Vision and Ophthalmology Optics and Refraction 3

Question 1

What is the purpose of a lensometer (lensmeter)?

Accepted Answer

Measure the power of a fabricated spectacle lens

Answer

A lensometer (lensmeter or focimeter) measures the prescription (sphere, cylinder, axis, and prism) of a finished spectacle or contact lens.

Question 2

Irregular astigmatism, unlike regular astigmatism, cannot be fully corrected by:

Accepted Answer

Spectacle lenses with cylindrical correction

Answer

Irregular astigmatism has principal meridians that are not perpendicular and cannot be fully corrected with spectacle cylindrical lenses; rigid lenses neutralize the irregular surface.

Question 3

Snellen visual acuity of 20/40 means the patient can see at 20 feet what a normal eye can see at:

Accepted Answer

40 feet

Answer

20/40 acuity means the patient must be at 20 feet to resolve detail that a person with normal vision can resolve at 40 feet.

Question 4

What is the near point of accommodation in a fully accommodating emmetropic eye?

Accepted Answer

Approximately 7–10 cm (varies by age)

Answer

In young emmetropes with maximal accommodation, the near point can be approximately 7–10 cm, with amplitude of accommodation decreasing with age.

Question 5

Which test uses polarized filters to measure stereoacuity (depth perception)?

Accepted Answer

Random dot stereotest (e.g., Randot)

Answer

Random dot stereotests like the Randot or TNO test use polarized or anaglyph filters to present disparate images to each eye, testing stereoscopic depth perception.

Vision and Ophthalmology Practice Test

Vision and Ophthalmology Practice Test

Vision and Ophthalmology Optics and Refraction 3