title: Changes in choroidal thickness after vitrectomy for epiretinal membrane combined with vitreomacular traction.
abstract: OBJECTIVE
  To compare choroidal thickness after vitrectomy between epiretinal membrane (ERM) with and without vitreomacular traction (VMT).
  
  
  METHODS
  In this retrospective study, 228 consecutive participants with ERM who underwent vitrectomy were categorized into two groups according to the presence of VMT on spectral domain-optical coherence tomography: VMT group (ERM with VMT, n = 21) and non-VMT group (ERM without VMT, n = 207). The primary outcome was the mean subfoveal choroidal thickness (SFCT) at baseline, and at 3 and 6 months postsurgery.
  
  
  RESULTS
  At baseline, the prevalence of VMT in eyes with ERM was 9.6% (21/228), and mean SFCT was greater in the VMT than in the non-VMT group (270.3 ± 93.4 vs. 223.7 ± 82.1 μm; p = 0.015). After surgery, mean SFCT decreased in the VMT group (241.7 ± 92.3 μm at 3 months and 228.8 ± 86.4 μm at 6 months; p < 0.001), but remained unchanged in the non-VMT group (223.6 ± 78.9 μm at 3 months and 223.3 ± 82.6 μm at 6 months; p = 0.696). There were no differences in mean SFCT between the groups at 3 and 6 months after surgery (p = 0.339 and p = 0.772, respectively).
  
  
  CONCLUSIONS
  Choroidal thickness was greater in ERM eyes with than without VMT possibly due to direct anteroposterior traction on the retina and choroid, increased vascular endothelial growth factor associated with stress on retinal pigment epithelial cells and inflammation. After vitrectomy, mean SFCT reduced in the eyes with VMT, but not in those without VMT.
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eui Chun
authors.initials: EC
authors.lastname: Kang
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Kyou Ho
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hyoung Jun
authors.initials: HJ
authors.lastname: Koh
mesh_terms: D000368:Aged; D002829:Choroid / Q000473:pathology*; D019773:Epiretinal Membrane / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012189:Retrospective Studies; D013997:Time Factors; D041623:Tomography, Optical Coherence / Q000379:methods*; D016896:Treatment Outcome; D014821:Vitrectomy / Q000379:methods*
keywords: choroidal thickness; epiretinal membrane; vitrectomy; vitreomacular traction