Intraocular pressure is very significant in ophthalmology and it is used to diagnose glaucoma. It is usually estimated by a tonometer based on the Imbert-Fick law. However, systematic investigation for the effect of the geometrical and mechanical characteristics of eye phantom on the validity of the tonometer pressure is rare. We fabricated polydimethylsiloxane eye phantoms of which 3-D geometries based on Archimedes principle and mechanical properties were tailored to those properties of human eye and applied to evaluate the validity of tonometer pressure. The shell thickness at the center as well as the mechanical modulus was controlled by the concentration of ethylene glycol and the formulation of PDMS, respectively. Optical coherence tomography and tonometer were used to determine the detailed geometrical information of eye phantom and tonometer pressure, respectively.
The thickness of the shell at the centre of eye phantom could be varied from 0.2 mm to 1.0 mm with different modulus. The range of eye phantom properties is comparable to the typical values of the modulus and the thickness of human eye of 0.4 MPa and 0.52 mm, respectively. The tonometer pressure was found to be dependent on the shell thickness as well as the modulus of the shell.
We have successfully developed eye phantoms for evaluating the validity of tonometer pressure. The values measured from eye phantoms are similar to the typical IOP of human eye if the modulus and thickness of the shell are similar to those of human eye.