title: Relationship between supernormal sectors of retinal nerve fibre layer and axial length in normal eyes.
abstract: OBJECTIVE
  To determine the effect of the axial length on the supernormal and false-positive sectors of the peripapillary retinal nerve fibre layer (RNFL) in healthy eyes using the normative database embedded in a spectral domain optical coherence tomographic (SD-OCT) instrument.
  
  
  METHODS
  This was a prospective, observational cross -sectional study. The right eyes of 126 healthy young volunteers were studied. The RNFL thickness was measured by SD-OCT in twelve 30-degree sectors (clock hours) around the optic disc. The sectors whose RNFL thickness was <5% probability level were labelled as false-positive sectors. The sectors >95% probability level were labelled as supernormal sectors. The relationships between the axial length and rates of supernormal and false-positive sectors were investigated.
  
  
  RESULTS
  A longer axial length was significantly associated with an increase in the rates of supernormal thickness in sector 8 (odds ratio, [OR], 1.494; p = 0.010) and sector 10 (OR, 1.529; p = 0.008). The supernormal sectors were mainly located in the temporal region. A longer axial length was significantly associated with a higher rates of false positives in sector 5 (OR, 1.789; p = 0.017), sector 6 (OR, 2.305; p < 0.001) and sector 12 (OR, 2.277; p = 0.035).
  
  
  CONCLUSIONS
  The axial length was significantly related to the rates of supernormal and false-positive sectors even in healthy eyes. These findings indicate that the specificity and sensitivity of SD-OCT will be affected especially in eyes with longer axial lengths.
authors.affiliation: Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Yamashita
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kii
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanaka
authors.forename: Wakako
authors.initials: W
authors.lastname: Yoshinaga
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nakao
authors.forename: Taiji
authors.initials: T
authors.lastname: Sakamoto
mesh_terms: D000328:Adult; D000368:Aged; D058452:Axial Length, Eye / Q000033:anatomy & histology* / Q000473:pathology; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure; D057066:Low Tension Glaucoma / Q000175:diagnosis; D008297:Male; D009216:Myopia / Q000150:complications; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology* / Q000473:pathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000473:pathology; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence; D055815:Young Adult
keywords: RNFL colour code; glaucoma; myopia; pseudo-negative; pseudo-positive; retina