Interocular Asymmetry of Minimum Rim Width and Retinal Nerve Fiber Layer Thickness in Healthy Brazilian Individuals

• Published in: Journal of glaucoma Vol. 27; no. 12; pp. 1136 - 1141
• Main Authors: Zangalli, Camila e Silva, Reis, Alexandre S C, Vianna, Jayme R, Vasconcellos, José P C, Costa, Vital P
• Format: Journal Article
• Language: English
• Published: United States Copyright Wolters Kluwer Health, Inc. All rights reserved 01-12-2018
• ISSN: 1057-0829; 1536-481X
• DOI: 10.1097/IJG.0000000000001078

PURPOSE:To determine interocular differences in Bruch’s membrane opening minimum rim width (BMO-MRW) and retinal nerve fiber layer thickness (RNFLT) in healthy Brazilian individuals.
MATERIALS AND METHODS:Both eyes of 220 healthy individuals were included in this observational, cross-sectional study. All individuals had normal clinical examination and visual fields. Global and sectorial interocular BMO-MRW and RNFLT differences, acquired and regionalized relative to the fovea to BMO center (FoBMO) axis, were calculated. The effect of age, axial length, and BMO area asymmetry on the parameters’ asymmetry was evaluated.
RESULTS:The 95th limits for interocular BMO-MRW and RNFLT global differences were 49 and 9 μm, respectively. BMO-MRW asymmetry was negatively correlated (β=−33.87 μm/mm, R=0.06, P<0.001), whereas RNFLT asymmetry was positively correlated (β= 6.13 μm/mm, R=0.09, P<0.001) with BMO area asymmetry. Neither BMO-MRW nor RNFLT asymmetries were correlated with axial length asymmetry (β=−16.90 μm/mm, R=0.00, P=0.15; β=−1.18 μm/mm, R=0.00, P=0.52, respectively). Similarly, BMO-MRW and RNFLT asymmetries were not correlated with age (β=0.17 μm/y, R=0.01, P=0.22; β=0.0 μm/y, R=0.00, P=0.19, respectively).
CONCLUSIONS:Our results suggest that global BMO-MRW and RNFLT interocular differences exceeding 49 and 9 μm, respectively, may indicate statistically abnormal asymmetry, which may suggest early structural damage. Asymmetry in BMO area should be accounted for when considering interocular asymmetry in BMO-MRW and RNFLT.