ABSTRACT
Because of the lack of symmetry of the eye and because the fixation point and fovea are not along a best-fit axis of symmetry, in order to fully describe the optical properties of the eye a number of axes are required. The axes influence the retinal image quality and have clinical applications, including the diagnosis of binocular anomalies and determining ablation patterns in corneal refractive surgery. This chapter describes these axes, their importance, their applications, and how they may be determined.
