chapter 14 refactometry

Question 1

Which of the following prescriptions denotes emmetropia?
a) +2.00 sphere
b) –2.00 sphere
c) Plano + 2.00 × 180
d) Plano sphere

Answer 1

D- plano sphere

Question 2

In hyperopia:
a) the object image focuses on the retina
b) the object image focuses on the cornea
c) the object image focuses in the vitreous
d) the object image focuses beyond the macula

Answer 2

D- the object image focuses beyond the macula

Question 3

Farsightedness may be caused by all of the following except:
a) heredity
b) removal of the crystalline lens
c) orbital tumor
d) migraine headaches

Answer 3

D- migraine headaches

Question 4

If your patient complains of blurred vision at near, the most likely cause is:
a) hyperopia
b) presbyopia
c) astigmatism
d) need more information

Answer 4

d- need more information

Question 5

The classic symptom of myopia is:
a) blurred vision at near
b) blurred vision at distance
c) blurred vision at near and distance
d) headaches

Answer 5

D- headaches

Question 6

Presbyopia is caused by:
a) removal of the crystalline lens
b) loss of muscle tone in the ciliary muscle
c) degeneration of the zonules
d) loss of elasticity of the crystalline lens

Answer 6

D- loss of elasticity of the crystalline lens

Question 7

A classic complaint of the presbyopic patient is:
a) “I cannot see where I’m going in a dark movie theater.”
b) “My arms are too short.”
c) “My eyes itch and burn.”
d) “My eyes draw and pull.”

Answer 7

B- my arms are too short

Question 8

A presbyopic myope with distance correction may find that his or her near vision improves if the patient: a) closes one eye
b) wears contact lenses
c) holds the reading material closer
d) takes off his or her glasses

Answer 8

D- takes off his or her glasses

Question 9

A 75-year-old patient states that he wears contact lenses because he had cataract surgery without implants. You need to remove the contacts for part of the exam, but the patient objects. Why?
a) He is virtually blind without them.
b) He can read without the contacts, but cannot drive. c) He can drive without the contacts, but cannot read. d) His eyes are more comfortable with the lenses in.

Answer 9

A- he is virtually blind without them

Question 10

An autorefraction reading would be helpful in all of the following cases except:
a) prescribing glasses (without subjective testing)
b) following cataract surgery
c) evaluating an aphasic patient
d) evaluating the refractive error of a child

Answer 10

A- prescribing glasses (without subjective testing)

Question 11

The key instruction to the patient during automated refractometry (AR) is:
a) “Don’t blink.”
b) “Tell me if the image blurs.”
c) “Look straight ahead.”
d) “Hold your breath.”

Answer 11

C- “look straight ahead.”

Question 12

Some autorefractors allow the assistant to manipulate the reading in order to provide the clearest image possible. This pushes the AR into the realm of:
a) subjective testing
b) retinoscopy
c) prescribing
d) duochrome testing

Answer 12

A- subjective testing

Question 13

Performing an AR after the patient is dilated:
a) provides no useful information
b) will be inaccurate
c) is needed when prescribing bifocals
d) may reveal additional hyperopia

Answer 13

D- may reveal additional hyperopia

Question 14

An AR measurement may be used:
a) to plug into an intraocular lens formula
b) to confirm change between current glasses and refraction
c) as a glasses prescription
d) to guide laser-assisted in situ keratomileusis (LASIK) surgery

Answer 14

B- to confirm change between current glasses and refraction

Question 15

The target in most autorefractors simulates distance viewing in order to avoid:
a) accommodation
b) unequal pupil size
c) induced prism
d) visual fatigue

Answer 15

A- accommodation

Question 16

An appropriate use of an AR measurement would be: a) to select final contact lens power
b) use in intraocular lens (IOL) calculation
c) starting point for retinoscopy
d) starting point for subjective refractometry

Answer 16

D- starting point for subjective refractometry

Question 17

Error in AR measurement can result from:
a) inaccurate pupillary distance
b) having the instrument in a lighted hallway
c) using the incorrect cylinder format
d) induced prism

Answer 17

B- having the instrument in a lighted hallway

Question 18

Which of the following is true regarding the difference between “refraction” and “refractometry”?
a) Objective measurement is used in refractometry.
b) Only refractions are written in the patient’s chart.
c) Clinical judgment is used in a refraction.
d) Only a licensed practitioner can perform refractometry.

