Epiretinal membranes (ERM) consist of an abnormal growth of tissue across the retina and are present about 6% of people aged 50 and over. They can cause symptoms of distortion (straight lines appearing bent) or blurred vision. Management options include observation if asymptomatic, or surgery to peel the membrane if symptomatic. Limited data exists regarding how to identify patients who are most likely to benefit from surgery.

We propose to measure the effects on distortion (using D chart), visual acuity and vision-related quality of life (using a validated vision-related quality of life questionnaire) of ERM surgery. This will allow us to investigate whether pre-operative D chart score can predict subsequent improvement in quality of life following surgery. We hope the results will help patients and VR surgeons decide whether or not to proceed with ERM surgery.

The study will be a prospective case series consisting of patients with symptomatic epiretinal membranes who choose to have epiretinal membrane surgery. The study participants will get standard care with the additional administration of a quality of life questionnaire and measurement of distortion (using a D-chart) at 3 different time points (pre-op, and post-op at 26 and 52 weeks). Recruitment will be in Glasgow, with a possibility of other sites being added on at a later stage.

Epiretinal membranes consist of a proliferation of fibrocellular tissue along the inner aspect of the retina. Over time, this membrane can result in anterior-posterior traction and cause disruption of the retinal architecture, which can lead to symptoms of blurred vision, or distorted vision (with straight lines appearing bent or wavy).

Patients with ERM now constitute one of the most common referrals to the vitreoretinal service. Management of epiretinal membrane includes observation or surgery for severely symptomatic membranes. The surgery consists of vitrectomy and epiretinal +/- inner limiting membrane peel. Currently there is limited evidence to help identify which patients with an epiretinal membrane are the most likely to benefit from this operation, which makes it more difficult for patients to be able to weigh up the benefits and risks of proceeding with this elective procedure.

Our study will measure the effects on distortion (using D chart), visual acuity and quality of life of ERM surgery. Hence it will allow us to investigate whether the pre-op D chart score can predict subsequent improvement in quality of life following surgery. This will provide vitreoretinal surgeons and patients with an evidence base regarding the success of this elective procedure and offer realistic expectations regarding surgical outcomes. Ultimately, we hope that the results of this study will facilitate the decision of whether or not to proceed with ERM surgery.

We plan to recruit patients with an epiretinal membrane who choose to undergo surgery at the time of their clinic appointment within the vitreoretinal service. In addition to standard care, the study participants will undergo measurements of distortion (using a D-chart, duration 5-10 minutes) and fill in a quality of life questionnaire. These measurements will be taken before the operation and at six and twelve months following the operation.

The aims of the study are:

• To investigate the sustained effect of epiretinal membrane surgery on distortion (using D-chart), visual acuity and vision-related quality of life (using NEI VFQ-25 questionnaire)
• To determine the relationship between pre-operative distortion score and post-operative vision-related quality of life score following ERM surgery

Our study will have a larger number of participants with a longer period of follow up (52 weeks) than comparable studies. It will be the first epiretinal membrane study that measures distortion using the D-chart, which we believe to be superior to existing tests (such as the M-chart) which have been used in similar studies.

Inclusion Criteria:

1. Idiopathic epiretinal membrane
2. Patients undergoing vitrectomy and gas surgery, under local or general anaesthetic
3. Able to give informed consent
4. 18 years old and over

Exclusion Criteria:

1. Epiretinal membrane secondary to retinal detachment, uveitis or retinal vascular disease
2. Previous vitreoretinal surgery
3. Pre-existing ophthalmic condition which limits the patient's visual acuity (Documented BCVA 6/36 or worse)
4. Pre-existing ophthalmic conditions which cause metamorphopsia (exudative ARMD, central serous retinopathy)
5. VA < 6/60

Patients with epiretinal membranes attending the vitreoretinal clinic at the Tennent Institute of Ophthalmology in Glasgow, UK, and meeting the inclusion criteria.