Epiretinal membrane: What is it?

21 March, 2017

Ophthalmology

The macula refers to the central part of the whole retina, which has the highest density of photoreceptors. It allows us to clearly visualize the central visual field ahead of us. Epiretinal membrane refers to a thin fibrotic membrane developing on the surface of the macula. As the membrane thickens and contracts, wrinkles will be created on the underlying macula. If the situation is severe, the macula maybe thickened. Patients with this condition will experience blurriness, distortion in vision, and can be debilitating at times. It has been reported that up to 3.4% of Chinese above the age of 30 suffer from this condition, and 10% of these are bilateral. 

Causes of epiretinal membrane can be divided into primary and secondary. Primary refers to patients in which a particular cause cannot be found. Majority of epiretinal membranes are primary. As for secondary epiretinal membrane, common causes include high myopia, diabetic retinopathy, retinal vacular diseases, retinal breaks, retinal detachment, just to name a few. It can also occur after trauma, retinal laser, or cryo treatment. 

Early stages can be totally asymptomatic, hence delaying the discovery of the condition. For mild cases, regular monitoring by an ophthalmologist maybe all that is required. However, in more severe cases where the membrane gradually thickens over time and in those with underlying macular thickening, treatment maybe indicated. At the moment, surgical removal of the membrane is the most effective solution. 

During surgery, the first step is to perform a vitrectomy. This involves creating three tiny holes on the sclera, through which the vitreous is removed. This allows later maneuvers on the macula. A colored stain will then be injected into the eye to stain up the epiretinal membrane, allowing easy visualization during removal. Peeling of the membrane will then be followed, with a pair of tiny forceps. Depending on the age and the presence of co-existing cataract in the same eye, the ophthalmologist may recommend cataract extraction at the same setting, to avoid the need to undergo cataract extraction surgery at a later time. As a general rule, patients with an epiretinal membrane that is milder and with a shorter history tend to have more potential for improvement after surgery. On the contrary, more severe cases tend to perform less well after surgery when compared to mild cases. Therefore, when indicated, intervention should be performed earlier for better outcomes.