Multimodal Heartbeat and Compression Optical Coherence Elastography for Mapping Corneal Biomechanics

Abstract

The biomechanical properties of the cornea have a profound influence on the health, structural integrity, and function of the eye. Understanding these properties may be critical for diagnosis and identifying disease pathogenesis. This work demonstrates how two different elastography techniques can be combined for a multimodal approach to measuring corneal biomechanical properties. Heartbeat optical coherence elastography (Hb-OCE) and compression OCE were performed simultaneously to measure the stiffness of the cornea in an in vivo rabbit model. Measurements were further performed after collagen crosslinking to demonstrate how the combined technique can be used to measure changes in corneal stiffness and map mechanical contrast. The results of this work further suggest that measurements from Hb-OCE and compression OCE are comparable, meaning that Hb-OCE and compression OCE may be used interchangeably despite distinct differences in both techniques.

Assessment of corneal stiffness ex-vivo at various IOPs measured by Heartbeat OCE

“…The fluctuations in IOP successfully mimicked the ocular pulse and caused measurable displacements at various IOPs similar to our previous work [13][14][15] . Figures 2 and 3 show the comparison of the expansion (red) and compression (blue) of a typical sample at (top) 15 mmHg and (bottom) 30 mmHg baselines, respectively.…”

“…Passive techniques take advantage of natural physiological forces, which act as the excitation source required for elastography. Our group has introduced Heartbeat-OCE (Hb-OCE) [13][14][15] , a truly passive technique that utilizes the heartbeat-induced ocular pulse 10 to gather mechanical properties of the cornea both in and ex-vivo. The ocular pulse is defined as the difference between systolic and diastolic measurements of intraocular pressure (IOP), which cause a pulsatile motion in the cornea too.…”

“…The ocular pulse is defined as the difference between systolic and diastolic measurements of intraocular pressure (IOP), which cause a pulsatile motion in the cornea too. The pulsatile motion due to the ocular pulse can elicit crucial information regarding the health of the eye and is strongly correlated to its biomechanical properties [14][15][16][17][18][19] .…”

In vivo corneal elastography: A topical review of challenges and opportunities

“…7 a briefly summarizes the OCE system according to the loading method and OCT detection method. Numerous loading strategies have emerged as a result of the development of OCE for multiple applications, such as static [216] , [217] or dynamic bulk compression [205] , [218] , [219] , [220] , needle probe compression [221] , [222] , magnetomotive [223] , [224] , nano-bomb [225] , [226] , audio sound [50] , [227] , pulsed laser (photothermal excitation) [228] , [229] , ultrasound [230] , [231] , [232] , and air-coupled ultrasound [233] , [234] , [235] -induced acoustic radiation force (ARF), air puff/pulse indentation [236] , [237] , [238] , and passive sources, such as the heartbeat [239] and noise-correlation approach [240] . These loading strategies can be sorted into different categories ( Fig.…”

Optical coherence elastography and its applications for the biomechanical characterization of tissues

“…OCE can evaluate the elasticity of biological tissues, such as the cornea [58][59][60][61][62][63][64][65], the lens [66][67][68], the retina [69], the artery [30], the tumor [15,[70][71][72][73][74][75][76][77], the brain [78], the skin [28], and some other tissues [79][80][81][82], providing new evidence for clinical research. This section presents a few recent applications in ophthalmology, endoscopy, and oncology.…”