title: Associations between preoperative OCT parameters and visual outcome 3 months postoperatively in patients undergoing vitrectomy for idiopathic epiretinal membrane.
abstract: OBJECTIVE
  To evaluate the effect of preoperative optical coherence tomography (OCT) features on postoperative visual acuity and change in acuity after epiretinal membrane (ERM) surgery.
  
  
  METHODS
  This was a retrospective consecutive case series of patients with symptomatic idiopathic ERMs who underwent vitrectomy and membrane peel between 2008 and 2013. The main outcomes were postoperative letter score and change in letter score. The association between visual acuity and OCT features was estimated using linear regression, correcting for important baseline covariates. OCT features included central foveal thickness, maximum retinal thickness, retinal cross-sectional area, central photoreceptor thickness, central epiretinal membrane, intraretinal cyst presence and location, retinal contraction, foveal ellipsoid zone and external limiting membrane integrity, and pseudoholes.
  
  
  RESULTS
  A total of 79 patients were included in the study. Mean visual acuity was 65.0 letters preoperatively and 68.9 letters postoperatively, with average follow-up of 92 days. Better postoperative visual acuity was associated with the presence of preoperative retinal contraction (6.4 letters P = 0.027) and lower preoperative maximum retinal thickness values (0.34 letters per 10 μm reduction, P = 0.003). Change in visual acuity was associated with preoperative foveal ellipsoid zone attenuation (6.6 letters more improvement when present, P = 0.013). Preoperative pseudoholes were associated with a smaller change in visual acuity (7.4 letters less improvement, P = 0.034). No other OCT features were significant, including intraretinal cyst presence and location. Better preoperative visual acuity was associated with better postoperative acuity, but less change in visual acuity postoperatively.
  
  
  CONCLUSIONS
  Preoperative maximum retinal thickness and retinal contraction were predictive of better postoperative visual acuity, while patients with a preoperative attenuated foveal ellipsoid zone were most likely to improve. Patients with preoperative pseudoholes had slightly worse visual acuity postoperatively. Although better preoperative vision was associated with better postoperative vision, it was associated with less change in visual acuity, emphasizing the importance of careful consideration of the desired surgical goals before advising surgery for ERM.
authors.affiliation: Discipline of Clinical Ophthalmology and Eye Health, The University of Sydney, Sydney, NSW, Australia. mshe8207@uni.sydney.edu.au.|C09- Clinical Ophthalmology and Eye Health, The University of Sydney, GPO Box, 4337, Sydney, NSW, 2001, Australia. mshe8207@uni.sydney.edu.au.
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Sheales
authors.affiliation: Academic Unit of Ophthalmology, The Australian National University, Canberra, ACT, Australia.
authors.forename: Zabrina S
authors.initials: ZS
authors.lastname: Kingston
authors.affiliation: Academic Unit of Ophthalmology, The Australian National University, Canberra, ACT, Australia.
authors.forename: Rohan W
authors.initials: RW
authors.lastname: Essex
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019773:Epiretinal Membrane / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D057234:Preoperative Period; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology*; D014821:Vitrectomy
keywords: Epiretinal membrane; Optical coherence tomography; Surgery; Visual acuity