Inability of a Confocal Scanning Laser Doppler Flowmeter to Measure Choroidal Blood Flow in the Pig Eye
S Pandav, W.H Morgan, R Townsend, S.J Cringle , D.Y Yu*
Identifiers and Pagination:Year: 2008
First Page: 146
Last Page: 152
Publisher ID: TOOPHTJ-2-146
Article History:Received Date: 15/9/2008
Revision Received Date: 27/10/2008
Acceptance Date: 28/10/2008
Electronic publication date: 14/11/2008
Collection year: 2008
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http: //creativecommons.org/licenses/bync/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
The aim of the study was to determine whether the Heidelberg Retinal Flowmeter (HRF), a confocal scanning laser Doppler flowmeter, can measure choroidal blood flow in pig eyes.
An HRF was used to obtain flow maps from In vitropig eyes under a range of perfusion flow rates (0 – 500 µL/min) under conditions in which only the choroid was perfused. In some cases choroidal blood flow was also measured simultaneously using a conventional fiberoptic based Laser Doppler Perfusion Monitor (LDPM) which used the same laser wavelength (780 nm). The relationship between perfusion flow, HRF measured flow and LDPM measured flow was determined. HRF flow maps were also obtained in vivo as a function of focal plane setting through the retina and choroid.
Across the range of perfusion flow rates through the isolated eyes there was a poor correlation with HRF measured choroidal flow and perfusion flow. In contrast, there was a strong linear relationship between perfusion flow and LDPM measured blood flow. Both In vitro and in vivo, no choroidal vessels could be visualised in the HRF flow maps, even when the focal plane was in the choroid
The HRF is unable to measure choroidal blood flow in pig eyes. This is not due to an inability of the 780 nm laser to penetrate into the choroid or due to red blood cell velocities in the choroid being higher than the measurement range of the instrument.