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| 1. Focal power is equal to: |
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A.
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Front Curve + Back Curve |
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B.
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Front Curve – Back Curve |
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C.
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Front Curve × Back Curve |
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D.
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Front Curve ÷ Back Curve |
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| 2. Plus lenses generally require _________ front (base) curves than ________ lenses: |
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A.
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steeper, plus |
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B.
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steeper, minus |
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C.
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Flatter, plus |
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D.
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Flatter, minus |
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| 3. In lens design, the term corrected curve is synonymous with the term: |
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A.
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Broken Lens |
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B.
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Best Form Lens |
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C.
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Bi-Concave Lens |
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D.
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Plano-Convex Lens |
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| 4. Flattened lens forms without asphericity generally do NOT provide: |
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A.
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Thinner Lenses |
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B.
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Lighter Lenses |
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C.
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Flatter Lenses |
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D.
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Good Peripheral Vision |
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| 5. Aspheric lens designs offer the following advantage(s): |
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A.
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Flatter Lens |
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B.
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Thinner Lens |
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C.
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Good Peripheral Vision |
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D.
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All of the Above |
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| 6. Best form lenses provide the following advantage(s): |
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A.
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Flatter Lens |
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B.
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Thinner Lens |
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C.
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Good Peripheral Vision |
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D.
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All of the Above |
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| 7. The following lens aberration is a primary concern for ophthalmic lens design: |
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A.
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Coma |
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B.
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Oblique Astigmatism |
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C.
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Spherical Aberration |
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D.
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Surface Waves |
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| 8. Oblique astigmatism produces the following type of focusing error: |
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A.
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Cylinder-like Error |
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B.
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Spherical-like Error |
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C.
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Color Error |
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D.
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Magnification Error |
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| 9. Curvature of the field or power error produces the following type of focusing error |
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A.
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Cylinder-like Error |
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B.
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Spherical-like Error |
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C.
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Color Error |
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D.
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Magnification Error |
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| 10. The factory-finished curve that becomes the basis from which the remaining curves are determined is called: |
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A.
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Side Curve |
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B.
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Eye Curve |
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C.
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Base Curve |
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D.
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High Curve |
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| 11. Tscherning's ellipse is a graph of the two recommended “best form” base (or front) curves for each: |
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A.
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Center Thickness |
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B.
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Back Curve |
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C.
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Lens Power |
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D.
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Color |
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| 12. Aspheric lenses use surface astigmatism to neutralize or eliminate: |
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A.
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Oblique Astigmatism |
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B.
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Coma |
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C.
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Surfacing Waves |
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D.
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Chromatic Aberration |
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| 13. A +4.00 D lens, made with a +8.00 D front curve, will have the following back curve: |
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A.
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+2.00 D |
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B.
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-2.00 D |
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C.
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-4.00 D |
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D.
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-6.00 D |
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| 14. Plus lenses generally produce the following type of distortion: |
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A.
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Orthoscopy (none) |
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B.
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Minus Distortion |
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C.
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Barrel Distortion |
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D.
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Pin-Cushion Distortion |
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| 15. Of the choices listed, the “best form” base (or front) curve for a +3.00 D lens would most likely be: |
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A.
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8.00 D Base |
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B.
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6.00 D Base |
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C.
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4.00 D Base |
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D.
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2.00 D Base |
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| 16. The base (or front) curve of a lens will generally influence: |
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A.
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Lens Aberrations |
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B.
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Lens Thickness |
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C.
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Magnification |
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D.
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All of the Above |
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| 17. A lens ___________ acts like a departure (or error) from the desired _______________: |
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A.
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Aberration, spectacle prescription |
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B.
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Impact, spectacle prescription |
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C.
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Aberration, impact resistance |
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D.
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Impact, atoricity |
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| 18. Minus lenses generally produce the following type of distortion: |
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A.
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Orthoscopy (none) |
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B.
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Plus Distortion |
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C.
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Barrel Distortion |
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D.
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Pin-Cushion Distortion |
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| 19. The flatter branch of “best form” base curves in Tscherning's ellipse is often associated with this person: |
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A.
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Wollaston |
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B.
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Ostwalt |
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C.
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Petzval |
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D.
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Seidel |
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| 20. A surface with asphericity that varies from meridian to meridian around the lens surface is referred to as: |
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A.
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Spherical |
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B.
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Toric |
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C.
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Aspheric |
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D.
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Atoric |
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| 21. The following curve(s) can be produced from a conic section: |
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A.
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Ellipse |
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B.
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Parabola |
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C.
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Hyperbola |
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D.
