Abstract
Purpose: :
To investigate the reproducibility of peripapillary retinal nerve fiber layer thickness (RNFLT) measurements obtained with optical coherence tomography (OCT) in glaucoma patients both before and after a comprehensive ophthalmic examination including Goldmann applanation tonometry and pupillary dilation. To determine if pre–dilation RNFLT measurements differ from those obtained after dilation.
Methods: :
Prior to examination and prior to instillation of any topical medications, the Stratus OCT was used to perform three consecutive scans of the peripapillary retinal nerve fiber layer (RNFL) of both eyes using the 3.4 mm Fast RNFL protocol. The subjects were allowed a brief rest prior to being repositioned for repeat imaging. Subjects underwent a comprehensive examination including dilation of the pupils with tropicamide 1.0% and phenylephrine 2.5%. During slit–lamp biomicroscopy, the degree of lens opacification was graded using the lens opacities classification system (LOCS) III. After completion of the examination, three additional OCT scans were obtained of the peripapillary RNFL of both eyes. The reproducibility of the Averge Thickness measurement obtained by the Stratus OCT was evaluated using repeated measures analysis of variance (ANOVA). The standard deviations (SD) among the repeated measurements were estimated using the residual variance from the ANOVA model. We compared the pre–dilation SD to the post–dilation SD using the variance ratio test. The mean Average Thickness obtained prior to dilation was compared with that obtained after dilation using the ANOVA main effect.
Results: :
28 eyes of 14 subjects were studied. The mean Average Thickness was 82.05 µm before dilation and 82.67 µm after dilation (p=0.47). The SD of the repeated measurements was 5.06 µm before dilation and 5.43 µm after dilation (p=0.60, F–test).
Conclusions: :
In this cohort of glaucoma subjects imaged with Stratus OCT, the Average Thickness measurement of the peripapillary RNFL obtained using the 3.4 mm Fast RNFL protocol, is highly reproducible both before and after pupil dilation. The pre–dilation measurements are not significantly different from those obtained after dilation.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • nerve fiber layer