title: The influence of posterior capsular opacification removal on anterior segment birefringence parameters as measured by scanning laser polarimetry.
abstract: OBJECTIVE
  To determine the effect of posterior capsular opacification (PCO) removal on anterior segment birefringence (ASB) and its influence on peripapillary retinal nerve fibre layer (RNFL) retardation measurements obtained by means of scanning laser polarimetry.
  
  
  METHODS
  In this prospective interventional study, scanning laser polarimetry was performed using GDx variable corneal compensation on 26 eyes of 26 patients who developed clinically significant PCO (after uncomplicated cataract surgery and with no other ocular pathology) both before and between 1 and 4 weeks after Nd:YAG capsulotomy. Best-corrected visual acuity (BCVA), intraocular pressure, corneal polarization axis (CPA), corneal polarization magnitude (CPM) were compared using the Student t-test and Wilcoxon signed ranks test. Spearman correlations between changes (differences between values after and before capsulotomy) in the CPA, CPM, BCVA and RNFL data were also performed.
  
  
  RESULTS
  PCO removal is associated with a shift in CPA (from 10.86 to 15.03 degrees, P = 0.004) and CPM (from 28.54 to 37.92 nm, P = 0.004). Significant correlations were found between changes in the parameters of ASB and BCVA. Furthermore, RNFL measurements (nerve fibre indicator, temporal-superior-nasal-inferior-temporal average and superior average) were also well related to the CPA and CPM shifts.
  
  
  CONCLUSIONS
  PCO induces an inaccurate compensation of ASB which affects RNFL assessment. Thus, it is necessary to recompensate ASB after posterior capsulotomy.
authors.affiliation: Ophthalmology Research Unit Santiago Grisolia, Department of Ophthalmology, Doctor Peset University Hospital, Valencia, Spain. josegarciam@yahoo.com
authors.forename: Jose J
authors.initials: JJ
authors.lastname: Garcia-Medina
authors.forename: Manuel
authors.initials: M
authors.lastname: Garcia-Medina
authors.forename: Vicente C
authors.initials: VC
authors.lastname: Zanon-Moreno
authors.forename: Roberto
authors.initials: R
authors.lastname: Gallego-Pinazo
authors.forename: Sheila
authors.initials: S
authors.lastname: Pons-Vazquez
authors.forename: Samuel
authors.initials: S
authors.lastname: Gonzalez-Ocampo
authors.forename: María D
authors.initials: MD
authors.lastname: Pinazo-Durán
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001718:Birefringence; D002386:Cataract / Q000209:etiology / Q000628:therapy; D003315:Cornea / Q000502:physiology*; D005260:Female; D006801:Humans; D053685:Laser Therapy; D007834:Lasers; D007903:Lens Capsule, Crystalline / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D011183:Postoperative Complications; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D014792:Visual Acuity