Abstract
Purpose: :
To determine if normal retinal nerve fiber layer (RNFL) thickness measurements by spectral domain optical coherence tomography (SD-OCT) vary by age, gender, and race.
Methods: :
The peripapillary RNFL thickness was determined by SD-OCT in an observational cross-sectional study. One randomly selected eye per subject was used for study analysis. RNFL thickness values were measured along a 3.4-mm circular scan diameter. The RNFL thickness values were divided into 4 quadrants. The superior and inferior quadrants were further divided into temporal and nasal sectors. Statistical associations of RNFL values with age were examined using Pearson correlation coefficient. Difference in RNFL thickness was examined using the student t-test with respect to gender and race.
Results: :
The study population consisted of 200 healthy patients (age range: 9 to 86 years) and was comprised of 34% (68/200) male subjects, 67.5% Caucasians, 13.5% African-Americans, 6.5% Hispanics, 9% Asians, and 3.5% other races. Mean RNFL thickness was 94.1 +/-12 microns for all subjects. The mean RNFL thickness values were 120 +/-20.5, 112 +/-18.5, 72.5 +/-16, and 71 +/-14 microns for the inferior, superior, nasal, and temporal quadrants, respectively. Average RNFL thickness significantly decreased with age (r= -0.16, p= 0.024). Mean RNFL thickness values were similar for females (95 +/- 13 microns) and males (92+/- 11 microns) (p = 0.09). Mean RNFL thickness was 92.7 +/- 12 microns and 97+/- 12 microns for Caucasians and non-Caucasians, respectively. Mean RNFL thickness values were significantly thicker in non-Caucasians (p = 0.02).
Conclusions: :
The thickest RNFL was noted in the inferior quadrant, followed by the superior, the nasal and temporal quadrants. Thinner RNFL measurements were associated with older age and Caucasian race. There was no significant difference in RNFL thickness based on gender. SD-OCT analysis of RNFL in normal subjects showed similar results to the reported literature with the time domain OCT.
Keywords: nerve fiber layer • imaging/image analysis: clinical