Abstract
Purpose :
To evaluate the influence of pupil dilation on the reliability of retinal nerve fiber layer (RNFL) measurements in patients with differing degrees of glaucoma severity using spectral domain optical coherence tomography (OCT).
Methods :
This prospective observational study recruited 23 patients who were suspected or diagnosed primary open-angle glaucoma (POAG) from the glaucoma service at the Yale Eye Center. The severity of glaucoma was determined based on the glaucoma staging system developed by the american glaucoma society work group. Four eyes carried a diagnosis of glaucoma suspect, 11 eyes with mild-stage POAG, 8 eyes with moderate-stage POAG, and 7 eyes with severe-stage POAG. Each eye underwent two separate RNFL measurements before and at least 30 minutes after dilation with one drop each of tropicamide 1% and phenylephrine 2.5%. The average RNFL thickness measurements and the measured thickness of each of 12 clock hours were compared with paired t-tests using the SPSS software package.
Results :
Mean age of patients was 67 years. There were 14 female and 16 male eyes. Average thickness of RNFL for all eyes was 67.4±2.2μm (mean±se, same below) undilated and 65.8±2.1μm dilated (p=0.14). Stratified into glaucoma severity, average thickness of RNFL for those with suspected POAG was 78.3±5.5μm and 73.0±4.5 (p=0.42), with mild POAG was 70.6±3.2 and 71.0±3.2 (p=0.68), with moderate POAG was 63.1±2.9 and 62.4±2.8 (p=0.52) and with severe POAG was 60.9±4.6 and 57.6±4.6 (p=0.21), none of which met statistical significance. The thickness of each of 12 clock-hours when stratified by glaucoma severity was also statistically insignificant with p-values ranging from 0.06 to 1.00, except for the 2 o’clock position in those with mild-stage POAG (p=0.02). Signal strength between undilated and dilated eyes was not statistically significant (p=0.60). As an internal control in our study, the reproducibility of the images (undilated versus undilated and dilated versus dilated RNFL measurements) was found consistent (p=0.30).
Conclusions :
The results revealed that glaucoma severity did not influence the reliability of OCT RNFL measurements through an undilated pupil. The signal strength was not significantly affected by pupil dilation either. Our study suggests pupil dilation may not be unnecessary when capturing OCT RNFL images for glaucoma evaluation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.