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1. A lens' focal length can be altered by: a. Changing the curvature of one surface b. Coating the surface c. Making the lens bigger d. Making the lens smaller Changing the curvature of one surface. A lens with a higher angle of curvature will have a shorter focal length because the light waves are refracted at a greater angle with respect to the optical axis of the lens. As the refractive index increases or becomes more curved, the focal length of the lens decreases. Coating the surface of the lens will only change the properties of the surface not the focal length and changing the diameter while keeping the curvature of the surfaces of the lens the same, does not impact the angle of curvature or how light waves are refracted. 2. The refraction that a patient likes the most is known as what? a. Cycloplegic refraction b. Comfortable refraction c. Objective refraction d. Subjective refraction The refraction that a patient likes most is the subjective refraction. The subjective refraction is a refinement of the objective refraction which requires patient input while looking through a phoropter with various spherical and cylindrical trial lenses to achieve what the prescription the patient prefers. A cycloplegic refraction is used to identify a patient's total refractive error by temporarily paralyzing the muscles that help in focusing the eye using eye drops. An objective refraction is obtained by the use of retinoscopy or an auto refractor and does not require any patient
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