ABO Ophthalmic Dispensing 2

Question 1

A patient's prescription reads +2.50 -1.00 x 090. What is the power in the 180° meridian?

Accepted Answer

+1.50 D

Answer

At 180°, the cylinder has no effect, so the power is the sphere (+2.50) plus the cylinder component at that meridian; the 90° axis means full cylinder effect at 180°, giving +2.50 + (-1.00) = +1.50 D.

Question 2

Which frame measurement represents the distance between the two lenses at their closest point?

Accepted Answer

DBL (distance between lenses)

Answer

DBL (distance between lenses) is the bridge measurement representing the narrowest gap between the two lenses.

Question 3

Progressive addition lenses typically have an unwanted astigmatism zone located:

Accepted Answer

In the lateral peripheral areas

Answer

Unwanted (peripheral) astigmatism in PALs is concentrated in the lateral areas on either side of the progressive corridor.

Question 4

When using a lensometer to verify a bifocal lens, the add power is determined by:

Accepted Answer

Subtracting the distance power from the near zone power

Answer

Add power equals the net near zone power minus the net distance power measured by the lensometer.

Question 5

A high-minus lens will have the thinnest point at the:

Accepted Answer

Edge of the lens

Answer

Minus lenses are thicker at the center and thinner at the edges, so the edge is the thinnest point.

ABO - American Board of Optometry Practice Test

ABO - American Board of Optometry Practice Test

ABO Ophthalmic Dispensing 2