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All of the Above |
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| 22. If asphericity is applied to the front surface of a plus lens, the surface will typically become: |
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A.
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Steeper Away from the Center |
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B.
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Atoric Away from the Center |
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C.
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Flatter Away from the Center |
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D.
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None of the Above |
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| 23. Asphericity is required for cataract lenses because Tscherning's ellipse has a maximum limit of: |
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A.
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+15.00 D |
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B.
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+7.50 D |
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C.
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-15.00 D |
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D.
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-23.00 D |
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| 24. The following lens aberration is due to the dispersive properties of the lens material: |
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A.
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Chromatic Aberration |
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B.
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Curvature of the Field |
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C.
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Oblique Astigmatism |
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D.
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Spherical Aberration |
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| 25. Aspheric lenses are typically ______________ than comparable lenses using spherical, “best form” base (or front) curves: |
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A.
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Thicker and steeper |
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B.
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Thinner and flatter |
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C.
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Thicker and flatter |
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D.
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Thicker and steeper |
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| 26. The small pupil aperture of the eye limits the effects of this lens aberration(s): |
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A.
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Spherical Aberration Only |
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B.
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Coma Only |
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C.
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Coma and Spherical Aberration |
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D.
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Oblique Astigmatism |
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| 27. Manufacturers group small ranges of prescriptions together upon common lens blanks to minimize |
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A.
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Inventory requirements |
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B.
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Costs |
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C.
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All lens errors |
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D.
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A & B only |
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| 28. The following is NOT NECESSARILY a potential benefit of aspheric lenses: |
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A.
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Flatter Height than Best Form Lenses |
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B.
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Thinner Center than Best Form Lenses |
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C.
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Lighter Weight than Best Form Lenses |
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D.
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Better Optics than Best Form Lenses |
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| 29. The prescription errors caused by lens aberrations will NOT increase with the following factor(s): |
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A.
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Distance from Optical Center |
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B.
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Departure from Best Form Design |
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C.
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Strength of the Prescription |
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D.
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Weight of the Lens |
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| 30. According to Vogel's formula, a -4.00 D prescription would require a front curve of: |
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A.
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8.00 D |
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B.
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6.00 D |
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C.
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4.00 D |
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D.
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2.00 D |
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| 31. The applications of asphericity generally do NOT include the following: |
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A.
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Better Optics in Flattened Lenses |
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B.
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Better Optics in Steepened Lenses |
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C.
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Better Optics in High Plus Lenses |
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D.
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Better Optics in Lenses with Cylinder |
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| 32. The widest fields of clear vision for a +4.00 -2.00 × 45 prescription can be obtained using: |
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A.
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Aspheric Designs |
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B.
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Atoric Designs |
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C.
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Best Form Designs |
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D.
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Corrected Curve Designs |
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| 33. Tilting a spectacle lens can introduce a form of: |
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A.
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Oblique astigmatism |
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B.
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Asphericity |
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C.
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Prescription compensation |
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D.
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Paraxial smoothing |
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| 34. The region in the vicinity of the optical center in which incident rays of light make small angles to the optical axis is known as: |
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A.
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Tangential Plane |
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B.
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Sagittal Plane |
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C.
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Paraxial Region |
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D.
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Axis of Symmetry |
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| 35. The term “corrected curve” is synonymous with |
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A.
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Best Form |
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B.
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Conic Curve |
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C.
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Base Curve |
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D.
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Atoric Surface |
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| 36. The following lens form is NOT a plus lens: |
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A.
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Bi-Convex |
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B.
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Bi-Concave |
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C.
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Plano-Convex |
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D.
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All of the Above |
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| 37. The two perpendicular planes associated with oblique refraction are referred to as: |
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A.
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Tangential and Sagittal Planes |
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B.
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Principal Meridians |
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C.
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Sphere and Cylinder Meridians |
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D.
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None of the Above |
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| 38. Unequal retinal image sizes caused by a difference in prescription between the right and left eyes is referred to as: |
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A.
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Spherical Aberration |
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B.
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Astigmatism |
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C.
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Aniseikonia |
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D.
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Curvature of the Field |
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| 39. The ________ surface is generally steeper than the far-point sphere: |
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A.
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Wollaston |
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B.
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Ostwalt |
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C.
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Petzval |
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D.
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Seidel |
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| 40. For every 2° of pantoscopic tilt, the optical center should ideally be located below the pupil center to avoid astigmatism due to lens tilt by: |
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A.
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-1.0 mm |
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B.
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0.5 mm |
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C.
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1.0 mm |
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D.
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2.0 mm |
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