Epiretinal Membrane (ERM)

What is an epiretinal membrane?

Epiretinal membrane is a thin fibrous membrane over the central retina which can cause blurred or wavy / distorted vision. It is quite common and if it is causing symptoms the patient needs to see a vitreo-retinal surgeon for  treatment.

A word on the retina, macula and vitreous gel

The retina is a thin “wallpaper” or “photographic sheet” lining the inside the eye.  It is comprised of layers of nerve tissue and acts like the photographic film in a camera, picking up the light that enters the eye and sending images to the brain.  The central part of the retina is called the macula and this is responsible for the sharp vision we use when reading and recognising faces and for colour vision.  The central part of the eye is called the vitreous gel, which is a transparent gel behind the lens and in front of the retina.

How does an ERM affects the retina?

Sometimes, a clin-film like thin fibrous scar tissue called an epiretinal membrane (ERM) forms over the back of the central retina, at the macula. ERM is a common eye condition associated with ageing changes in the eye.

Epiretinal membranes are also more likely to occur following inflammation in the eye, injuries, or after eye surgery.  The ERM can grow across the macula.

Although it has been observed in about 7 – 11% of people, most cases do not give rise to symptoms.  It is likely to remain stable over time and usually does not require regular observation. However, when it causes wavy or distorted vision, or blurred vision, an ophthalmologist should examine the eye.

How does an ERM affects vision?

Most patients will not notice a significant visual problem from an ERM. Occasionally, if the fibrous tissue of the ERM thickens and contracts, it will start to twist and crinkle the retina.  In this case, some people can become aware of blurred vision and distortion, where images look bent out of shape. All patients with vision symptoms should see a vitreo-retinal specialist for special diagnostic scans of the back of the eye and possible treatment.

How is an ERM is diagnosed?

The ERM can be seen at the back of the eye by the vitreo-retinal specialist as a thin clin-film like distortion at the macula. Vision disturbance is confirmed using an Amsler chart. The thin fibrous tissue is visualised using optical coherence tomography (OCT) test, which shows the fine structure of the retina, macula and membrane in cross section.