Retinal Nerve Fiber Layer Thickness in Normals Measured by Spectral Domain OCT

PURPOSETo determine normal values for peripapillary retinal nerve fiber layer thickness (RNFL) measured by spectral domain Optical Coherence Tomography (SOCT) in healthy white adults and to examine the relationship of RNFL with age, gender, and clinical variables. PATIENTS AND METHODSThe peripapillary RNFL of 170 healthy patients (96 males and 74 females, age 20 to 78 y) was imaged with a high-resolution SOCT (Spectralis HRA+OCT, Heidelberg Engineering) in an observational cross-sectional study. RNFL thickness was measured around the optic nerve head using 16 automatically averaged, consecutive circular B-scans with 3.4-mm diameter. The automatically segmented RNFL thickness was divided into 32 segments (11.25 degrees each). One randomly selected eye per subject entered the study. RESULTSMean RNFL thickness in the study population was 97.2±9.7 μm. Mean RNFL thickness was significantly negatively correlated with age (r=−0.214, P=0.005), mean RNFL decrease per decade was 1.90 μm. As age dependency was different in different segments, age-correction of RNFL values was made for all segments separately. Age-adjusted RNFL thickness showed a significant correlation with axial length (r=−0.391, P=0.001) and with refractive error (r=0.396, P