Axes and Angles. This section introduces various methods of optometry to emphasize the principles of refraction, the vergence of light, and ametropia. Students must be able to explain the principles of Badal optometry, and calculate the vergence of light at the Badal lens and at the eye, using a formula as well as by computing vergence from the target distance. Students must know the advantages and disadvantages of Badal optometry. The Scheiner principle is described as a method for refining focus and determining ametropia.
Application is made to recording optometers and the inversion of the retinal image.
Laser optometry is introduced and incorporated into Badal optometry. Students must understand the principles of speckle production and its motion, and the relation between speckle motion and ametropia. Students must know how and why the laser optometer is used to measure the dark focus of accommodation. Optometers are demonstrated in the laboratory. Discomfort and disability glare are compared and contrasted.