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9 Cards in this Set
- Front
- Back
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Presbyope with Rx: +0.25 - 0.75 X 180 OU
Requesting a trifocal lens. Which lens material will you choose? |
Trifocals only available in CR39 (1.39), polycarbonate (1.58) and crown glass (1.52). Since this Rx is low would choose CR39.
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What type of bevel is in a zyl frame?
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Inverted V bevel
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What depth (of intermediate) and width (of segment) are available in trifocals?
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7/28
8/35 |
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Presbyope with Rx: +3.75 - 0.50 X 180 OU
Requesting an executive trifocal. Any potential problem with this? |
High plus Rx. Executive trifocals only available in crown glass or CR39. Glass will be thinner since n is higher but will be heavy. CR39 will be very thick with this Rx.
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What minimum add power do you need for trifocal?
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+200
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How is the height measurement different for a bifocal vs a trifocal
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Bifocal measure to lower lid margin
Trifocal measure to lower pupil margin as the bifocal line/height is set automatically by the manufacturer. |
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What %Add are possible for vocational lenses?
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50%, 66%, 100%
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What is the standard depth requirement for vocational lenses? What lens materials are available?
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- distance separation between the lower set and upper set is automatically 13mm
- frame should have enough room for distance portion + 2 add segments - available in CR39, polycarbonate, crown glass |
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What consideration will you explain about your patient's vocational lenses?
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- these are recommended for work only
- not ideal for driving - recommend a separate pair of 'dress' glasses |
