In the Lighthouse method, the working distance is expressed in which unit?

Study for the NBEO Physiological Optics Test. Prepare with flashcards and multiple-choice questions, each question has hints and explanations. Ace your exam!

Multiple Choice

In the Lighthouse method, the working distance is expressed in which unit?

Explanation:
In this method, the distance from the eye to the instrument is tied directly to refractive power, so the working distance is expressed as diopters. Diopters are the reciprocal of distance in meters, which lets you convert the viewing distance into a lens power that you then use to determine the refraction. For example, a common 50 cm working distance equals 0.50 m, which is 2 diopters. Thus, the unit used is diopters, because the measurement serves to indicate refractive power rather than just a physical distance.

In this method, the distance from the eye to the instrument is tied directly to refractive power, so the working distance is expressed as diopters. Diopters are the reciprocal of distance in meters, which lets you convert the viewing distance into a lens power that you then use to determine the refraction. For example, a common 50 cm working distance equals 0.50 m, which is 2 diopters. Thus, the unit used is diopters, because the measurement serves to indicate refractive power rather than just a physical distance.

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