Answer 18

C- clinical judgement is used in a refraction

Question 19

Which of the following will give the technician the most useful information regarding the patient’s refractive status?
a) the history
b) the muscle balance check
c) the slit-lamp exam
d) the fundus exam

Answer 19

A- the history

Question 20

In order to avoid compromising the distance measurement, refractometry should be performed prior to:
a) tonometry
b) retinoscopy
c) pupil exam
d) muscle balance testing

Answer 20

A- tonometry

Question 21

Before beginning the refractometric measurement on an adult, it is important to:
a) explain the procedure
b) have an autorefractor reading
c) make sure he or she can read 20/20 d) instill artificial tears to clear the tear film

Answer 21

A- explain the procedure

Question 22

All of the following are true regarding fogging except: a) it may be used to avoid giving too much plus at near
b) it may be used to help prevent giving too much minus
c) it can be used as an alternative to occlusion
d) it can be used to relax accommodation

Answer 22

A- it may be used to avoid giving too much plus at near

Question 23

Fogging is accomplished by:
a) placing a polarized lens in front of the eye to blur the vision
b) placing the Bagolini lens in front of the eye to blur the vision
c) placing enough plus power in front of the eye to blur the vision
d) placing a Maddox rod in front of the eye to blur the vision

Answer 23

C- placing enough plus power in front of the eye to blur the vision

Question 24

When offering the patient changes in spheres, a good general rule is to:
a) refine the axis before the power
b) offer more plus first
c) offer more minus first
d) always use minus cylinder

Answer 24

B- offer more plus first

Question 25

The astigmatic dial2 is useful for:
a) finding the exact cylinder power
b) refining astigmatic correction
c) finding the exact cylinder direction
d) estimating the cylinder axis

Answer 25

D- estimating the cylinder axis

Question 26

When using plus cylinder, if the patient says that all the lines on the astigmatic dial seem to be equally clear:
a) the test is over; proceed directly to cross-cylinder refinement
b) turn the cylinder axis knob 45 degrees, and ask again if any lines are darker
c) add +0.50 sphere, and ask again if any lines are darker
d) open the aperture, and try the test with both eyes together

Answer 26

C- add +0.50 sphere, and ask again if any lines are darker

Question 27

When using the astigmatic dial, once you have set your axis, you should:
a) add cylinder until all lines are equally clear
b) add sphere until all lines are equally clear
c) use the cross-cylinder until all lines are equally clear d) remove the dial and refine with the cross-cylinder

Answer 27

a- add cylinder until all lines are equally clear

Question 28

You are measuring a patient from scratch (no retinoscopy, lensometry, or prior records). Your best spherical correction is +2.00 sphere for 20/60 vision. You use the astigmatic dial and find that the lines are equally black with cylinder –1.50 × 180. What is your next step?
a) Change the sphere setting to +2.75.
b) Change the sphere setting to +1.25.
c) Refine the cylinder axis.
d) Record the measurement.

Answer 28

a- change the sphere setting to +2.75

Question 29

Before cross-cylinder testing, it is important to:
a) be close to the sphere power endpoint
b) refine sphere power to the endpoint
c) measure for bifocal add
d) balance the two eyes

Answer 29

a- be close to the sphere power endpoint

Question 30

On cross-cylinder testing:
a) the power of the sphere should always be measured first, then its axis
b) the axis of the sphere should be measured first, then its power
c) the power of the cylinder should be measured first, then its axis
d) the axis of the cylinder should always be measured first, then its power

Answer 30

A- the power of the sphere should always be measured first, then its axis

Question 31

When refining the axis using minus cylinder, you should follow which dot on the cross-cylinder?
a) red
b) white
c) blue
d) there are no dots on the cross-cylinder

Answer 31

A- red

Question 32

You are using plus cylinder and are refining cylinder power. The present cylinder power is +0.50. The patient says that the letters are more clear when the white dot is showing on the cross-cylinder. What should you do now?
a) rotate the axis toward the white dot
b) change the cylinder power to zero
c) change the cylinder power to +1.00
d) stop because you are at the endpoint

