Single-channel stereoscopic fundus imaging modality

Purpose: Stereoscopic imaging includes two slightly different views for each eye at the same time and provides stereovision via various stereo display methods. In the imaging modality, two slightly different view angles are obtained through a rotating refractor (RR), which is mounted on a stepping motor and placed inside an optical channel. Therefore, the stereo angle becomes a function of the refractive index and rotation angle of the RR. The feasibility of single-channel stereoscopic fundus video imaging modality based on a rotating refractor (SFIM-RR) was investigated.Methods: The RR was placed in front of the objective lens within the working distance. It laterally displaced the illumination and observation optical paths with respect to the pupil center; thus, stereo parallax was generated, resulting in image disparity. Capturing an image at each end of the rotation arc of the RR leads to the generation of two virtual optic channels with slightly different imaging axes.Results: The SFIM-RR allows rapid sequential imaging acquisition, which is easily developed on standard monocular fundus cameras. The optical simulation, stereo-base measurements, eyeball model, and rabbit-eye imaging show that the SFIM-RR may be used in real-time retinal imaging to overcome some limitations of the conventional methods.Conclusion: Stereoscopic-imaging methods can be greatly beneficial and sometimes necessary in surgical microscopes, stereo fundus imaging, and other extra- and intra-ocular purposes in ophthalmology. Currently, two main approaches are available in stereo image pairs of the fundus: sequential image acquisition using a standard fundus camera at different positions and simultaneous image acquisition using stereo fundus cameras. Although the simultaneous images are captured under exactly the same conditions, the sequential imaging approaches are cheaper. The SFIM-RR provides a rapid sequential automatic image acquisition that can be easily developed on standard monocular fundus cameras