American Board of Opticianry (ABO) Practice Test

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Prepare for the ABO (American Board of Opticianry) Test with interactive flashcards and hundreds of multiple choice questions. Updated for 2025 to help you excel on exam day

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What is the relationship between the bifocal add and the lens when using a lensometer?

Front side
Back side
Bottom side
Top side

The correct answer is: Back side

The relationship between the bifocal add and the lens when using a lensometer is that it is typically measured on the front side of the lens. When taking measurements, the lensometer requires the lens to be placed with the front surface facing the lensometer. This allows for accurate readings of both the distance and near prescriptions, including the bifocal add. In the case of bifocal lenses, the "add" refers to the additional power prescribed for near vision, which is located in the lower segment of the lens. When measuring, it's essential to focus on the front side where both segments can be evaluated. Hence, the front side of the lens is where the lensometer will measure the overall curvature and power, including the bifocal addition. This process ensures that the eyecare practitioner can accurately confirm that the bifocal prescription aligns correctly for patient use.