We demonstrate high spatial resolution imaging of a stromal cut in the ex-vivo pig
cornea, using second- and third-harmonic generation microscopy. From these images,
we see in detail how the cut affects the corneal layers. In the beginning of the cut, the
anterior layers, in which the blade is passing through, are disorganized, which could
explain the shadows observed on the images. In the stroma, the cut can be imaged by
third harmonic microscopy, probably due to the χ<sup>3</sup> contrast. Although the current
results were obtained from the healthy ex-vivo cornea, it already allows one to
understand the effects of the cut on the tissue characteristics (such as scattering).
Advanced imaging methods are essential tools for improved outcome of refractive surgery. Second harmonic generation
(SHG) and third harmonic generation (THG) microscopy are noninvasive high-resolution imaging methods, which can
discriminate the different layers of the cornea, thus having strong impact on the outcome of laser surgery. In this work,
we use an Ytterbium femtosecond laser as the laser source, the longer wavelength of which reduces scattering, and
allows simultaneous SHG and THG imaging.
We present SHG and THG images and profiles of pig corneas that clearly show the anterior surface of the cornea, the
entry in the stroma and its end, and the posterior surface of the cornea. These observations allow localizing the
epithelium, the stroma and the endothelium. Other experiments give information about the structure and cytology of the