for post-operative VA
  • Intraretinal fluid: Cystoid spaces in INL or OPL; indicates traction-related oedema

Pseudohole vs Lamellar Macular Hole vs Full-Thickness Macular Hole

  • Pseudohole: ERM with central opening; OCT shows no full-thickness break; V-shaped foveal contour; no subretinal fluid
  • Lamellar macular hole (LMH): Partial-thickness defect (inner layers only); irregular foveal contour; ERM often present; distinct OCT pattern
  • Full-thickness macular hole (FTMH): Full-thickness break; surrounded by subretinal fluid cuff; requires urgent surgery
  • Age >50 years: Most important risk factor; prevalence increases sharply with age (~2% at 50–59, ~20% at 75+); correlates with age-related PVD incidence
  • Posterior vitreous detachment (PVD): Major precipitant for idiopathic ERM; ERM detected in ~10% of eyes with symptomatic PVD
  • History of retinal tear or detachment: RPE cell liberation and inflammation during or after tear; post-surgical ERM common
  • Prior intraocular surgery: PPV, scleral buckling, cataract surgery — RPE cells seed the ILM post-operatively
  • Uveitis: Any chronic inflammatory condition — intermediate, posterior, panuveitis; ERM present in up to 30% of uveitis patients
  • Diabetic retinopathy: VEGF-driven cellular proliferation and tractional component; ERM contributes to DMO
  • Retinal vein occlusion: BRVO/CRVO; inflammatory and ischaemic mediators promote ERM formation
  • Ocular trauma: Blunt or penetrating; disruption of retinal barriers → RPE and glial cell migration
  • High myopia: Associated with earlier PVD → earlier ERM; myopic vitreoretinal interface changes increase risk
  • Contralateral ERM: ~20–30% of idiopathic ERMs are bilateral; contralateral eye at risk

Fundus Signs (Slit-lamp / Fundus Photography)

  • Glistening/cellophane reflex: Irregular, golden or silvery light reflex over the macular area; best seen with retroillumination or indirect ophthalmoscopy; classic early sign even without distortion
  • Macular pucker / retinal striae: Radial or concentric wrinkling of the inner retinal surface radiating from the ERM centre; pathognomonic of Stage 1–2 ERM
  • Heterotopic / dragged vessels: Retinal vessels distorted, tortuous, and pulled toward the centre of the ERM; loss of normal vessel course from disc to periphery
  • Pseudohole: Round, reddish, hole-like appearance at the centre of the ERM where membrane has split; no full-thickness break (confirmed by OCT); no surrounding cuff of subretinal fluid
  • Generalised macular elevation: Subtle greyish thickening of the macular area; confirmed by OCT as retinal thickening

OCT Signs

  • Hyperreflective line on inner retinal surface: The ERM itself; may be focal or diffuse; separate from or adherent to ILM
  • Retinal thickening (↑ CST): Central subfield thickness increased; correlates with VA and symptom severity
  • Loss of foveal pit: Foveal contour flattened or inverted from traction; foveal ectopia in severe cases
  • Inner retinal layer disruption: Cystoid spaces in inner nuclear layer (INL); intraretinal schisis
  • Ellipsoid zone (EZ) disruption: Discontinuity or loss of the photoreceptor inner/outer segment junction line; most important adverse prognostic sign
  • Ectopic inner foveal layers: Inner retinal layers present at the fovea (normally absent) — a sign of chronic ERM-related distortion
  • Metamorphopsia (distortion): Most common and functionally significant symptom; straight lines appear wavy, bent, or irregular; detected on Amsler grid testing; may be severe even with preserved Snellen acuity
  • Blurred/reduced central vision: From retinal thickening, traction, and distortion at the fovea; VA ranges from 6/6 (mild ERM) to counting fingers (advanced ERM with outer retinal damage)
  • Micropsia: Objects appear smaller than actual size; caused by spreading/crowding of photoreceptors as the macula is distorted by traction; a hallmark symptom of ERM
  • Monocular diplopia: Ghost images or double vision from one eye; due to irregular retinal surface creating two focal points; highly characteristic of ERM
  • Reduced contrast sensitivity: Difficulty distinguishing objects from similar-coloured backgrounds; often disproportionate to Snellen acuity reduction
  • Reading difficulty: Letters may appear broken, distorted, or crowded together; affects quality of life significantly before VA formally drops
  • Asymptomatic (Stage 0): Many early ERMs are discovered incidentally on routine fundus examination or OCT during diabetic screening, drusen monitoring, or PVD follow-up

Structural / Retinal

  • Outer retinal disruption (EZ loss): Ellipsoid zone discontinuity from chronic traction; indicates irreversible photoreceptor damage; limits VA recovery even after successful surgery
  • Foveal ectopia: Displacement of fovea from its anatomical position by eccentric ERM contraction; causes persistent metamorphopsia post-surgery even when anatomically corrected
  • Lamellar macular hole (LMH): Partial-thickness foveal defect from tangential traction; may be stable for years or progress to FTMH; distinct OCT features
  • Full-thickness macular hole (FTMH): Rare ERM complication; extreme traction causes complete foveal rupture; requires urgent surgical repair (PPV + gas tamponade)
  • Progressive VA decline: Most ERMs progress slowly; a minority progress rapidly; unpredictable in individual patients

