Refractive Consequences of Epiretinal Membrane Surgery
Condition: Epiretinal Membrane
MeSH terms: Epiretinal Membrane
Study type: Interventional

Summary: 
      Epiretinal membrane is treated with vitrectomy and peeling. Afterwards cataract is usually
      developed, which requires a cataract surgery.

      The aim of this study is to investigate the refractive consequences of surgery for Epiretinal
      membrane and cataract.

      Investigators investigate the sequence of surgery in patients having surgery for Epiretinal
      membrane and cataract in a prospective clinically randomized intervention trial. Patients are
      randomized to 1) start with vitrectomy, 2) start with cataract surgery, 3) combined surgery.
      Investigators want to find the sequence of surgery that gives the most optimal refractive
      result, the most stabile intraocular lens, and the minimal loss of corneal endothelial cells.
    

Detailed description: 
      Aim: To evaluate the impact of the sequence of surgery on the Refractive Error and the
      Corneal Endothelial Count in phakic individuals undergoing surgery for Epiretinal membrane.

      Study design: Prospective interventional randomized clinical trial. Primary outcome:
      Refractive error (i.e. Intraocular lens power prediction error), Corneal Endothelial Count,
      and postoperative macular oedema.

      Secondary outcome: Changes in axial length, anterior chamber depth and keratometry; the
      accuracy of formulas used to calculate the power of the intraocular lens.

      Study population:

      Identification of participants: Individuals referred to the Macular Surgery Clinic, Surgical
      Retina Team, Department of Ophthalmology, Glostrup University Hospital, Copenhagen, Denmark.
      The individuals should be signed up for surgery because of Epiretinal membrane at the clinic.

      Method:

      Individuals are randomized to the possible sequences of surgery (i.e. start with cataract
      surgery, start with vitrectomy, or combined surgery). Based on an estimated clinical relevant
      refractive prediction error of 0,50 diopter and a standard deviation of 0,50 diopter, a
      number of 20 individuals in each of the three groups are needed to obtain a power of 80 % and
      a type 1 error of 5 %. Total number of individuals is thus 60.

      Clinical examinations are performed preoperatively and 2 weeks after each surgery (cataract
      surgery, vitrectomy or combined surgery), and 3 and 12 months postoperatively. The
      examinations include best corrected distance visual acuity, autorefraction/keratometry
      (Retinomax®, Nikon, Tokyo, Japan), subjective refraction, slit-lamp examination, fundoscopy
      and tonometry. Biometry by IOLMaster (Carl Zeiss, Meditec AG, Germany), intraocular power
      calculation with the SRK/T formula. Pentacam Scheimpflug Cornea tomography (Topcon, Tokyo,
      Japan). Corneal Endothelial Count obtained by three images of the central region of the
      corneal endothelium (Topcon SP-3000P, Tokyo, Japan). Heidelberg Optical Coherence Tomography,
      (Heidelberg Engineering, Heidelberg, Germany).

      Sequence of surgery depends on randomization. In all cases a standard phacoemulsification
      (scleral tunnel or clear corneal incision) with in-the-bag intraocular lens implantation. In
      combined surgery, the cataract surgery is performed before vitrectomy during the same
      session. Vitreoretinal procedures include a standard three-port 23 gauge pars plana
      vitrectomy, membrane peeling, and the use of dyes. Cataract surgery is performed by one of
      two experienced surgeons, and vitrectomy is carried out by one experienced surgeon.

      Analysis: A computer database will be created as a fill-in form to record all patient data,
      and a masked statistical analysis of all outcome measures will be performed. Statistical
      analysis will be performed to determine differences in baseline data among the three groups
      (age, sex, visual acuity, keratometry, axial length, anterior chamber depth, Corneal
      Endothelial Count). To identify independent predictors for all outcome measures at different
      follow-up times, multivariate regression analysis is performed. All calculations will be
      performed using SAS software.
    

Intervention name(s): Vitrectomy; Cataract surgery; Combined surgery
Intervention type(s): Procedure; Procedure; Procedure
Intervention description(s): Vitrectomy; Cataract surgery; Combined vitrectomy and cataract surgery at the same time
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment