Determinants of normal retinal nerve fiber layer thickness measured by Stratus OCT.
OBJECTIVE
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).


METHODS
Cross-sectional observational study.


METHODS
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.


METHODS
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 microm (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 microm (95% confidence interval [CI], 1.2-2.8). For every 1-mm-greater axial length, mean RNFL thickness measured thinner by approximately 2.2 microm (95% CI, 1.1-3.4). For every increase in square millimeter of optic disc area, mean RNFL thickness increased by approximately 3.3 microm (95% CI, 0.6-5.6). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (98.1+/-10.9 microm) slightly thinner than those of Hispanics (103.7+/-11.6 microm; P = 0.022) or Asians (105.8+/-9.2 microm; 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.
Budenz
Donald L
DL
Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA. dbudenz@med.miami.edu
Anderson
Douglas R
DR
Varma
Rohit
R
Schuman
Joel
J
Cantor
Louis
L
Savell
Jonathan
J
Greenfield
David S
DS
Patella
Vincent Michael
VM
Quigley
Harry A
HA
Tielsch
James
J
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005123:Eye / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers; D009898:Optic Disk / Q000033:anatomy & histology*; D012016:Reference Values; D012030:Refractive Errors / Q000150:complications; D012165:Retinal Ganglion Cells / Q000166:cytology*; D012737:Sex Factors; D041623:Tomography, Optical Coherence / Q000379:methods*