title: Macular ganglion cell imaging study: interocular symmetry of ganglion cell-inner plexiform layer thickness in normal healthy eyes.
abstract: OBJECTIVE
  To determine cutoffs for interocular differences in ganglion cell-inner plexiform layer thickness in normal healthy eyes and to evaluate the diagnostic performance of these values for differentiating between normal subjects and glaucoma patients.
  
  
  METHODS
  Observational, cross-sectional study.
  
  
  METHODS
  Macular and optic disc scanning were performed in 275 normal subjects, 58 glaucoma patients, and 58 normal controls by high-definition optical coherence tomography. The ganglion cell-inner plexiform layer thickness was calculated, and the normal ranges of the interocular differences were determined as 2.5th and 97.5th percentiles. The signed and absolute interocular differences were compared between normal subjects and glaucoma patients.
  
  
  RESULTS
  The mean ± standard deviation interocular difference in the average ganglion cell-inner plexiform layer thickness thickness was 0.10 ± 2.31 μm, which was not statistically significant (P = .466). The 2.5th and 97.5th percentiles of the interocular difference were -4.10 μm and +5.00 μm, respectively. On multiple regression analysis, the interocular difference in axial length was correlated with the interocular difference in average ganglion cell-inner plexiform layer thickness thickness (β = 2.044, P = .003). The signed and absolute interocular differences in ganglion cell-inner plexiform layer thickness were higher in glaucoma patients than in normal subjects (all P < .001). Sensitivity and specificity of absolute interocular differences ranged from 25.9% to 51.7% and from 93.1% to 100.0%, respectively.
  
  
  CONCLUSIONS
  Ganglion cell-inner plexiform layer thickness shows significant interocular symmetry in normal subjects. An absolute interocular difference exceeding normal limits may be indicative of glaucoma.
authors.affiliation: Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea; Department of Ophthalmology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Sang-Yoon
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea; Department of Ophthalmology, Seoul National University College of Medicine, Seoul, South Korea. Electronic address: neuroprotect@gmail.com.
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Jeoung
authors.affiliation: Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea; Department of Ophthalmology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Ki Ho
authors.initials: KH
authors.lastname: Park
authors.affiliation: Department of Ophthalmology, Seoul National University Hospital, Seoul, South Korea; Department of Ophthalmology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Dong Myung
authors.initials: DM
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005901:Glaucoma / Q000175:diagnosis; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology* / Q000473:pathology; D009901:Optic Nerve Diseases / Q000175:diagnosis; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000473:pathology; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence; D055815:Young Adult