title: The occurrence and features of the atypical birefringence pattern in scanning laser polarimetry using GD × VCC in healthy children and its impact on the retinal nerve fiber layer thickness values.
abstract: OBJECTIVE
  To investigate the occurrence and features of the atypical birefringence pattern (ABP) images in scanning laser polarimetry with variable corneal compensation (GD×VCC) in healthy children and to assess their impact on the values of the retinal nerve fiber layer (RNFL) thickness.
  
  
  METHODS
  GD×VCC scans in 120 healthy white school-aged children with mean age ± standard deviation (SD) 12.85 ± 3.0 years were evaluated using typical scan score (TSS) calculation and by subjective grading of the scans. Statistical analysis including the impact of ABP on the RNFL thickness in GD × VCC Temporal-Superior-Nasal-Inferior-Temporal (TSNIT) parameters was done.
  
  
  RESULTS
  The ABP was found in 18 out of 120 patients (15%) at cut-off value of TSS <80. Subjective evaluation of the scans raised the frequency of ABP to 20% of patients. The mean ± SD values of TSNIT Average, Superior Average, and Inferior Average in 26 eyes with ABP versus 214 eyes with normal birefringence pattern were 66.99 ± 7.29 μm versus 58.00 ± 6.22 μm (P = 7.2E to -11), 78.43 ± 9.27 μm versus 72.33 ± 8.72 μm (P = 0.001) and 80.87 ± 12.01 μm versus 70.00 ± 10.20 μm (P = 0.000001), respectively. The same comparison in TSNIT SD showed minimal difference and was 25.42 ± 5.84 μm versus 26.41 ± 4.81 μm (P = 0.41).
  
  
  CONCLUSIONS
  The occurrence of ABP in children is not rare and may significantly distort the measured values of the RNFL thickness in TSNIT parameters using GD × VCC.
authors.affiliation: Department of Ophthalmology for Children and Adults, Charles University in Prague, 2nd Faculty of Medicine, Prague, Czech Republic. ales.filous@lfmotol.cuni.cz
authors.forename: Ales
authors.initials: A
authors.lastname: Filous
authors.forename: Martin
authors.initials: M
authors.lastname: Hlozánek
authors.forename: Marie
authors.initials: M
authors.lastname: Hladíková
mesh_terms: D016477:Artifacts; D001718:Birefringence; D002648:Child; D003315:Cornea / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology*; D012029:Refraction, Ocular / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000166:cytology*; D057109:Scanning Laser Polarimetry; D012737:Sex Factors; D014065:Tonometry, Ocular