AOA Optics and Refraction

Question 1

In an eye with simple myopia, the far point is located:

Accepted Answer

At a finite distance in front of the eye

Answer

In myopia the parallel rays from infinity focus in front of the retina; the far point (where diverging rays appear to come from) is at a finite real distance anterior to the eye.

Question 2

When performing retinoscopy, a 'with' reflex indicates that the eye's far point is:

Accepted Answer

Behind the examiner (hyperopia or low myopia)

Answer

A 'with' motion reflex during retinoscopy means the far point is beyond the examiner's working distance, indicating hyperopia or myopia less than the working lens.

Question 3

The principal effect of a minus cylinder lens is to:

Accepted Answer

Reduce power in one meridian while leaving the other unchanged

Answer

A minus cylinder lens has zero power along its axis meridian and maximum minus power 90° away, selectively reducing power in one meridian.

Question 4

Chromatic aberration in the eye is primarily responsible for which clinical phenomenon?

Accepted Answer

Blue light focusing slightly anterior to red light (longitudinal chromatic aberration)

Answer

The ocular media have higher refractive index for shorter wavelengths; blue light focuses about 2D anterior to red, a phenomenon used in the duochrome (red-green) test.

Question 5

The power of a thin lens required to correct a 4D myope is:

Accepted Answer

-4.00 D

Answer

To move the far point from 25 cm in front of the eye to optical infinity, a diverging lens of -4.00 D (focal length -25 cm) is required.

AOA - American Optometric Association Practice Test

AOA - American Optometric Association Practice Test

AOA Optics and Refraction