Enhancement of multimodal imaging of rabbit eyes using optical clearing agents

The imaging depth of conventional Optical Coherence Tomography (OCT) is limited by high scattering of biological tissues, while the signal intensity of deep tissue imaged by Photoacoustic Microscopy (PAM) is also affected by the weak light excitation of biological tissues. In this paper, glycerol solution was used as the optical clearing agent (OCA) to enhance tissue transparency and reduce light attenuation during deep tissue imaging. We performed optical clearing treatment on the anterior and posterior segments of rabbit eyes by topically applying glycerol to the conjunctival opening and through posterior injection, respectively. Then the anterior and posterior segments of rabbit eyes were imaged using the PAM and OCT systems. The results demonstrate that the optical transparency alteration of the anterior and posterior segments of rabbit eyes changes the tissue refractive index, increases the signal intensity of OCT and PAM, and enhances the imaging depth of both OCT and PAM. Consequently, the optical clearing agent provides a powerful tool for ophthalmic research and early diagnosis of ocular diseases, and also expands the imaging applications of OCT and PAM.