Post-Surgical

  • Persistent metamorphopsia: Most common post-surgical complaint; may take 12–24 months to resolve; complete resolution in only 30–50%
  • Cataract: Develops in ~80% of phakic eyes within 2 years of PPV; often performed simultaneously (phaco-vitrectomy)
  • ERM recurrence: ~1–2% with ILM peeling; ~10% without ILM peeling
  • Iatrogenic macular hole: Rare; from aggressive ILM peeling near the fovea
  • Diabetes mellitus: ERM is highly prevalent in diabetic retinopathy (20–30%); traction from ERM contributes significantly to DMO — anti-VEGF response may be attenuated; vitrectomy with ERM/ILM peeling often needed to address both components; RP and DMO management should be coordinated
  • Retinal vein occlusion (BRVO/CRVO): ERM forms in 10–25% of RVO cases; traction worsens post-RVO macular oedema; combined vitrectomy + membrane peeling ± anti-VEGF may be required; BP control reduces RVO and secondary ERM risk
  • Uveitis: Chronic intraocular inflammation (intermediate, posterior, pan-uveitis) promotes ERM; control of uveitis with systemic immunosuppression may slow ERM progression; surgical risk increased in active uveitis — plan surgery in quiescent phase
  • Systemic hypertension: Indirectly — through increased risk of RVO (which causes secondary ERM) and DR; BP control targets (<130/80 mmHg) reduce both RVO and DR risk
  • Post-surgical ERM (systemic link): Patients with diabetes, uveitis, or sickle cell disease undergoing intraocular surgery have higher risk of ERM formation post-operatively; RPE cell liberation during PPV or scleral buckling seeds the ILM; more common and more severe in inflamed eyes
  • Slit-lamp biomicroscopy (90D/78D lens): Glistening or cellophane reflex at the macular surface; macular pucker and striae; retroillumination enhances early Stage 0 ERM detection; pseudohole visible as central red spot; compare with normal fundus appearance
  • OCT (gold standard): Identifies hyperreflective ERM on ILM surface; quantifies central subfield thickness (CST); assesses foveal morphology (intact pit / flattened / pseudohole / LMH / FTMH); evaluates ellipsoid zone and ELM integrity; guides surgical decision-making; essential for follow-up monitoring; differentiates ERM from VMT (vitreous still attached in VMT)
  • Amsler grid: Detects and documents metamorphopsia; easy clinical tool; patient self-monitoring; may underestimate severity due to neural adaptation (filling-in effect); useful for home monitoring between appointments
  • Visual acuity (ETDRS or Snellen): Baseline and serial monitoring; VA alone insufficient — metamorphopsia may be severe with 6/6 acuity; important for surgical decision-making threshold (≤6/12)
  • Microperimetry: Maps retinal sensitivity across the macula; identifies scotomas and reduced sensitivity associated with ERM; correlates with photoreceptor function; predicts surgical outcomes; useful pre-operative assessment tool
  • Fundus photography / wide-field imaging: Baseline documentation; serial comparison for progression; identifies striae, vessel distortion, pseudohole
  • Fluorescein angiography (FFA): Not routinely required; pseudohole shows no leakage (differentiates from FTMH — which shows cuff of SRF); useful in secondary ERM to assess RVO/DR-related leakage
  • Contrast sensitivity testing: Often disproportionately reduced relative to Snellen VA; useful for patient counselling and outcome assessment

1. Observation (appropriate for most early ERMs)

  • Indicated when VA is ≥6/9, metamorphopsia is minimal, and OCT is stable
  • Monitor every 6–12 months: VA, Amsler grid, OCT (CST and EZ integrity)
  • ~80% of idiopathic ERMs are stable or very slowly progressive over years
  • Counsel patient: report new or worsening distortion, blur, or reading difficulty promptly
  • Offer home Amsler grid monitoring; educate on when to seek urgent review

2. Pars Plana Vitrectomy (PPV) + ERM Peeling ± ILM Peeling (definitive treatment — ophthalmology)

  • Indications: VA ≤6/12 and symptomatic; significant metamorphopsia affecting daily life or occupation; documented progression on serial OCT; patient preference with adequate counselling
  • Technique: 23G or 25G micro-incision vitrectomy (MIVS); core vitrectomy; posterior hyaloid separation; ERM identification with ILM staining dyes (Brilliant Blue G preferred, or Membrane Blue Dual); careful peeling with end-gripping forceps using angulated picks
  • ILM peeling (strongly recommended): Removes the scaffold for ERM re-growth; reduces recurrence rate to ~1–2% (vs ~10% without ILM peeling); improves anatomical outcome; slightly increases risk of iatrogenic macular hole near fovea if overly aggressive
  • Combined phaco-vitrectomy: If PSC cataract is present, phacoemulsification is performed at the same sitting; prevents the need for second surgery and improves fundus visualisation
  • Post-operative course: Face-down positioning not required (unlike FTMH); VA improvement begins within weeks; metamorphopsia resolution may take 12–24 months
  • Outcomes: VA improves in 70–90% of operated eyes; average gain 2–3 ETDRS lines; intact pre-operative EZ → best VA outcomes

