Free NBEO Applied Basic Science Questions and Answers

Question 1

A +7.00 D lens has a real object located 20 cm from the lens. The conjugate image is:

Accepted Answer

real and located 50 cm from the lens

Answer

Explanation:
With a +7.00 D lens and a real object 20 cm from the lens, the image is real and located 50 cm from the lens. This is because the lens equation yields this result.

Question 2

A lens is made of glass with a refractive index of 1.65. What would be the refractive index for the ideal anti-reflection coating?

Accepted Answer

1.28

Answer

Explanation:
An ideal anti-reflection coating aims to minimize reflection by having a refractive index that's the geometric mean of the lens material (1.65) and air (approximately 1.0). So, the coating's refractive index would be approximately 1.28.

Question 3

An eye under the influence of an extremely strong miotic agent has a pupil diameter of 1 mm. The resolution of this eye is considered to be limited by:

Accepted Answer

diffraction

Answer

Explanation:
When the pupil diameter is very small (like 1 mm under the influence of an extremely strong miotic agent), the resolution of the eye is mainly limited by diffraction. Diffraction causes light waves to bend around the edges of the pupil, leading to a blurring effect on the image formed on the retina.

Question 4

The Jackson crossed cylinder subjective test begins with a -1.00 -1.75 x 090 lens in front of a patient's eye. If the correcting cylinder power is changed to -0.75 x 090, then the spherical power should now be:

Accepted Answer

-1.50 DS

Answer

Explanation:
In the Jackson crossed cylinder subjective test, when the correcting cylinder power is changed from -1.00 -1.75 x 090 to -0.75 x 090, the spherical power should be adjusted in the opposite direction. Since the cylinder power is being reduced by 0.25 D (from -1.75 to -1.00), the spherical power should be increased by the same amount to maintain the patient's prescription. Therefore, the new spherical power should be -1.50 DS.

Question 5

A 53-year-old male complains of occasional blur at a distance and near. His visual acuities are 20/30 in each eye at distance and near with his present lens correction of +1.00 DS OU,  Add +1.75 D. Your distance refraction for 20/20+  acuity is +1.50 DS OU. The BEST  tentative Add for the new prescription will have the power of:

Accepted Answer

+1.75 D

Answer

Explanation:
To find the added power, subtract the distance refraction (+1.50 DS OU) from the near refraction (+1.00 DS OU + Add). This gives us +1.75 D. Therefore, the best tentative add for the new prescription is +1.75 D.

NBEO - National Board of Examiners in Optometry Practice Test

NBEO - National Board of Examiners in Optometry Practice Test

Free NBEO Applied Basic Science Questions and Answers