Answer 32

C- change the cylinder power to +1.00

Question 33

You are using minus cylinder and are refining cylinder power. The present cylinder power is –1.00. The patient says that the letters are clearer when the white dot is showing on the cross-cylinder. What should you do now?
a) switch to plus cylinder
b) change the cylinder power to –1.50
c) change the cylinder power to –0.50
d) change the sphere power by +0.50

Answer 33

c- change the cylinder power to -0.50

Question 34

The generally accepted endpoint for the cross-cylinder test (for either axis or power refinement) is: a) when the first choice is better than the second choice
b) when the second choice is better than the first choice
c) when the two choices appear equal
d) when the patient states his or her vision is most comfortable

Answer 34

c- when the two choices appear equal

Question 35

Your patient reads 20/20 with the following setting: –2.00 + 1.25 × 065. To refine the sphere, you first change the sphere setting to –1.75. The patient says the 20/20 line is now a bit blurred. You show her –2.00 again, and she says it is clearer. Now, you change the sphere to –2.25. The patient says the letters are smaller but clearer. She cannot read 20/15 at any setting. What is your next step?
a) see if –2.50 helps
b) record the final measurement as –2.25 + 1.25 × 065 c) record the final measurement as –2.00 + 1.25 × 065 d) record the final measurement as –1.75 + 1.25 × 065

Answer 35

a- see if - 2.50 helps

Question 36

The duochrome technique3 of refining sphere depends on:
a) the fact that green rays are refracted more than red rays
b) red rays will appear orange, and green rays will appear blue
c) the patient having normal color vision
d) contrast sensitivity to red light as opposed to green light

Answer 36

a- the fact that green rays are refracted more than red rays

Question 37

The duochrome test is useful to:
a) determine a patient’s color vision
b) help prevent giving too much plus
c) help prevent giving too much minus
d) refine cylinder correction

Answer 37

c- help prevent giving too much minus

Question 38

Before beginning the duochrome test, do all of the following except:
a) occlude one eye
b) get a final distance correction
c) place a red filter in front of the eye
d) fog with +0.50 sphere

Answer 38

c- place a red filter in front of the eye

Question 39

If the patient says that the letters in the red panel are sharper, you should:
a) record this as your endpoint
b) add more cylinder
c) add more plus power to the sphere
d) add more minus power to the sphere

Answer 39

d- add more minus power to the sphere

Question 40

The endpoint for the duochrome test generally is accepted to be when the letters:
a) in the red panel are clearer
b) in the green panel are faded out
c) are equally clear in both panels
d) are no longer visible in both panels

Answer 40

c- are equally clear in both panels

Question 41

How is the duochrome test done if a patient is red-green color blind?
a) The duochrome test cannot be used.
b) Place a Maddox rod in front of the right eye.
c) Place a Bagolini lens in front of the right eye.
d) Refer to left and right sides instead of red and green.

Answer 41

d- refer to the left and right sides instead of red and green

Question 42

If the patient is accommodating during refractometry, this may result in:
a) a prescription that has excess plus
b) a prescription that has excess minus
c) a prescription without necessary cylinder correction
d) a prescription that will cause the eyes to relax too much

Answer 42

b- a prescription that has excess minus

Question 43

If a patient is known to be myopic:
a) one need not worry about accommodation
b) one must still reduce or eliminate accommodation c) the eye has no ability to accommodate
d) avoiding too much minus is not critical

Answer 43

b- one myst still reduce or eliminate accommodation

Question 44

Your healthy patient has clear media, although you have not looked at the retina. Your best refractometric measurement yields only 20/40 vision. What should you do next?
a) Record the measurement as final.
b) Label that eye as amblyopic.
c) Get a pinhole vision.
d) Perform a stereo test.

Answer 44

c- get a pinhole vision

Question 45

To test for the reading add, the standard near card is placed: a) at the distance preferred by the patient
b) at 10 inches
c) at 14 inches
d) at 20 inches

Answer 45

a- at 10 inches

Question 46

The patient with nystagmus should be refracted using:
a) no special adaptations
b) the astigmatic dial
c) +3.00 lens instead of an occluder
d) –3.00 lens instead of an occluder

Answer 46

c- +3.00 lens instead of an occluder