title: Comparison of refractive error in phacovitrectomy for epiretinal membrane using ultrasound and partial coherence interferometry.
abstract: OBJECTIVE
  To compare the postoperative refractive error (RE) using A-scan ultrasound (US) and partial coherence interferometry (PCI) after phacovitrectomy for idiopathic epiretinal membrane (iERM) and cataract.
  
  
  METHODS
  Eighty-eight participants (88 eyes) with iERM and cataracts underwent phacovitrectomies with internal limiting membrane removal. Postoperative RE was the main outcome measured, calculated by subtracting intended spherical equivalent (SE) from 6-month postoperative SE. Secondary outcomes included axial length (AL) measured by 2 methods, change in best-corrected visual acuity (BCVA), and change in central subfield thickness (CSFT).
  
  
  RESULTS
  Mean postoperative RE using US showed greater myopic shift compared with that using PCI (-0.569 ± 0.571 D vs -0.169 ± 0.415 D, respectively, p&lt;0.001). The 6-month postoperative RE was within ±0.50 D in 43.2% (38/88) using US vs 84.1% (74/88) using PCI and within ±1.00 D in 84.1% (74/88) using US vs 96.6% (85/88) using PCI. Mean AL measured by US was shorter than that measured by PCI (23.50 ± 1.27 mm vs 23.58 ± 1.30 mm, respectively, p&lt;0.001). Postsurgery, BCVA improved from 0.374 ± 0.264 logMAR to 0.144 ± 0.124 logMAR (p&lt;0.001), and CSFT decreased from 449.2 ± 78.5 µm to 378.2 ± 47.0 µm (p&lt;0.001). The BCVA improvement significantly correlated with decreased CSFT (R = 0.268, p = 0.011).
  
  
  CONCLUSIONS
  Estimation of intraocular lens power for phacovitrectomies for iERM and cataracts is more accurate when assessed by PCI than by US.
authors.affiliation: Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul - Korea.
authors.forename: Eui C
authors.initials: EC
authors.lastname: Kang
authors.affiliation: Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul - Korea.
authors.forename: Kyou Ho
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul - Korea.
authors.forename: Hyoung J
authors.initials: HJ
authors.lastname: Koh