Abstract
Purpose: :
The onset of diabetic retinopathy has been linked to changes in oxygen saturation and flow in retinal vessels. Oxygen saturation measurements in tissues rely on the hemoglobin absorbance spectrum to calculate the oxygen content. Saccadic eye movements add to the complexity of retinal oximetry but can be circumvented with spectroscopic snapshot image acquisition. The study is designed to develop a snapshot spectroscopic image acquisition system.
Methods: :
The setup of the image acquisition system is composed of a fundus ophthalmoscope and a scientific camera. Wavelength differentiation is obtained by using a lenslet array combined with a filter array. In such layout, the fundus image is divided into nine identical wavelength sensitive sub-images. The figure on the left illustrates the experimental setup.
Results: :
Images of the retina absorbance are processed with parametric algorithms, ultimately producing maps of oxygen saturation. Calculated SO2 maps of arteries clustered around 95% while arteries showed SO2 values close to 50%.
Conclusions: :
An original and multi-wavelength snapshot image acquisition system for fundus oximetry has been developed. The system is designed to help to improve retinal oxygen saturation measurements. The system may be coupled with laser Doppler measurement system for retinal flow; the results can be subsequently compared to OCT measurements.
Keywords: imaging/image analysis: non-clinical • optical properties • retina