Optical aberrations degrade the images of the outside world projected on the retina. Beyond conventional refractive errors (astigmatism and defocus), optical aberrations arise from the geometry of the ocular surfaces and misaligments. The Spatially Resolved Refractomer (SRR), Laser Ray Tracing aberrometer (LRT) and Hartmann-Shack wavefront sensing have allowed us to measure optical aberrations in normal eyes, eyes with pathologies and following surgery. We have measured aberrations in aging eyes, young eyes as a function of dynamic accommodation, as a function of refractive error (myopes and hyperopes), in keratoconic eyes, investigated their change with myopic and hyperopic LASIK, and cataract surgery (with aspheric and spherical IOLs, accommodating IOLs), intracorneal ring segment implantation. We have also measured optical aber rations in experimental models for myopia (chicken, mouse and marmoset). Measurement of anterior and posterior corneal surface geometry, lens alignment and geometry allows constructing computer eye models customized to the anatomical parameters of each patient. Virtual ray tracing on these model eyes allow calculation of ocular aberrations (with high agreement to measured aberrations) and understanding the contributions of each factor to optical degradation.