Epi-retinal membrane (ERM) or macular pucker is a cellophane-like membrane that forms over the macula. It is typically a slow-progressing problem that affects the central vision by causing blur and distortion. As it progresses, the traction of the membrane on the macula may cause swelling.
ERM is seen most often in people over 75 years of age. It usually occurs for unknown reasons, but may be associated with certain eye problems such as: diabetic retinopathy, posterior vitreous detachment, retinal detachment, trauma, and many others.
The eye care practitioner is able to detect ERM with ophthalmoscopy during an examination of the retina. It has a glistening, cellophane-like appearance. The affect of ERM on the patient's central vision is assessed with a visual acuity test and the Amsler Grid. If the eye care practitioner suspects macular swelling, he may order fluorescein angiography.
A procedure called a membrane peel is performed when vision has deteriorated to the point that it is impairing the patient's lifestyle. Most vitreo-retinal surgeons recommend waiting for treatment until vision has decreased to the point that the risk of the procedure justifies the improvement.
The membrane peel is performed under local anaesthesia in an operating theatre. After making tiny incisions the membrane peel is often done in conjunction with a procedure called a vitrectomy.
Illustrations by Mark Erickson
With acknowledgement to St. Lukes Eye Hospital.