If a bifocal has 3 prism diopters, the seg height adjustment would be 1 mm. Which statement is true?

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Prepare for the Ophthalmic Optics Exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

If a bifocal has 3 prism diopters, the seg height adjustment would be 1 mm. Which statement is true?

Explanation:
The segment height is adjusted to compensate for vertical prism so the near portion lines up with the pupil. A handy rule is: for every about 3 prism diopters of vertical prism, raise the bifocal segment by 1 mm. So with 3 prism diopters, you increase the seg height by 1 mm to keep the reading portion properly aligned. Increasing by 2 mm would correspond to about 6PD, and decreasing by 1 mm would worsen misalignment.

The segment height is adjusted to compensate for vertical prism so the near portion lines up with the pupil. A handy rule is: for every about 3 prism diopters of vertical prism, raise the bifocal segment by 1 mm. So with 3 prism diopters, you increase the seg height by 1 mm to keep the reading portion properly aligned. Increasing by 2 mm would correspond to about 6PD, and decreasing by 1 mm would worsen misalignment.

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