Abstract
Purpose :
To assess the intra-observer repeatability and inter observer reproducibility of laser speckle flowgraphy (LSFG) for retinal blood flow measurement in wild type (C57BL/6J) mouse model.
Methods :
The study was approved by the Institutional Animal Care and Use Committee of SingHealth, Singapore and adhered to the guidelines of the Association for Research in Vision and Ophthalmology (ARVO) Statement for the Use of Animals in Ophthalmic and Vision Research for conducting all animal procedures.
Twenty eyes of ten wild type C57BL/6J mice (4 months old) were included in the study and were anesthetized using the combination of ketamine hydrochloride (50 mg/kg) and xylazine hydrochloride (0.5 mg/kg) according to schedule 1, under ARVO guidelines. A drop of each 0.5% tropicamide and 2.5% phenylephrine hydrochloride was applied on the surface of the eye ball to dilate the pupil and each eye retinal blood flow was measured using LSFG-Micro instrument (Softcare Co., Ltd., Fukuoka, Japan).
For retinal blood flow the “mean blur rate (MBR)” was measured for tissue area (MT), vessel (MV) and total area (MA) of the optic nerve head (ONH) region. Bland-Altman plot method, coefficient of variation (COV) and interclass correlation coefficient (ICC) were used to assess the intra and inter-observer variability using MedCalc Statistical Software version 16.8 (MedCalc Software bvba, Ostend, Belgium; https://www.medcalc.org; 2016).
Results :
For retinal blood flow the Bland-Altman plots illustrate the intra and inter-observer variability for all the measured regions of ONH (MA, MV and MT) were present within the 95% limits of agreement (mean difference ± 1.96 SD of the differences). COV of intra and inter-observer variability was varied from 5.7 to 15.54% and 13.94 to 47.34%, respectively. In ICC, the level of reliability was excellent for intra-observer repeatability measurements (ICC values 0.92 to 0.99) and was poor to excellent for inter-observer reproducibility measurements (ICC values 0.32 to 0.95) for all the measured ONH regions.
Conclusions :
LSFG-Micro showed favorable intra-observer repeatability in evaluation of retinal blood flow in wild type C57BL/6J mouse model. The study results suggest that the LSFG experiments performed by single examiner could be more reliable than multiple examiners for longitudinal studies in mouse models.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.