Does internal limiting membrane peeling during epiretinal membrane surgery induce microscotomas on microperimetry? Study protocol for PEELING, a randomized controlled clinical trial

BACKGROUND: The epiretinal membrane (ERM) is a degenerative condition associated with age, which can cause loss of vision and/or metamorphopsia. The treatment of symptomatic ERM involves surgical removal including a vitrectomy followed by peeling of the ERM using a microforceps. As the internal limiting membrane (ILM) is adherent to the ERM, it is sometimes removed with it (spontaneous peeling). If ILM remains in place, it can be removed to reduce ERM recurrence. However, it is important to clarify the safety of ILM peeling, while it increases surgical risks and cause histological disorganization of the retina that can lead to microscotomas, may be responsible for definitive visual discomfort. METHODS: PEELING is a prospective, randomized, controlled, single-blind, and multicentered trial with two parallel arms. This study investigates the benefit/risk ratio of active ILM peeling among individuals undergoing ERM surgery without spontaneous ILM peeling. Randomization is done in the operating room after ERM removal if ILM remains in place. After randomization, the two groups—“active peeling of the ILM” and “no peeling of the ILM”—are compared during a total of three follow-up visits scheduled at month 1, month 6, and month 12. Primary endpoint is the difference in microscotomas before surgery and 6 months after surgery. Patients with spontaneous peeling are not randomized and are included in the ancillary study with the same follow-up visits and the same examinations as the principal study. Relevant inclusion criteria involve individuals aged > 18 years living with idiopathic symptomatic ERM, including pseudophakic patients with transparent posterior capsule or open capsule or lensed patients with age-related cataracts. The calculated sample size corresponds to 53 randomized eyes (one eye/patient) per arm that means 106 randomized eyes (106 randomized patients) in total and a maximum of 222 included patients (116 spontaneous peeling). DISCUSSION: ILM peeling is often practiced in ERM surgery to reduce ERM recurrence. It does not impair postoperative visual acuity, but it increases the surgical risks and causes anatomical damages. If active ILM peeling is significantly associated with more microscotomas, it may contraindicate the ILM peeling during primitive idiopathic ERM surgery. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02146144. Registered on 22 May 2014. Recruitment is still ongoing.