Epiretinal Membrane (ERM)

Epiretinal Membrane (ERM)
SYMPTOMS Typically asymptomatic
Can develop central vision loss and metamorphopsia (depends on the thickness of the epiretinal membrane as well as the extent of shrinkage and contraction of the epiretinal membrane)
SIGNS Absent foveal reflex, Transparent membrane (as membrane gets thicker, it will become more opaque and begin to obscure retinal vessels), Glistening light reflex on the inner retinal surface, Retinal striae, Macular distortion, Loss of foveal pit, Macular puckering, Cystoid macular edema, Intraretinal hemorrhages, Preretinal/subhyaloid hemorrhages, Pseudohole, Foveal ectopia, Lamellar hole, Full thickness hole, Displacement of retinal vasculature
Gass Grades for an ERM:
Grade 0: ERM with no effect on macular architecture with no visual symptoms
Grade 1 (Cellophane maculopathy): Early change in macular architecture with mild visual symptoms
Grade 2 (Macula pucker): White-grey ERM with obscuration of retinal vessels with retinal striae, retinal traction, and central vision loss
WORK-UP Full eye exam with dilated retinal exam, OCT analysis of the macula (signs of an ERM are best seen with an OCT), Fluorescein Angiography, Fundus photos, Watzke-Allen test, Macular photostress test, Amsler grid
TREATMENT Grade 0 and Grade 1 ERMs typically do not require any treatment. Give take home Amsler grid in order to monitor for change
Grade 2 ERMs typically require treatment and will need to be referred to a retinal specialist for a vitrectomy with an ILM peel (44-55% of patients will end up seeing 20/50 or better after the surgery)
Criteria for surgery: Vision that is less than or equal to 20/60 or vision that is better than 20/60 but patient reports metamorphopsia
FOLLOW-UP Grade 0 ERM: Patient should be seen back in 1 year
Grade 1 ERM: Patient should be seen back in 6-9 months
Grade 2 ERM: If monitoring, patient should be seen back in 3-4 months
Once patient is stable following ERM removal/surgery, patient should be seen back every 6-12 months
ETIOLOGY Idiopathic ERM: Defects in the ILM, that occur due to a posterior vitreous detachment, allows retinal cells to migrate through the defects and develop a membrane along with cells from partial remnants of the posterior hyaloid membrane
Secondary ERM: Reactive gliosis (which occurs due to trauma, injury, or inflammation) and growth factors lead to the formation of a membrane
DIFFERENTIAL DX Fibrovascular proliferation associated with proliferative retinopathy, Cystoid macular edema
NOTES The most common cause of an ERM is idiopathic
Epiretinal membranes are associated with posterior vitreous detachments 90% of the time
Only 9.3% of Grade 1 epiretinal membranes become Grade 2 epiretinal membranes
Inner retinal dimples are common to see on en face imaging following surgical removal of the ERM (does not seem to affect vision)
Epiretinal Membrane (ERM): OCT of the macula demonstrating a Grade 2 epiretinal membrane (ERM) https://www.retinaky.com/macular-pucker-louisville/