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Margaret M. O' Halloran, Chris Dainty, Eamonn O' Donoghue; Retinal Hemodynamic Response to Hyperoxia. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2202.
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© ARVO (1962-2015); The Authors (2016-present)
To improve the accuracy in the determination of the vascular reactivity of normal, healthy eyes during hyperoxic provocation using a high resolution imaging modality - a confocal scanning laser ophthalmoscope.
Imaging is performed with a manufacturer modified HRT classic. It has been modified to enable imaging of the retina at a 10, 2, or 1 degree field of view (FOV). It acquires a sequence of 32 frames at a single focal plane to obtain a video of the vasculature in approximately 1.5 s. A number of sequences were obtained, at the 2 degree FOV, of a selected vessel segment before and during the administration of 100% oxygen via a non-rebreather mask. Each sequence was then registered and averaged. The vessel diameter before and during hyperoxic provocation was determined using vessel tracking and edge detection techniques applied to the average image, and the magnitude of vasoconstriction was subsequently calculated.
8 eyes of 7 normal subjects were imaged. Arterioles approximately 1 disc diameter from the optic nerve head were imaged before and during hyperoxia. A constriction of the vessels was observed in all cases, with a mean % constriction of 8.1 ± 2.0 %. To investigate the repeatability, the same vessel segment in one subject was measured during 3 different imaging sessions. A mean % constriction of 8.32 ± 0.2 % was obtained.
To the best of our knowledge, this is the first application of a high resolution imaging modality to the assessment of retinal vascular reactivity. This promises to improve the accuracy and reproducibility of the assessment of reactivity.
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