Determinants of Normal Retinal Nerve Fiber Layer Thickness Measured by Stratus OCT
Received 29 March 2006; accepted 14 August 2006. published online 08 January 2007.
Refers to erratum:
Determinants of Normal Retinal Nerve Fiber Layer Thickness Measured by the Stratus OCT
Ophthalmology
March 2008 (Vol. 115, Issue 3, Page 472) Full Text |
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Purpose
To determine the effects of age, optic disc area, ethnicity, eye, gender, and axial length on the retinal nerve fiber layer (RNFL) in the normal human eye as measured by Stratus OCT (optical coherence tomography).
Design
Cross-sectional observational study.
Participants
Three hundred twenty-eight normal subjects 18 to 85 years old.
Methods
Peripapillary Fast RNFL scans performed by Stratus OCT with a nominal diameter of 3.46 mm centered on the optic disc were performed on one randomly selected eye of each subject.
Main Outcome Measures
Linear regression analysis of the effects of age, ethnicity, gender, eye, axial length, and optic disc area on peripapillary RNFL thickness.
Results
The mean RNFL thickness for the entire population was 100.1 μm (standard deviation, 11.6). Thinner RNFL measurements were associated with older age (P<0.001); being Caucasian, versus being either Hispanic or Asian (P = 0.006); greater axial length (P<0.001); or smaller optic disc area (P = 0.010). For every decade of increased age, mean RNFL thickness measured thinner by approximately 2.0 μm (95% confidence interval [CI], 1.2–2.8). For every 1-mm-greater axial length, mean RNFL thickness measured thinner by approximately 2.2 μm (95% CI, 1.1–3.4). For every increase in square millimeter of optic disc area, mean RNFL thickness increased by approximately 3.3 μm (95% CI, 0.6–5.6). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (98.1±10.9 μm) slightly thinner than those of Hispanics (103.7±11.6 μm; P = 0.022) or Asians (105.8±9.2 μm; P = 0.043). There was no relationship between RNFL thickness and eye or gender.
Conclusions
Retinal nerve fiber layer thickness, as measured by Stratus OCT, varies significantly with age, ethnicity, axial length, and optic disc area. These variables may need to be taken into account when evaluating patients for diagnosis and follow-up of glaucoma, particularly at the lower boundary of the normal range. Due to the relatively small numbers of subjects of Asian and African descent in the normative database, conclusions regarding the effect of ethnicity should be interpreted with caution.
1Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida.
2Doheny Eye Institute, Department of Ophthalmology, University of Southern California, Los Angeles, California.
7Wilmer Institute, Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, Maryland.
8Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Correspondence to Donald L. Budenz, MD, MPH, Bascom Palmer Eye Institute, 900 NW 17th Street, Miami, FL 33136.
Manuscript no. 2006-381.
Collection of the normative database used in this study was supported by a grant from Carl Zeiss Meditec. The study also was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York.
a Dr Schuman is currently at the Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
b Dr Schuman is a co–patent holder of the optical coherence tomography technology.
c Dr Patella is an employee of Carl Zeiss Meditec.
d Dr Quigley is a consultant for Carl Zeiss Meditec.
ABSTRACT