Effect of Pupillary Dilation on Retinal Nerve Fiber Layer Thickness Measurements Using Optical Coherence Tomography

Purpose: To evaluate the effect of pupillary dilation on retinal nerve fiber layer thickness (RNFL) measurements using optical coherence tomography (OCT-3). Methods: Randomly chosen eyes of healthy individuals were scanned before and after pupillary dilation by two trained operators (R.G.O., R.V.) using OCT-3 (Carl Zeiss Meditec, Inc., Dublin, CA). Fast and regular RNFL (256 A-scans) OCT-3 protocols (software version A 1.1) were used in each scanning session. RNFL thickness measurements before and after dilation were compared. Results: Ten eyes of 10 subjects (6 females, 4 males) were enrolled. Mean age was 32.0 ± 11.2 years (range, 21 to 52 years). Mean pupillary diameter before and after dilation was 2.9 ± 0.6 mm and 7.6 ± 0.8 mm, respectively (P < 0.0001, paired t-test). There was no significant difference in RNFL thickness measurements before and after dilation using both fast and regular RNFL protocols (P ≥ 0.05 for all comparisons, paired t-test). Mean coefficients of variation for mean RNFL thickness measurements were 15.3% before and 13.7% after dilation for operator 1; and 10.8% before and 12.7% after dilation for operator 2 for the fast RNFL protocol and 11.3% versus 10.4% and 12.9 versus 11.1%, respectively, for the regular RNFL protocol. Conclusion: Pupillary dilation is not necessary in all subjects to obtain reproducible RNFL thickness measurements using OCT-3.