The distance at which mires without a lens become clear, when the lensmeter is properly calibrated, is:

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Prepare for the Certified Paraoptometric Assistant (CPOA) Exam. Study with extensive flashcards and multiple choice questions with explanations. Enhance your skills and knowledge to succeed.

Multiple Choice

The distance at which mires without a lens become clear, when the lensmeter is properly calibrated, is:

Explanation:
When the lensmeter is properly calibrated, the mires are sharp when there’s no lens in the path because the optical system is set so that the image sits right at the instrument’s own optical plane. That means no additional distance is needed to bring the pattern into focus—the working distance is zero. In this device, that zero reference is given in feet, so the correct way to express it is zero feet. The other units would still represent zero distance, but the instrument’s standard reporting unit is feet, so zero feet is the appropriate choice.

When the lensmeter is properly calibrated, the mires are sharp when there’s no lens in the path because the optical system is set so that the image sits right at the instrument’s own optical plane. That means no additional distance is needed to bring the pattern into focus—the working distance is zero. In this device, that zero reference is given in feet, so the correct way to express it is zero feet. The other units would still represent zero distance, but the instrument’s standard reporting unit is feet, so zero feet is the appropriate choice.

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