UC Irvine

The transparent outer layer of the eye, known as the cornea, has a vital function inbending and directing light onto the retina, which is essential for achieving clear vision. Current methods of correcting refractive errors that are becoming increasingly popular include LASIK and PRK surgeries; however, these invasive techniques come with downsides as well such as permanent thinning of the cornea. This thesis proposes the use of a non-invasive technique called electromechanical reshaping (EMR) that can be applied to the cornea to induce curvature change. EMR was performed on New Zealand white rabbit globes using a concave platinum lens as the working electrode in a 3-electrode setup. The primary outcomes to be measured include the aforementioned curvature change of the cornea and the change in distribution of collagen orientation: to observe such changes the advanced imaging modalities of optical coherence tomography (OCT) and second harmonic generation (SHG) have been employed. The curvature data can be analyzed through a developed MATLAB approach that reconstructs the 3D surface of the cornea from 2D cross-sectional OCT images and sphere-fits the surface to extract the radius of curvature. The collagen structural change can be analyzed in FIJI software using OrientationJ to quantify the orientation of collagen fibers. These methods serve as a sound quantitative way to analyze the outcomes of EMR. This thesis found that the mean curvature increased from 5193.73 µm ± 597.09 µm to 5429.16 µm ± 736.08 µm following EMR application. Regarding collagen structural change, most of the eyes did not show a statistically significant difference following EMR application. Due to experimental error because of the lack of standardization of pressure, however, the corneal curvature did not consistently increase and the corneas did not resemble the radius of curvature of the platinum lens used in EMR (7.486 mm). Future directions include standardization of the pressure applied on the cornea by the platinum lens, simultaneous OCT imaging during EMR application, seeing if corneas post-EMR retain curvature changes, and transitioning to applying EMR on eyes intact in New Zealand white rabbit heads.