19 Dec 2023
Company's approach combines fundus imaging and diffuse reflectance techniques.Zilia, a Quebec-based healthcare developer working towards diagnosis of diseases through optical imaging of the eye, has demonstrated a targeted spectroscopy technique for better identification of biomarkers of interest.
The approach combines diffuse reflectance and fluorescence spectroscopy in specific regions of the eye fundus, rather than attempt measurements from larger areas of tissue.
Biomarkers for conditions such as Alzheimer's are known to become broadly dispersed throughout the eye fundus, while the signs of diabetic retinopathy can be more localized, so a technique flexible enough to accurately detect biomarkers in different distributions would be a valuable diagnostic tool.
"Most spectroscopy-based methods can only make measurements over a large region of the eye fundus, which hinders their ability to detect fine spectral changes in small retinal structures," commented the developers.
"On the other hand, techniques that can make localized spectral measurements require the fixation of the patient, which can be very tedious and uncomfortable."
A study in collaboration with the University of Alberta published in Journal of Biomedical Optics has assessed the targeted spectroscopy approach in vitro using a reference model eye and also in vivo.
The platform is designed to allow three different light paths to and from the eye fundus to coexist without hampering each other. Illumination LEDs, a color camera and a spectrometer can be used simultaneously to provide continuous color imaging and spectral measurements from the eye under examination.
The spectrometer section of the device focuses an LED onto a small region of the eye fundus, and the position of this region can be adjusted using simple mechanical actuators to rotate the beam splitter feeding the camera and the spectrometer, according to the company.
Changes in the way eye disease is diagnosed and treated
"The user can select a target and move it to any location within the eye fundus region being imaged without any realignment or change of the fixation target, while continuously receiving spectral information of the targeted sampled area," commented Dominic Sauvageau, CTO and co-founder of Zilia.
"This feature makes it easy to take spectral measurements from very specific anatomical structures such as the optic nerve or the retina, from leakage of blood, or fat deposits, or any type of lesion. Notably, the system can also be used to conduct fluorescence measurements by adjusting the illumination source, which extends its applicability to detect an even wider variety of biomarkers."
The in vitro experiments involved targeting colored areas in a reference target with a grid-like pattern and taking spectral measurements of an eye model that simulated a macula, blood vessels, a foreign body, and the optic nerve, according to the project. Then in vivo measurements were performed on the retinas of eight healthy subjects, which exhibited differences in the spectral profiles of the optic nerve and the parafoveal region.
"Targeted ocular spectroscopy has the potential to assess the presence of different chromophores and fluorophores, such as hemoglobin, oxyhemoglobin, melanin, and lipofuscin, associated with disease progression," said Dominic Sauvageau. "This could open the door to changes in the way we diagnose and treat eye diseases, and targeted ocular spectroscopy could become an increasingly important tool in eye care in the coming years."
Zilia, officially launched in 2017, has been developing a retinal camera named Zilia Ocular, combining a fundus camera and cloud-based image analysis system. This enables the continuous measurement of oxygenation through diffuse reflectance spectroscopy, and determines oxygen concentration at specific points in the retina or the optic nerve.
The Zilia Ocular device received FDA 510(k) clearance in November 2023, and the company indicated at that time that it would proceed to seek a further FDA De Novo classification for ocular oximetry, as an indication of its low risk in clinical scenarios.