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Camila Zangalli, Alexandre Soares Castro Reis, Jayme R Vianna, Jose Paulo C Vasconcellos, Vital P Costa; Interocular asymmetry of minimum rim width and retinal nerve fiber layer thickness in healthy Brazilian individuals. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4007.
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© ARVO (1962-2015); The Authors (2016-present)
To determine interocular differences of retinal nerve fiber layer thickness (RNFLT) and minimum rim width (MRW), acquired relative to the fovea to Bruch’s membrane opening center axis (FoBMO), in healthy Brazilian individuals.
Both eyes of 213 healthy individuals were included in this prospective, cross-sectional study. All individuals had normal clinical examination and visual fields. Twenty four radial scans centered on the Bruch's membrane opening (BMO) and a peripapillary circle scan (3.5-mm nominal scan diameter) were acquired relative to the FoBMO axis, with the Spectralis SDOCT. Global and sectorial interocular RNFLT and MRW differences (larger minus smaller) and percentage interocular RNFLT and MRW differences (larger minus smaller divided by the larger value) were calculated. The effect of age, axial length and BMO area asymmetry on the parameters’ asymmetry was evaluated. Finally, we evaluated the relationship between the RNFLT asymmetry and MRW asymmetry, after adjustment for BMO area.
The mean age of participants was 43.92 (± 13.99) years and 134 participants (63%) were female. The 95th tolerance limits for interocular MRW and RNFLT global differences were 48.9 µm and 9 µm, respectively. The global and sectorial interocular asymmetry percentile distributions are shown in Table 1 and Figure 1. RNFLT asymmetry was positively correlated with BMO area asymmetry (ß=6.0 µm/mm2, R2=0.08, p<0.01), whereas MRW asymmetry was negatively correlated with BMO area asymmetry (ß= -34.6 µm/mm2, R2=0.06, P<0.01). After adjustment for BMO area, neither MRW nor RNFLT asymmetry were correlated with age (ß= -0.0 µm/year, P=0.07; ß= -0.0 µm/year, P=0.21, respectively) or AXL asymmetry (ß= -3.7 µm/mm, P=0.75; ß= -0.7 µm/mm, P=0.69, respectively). MRW asymmetry was positively correlated with RNFLT asymmetry (ß= 2.5 µm/µm, R2=0.15, P<0.01).
Our results suggest that global MRW and RNFLT interocular differences exceeding 49 µm and 9 µm, respectively, suggest statistically abnormal asymmetry, which may suggest early structural change. RNFLT asymmetry is correlated with MRW asymmetry, and both are correlated with BMO area asymmetry.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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