ABO Refraction & Visual Acuity

Question 1

What does a myopic patient experience without corrective lenses?

Accepted Answer

Blurred distance vision

Answer

Myopia (nearsightedness) causes light to focus in front of the retina, making distant objects appear blurry while near vision remains clear.

Question 2

Which instrument is used to objectively measure a patient's refractive error?

Accepted Answer

Autorefractor

Answer

An autorefractor automatically determines the refractive error of the eye by measuring how light changes as it enters the eye.

Question 3

A prescription reads -2.50 -1.00 x 180. What type of correction does this represent?

Accepted Answer

Compound myopic astigmatism

Answer

A negative sphere with a negative cylinder indicates compound myopic astigmatism, where both principal meridians are myopic.

Question 4

What is the Snellen fraction for a patient who can read the 20/40 line?

Accepted Answer

The patient sees at 20 feet what a normal eye sees at 40 feet

Answer

In Snellen notation, 20/40 means the patient must be at 20 feet to read what a person with normal vision can read at 40 feet.

Question 5

Which lens power would be prescribed for a patient with +3.00 D of hyperopia?

Accepted Answer

Convex (plus) lens of +3.00 D

Answer

Hyperopia requires a convex (plus) lens to add convergence and move the focal point forward onto the retina.

ABO - American Board of Optometry Practice Test