Certified Ophthalmic Assistant Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The formula used to calculate the induced prismatic effect caused by spectacle lenses with decentered optical centers is the Prentice rule. The Prentice rule states that the amount of prism induced by a lens with a decentered optical center can be calculated by multiplying the prism power by the distance (in meters) from the optical center to the patient's pupil. This rule is essential in correcting for induced prismatic effects to ensure accurate vision correction for the patient.

Option A, the Fresnel equation, is used to calculate the thin lens equation for lenses with very small thicknesses, typically for Fresnel lenses used in low vision aids.

Option B, the Gullstrand equation, is used in ophthalmic optics to calculate the power of an intraocular lens based on the desired refractive outcome.

Option D, Snell's Law, describes the behavior of light rays as they pass through the boundary between two different media and is not directly related to calculating induced prism caused by decentered optical centers in spectacle lenses.