title: Comparison of methods to quantify posterior capsule opacification using forward and backward light scattering.
abstract: OBJECTIVE
  To compare forward and backward light scattering measurements to quantify posterior capsule opacification (PCO).
  
  
  METHODS
  Vienna Institute for Research in Ocular Surgery, Vienna, Austria.
  
  
  METHODS
  Prospective single-center study.
  
  
  METHODS
  This observational study comprised consecutive patients scheduled for neodymium:YAG (Nd:YAG) capsulotomy for regeneratory PCO. The corrected distance visual acuity (CDVA) using Early Treatment of Diabetic Retinopathy Study charts and the contrast sensitivity under mesopic and photopic conditions using Pelli-Robson charts were assessed before an Nd:YAG capsulotomy was performed. Retroillumination images, rotating Scheimpflug scans (Pentacam HR), and straylight meter (C-Quant) and point-spread function (PSF) meter (Optical Quality Analysis System) measurements were performed before and after Nd:YAG capsulotomy.
  
  
  RESULTS
  The study enrolled 50 eyes of 50 patients. The mean uncorrected distance visual acuity and CDVA were 0.76 logMAR ± 0.18 (SD) and 0.68 ± 0.2 logMAR, respectively. The mean log contrast sensitivity (logCS) was 1.2 ± 0.15 logCS under photopic conditions and 1.05 ± 0.15 logCS under mesopic conditions. There was a moderate correlation between the Scheimpflug score and the Automated Quantification of After-Cataract score (r(2) = 0.37, P=.03). Furthermore, a moderate and close to significant correlation between the PSF meter and the straylight meter was observed (r(2) = 0.32; P=.07).
  
  
  CONCLUSIONS
  Each of the 4 devices assesses different aspects of a patient's quality of vision. Further developments should focus on methods that measure forward scatter of light in a large visual angle and are not too patient or examiner dependent.
authors.affiliation: From Moorfields Eye Hospital NHS Foundation Trust (Hirnschall, Crnej, Gangwani, Findl), London, United Kingdom; the Department of Ophthalmology (Hirnschall, Findl), Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria.
authors.forename: Nino
authors.initials: N
authors.lastname: Hirnschall
authors.affiliation: From Moorfields Eye Hospital NHS Foundation Trust (Hirnschall, Crnej, Gangwani, Findl), London, United Kingdom; the Department of Ophthalmology (Hirnschall, Findl), Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria.
authors.forename: Alja
authors.initials: A
authors.lastname: Crnej
authors.affiliation: From Moorfields Eye Hospital NHS Foundation Trust (Hirnschall, Crnej, Gangwani, Findl), London, United Kingdom; the Department of Ophthalmology (Hirnschall, Findl), Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria.
authors.forename: Vinod
authors.initials: V
authors.lastname: Gangwani
authors.affiliation: From Moorfields Eye Hospital NHS Foundation Trust (Hirnschall, Crnej, Gangwani, Findl), London, United Kingdom; the Department of Ophthalmology (Hirnschall, Findl), Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria. Electronic address: oliver@findl.at.
authors.forename: Oliver
authors.initials: O
authors.lastname: Findl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058442:Capsule Opacification / Q000175:diagnosis* / Q000601:surgery; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use; D019654:Lens Implantation, Intraocular; D008027:Light; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D057852:Posterior Capsule of the Lens / Q000473:pathology*; D064727:Posterior Capsulotomy; D011446:Prospective Studies; D012542:Scattering, Radiation