Epiretinal membrane (ERM)

What is an epiretinal membrane?

An epiretinal membrane is a condition where a very thin layer of scar tissue forms on the surface of the macula — the central retina responsible for clear, detailed vision. When it contracts, it can crumple the macular retina, causing distorted and blurred vision.

In most cases this is related to normal ageing changes inside the eye, though it can also follow diabetes, vein occlusion, inflammation, or previous retinal surgery. Epiretinal membranes are not related to macular degeneration, do not usually affect the other eye, and are quite common — affecting up to 8% of people in later years.

Symptoms — questions Rahila usually asks

With both eyes open (with glasses or contact lenses if you use them):

• Are you having difficulty seeing the TV screen clearly or reading subtitles?
• Do you have distorted vision — do straight lines look bent or wavy?
• Is it difficult reading small print unless you close the affected eye?
• Has your optician said a new glasses prescription can't improve your vision?
• Is it difficult to see clearly when you are driving?
• Are you having difficulty reading music?
• Is your vision affecting your work or a hobby you enjoy?
• Can you see better when you close the affected eye?

How is it detected?

An epiretinal membrane is detected during an eye examination using dilating drops. Sometimes an OCT (optical coherence tomography) scan of the back of the eye is needed to confirm its presence and assess how much it is affecting the retinal surface.

Do I need treatment?

Many epiretinal membranes are discovered by chance at a routine examination and may not change or affect vision. Treatment is only required when the membrane affects your vision, and your symptoms help decide whether and when to proceed with surgery.

Surgery: vitrectomy and membrane peel

If an epiretinal membrane affects vision, the only treatment is surgical removal. This is achieved by a vitrectomy and epiretinal membrane peel, where specialised instruments remove the vitreous, and the membrane is carefully peeled off the retinal surface using fine forceps.

The operation takes about an hour and can be performed under local or general anaesthetic. In some cases a small gas bubble is left inside the eye at the end of surgery, which disappears on its own over a few weeks — in this case you may be asked to position your head in a specific way for a few days.

Following surgery, vision is typically blurred and can take some months to improve. Distortion usually improves sooner than overall sharpness. Most people need at least two weeks off work.

Eye pressure sometimes rises in the days after surgery. If you notice pain in or around the eye, contact the team for a pressure check — this usually responds well to additional drops for a few weeks.

For further information: RNIB helpline 0303 123 9999  ·  Macular Society helpline 0300 3030 111.