The goal of this study is to compare the novel ILM sharkskin forceps with a conventional ILM forceps utilizing iOCT assistance during surgery at this "grasp site". The main questions it aims to answer are:

1. are there differences in grasp attempts between both forceps
2. are there differences in Instrument tissue interactions between both forceps
3. are there differences in postsurgical anatomical and functional outcomes at the grasp site between both forceps.

Epiretinal membranes are a disease of the retinal surface, that may affect visual acuity acuity and cause metamorphopsia, occurring in approximately 20% of the population older than 60 years. Using vitrectomy with membrane peeling, postoperative improvement of visual acuity and metamorphopsia may be achieved in a majority of patients. The surgical method has been used for some time, the first report on the surgical method of vitrectomy with membrane peeling dates back to 1978, and since the introduction of intraoperative optical coherence tomography (iOCT), intraoperative iatrogenically induced changes in retinal tissue can be detected and correlated with postoperative changes. Our group has been able to record "stretching" of the retinal tissue using this technique and has also been able to record the rarely occurring subfoveal and extrafoveal elevations of the ellipsoidal zone due to membrane peeling. These changes did not significantly affect postoperative visual acuity in our study population but did affect the development of postoperative microscotomas. Besides "retinal stretching" during surgery, ILM peeling is shown to be another factor with association of new postoperative microscotomas. New postoperative microscotomas developed in some patients without "retinal stretching" and ILM peeling. Apart from these already known iatrogenic changes, the analysis of the "grasp site" at the "starting point" of epiretinal membrane peeling is of great interest, because at this location, grasping of the epiretinal membrane may be difficult especially in case of an adherent ERM and superficial retinal lesions may be induced.

Diaz et al. demonstrated that there are postoperative changes in the "nerve fiber layer" after ILM peeling, but in that study, no recording of instrument/tissue interactions was performed using iOCT.

The aim of this study is to compare the novel ILM sharkskin forceps with a conventional ILM forceps utilizing iOCT assistance during surgery at this "grasp site".

Inclusion Criteria:

• Idiopathic ERM
• Sheduled surgery (vitrectomy with membrane peeling), as defined by vision loss and/or metamorphopsia
• Age 18 and older
• Written informed consent for participation in the study

Exclusion Criteria:

• Macular edema due to other reasons than iERM
• Pregnancy (pregnancy test will be performed in women of reproductive age)