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 2024 to help you excel on exam day

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What does the equation P squared times the millimeters moved divided by 1000 represent?

a. Down
b. Vertex compensation formula
c. Less chromatic aberration
d. Wet/dry

The correct answer is: b. Vertex compensation formula

The equation P squared times the millimeters moved divided by 1000 is representative of the vertex compensation formula. This formula is crucial in opticianry as it calculates how much the power of a lens changes as the distance from the lens to the eye changes, particularly in situations where the lens is not positioned at the standard distance (usually 12 mm) from the eye. When considering lenses and their power, it's essential to account for the vertex distance, which can significantly affect how light is focused by the lens onto the retina. The formula captures this relationship effectively, allowing opticians to compensate for any discrepancies caused by the position of the lens, ensuring accurate vision correction for the wearers. This is especially pertinent for higher prescription lenses, where even small changes in vertex distance can have a pronounced effect on visual acuity. Understanding vertex compensation through this formula is vital for providing optimal lens fittings and improving patient satisfaction with their visual correction.