This module introduces students to the basic fundamental principles of physical, geometric and physiological optics, which underpin orthoptic practice. These principles are required for orthoptic practice delivered in subsequent modules across the programme (ORTH140, ORTH237, ORTH240, ORTH330 and ORTH335), as well as a module specific to refraction of patients in the final year (ORTH332). On completion of the module, successful students will be able to apply geometric optical principles to various theoretical calculations and problems, including: reflection, refraction, prismatic effect and lens theory. They will also understand the eye as an “optical instrument”, the basis of refraction and the correction of refractive error. The module is delivered through a series of interactive lectures and tutorials that enable the student to work systematically through a series of concepts, applying principles to various theoretical situations. The student must be able to apply formulae, rearrange equations and ray trace in order solve optical questions. The aforementioned concepts are required when the physiological optic topics are explored later in the module. The assessment of the module is via a one and a half hour written exam, this will involve the student recalling information regarding physical optics, solving a series of geometrical optical problems, and demonstrating understanding of physiological optics.