The role of light in measuring ocular biomechanics

Abstract

The cornea is a highly specialised tissue with a unique set of biomechanical properties determined by its complex structure. The maintenance of these mechanical properties is fundamental to maintain clear vision as the cornea provides the majority of the focussing power of the eye. Changes to the biomechanics of the cornea can occur during ageing, disease, and trauma, or as a result of surgery. Recently there has been increased interest in the mechanical properties of the cornea as knowledge of these properties has significant implications for the improvement of current ocular treatments including PRK and LASIK, and for the diagnosis and tracking of corneal diseases and therapy such as keratoconus and crosslinking. Biomechanics are also important for the development of artificial corneal replacements. This paper describes the use of a novel, non-destructive lateral electronic speckle pattern shearing interferometer (ESPSI). The data generated via this technique give a full-field view of the mechanical response of the cornea under simulated physiological loading conditions, and enables strain and displacement to be determined in three planes. The technique allows corneal stiffness to be quantified and enables changes and non-homogeneities that occur due to surgery or disease to be detected.

An interferometric ex vivo study of corneal biomechanics under physiologically representative loading, highlighting the role of the limbus in pressure compensation

“…The biomechanics of the cornea govern its shape and hence its refractive power. Understanding how the mechanical properties of the cornea contribute to its shape has become of increasing importance since the advent and rapid dissemination of refractive surgery in the 1990's, as the introduction of surgical incisions to the cornea results in modifications to its mechanical properties [1,2]. It is now even more pertinent given the possibility of direct topographic manipulation of corneal stiffness via corneal crosslinking (CXL) [3], which has demonstrated potential as a minimally-invasive means to provide small refractive correction [4].…”

Importancia y uso de la biomecánica corneal y su utilidad diagnóstica

“…Entre las descritas tenemos métodos in vivo, como la tonometría de aplanación bidireccional 6,7 , la tonometría de Scheimpflug sin contacto 8,9 , la microscopía de Brillouin 10 , el análisis ultrasonográfico de alta frecuencia 11 y la elastografía ultrasónica. Entre los métodos ex vivo se encuentran la interferometría electrónica de patrón moteado 12 y la interferometría de patrón moteado de corte radial.…”

The Potential Roles of Genetic Testing and Biomechanical Evaluation in Keratoconus

“…So far, SI has successfully demonstrated efficacy for mapping the displacement of the anterior surface of the cornea in response to IOP perturbations on the scale of those that occur during the cardiac cycle [101,102,106]. Recent investigations have shown similar displacement distributions of the anterior surface across different corneas, and due to this, it has been possible to identify corneas with superficial damage through identifying changes in the distribution of the displacement response from that of undamaged corneas [101].…”