title: Assessment of axial length measurements in mouse eyes.
abstract: OBJECTIVE
  To compare measurements of murine ocular axial lengths (ALs) made with 780 nm partial coherence interferometry (PCI) and 1310 nm spectral domain-optical coherence tomography (SD-OCT).
  
  
  METHODS
  AL was measured at postnatal day (P) 58 in C57BL/6J mice. Repeated AL measurements were taken using a custom-made 780 nm PCI and a commercial 1310 nm SD-OCT. Intra- and interuser variability was assessed along the central optical axis and 2-degree off-axes angles with the SD-OCT. Data were collected and analyzed using Cronbach alpha (α), Bland-Altman coefficient of repeatability, agreement plots, and intraclass correlation coefficients (ICC).
  
  
  RESULTS
  AL measurements agreed well between the two instruments (3.262 ± 0.042 mm for PCI; 3.264 ± 0.047 mm for SD-OCT; n = 20 eyes). The ICC for PCI compared with SD-OCT was 0.92, confirming high agreement between the two instruments. Intrauser ICC for the PCI and SD-OCT were 0.814 and 0.995, respectively. Similarly, interuser ICC for PCI and SD-OCT were 0.970 and 0.943, respectively. Using SD-OCT, a 2-degree misalignment of the eye along the horizontal meridian produced mean differences in AL of -0.002 ± 0.017 mm relative to the centrally aligned images, whereas similar misalignment along the vertical meridian created 0.005 ± 0.018 mm differences in AL measurements.
  
  
  CONCLUSIONS
  AL measurements from the 780 nm PCI and 1310 nm SD-OCT correlate well. Multiple statistical indices indicate that both instruments have good precision and agreement for measuring murine ocular AL in vivo. Although the vertical meridian had the greater variability in AL in the small mouse eye; 2-degree off-axes differences were within the SD of centrally aligned AL.
authors.affiliation: Department of Ophthalmology, School of Medicine, Emory University, Atlanta, Georgia, USA.
authors.forename: Han na
authors.initials: Hn
authors.lastname: Park
authors.forename: Yureeda
authors.initials: Y
authors.lastname: Qazi
authors.forename: Christopher
authors.initials: C
authors.lastname: Tan
authors.forename: Seema B
authors.initials: SB
authors.lastname: Jabbar
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.forename: Gregor
authors.initials: G
authors.lastname: Schmid
authors.forename: Machelle T
authors.initials: MT
authors.lastname: Pardue
mesh_terms: D000818:Animals; D058452:Axial Length, Eye / Q000033:anatomy & histology*; D004195:Disease Models, Animal; D051379:Mice; D008810:Mice, Inbred C57BL; D009216:Myopia / Q000175:diagnosis; D015588:Observer Variation; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000379:methods*