3. No Pharmacological Treatment for Primary ERM

  • Intravitreal anti-VEGF: No role in primary idiopathic ERM; may be used for concurrent DMO or RVO-related oedema in secondary ERM
  • Ocriplasmin (Jetrea): Pharmacological vitreolysis; approved for vitreomacular traction (VMT) syndrome — a different entity where the vitreous remains attached; not effective for established ERM; VMT and ERM may co-exist
  • Intravitreal steroids: No role in primary ERM; may reduce inflammation in uveitis-associated ERM pre-operatively

Singapore Optometry Scope Note: Optometrists in Singapore use fundus cameras and OCT imaging to assess the macula — dilated slit-lamp fundus examination is not within optometry scope of practice. Optometrists may perform and interpret OCT imaging, assess metamorphopsia with Amsler grid, and monitor VA progression. Therapeutic-endorsed optometrists may manage co-existing conditions (dry eye, ocular surface disease). Surgical referral — PPV with ERM and ILM peeling — is indicated when VA drops to ≤6/12 or metamorphopsia significantly affects quality of life; refer to ophthalmology promptly to avoid delay and prevent outer retinal damage. Counsel patients to monitor daily with an Amsler grid and report worsening distortion immediately.

  • Natural history: ~80% of idiopathic ERMs are stable or very slowly progressive; a minority (~5–10%) progress rapidly and significantly; spontaneous separation of ERM occurs in ~3–5% (rare, associated with good visual recovery)
  • Surgical VA outcomes: Improvement in 70–90% of operated eyes; average gain 2–3 ETDRS lines; final VA correlates strongly with pre-operative VA and outer retinal integrity
  • Metamorphopsia resolution: Slower and less complete than VA recovery; resolution takes 12–24 months post-surgery; complete resolution in only 30–50%; persistent metamorphopsia is the most common post-operative complaint
  • Ellipsoid zone (EZ) integrity — key prognostic marker: Intact EZ pre-operatively → good VA recovery; disrupted EZ → poor VA recovery regardless of successful membrane removal; earlier surgery prevents EZ disruption
  • ERM recurrence: ~1–2% with ILM peeling at PPV; ~10% without ILM peeling; recurrent ERM may require repeat vitrectomy
  • Timing of surgery: Earlier surgery (before EZ disruption and foveal ectopia) yields superior outcomes; prolonged observation in symptomatic patients risks permanent photoreceptor damage
  • Secondary ERM: Prognosis depends on control of underlying disease (DR, RVO, uveitis); DR-related ERM may have worse outcomes due to concurrent macular ischaemia and limited functional reserve
  • Key favourable factors: Intact EZ pre-operatively; good pre-operative VA; shorter symptom duration; idiopathic ERM; no foveal ectopia
  • Key poor factors: Disrupted EZ; long-standing membrane; foveal ectopia; secondary ERM from poorly controlled DR or uveitis; concurrent macular ischaemia
ConditionKey Differentiator from ERM
Vitreomacular Traction (VMT)Vitreous not yet fully detached from fovea; OCT shows vitreous strand(s) pulling on fovea causing elevation; no ERM membrane line; may respond to ocriplasmin; ERM can co-exist with VMT
Lamellar Macular Hole (LMH)Partial-thickness foveal defect (inner retinal layers only); irregular foveal contour with intraretinal split; OCT shows distinctive lamellar appearance without full-thickness break; ERM often co-exists and may be causative
Full-Thickness Macular Hole (FTMH)Complete foveal break (all layers); absolute central scotoma; round red spot with cuff of subretinal fluid on fundoscopy; FFA shows hyperfluorescence with leakage; OCT confirms FTMH; requires urgent PPV + gas tamponade
Pseudohole (ERM variant)Subset of Stage 2 ERM; central opening in ERM creates hole-like appearance; OCT confirms no full-thickness break; V-shaped foveal contour; usually stable without urgent surgery
Diabetic Macular Oedema (DMO)Fluid accumulation from leaking microaneurysms (not traction); anti-VEGF responsive; OCT shows cystoid intraretinal fluid without hyperreflective ERM line; ERM may co-exist and contribute to tractional DMO
Central Serous Chorioretinopathy (CSCR)Subretinal fluid (SRF) accumulation beneath detached neurosensory retina; leak at RPE level; FFA shows inkblot or smokestack fluorescein leakage; typically young-to-middle-aged men; resolves spontaneously in most; no ERM
Wet AMD (nAMD)Subretinal fluid, intraretinal fluid, CNV network; drusen; haemorrhage; responds to anti-VEGF; OCT shows SRF ± IRF with CNV; predominantly older patients; no cellophane reflex
Macular Dystrophies (Best, Stargardt)Hereditary; bilateral and symmetric; fundus autofluorescence and ERG/EOG abnormalities; genetic diagnosis; no ERM on OCT; age of onset earlier than ERM; distinct OCT and FAF patterns
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