POST TEST FOR MODULE 17:  Clinical Optics, Part 1                  Catalog      

Including:
Section 1: Lens Aberrations
Section 2: Base Curve

Section 3: Optical Center

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Section 1

1. Light rays from the edge of a lens are refracted to a greater degree than those through the center.  This describes:

A. distortion

B. coma

C. spherical aberration

D. chromatic aberration   

2. A minus lens will cause ______ distortion.

A. pincushion

B. barrel

C. curvature of field

D. magnification     

3. Which aberration is most completely eliminated by the pupil (pinhole effect)?

A. distortion

B. coma

C. spherical aberration

D. chromatic aberration   

4. Chromatic aberration is measured by the:

A. mm ruler

B. color scale

C. Index of refraction

D. Abbe value    

5. Magnification and minification are affected by:

A. pupil size

B. lens power

C. vertex distance

D. B and C          

Section 2

6. When making a glasses lens, the lab uses _____ to minimize distortion in the lens.

A. corrected curve theory

B. the flattest base curve

C. the steepest base curve

D. trial and error         

7. The front surface curve of a glasses lens is:

A. the base curve

B. the ocular curve

C. the most minus curve

D. always plano        

8. If the base curve of a lens is +6 and the ocular curve is -3, then the lens power is:

A. +6.00

B. -3.00

C. +3.00

D. -6.00        

9. If the lens power is +2.00 and the base curve is +6.00, then the ocular curve is:

A. +4.00

B. -4.00

C. +8.00

D. -8.00      

10. The base curve of a glasses lens is measured with a:

A. radiuscope

B. lensometer

C. Geneva lens measure

D. mm ruler        

Section 3

11. Which is not part of the definition of the optical center of a lens?

A. thickest part of a plus lens

B. thickest part of a minus lens

C. thinnest part of a minus lens

D. base curve - ocular curve       

12. The optical center of a progressive lens can be found by:

A. centering the mires in the lensometer

B. measuring 6mm from the top edge of the lens

C. finding and marking the engravings on the lens

D. subtracting the ocular curve from the base curve     

13. Optical center decentration occurs when the:

A. PD = OCD

B. PD does not equal the OCD

C. base curve = the ocular curve

D. base curve does not equal the ocular curve     

14. If a patient is looking through a plus lens, and the PD is less than the OCD, then a ____ prismatic effect results.

A. base-up

B. base-down

C. base-in

D. base-out     

15. What is the induced prism created when a 5 D lens is decentered 2mm?

A. 1 D

B. 10 D

C. 2.5 D

D. 3 D