<p>A Shack-Hartmann wavefront sensor is a specialized optical instrument used to analyze and measure refractive errors in the eye. It consists of a grid of small lenses, known as lenslets, that focus incoming light into an array of spots on a detector. When refractive errors are present, these spots shift from their expected positions due to changes in the phase and slope of the wavefront. In this study, we simulated the optical behavior of the visual system under different refractive errors, including myopia, hyperopia, and astigmatism. ZEMAX software was used to model the eye’s optical system based on the Liou-Brennan schematic eye model. The Shack-Hartmann wavefront sensor was designed to detect displacements in focal spots caused by phase variations resulting from these refractive errors. Aberrations such as defocus, astigmatism, and spherical aberration were identified using Zernike polynomial coefficients. We also reconstructed the wavefront to support refractive error correction and assess the effects of corrective contact lenses on visual quality. This method provides reliable accuracy in detecting and analyzing optical aberrations, serving as a valuable tool for developing personalized lenses, laser eye surgery techniques, and enhancing visual systems.</p>