Purchase this article with an account.
P.-J. Bernard, V. Vucea, V. Diaconu; Foveolar Micro-capillaries Blood Oxygenation Assessed by Multichannel Spectroreflectometry. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1405.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Recent developments in the field of multi channel spectroreflectometry measurements propose a mathematical model to derive haemoglobin and oxyhaemoglobin blood content in the optic nerve micro-capillaries (Diaconu, Applied Optics, 2008). The goal of the current study was to develop the proposed mathematical model to derive haemoglobin, and oxyhaemoglobin absorption factors from full spectrum reflectometry measurements of fovea choroidal micro-capillaries.
The full spectral-reflecometry measurements (430 to 665 nm) were performed using a version of the OSOME instrument (US Patent # 5,919,132). Seven young healthy non-smokers subjects between 20 and 30 years old participated in the study. Two different sessions of reflectometry measurements were performed from optic nerve and from fovea areas respectively. An experimental session of reflectometry measurement was obtained for 360 seconds of continual recording for a steady state light intensity of retinal illumination. Each session included first a period of 60 seconds of ambient air breathing followed of 180 seconds of hyperoxia with a 60% oxygen air mixture breathing and finishing with 120 seconds of ambient air breathing. The mathematical model used to derive oxyhaemoglobin absorption factors was adopted from the linear model proposed by Diaconu (2008), by including the spectral absorption of the L and M cones. This model was applied to the two types of reflectometry measurements from optic nerve and fovea respectively.
The reflectometry function from the optic nerve capillaries can be completely explained when the model was applied only for 550 to 665 nm spectral area. The reflectometry function from the fovea can be fitted by the model only for the data from 580 to 665 nm spectral area. Using the optical media factor derived from optic nerve measurements, we can optimise the model for a L and M cone ratio specific for each subject. The model results for oxyhaemoglobin derivations show that systemic hyper-oxygenation create an increase in oxyhaemoglobin content in optic nerve (2%) and in fovea (5%) choroidal micro-capillaries.
This PDF is available to Subscribers Only