Optical Coherence Tomography Angiography (AngioVueTM, Optovue Inc., Fremont, Calif., USA) Changes in Patients With Epiretinal Membranes (ERM) With and Without Peeling of the Internal Limiting Membrane (ILM) - a Pilot Study

Main objective

The objective is to compare two surgical options in vitrectomies for epiretinal membranes using parameters of optical coherence tomography angiography.

Background

State of the art treatment for epiretinal membranes consists of pars plana vitrectomy, staining of the epiretinal membrane with a blue colouring dye and epiretinal membrane peeling. The vitrectomized space is filled with fluid (balanced salt solution) during the procedure and the fluid can optionally be replaced with air as a final step. After ERM peeling (but before the selection of the tamponade), the internal limiting membrane (the innermost layer of the retina) is either peeled as well or left untouched and the question which method should be preferred has been a hot topic in recent years. The investigators want to investigate possible effects of the used method (peeling vs. nonpeeling) on retinal perfusion parameters represented by OCTA. Two epiretinal membrane patient groups will therefore be formed: The first group's (group 1) ILM will be peeled, the second group's (group 2) ILM will not be peeled. After recruitement, patients will therefore be electronically randomized to one of the two groups. The groups will then be compared by the means of OCTA.

Study design

• Since there are no previous data on our research question, this investigation is defined as a pilot study.
• 40 patients with epiretinal membranes will be included. This appears to be a reasonable number given the incidence of epiretinal membranes. Previous studies that compared peeling versus nonpeeling in ERM used similar sample sizes. The detectable effect size was calculated at d = 0.91. We intend to complete this pilot study within 9 months.
• Randomization will be performed using electronic randomization. 20 patients each will be randomized to either group 1 or group 2.
• Both eyes in each patient will be imaged.
• No treatment decisions will be made based on OCTA findings. Treatment decisions will be made according to the clinic's standard of care.
• Three follow-up visits specific to the study are needed. These visits will be scheduled one week, one month and three months after surgery. All other preoperative and follow-up visits will be decided by the treating physician and follow the clinic standard of care.

Examinations

• Distance visual acuity using ETDRS (Early Treatment Diabetic Retinopathy Study) standard at 4 meters as per clinic standard of care.
• Tonometry as per clinic standard of care.
• Slit-lamp evaluation as per clinic standard of care.
• Arterial blood pressure.
• Axial eye length.
• Heidelberg Spectralis conventional OCT.
• The following 2 AngioVue scans will be taken:

A. One 3mm x 3mm, 304 x 304 A-scan OCTA of the macula B. One 6mm x 6mm, 304 x 304 A-scan OCTA of the macula

Hypothesis

The null hypothesis of our investigation indicates that there are no statistically significant differences in OCTA perfusion parameters based on the used option.

The alternative hypothesis states that there are statistically significant differences in OCTA perfusion parameters based on the used option.

Primary Objective

To demonstrate possible differences in OCTA perfusion parameters based on the used option.

Secondary Objectives

To assess the feasibility of the AngioVue optical coherence tomography angiography system in evaluating subtle changes in the retinal perfusion of patients with epiretinal membranes.