Título

INTEROCULAR ASYMMETRY OF MINIMUM RIM WIDTH AND RETINAL NERVE FIBER LAYER THICKNESS IN HEALTHY BRAZILIAN INDIVIDUALS

Objetivo

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.

Método

Both eyes of 213 healthy individuals were included in this prospective, cross-sectional study. Subjects had normal clinical examinations and visual fields. ONH (24 radial scans centered on BMO) and peripapillary circle scans (3.5-mm diameter) were acquired relative to the FoBMO axis, with the Spectralis SD OCT. Global and sectorial interocular RNFLT and MRW differences (larger minus smaller value) and percentage interocular RNFLT and MRW differences (larger minus smaller value 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.

Resultado

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 RNFLT asymmetry was positively correlated with BMO area asymmetry (ß=6.04 μm/mm2, R2=0.08, p<0.01), whereas MRW asymmetry was negatively correlated with BMO area asymmetry (ß= -34.61 μm/mm2, R2=0.06, P<0.01). After adjustment for BMO area, neither MRW nor RNFLT asymmetry were correlated with age (ß= -0.03 μm/year, P=0.07; ß= -0.00 μm/year, P=0.21, respectively) and AXL asymmetry (ß= -3.69 μm/mm, P=0.75; ß= -0.71 μm/mm, P=0.69, respectively). MRW asymmetry was positively correlated with RNFLT asymmetry (ß= 2.56 μm/μm, R2=0.15, P<0.01).

Conclusão

Our results suggest that global RNFLT and MRW interocular differences should not exceed 48.91 μm and 9 μm, respectively, in healthy Brazilian individuals. RNFLT asymmetry is correlated with MRW asymmetry, and both are correlated with BMO area asymmetry.