Imaging and Instrumentation in Contact Lens Practice

By: David A. Berntsen, OD, MS, FAAO

1. The index of refraction used by most keratometers is:
a. 1.3375
b. 1.3475
c. 1.3575
d. 1.3675

2. Axial topographic maps are also referred to as:
a. Tangential maps
b. Sagittal maps
c. Elevation maps
d. Depression maps

3. Which type of topography map is especially sensitive to tear film debris?
a. Sagittal
b. Tangential
c. Elevation
d. Depression

4. Higher-order aberrations do not have a greater impact on visual quality under conditions of:
a. Low-contrast viewing
b. High-contrast viewing
c. Mesopic lighting
d. Pupil dilation

5. The 34-year-old male patient with mild keratoconus had a decrease of higher-order aberrations in his right eye from 0.92µm to:
a. 0.88µm
b. 0.78µm
c. 0.68µm
d. 0.58µm

6. A corneal topographer measures:
a. Tens of points
b. Hundreds of points
c. Thousands of points
d. Millions of points

7. Tangential maps are useful when trying to identify the location of corneal:
a. Ectasias
b. Astigmatism
c. Ulcers
d. Infiltrates

8. It takes about how many seconds to acquire topography data with a rotating Scheimpflug camera and scanning slits:
a. 0.5 to 1.0
b. 1.5 to 2.0
c. 2.5 to 3.0
d. 3.5 to 4.0

9. Aspheric soft contact lenses have been reported to produce worse visual acuity than toric or spherical lenses when worn by:
a. Low astigmats who have small pupils
b. Low astigmats who have large pupils
c. High astigmats who have small pupils
d. High astigmats who have large pupils

10. The Visante OCT used with the patient in Figure 7 had a LASIK flap measurement of:
a. 194µm
b. 184µm
c. 174µm
d. 164µm

11. Keratometers measure four points on the central cornea separated by about:
a. 1mm
b. 2mm
c. 3mm
d. 4mm

12. A corneal topographer is absolutely essential when fitting:
a. Orthokeratology lenses
b. Keratoconus lenses
c. Post-surgical lenses
d. Post-refractive surgery lenses

13. Elevation maps report changes in corneal elevation in:
a. Millimeters
b. Centimeters
c. Microns
d. Inches

14. Which topography system uses scanning slits to measure the cornea?
a. Occulus Pentacam
b. Ziemer Galilei
c. Obscan IIz
d. Coherent Zip

15. There is a significant increase with overnight orthokeratology lenses with what type of aberrations?
a. Spherical
b. Coma
c. Trefoil
d. Secondary astigmatism

16. The refractive index of the cornea is about:
a. 1.366
b. 1.376
c. 1.386
d. 1.396

17. Tangential maps are also referred to as:
a. Sagittal maps
b. Elevation maps
c. Depression maps
d. Instantaneous curve maps

18. Which of these shape factors indicates a perfectly spherical surface?
a. 0.3
b. 0.6
c. 1
d. 0

19. Prism-ballast toric lenses versus thin-zone toric lenses induce more:
a. Horizontal coma
b. Spherical aberrations
c. Trefoil
d. Vertical coma

20. The Visante OCT does not allow the user to obtain cross sections of:
a. Anterior segment
b. Posterior segment
c. High resolution corneal images
d. Total corneal pachmetry


Please enter the following personal information for our records:
Business Activity:
First Name:
Last Name:
Address 1:
Address 2:
Address 3:
City:
State:      Zip:
Email Address:
All fields are required before submitting the test.



Please Note: Pressing the above Submit button will complete the test process.
Please only press the button once.