ABO Ametropia/Ophthalmic Optics 5

Question 1

Anisometropia is clinically significant when the difference in refractive error between the two eyes exceeds approximately:

Accepted Answer

1.00 D

Answer

A difference of 1.00 D or more between eyes is generally considered clinically significant anisometropia that may affect binocular vision.

Question 2

What is the prismatic effect at a point 8 mm below the optical center of a -5.00 D lens (Prentice's rule)?

Accepted Answer

4.0Δ base-up

Answer

P = c × F = 0.8 cm × 5.00 = 4.0Δ; a minus lens produces base-up prism in the inferior portion (base toward optical center).

Question 3

Which of the following best describes 'lenticular myopia'?

Accepted Answer

Myopia caused by increased curvature or index of the crystalline lens

Answer

Lenticular myopia results from optical changes within the crystalline lens, such as increased curvature, thickness, or index of refraction.

Question 4

The power of a spherical refracting surface is calculated using which formula?

Accepted Answer

P = (n' - n) / r

Answer

The power of a single refracting surface is P = (n' - n) / r, where n' is the exit medium, n is the entry medium, and r is the radius in meters.

Question 5

A patient with high myopia (-10.00 D) is best served by high-index lens materials primarily because:

Accepted Answer

They reduce lens thickness and weight

Answer

Higher index materials allow the same power to be achieved with less curvature, resulting in thinner and lighter lenses for high prescriptions.

ABO - American Board of Optometry Practice Test