Brillouin Spectroscopy in Ophthalmology. / Gegenwärtiger Stand der Brillouin-Spektroskopie in der Ophthalmologie.

BACKGROUND: Information about corneal biomechanics is crucial for achieving satisfactory outcomes after surgical corneal interventions, e.g., for astigmatic keratotomies, but also to identify corneas that are at risk for postoperative complications such as corneal ectasia. Hitherto, approaches to characterize corneal biomechanics in an in vivo setting have yielded only minor success, demonstrating the unmet medical need for a diagnostic technique to measure ocular biomechanics. OBJECTIVE: This review shall explain the mechanism of Brillouin spectroscopy and summarize the current scientific knowledge for ocular tissue. METHODS: PubMed research of relevant experimental and clinical publications, as well as reporting of own experience using Brillouin spectroscopy. RESULTS: Brillouin spectroscopy can measure different biomechanical moduli with a high spatial resolution. Currently, available devices are able to detect focal corneal weakening, e.g., in keratoconus, as well as stiffening after corneal cross-linking. Also, the mechanical properties of the crystalline can be measured. Corneal anisotropy and hydration, together with the dependence on the angle of the incident laser beam in Brillouin spectroscopy, are challenges in the precise interpretation of measured data. A clear advantage in the detection of subclinical keratoconus compared to corneal tomography, however, has not been shown yet. CONCLUSION: Brillouin spectroscopy is a technique to characterize biomechanical properties of ocular tissue in vivo. Published results confirm ex vivo data of ocular biomechanics; however, further improvements in the acquisition and interpretation of measured data are required until this technique can be used in a clinically viable setting.