Epiretinal Membrane

Epimacular membrane, Cellophane maculopathy, Macular pucker, Silk-screen retinopathy, Preretinal macular gliosis, Preretinal fibrosis.

Description

An epiretinal membrane (ERM) is a proliferation of predominantly collagenous tissue on the internal limiting membrane (ILM), the most anterior layer of the neurosensory retina. ERMs vary widely in severity and appearance, and form part of a continuum of conditions that include vitreomacular traction syndrome and macular holes. It is common and typically occurs in people over 50 years of age. Approximately one fifth of cases are bilateral

Aetiology

Any condition associated with a break in the ILM may allow the escape of glial cells (e.g. astrocytes) or other retinal or pigment cell types that may then proliferate on the ILM to form a membrane. Possible causes of an ERM include:

• Idiopathic
• Posterior vitreous detachment
• Retinal tears and detachments
• Retinal vascular occlusive disease
• Following retinal surgery
• Following ocular trauma
• Ocular inflammatory disease
• Vitreous haemorrhage

Symptoms

Most patients with ERMs do not have symptoms with the condition usually being discovered during a routine eye examination. Others may have a mild to moderate blurring of vision and a distortion of vision or metamorphopsia.

Signs

(1) Cellophane maculopathy. If the membrane is thin it tends to glisten in the beam of the direct ophthalmoscope or when observed during slit-lamp fundus microscopy. Red-free illumination aids in its detection.

(2) Thicker ERMs have a yellow-white or grey appearance. Contraction of the membrane may lead to retinal folds and tortuosity of some retinal vessels and straightening of others.

(3) Severe ERMs are associated with macular pathology such as cystoid macular edema, disturbance of the retinal pigment epithelium or local retinal detachment. A fluorescein angiogram may reveal leakage from the retinal vessels or macular edema.

A defect in the ERM may cause the macula may take on the appearance of a pseudo hole. Signs relating to a causative disease may be present.

Prevalence

Common (approximately 1/1,000) to very common (1/10) particularly in the older age groups or following ophthalmic surgery.

Significance

While an ERM may be described as a threat to sight in some cases, the consideration of a surgical opinion is routine. The visual outcome following a membrane peel is often excellent.

DiffERENTIAL Diagnosis

Macular edema, macular hole, posterior vitreous detachment, vitreomacular traction syndrome

Management

Review and advice

Patients with ERMs that are asymptomatic should be followed at regular intervals and warned to present if they note a change in their visual status. In rare cases, the ERM may spontaneously separate from the retina and vision can return to normal. If a causative condition is identified, this should be treated.

Additional investigations

The patient may be provided with an Amsler macular grid for regular home use in assessing each eye for metamorphopsia. Ocular coherence tomography or fluorescein angiography may be useful for assessing macular changes or other retinal pathology.

 

Incisional surgery

Some retinal specialists suggest that patients who have a visual acuity of 6/12 or worse should be considered for surgical peeling of the membrane. Vitrectomy and management of any retinal breaks may also be considered. A recurrence of the ERM following surgical removal has been reported but this is uncommon.