title: The study of retinal nerve fiber layer thickness of normal eyes using scanning laser polarimetry.
abstract: OBJECTIVE
  To evaluate retinal nerve fiber layer (RNFL) thickness measurements in local normal Chinese subjects of different age groups and analyse the correlation of RNFL thickness with age using scanning laser polarimetry (SLP, GDxVCC). To assess the reproducibility of RNFL thickness measurement with GDxVCC.
  
  
  METHODS
  The RNFL thickness of 67 normal subjects (123 eyes) were measured by GDxVCC. The average TSNIT parameters were calculated. The differences of RNFL thickness between sex, right and left eyes, superior and inferior were compared. The relationship between RNFL thickness and age was analyzed with correlation analysis and linear regression analysis. The intraclass correlation coefficients (ICC) of three images in every eye were calculated.
  
  
  RESULTS
  The average peripapillary RNFL thickness at the superior, inferior and whole ellipse regions in 123 eyes of 67 normal subjects were (70.30 +/- 6.76) microm, (67.35 +/- 6.77) microm and (56.87 +/- 4.53) microm, respectively. The average TNSIT standard deviation was 23.68 +/- 4.61 and the average inter-eye symmetric value was 0.86 +/- 0.11. There were significant difference of RNFL thickness between superior and inferior (t = 4.952, P < 0.001). There were significant difference of inferior RNFL thickness and TNSIT standard deviation between right and left eyes (P = 0.005 and 0.002), while not significant difference of superior RNFL thickness and whole mean RNFL thickness between right and left eye (P = 0.086 and 0.529). There was no significant difference in TSNIT parameters between different genders. There was a slight negative correlation average RNFL thickness in superior sector with age (decreased approximately 0.15 microns per year, P = 0.047) in the subjects aged below 60 years old. The ICC values of RNFL thickness were > 0.8 in superior, inferior and global.
  
  
  CONCLUSIONS
  The RNFL thickness can be measured accurately by GDxVCC and the reproducibility of RNFL thickness measurement by GDxVCC is good. There was a slight negative correlation between average RNFL thickness in superior with age. More researches on the effects of age on RNFL thickness by GDxVCC are needed.
authors.affiliation: Key Laboratory of Ophthalmology of the Ministry of Education and Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Liu
authors.forename: Jingjing
authors.initials: J
authors.lastname: Huang
authors.forename: Jian
authors.initials: J
authors.lastname: Ge
authors.forename: Yunlan
authors.initials: Y
authors.lastname: Ling
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zheng
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D012160:Retina / Q000033:anatomy & histology*; D012165:Retinal Ganglion Cells