Combined photoacoustic and fluorescence label-free microscopy for the ex-vivo investigation of ocular tissues

We demonstrate the application of an extended field of view microscope, combining photoacoustic and fluorescence label-free contrast modalities, for the ex vivo investigation of ocular tissues including the ciliary muscle in healthy rabbit eyes and surgical biopsies of benign nevi removed from human eyes. In the case of ciliary muscle samples, the intrinsic photoacoustic and the glutaraldehyde-induced autofluorescence signals were observed to be spatially complementary, offering specific and high resolution morphological information as regards to Pars plana and Pars plicata ciliary body portions, iris, and zonule fiber strands. On the other hand, the biopsy samples presented a remarkable spatial overlap of the two signals in the nevus region, indicating a positive correlation between them. The bimodal microscopy approach presented in this work, has the potential to contribute in the understanding of the physiological function of the eye involving the detailed study of the ocular accommodation system and the elucidation of ageing effects such as presbyopia. Finally, the proposed hybrid diagnostic approach could be employed for the differentiation between benign and malignant intraocular tumors of the uvea in surgical biopsies, simplifying the relevant procedures for this purpose.