Vitrectomy to remove an epiretinal membrane (ERM) is one of the most common procedures performed by retinal surgeons. Patients who present with significant macular changes on optical coherence tomography (OCT) but relatively good vision are often advised to defer surgery until vision declines to 20/40 or worse. However, it is unknown if delaying surgery, which allows the foveal architecture to remain compromised and potentially to deteriorate, results in worse visual acuity outcomes than if surgery is performed earlier. In addition, there is a need to better understand predictors of outcomes when surgery is performed and predictors of progression when surgery is deferred. Finally, one of the most common presenting symptoms from an ERM is distortion or metamorphopsia. There are several objective measures of metamorphopsia but none have ever been employed to evaluate ERMs in a randomized clinical trial (RCT) and their usefulness is unknown. The purposes of this study are to better understand the optimal timing of surgery to produce the best visual result, to better understand predictors of outcomes in those who undergo surgery and predictors of progression in those whose are observed, and to better characterize and evaluate the usefulness of metamorphopsia and reading speed measures.

Key Inclusion Criteria:

• Age ≥ 45 years

• E-ETDRS visual acuity 20/40 or better (≥69 letters)

  o ERM must be thought to be the primary cause of vision loss

• ERM meeting the following criteria, according to the investigator

  • ERM is not secondary to another condition
  • Symptoms of visual loss and/or distortion (in the opinion of the investigator, the ERM is contributing to the participant's symptoms); either new or worsening in the past 24 months
  • Epiretinal membrane involving or altering the central 3 mm of the macula on OCT
  • Distortion within the central subfield due to ERM on OCT

• Immediate vitrectomy not required (investigator and participant are willing to wait at least 4 weeks to see if vision remains stable without having to proceed to vitrectomy)

• No known medical problems that will be a contraindication to surgery

Key Exclusion Criteria:

• History of retinal vascular disease

• History of vitreous hemorrhage if vitreous hemorrhage is thought to have caused the ERM

  o History of vitreous hemorrhage is permitted provided the vitreous hemorrhage did not cause the ERM in the investigator's opinion

• History of inflammatory disease unless mild and completely resolved at least one year prior to randomization

• History of diabetic macular edema (DME), retinal vein occlusion (RVO), or uveitis (except mild uveitis that resolved >1 year prior to randomization)

• Prior intraocular surgery (except uncomplicated cataract extraction)

• Cataract extraction within prior 3 months

• Laser or cryosurgical retinopexy within one month of randomization

• Pneumatic retinopexy within one year of randomization

• Current untreated retinal tear or detachment

  o A previously treated retinal tear with up to one disc diameter radius of subretinal fluid is permitted

• Macular hole

• Degenerative lamellar macular hole

  o ERM foveoschisis ("tractional" lamellar hole) is permitted

• Vitreomacular traction within 1,500 microns of foveal center

• Central serous chorioretinopathy

• Nonproliferative diabetic retinopathy or worse (DR severity >20)