title: Interocular symmetry of the peripapillary choroidal thickness and retinal nerve fibre layer thickness in healthy adults with isometropia.
abstract: BACKGROUND
  The aim of this study was to determine the interocular differences in the peripapillary retinal nerve fibre layer (RNFL), peripapillary choroidal thickness (PCT) and subfoveal choroidal thickness (SFCT) in healthy adults with isometropia, using enhanced depth imaging optical coherence tomography (EDI SD-OCT).
  
  
  METHODS
  One hundred healthy Chinese adults with spherical equivalents of ≤ ±3 dioptres and interocular differences of <0.5 dioptres were prospectively enrolled in this study. They underwent RNFL and PCT measurements via EDI SD-OCT, with a 3.4 mm scan circle centred on the optic nerve head. Subfoveal choroidal thickness (SFCT) measurements were also taken with a horizontal line scan centred on the macula. Right and left eyes were compared by a paired t-test, and the interocular differences were calculated. The agreement and correlations of the RNFLs, PCTs and SFCTs between the right and left eyes were analysed.
  
  
  RESULTS
  Eighty-six subjects (172 eyes) were included in the final analysis, consisting of 44 (51.6 %) males and 42 (48.8 %) females; 55 (63.9 %) had emmetropia and 33 (36.1 %) had ametropia. The RNFL was statistically significantly thicker in the right eyes when compared to the left eyes in the temporal quadrant, and thinner on average in the nasal superior quadrant (p < 0.05). However, the differences in the choroidal thicknesses in all of the quadrants between the right and left eyes were not statistically significant. The tolerance limits of the average RNFL were -21.1 μm and 7.1 μm, and the mean and standard deviation of the interocular difference in the average PCT was -2.2 ± 24.2 μm. The RNFLs and PCTs in all of the locations in the right eyes were significantly correlated with those in the left eyes. However, no significant associations between the age, sex, interocular asymmetry of spherical the equivalent or interocular differences in the RNFL and PCT were detected.
  
  
  CONCLUSIONS
  The PCT did not differ significantly between the right and left eyes, although interocular asymmetry of the RNFL existed in this Chinese population with isometropia.
authors.affiliation: Department of Ophthalmology, Chinese PLA General Hospital, Fuxing Road NO.28, Beijing, Haidian District, China.|Department of Ophthalmology, Shanxi Grand Hospital, Taiyuan, China.
authors.forename: Mo
authors.initials: M
authors.lastname: Yang
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology, Chinese PLA General Hospital, Fuxing Road NO.28, Beijing, Haidian District, China.|Department of Neurology, Chinese PLA General Hospital, Beijing, China.
authors.forename: Quangang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology, Chinese PLA General Hospital, Fuxing Road NO.28, Beijing, Haidian District, China.
authors.forename: Shaoying
authors.initials: S
authors.lastname: Tan
authors.affiliation: Department of Ophthalmology, Chinese PLA General Hospital, Fuxing Road NO.28, Beijing, Haidian District, China. weishihui706@hotmail.com.
authors.forename: Shihui
authors.initials: S
authors.lastname: Wei
mesh_terms: D000328:Adult; D000368:Aged; D002829:Choroid / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D011446:Prospective Studies; D012030:Refractive Errors / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods; D055815:Young Adult
keywords: Choroidalthickness; EDI SD-OCT; Emmetropia; RNFL; Symmetry