ABO Ophthalmic Dispensing 3

Question 1

Which lens material has the highest Abbe value among common ophthalmic materials?

Accepted Answer

CR-39 (plastic)

Answer

CR-39 has an Abbe value of approximately 58, the highest among common ophthalmic lens materials, meaning least chromatic aberration.

Question 2

In frame adjustment, the 'face-form angle' (wrap) primarily affects which aspect of the fit?

Accepted Answer

The degree to which the frame curves to follow the face

Answer

Face-form angle (wrap) describes how much the frame front curves horizontally to follow the contour of the face.

Question 3

A prescription with cylinder power is written in minus cylinder form as -2.00 -1.50 x 045. What is the equivalent plus cylinder form?

Accepted Answer

-3.50 +1.50 x 135

Answer

To transpose: new sphere = algebraic sum of sphere and cylinder (-2.00 + -1.50 = -3.50), new cylinder = same magnitude with opposite sign (+1.50), new axis = 90° away (045 + 90 = 135).

Question 4

The segment height for a flat-top bifocal is measured from the:

Accepted Answer

Bottom of the frame to the top of the segment

Answer

Segment height is measured from the lowest point of the frame's inner groove (bottom) up to the top of the bifocal segment.

Question 5

Which of the following coatings primarily reduces internal lens reflections that reach the wearer's eyes from behind?

Accepted Answer

Anti-reflective (AR) coating

Answer

AR coating reduces reflections on both front and back lens surfaces, including light entering from behind that would otherwise reflect into the wearer's eyes.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Ophthalmic Dispensing 3