Inner ear cellular imaging through scattering bone

Inner ear imaging is important for the assessment of hearing disorders. A major cause of hearing loss is the damage to the sensory hair cells, which are located inside the cochlea, a spiral-shaped bone in the inner ear. Imaging of intracochear hair cells is of high interest because it can provide precise diagnosis and treatment of hearing loss. However, this goal is very challenging because the cochlea is very small and enclosed by a dense bone, thus preventing visualization of intracochlear microanatomy. In this paper, we present a novel technique for imaging cochlear cells through the bone by two-photon microscopy. We optimized the imaging quality by thinning the obscuring scattering bone above the hair cells using a femtosecond laser. We controlled the ablation with an optical coherence tomography system and a bright-field camera for real time visualization. The proposed method enables optical access to the cochlea by thinning the cochlear bone, thus allowing imaging of cells underneath.