Abstract
Purpose :
The purpose of this research is to develop a 3D tomographic model of the human cornea, which can then be utilized to assess various optical performance metrics (visual acuity, MTF, visual disturbance, etc.) of pseudophakic patients.
Methods :
First, human corneal elevation data are collected from a corneal tomography device (Alcon WaveLight Oculyzer®). These data belong to patients with normal corneas as well as those who experienced LASIK surgery. A mathematical model based on the “Zernike surface” is created to fit the raw corneal tomography data. This modeling decomposes 3D corneal tomography into fitting parameters such as radius of curvature, aspheric coefficients, and Zernike coefficients related to various aberrations. Residual, the difference between the actual and fitted corneal tomography, is analyzed. Then, ray-tracing software is used to import these and analyze the optical performance metrics (visual acuity, MTF, visual disturbance, etc.) of IOLs.
Results :
The corneal tomography results of three normal patients and three post-LASIK patients were acquired using the WaveLight Oculyzer device. These tomography data are in a square grid with a step size of 100 µm. The region of interest for this corneal tomography is restricted to 6 mm in diameter centered on the corneal apex. “Zernike surface” based mathematical model is then applied to fit these raw corneal data within the specified diameter. The residual falls within 1.5±0.4 µm for regular corneas, while for post-Lasik corneas, the residual is within 4±1.8 µm. The fitting parameters are also captured for each corneal tomography map.
Conclusions :
In this work, we have developed a mathematical model of the human cornea based on the Zernike surface by utilizing human corneal tomography data. Both regular and post-LASIK corneal tomography data are fitted to this model and the residuals are also analyzed for all cases. These fitting parameters are used in raytracing software to investigate the vision matrices (visual acuity, MTF, visual disturbance, etc.) of IOLs. This modeling of the 3D corneal surface with raytracing software has the potential for the researchers to incorporate more realistic cornea models into IOL designs and for surgeons to select patient-specific IOLs.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.