Objectives: At the conclusion of this conference the resident will have an understanding of the principles of thick lens systems and will be able to define and describe:

• the basic optics of thick lens systems:  2 principal points, 2 nodal points and 2 focal points
• be able to trace light rays through a thick lens system
• be able to calculate vergence and image/object location through a thick lens system
• describe basic clinical applications of a thick lens systems
• the Schematic Eye:  Gullstrand's eye and reduced schematic eye
• Refractive Error:  refractive vs. axial errors, astigmatism
• be able to reproduce rays tracings of refractive errors
• Far Points/Far Lines:  calculations and ray tracings
• Conjugate Points and Planes:  knowledge of basic concepts as well as clinical applications

Reading Assignment: Please read David Guyton's Ophthalmic Optics and Clinical Refraction pages 20-25