Introduction
Epiretinal membranes ERM is a common finding, affecting approximately 7% of the population. The incidence increases with age. While they are typically idiopathic, they can also be secondary:
- Trauma
- Inflammation
- Intraocular surgery
- Tumours
- Vascular disease
- Retinal tears and detachment
Clinically, every ERM presents as a sheet-like fibrocellular structure:
- Develops either on or above the surface of the retina, causing a wrinkling of the retinal surface, and an abnormal sheen or reflectivity of the retina.
Pathophysiology:
- PVD causes a break in the ILM through which glial cells can move and proliferate on the inner retinal surface.
- Vitreoschisis occurs, leaving remnants of the cortical vitreous attached to the ILM. Theses can proliferate, transdifferentiate and form the ERM.
Dead Giveaways
Fundus Appearance:
Characterised by hyper-reflective lines which slightly resemble the retinal nerve fibre layer, however, does not follow an arcuate pattern, and instead is more randomised, typically spanning radially outwards
OCT Appearance:
The appearance is a big more obvious on OCT, which presents as a thin hyper-reflective layer just above the ILM. Since it is fibrovascular, it can contract which causes wrinkling.
The tractional stress can also cause the growth of cystic spaces.
From Istanbul Retina Institute. Shows the ERM with wrinkling on the top, as well as tractional stress leading to maculoschisis
diagnostic features
Signs:
Distortion or loss of the foveal pit
Retinal thickening
Intraretinal cystic spaces
Symptoms:
Reduced VA
Metamorphopsia
Less commonly macropsia or micropsia
Less commonly monocular diplopia