A corneal elastic dynamic model derived from Scheimpflug imaging technology.
OBJECTIVE
To simultaneously extract the corneal Young's modulus and the damping ratio from Scheimpflug imaging data.


METHODS
A spherical diaphragm model can better represent the geometry and physics of an eyeball than the popular mass-spring-damper model. This research derived the dynamic model of a water-filled spherical diaphragm based on the hydrodynamics and wave propagation theories. By applying modal analysis on the model, one can decouple the cornea vibration into individual modes and reconstruct the air puff vibration from the decoupled responses. By matching this response with the Scheimpflug imaging data from the Corvis(®) ST, it was then possible to extract multiple physiological properties as desired.


RESULTS
The dynamic modal analysis was employed to extract the corneal physiological properties of 25 Taiwanese normal subjects. Specifically, the corneal Young's moduli and damping ratios were estimated. In fact the model is dependent on the physiological parameters such as cornea thickness, densities, and intraocular pressure. It is thus also possible to extract these parameters through multi-goal minimisation processes.


CONCLUSIONS
The spherical diaphragm model was able to better describe the dynamic response of the eyeball. The model analysis also provides additional corneal physiological properties that were not available through other means.
Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan.
Po-Jen
PJ
Shih
Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan.
Huei-Jyun
HJ
Cao
Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan.
Chun-Ju
CJ
Huang
Department of Ophthalmology, College of Medicine, National Taiwan University, Taipei, Taiwan.
I-Jong
IJ
Wang
Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan.
Wen-Pin
WP
Shih
Department of Mechanic Engineering, National Taiwan University, Taipei, Taiwan.
Jia-Yush
JY
Yen
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D003315:Cornea / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009799:Ocular Physiological Phenomena; D014065:Tonometry, Ocular / Q000379:methods; D055815:Young Adult
Cornea; Corvis® ST; forced vibration; tonometer