the goal is to develop and refine the prescription
can have subjective refraction after retinoscopy or subjective refraction without retinoscopy - you would do it if you are unable to do retinoscopy or are not happy with the result from retinoscopy
if you have not done retinoscopy you would measure the unaided vision, find the best vision sphere then check the cylinder with Jackson cross or fan and block (axis and power) and then recheck sphere. complete for both eyes.
the circle of least confusion is the dioptric midpoint between the anterior and posterior focal lines - it is moved to the retina with spherical lenses then the cylinder is calculated
astigmatic midpoint is the linear distance between the two focal lines
the best vision sphere is the most plus or least minus spherical lens that provides best visual acuity
using the best vision sphere you move the circle of least confusion onto the retina
