We developed an intraocular pressure (IOP) analytic model utilizing fluid dynamics (simulating air-puff), solid mechanics (simulating cornea structure deformation), and ray-tracing technique (simulating applanation detection) to simulate the air-puff noncontact tonometry (NCT) for post-SMILE and post-LASIK IOP measurement. This novel model is validated by a retrospective review of a database with 174,666 eyes undergoing LASIK surgery<sup>1,2</sup>. Our novel analytic model is able to comprehensively analyze the components of IOP changes after SMILE and LASIK in addition to the corneal thickness. Based on our study, the factors affecting the IOP changes after SMILE and LASIK surgeries in order include the Young’s modulus of corneal stroma, geometric shape of ablated stroma, diameter of ablated zone, corneal thickness, and corneal curvature.
Abnormal corneas with corneal tissue defects like ulceration, melting, laceration, thinning scar, keratoconus etc., poses special challenges for ophthalmologist to measure intraocular pressure (IOP) correctly using air-puff noncontact applanation tonometry. Here, we propose an novel model, Abnormal Applanation IOP Model (AAIOP), to simulate IOP in these abnormal corneas on an air-puff noncontact applanation tonometry system, and the simulated IOP results are correctly fit in those of IOP measured database on human eyes of 91,024 patients (174,666 eyes)<sup>1</sup>). Our simulated IOP indicates that every 10 μm of central corneal thickness change results in 0.36 mmHg of IOP change. Using our simulation model, the IOP on abnormal eyes with irregularly-shaped corneas can be correctly expected and reported.