Abstract
Purpose :
The purpose of this study is to explore the imaging capabilities of a simplified adaptive optics (AO) flood illumination fundus camera using incoherent illumination for high contrast parafoveal retinal imaging.
Methods :
A simplified fundus camera has been developed that uses a 4mm detection pupil with incoherent illumination from a fibre-guided tungsten-halogen lamp (Edmund Optics) in conjunction with an AO closed-loop system consisting of a deformable mirror (Mirao-52e, Imagine Eyes) and CMOS wavefront sensor (Thorlabs) with a near-IR laser (850nm) as guide star. High-resolution fundus images were captured at 30 fps with a scientific-graded CMOS camera (Andor). The system is a simplified version of an AO fundus camera that we used for differential detection of retinal directionality (Qaysi et al, Biomed. Opt. Express 2018).
Results :
Parafoveal widefield images (10°) were captured in healthy subject eyes revealing the cone photoreceptor mosaic even without pupil dilation and with a simplified system. The broadband incoherent illumination significantly enhanced the image contrast aided by the smaller pupil that allowed elimination of unwanted backscatter from the cornea and crystalline lens and thereby enhance the visibility of detail in fundus images. Global image quality metrics were evaluated and the contrast improvement determined for the cone mosaic and blood vessels. The Michelson contrast between cones and the intracellular space was higher than 40%.
Conclusions :
The simplified AO fundus camera has clinical potential as it is simpler to operate than a wide-pupil fundus camera and provides a wider field of view without image stitching. The reduction in transversal resolution with the smaller pupil is insignificant for the parafoveal retina. The system will be explored in parallel with AO scanning light ophthalmoscopy with clinical partners for diagnostic imaging of retinal disease.
This is a 2020 ARVO Annual Meeting abstract.