Influence of pupil dilation on retinal nerve fibre layer measurements with spectral domain OCT

Purpose To evaluate the influence of pupil dilation on retinal nerve fibre layer (RNFL) measurements with spectral domain optical coherence tomography (OCT). Patients and Methods In total, 29 healthy individuals and 26 glaucoma patients underwent RNFL measurements with the Cirrus HD-OCT Model 4000 (Carl Zeiss Meditec Inc.) before and 30-40 min after pupil dilation with one drop of tropicamide 1%. Average thickness, quadrant thickness, and clock-hour thickness measurements were compared with the paired Student's t-test. We also compared the quality scores of the images obtained pre- and post-pupil dilation. Results Mean ages in the glaucoma and control groups were 58.3 +/- 13.4 and 41.6 +/- 16.4 years respectively (P<0.001). Mean deviation values were -6.96+6.31 dB in the glaucoma group and -1.26+0.79 dB in the control group (P<0.001). Mean RNFL measurements obtained in the glaucoma group were significantly lower than those obtained in the control group (P<0.001). There were no statistically significant differences between mean quality scores obtained before and after dilation neither in the glaucoma group (7.73 +/- 0.92 vs 7.54 +/- 1.10, P=0.232) nor in the control group (8.14 +/- 0.88 vs 8.00 +/- 0.71, P-0.380). There was no statistically significant difference between mean RNFL measurements obtained pre- and post-pupil dilation neither among normal individuals (P>0.05), nor among glaucoma patients (P>0.05). Conclusion The results of this study indicate that RNFL measurements obtained with spectral domain OCT are not influenced by pupil size. Eye (2010) 24, 1498-1502; doi:10.1038/eye.2010.72; published online 28 May 2010