To determine the effects of age, sex, and race on the retinal nerve fiber layer (RNFL) in the normal human eye as measured by the spectral domain optical coherence tomography (SD-OCT) Spectralis machine (Heidelberg Engineering).
Peripapillary SD-OCT RNFL thickness measurements were determined in normal subjects seen at a university-based clinic. One randomly selected eye per subject was used for analysis in this cross-sectional study. Multiple regression analysis was applied to assess the effects of age, sex, ethnicity, and mean refractive error on peripapillary RNFL thickness. Results are expressed as means±SD wherever applicable.
The study population consisted of 190 healthy participants from 9 to 86 years of age. Of the 190 participants, 62 (33%) were men, 125 (66%) Caucasians, 26 (14%) African Americans, 14 (7%) Hispanics, 16 (8%) Asians, and 9 (5%) other races. The mean RNFL thickness for the normal population studied was 97.3±9.6 µm. Normal RNFL thickness values follow the ISNT rule with decreasing RNFL thickness values starting from the thickest quadrant inferiorly to the thinnest quadrant temporally: inferior quadrant (126±15.8), superior quadrant (117.2±16.13), nasal quadrant (75±13.9), and temporal quadrant (70.6±10.8 µm). Thinner RNFL measurements were associated with older age (P<0.001); being Caucasian, versus being either Hispanic or Asian (P=0.02 and 0.009, respectively); or being more myopic (P<0.001). For every decade of increased age, mean RNFL thickness measured thinner by approximately 1.5 µm (95% confidence interval, 0.24-0.07). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (96±9.2 µm) slightly thinner than those of Hispanics (102.9±11 µm; P=0.02) or Asians (100.7±8.5 µm; P=0.009). African Americans RNFL values (99.2±10.2 µm) were not significantly different when compared with Caucasians. There was no relationship between RNFL thickness and sex.
The thickest RNFL measurements were found in the inferior quadrant, followed by the superior, nasal, and temporal quadrants (ISNT rule applied to the RNFL). Thinner RNFL measurements were associated with older age and increasing myopia. Caucasians tend to have thinner RNFL values when compared with Hispanics and Asians. SD-OCT analysis of the normal RNFL showed results similar to time domain OCT studies.
*Department of Ophthalmology, Massachusetts Eye and Ear Infirmary
†Harvard Medical School
§Department of Biostatistics, Massachusetts General Hospital and the Harvard Catalyst Program, Boston, MA
‡National Institute for Health Research Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital National Health Services Foundation Trust and University College London Institute of Ophthalmology, London, UK
∥Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
P.A.K. receives funding from the Department of Health’s National Institute for Health Research Biomedical Research Centre for Ophthalmology at Moorfields Eye Hospital and University College London Institute of Ophthalmology. J.F.d.B. has received past research support from Nidek. Also, J.F.d.B. has patents in spectral domain OCT technology. This work was conducted with support from Harvard Catalyst, The Harvard Clinical and Translational Science Center (NIH Award #UL1 RR 025758 and financial contributions from Harvard University and its affiliated academic healthcare centers).
Disclosure: The authors declare no conﬂict of interest.
Reprints: Teresa C. Chen, MD, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA 02114 (e-mail: email@example.com).
Received May 23, 2011
Accepted March 7, 2012