Cross Cylinder Technique: Basics of Astigmatism and Testing

This is part 1 of a 5-part series titled "Subjective Refraction: Cross Cylinder Technique," which reviews the Jackson cross cylinder, emmetropia and astigmatism, cycloplegic refraction, how to determine add, accommodation and lens correction, and how to prescribe multifocal lenses.

Part 1: Cross Cylinder Technique: Basics of Astigmatism and Testing
Part 2: Cross Cylinder Technique: Adjusting the Sphere
Part 3: Cross Cylinder Technique: Cross Cylinder Testing
Part 4: Cross Cylinder Technique: Refinement, Balancing, and Lens Correction
Part 5: Cross Cylinder Technique: Cycloplegia, Determining Add, and Prescribing Lenses