Abstract
Purpose: :
Hyperspectral imaging of the retina provides a unique non-invasive approach to measuring the oxygen saturation of the retinal vasculature in humans. This study aims to establish the ability of hyperspectral imaging to detect oximetric changes in the retinal vasculature of patients with asymmetrical primary open angle glaucoma (POAG) using quantitative spectral analysis techniques.
Methods: :
High resolution en face hyperspectral retinal images were acquired using a modified conventional fundus camera. Normal subjects (n=10) and subjects with asymmetrical POAG (n=10) were imaged. Algorithms incorporating physical optics models for light propagation within the retina were used to calculate the blood oxygen saturation along the larger retinal blood vessels.
Results: :
Quantitative oximetric maps of the retinal vasculature showed significantly higher venous oxygen saturation in eyes more severely affected by glaucomatous damage compared to the fellow eye (Figure 1) and subjects with normal eyes.
Conclusions: :
Hyperspectral imaging in subjects with asymmetrical POAG is able to detect asymmetric oxygen saturation content within the venular retinal circulation. The increased venular oxygen saturation in the more severely affected glaucomatous eye may indicate reduced inner retinal oxygen consumption as a result of reduced functional ganglion cell mass. Further improvements in the analysis algorithms could enable the measurement of oxygen saturation in the retinal capillaries and other retinal chromophores (e.g neuroglobin) relevant to assessing the functional health of the retina in glaucoma. These techniques could be used to screen for glaucoma and monitor the effects of medical and surgical treatment.
Keywords: oxygen • imaging/image analysis: clinical • intraocular pressure