Near Point Accommodation

Question 1

Depth of focus

Answer 1

variation in image distance without a noticeable decrease in sharpness of focus.

Question 2

Depth of field

Answer 2

variation in object distance without a noticeable decrease in sharpness of focus.

Question 3

Lag of Accommodation

Answer 3

the human’s ability to accommodate less than the stimulus and see clearly, making full use of the depth of focus and depth of field

Question 4

Normal lag of accommodation values

Answer 4

0.50D to 0.75D

Question 5

If a patient has a normal lag, that patient is accommodating ____ than the stimulus by 0.50D to 0.75D

Answer 5

less

Question 6

If a patient accommodates equal to the stimulus, that patient is “___________________” in human vision terms

Answer 6

over accommodating

Question 7

If a patient accommodates more than the stimulus, that patient is said to have a “________________”

Answer 7

lead of accommodation

Question 8

Where is the near lag determination applied?

Answer 8

It is applied to any near reading distance at which the patient looks, even though the tests distance may not be where the patient reads.

Question 9

What is the purpose of FCC?

Answer 9

the purpose of the 40cm cross cylinder testing is to subjectively determine the lag of accommodation

Question 10

What is the target for FCC testing? Why?

Answer 10

The target is a cross grid, or a “T” to minimize the accommodative stimulus involved in attempting to discern letters

Question 11

FCC setup

Answer 11

• The illumination is dim. This causes the pupil to dilate and decreases depth of focus.
• The cross grid and the dim light are to minimize extra accommodation, so that the patient is only accommodating to the incident vergence at 40cm.
• Add +/- .50D to have artificial sturm

Question 12

In FCC, if the patient reports that the lines are equal or the horizontal set is darker, add more ___ until the vertical lines are blacker. Then decrease until they are equal.

Answer 12

plus