Visual Fields CH19

Question 1

The extent of vision beyond the central fixation point is known as the:
a) binocular field
b) visual field
c) neurological field
d) pathway of light

Answer 1

b) Vision beyond fixation is the visual field. Binocular field is the visual field with both
eyes. A neurological field is a particular method of testing. The pathway of light refers to the ocular structures through which light must pass to reach the retina.

Question 2

The peripheral vision of a normal person is:
a) 60 degrees temporal, 60 degrees inferior, 75 degrees nasal, and 95 degrees superior
b) 75 degrees temporal, 60 degrees inferior, 95 degrees nasal, and 60 degrees superior
c) 95 degrees temporal, 60 degrees inferior, 75 degrees nasal, and 60 degrees superior
d) 95 degrees temporal, 75 degrees inferior, 60 degrees nasal, and 60 degrees superior

Answer 2

d) The normal visual field is approximately 95 degrees temporal, 75 degrees inferior,
60 degrees nasal, and 60 degrees superior. You could pick this out even if the numbers were slightly different, if you remember that the temporal field is the widest and the nasal and superior fields are the narrowest.

Question 3

The configuration of the normal visual field is delimited by:
a) the ear and nasal bridge
b) the brow and nose
c) the location of the fovea
d) the size of the optic nerve

Answer 3

b) The superior and nasal fields are limited by the anatomical boundaries of the brow and
nose. (The superior field also is limited by the lids, which are not mentioned in this question.)

Question 4

The key to performing any type of peripheral vision exam is to have the patient:
a) maintain fixation
b) look at the moving target
c) gaze into all four quadrants
d) use both eyes

Answer 4

a) Without proper fixation, any test of peripheral vision is invalidated. Generally, the eyes are checked separately.

Question 5

An object on the patient’s right will be perceived by the patient’s:
a) temporal retina OU
b) nasal retina OU
c) temporal retina OS and nasal retina OD
d) foveae OU

Answer 5

c) An object on the patient’s right will stimulate the temporal retina of the left eye and the nasal retina of the right eye. The foveae (plural of fovea) are used during central fixation, not for peripheral vision.

Question 6

The anatomic pattern of the nerve fibers produces visual field defects:
a) that are total blind spots
b) that correspond to the location of the rods and cones
c) that correspond to the location of the nerve fibers
d) that respond well to treatment

Answer 6

c) Because the nerve fibers fan out in a specific anatomic pattern, visual field defects occurring in the nerve fibers also follow the same pattern. This makes diagnosis easier because the patterns are identifiable.

Question 7

The “blind spot” as plotted on a visual field test corresponds to:
a) the macula
b) the fovea
c) the optic disc
d) the angle

Answer 7

c) The optic disc has no rods or cones to receive light impulses. It is, therefore, an area of blindness commonly called the “blind spot.” The macula and fovea are at the center of the visual field and are normally the areas of highest sensitivity. The angle refers to the internal point where the cornea and iris meet.

Question 8

On the visual field, the average blind spot is located:
a) 25 degrees temporal to fixation
b) 5 degrees nasal to fixation
c) 15 degrees nasal to fixation
d) 15 degrees temporal to fixation

Answer 8

d) The average blind spot is located 15 degrees temporal to fixation. (The optic disc is
anatomically located in the nasal part of the retina, which picks up the temporal field.)

Question 9

Visual nerve fibers terminate at the:
a) brain stem
b) occipital cortex
c) thalamus
d) pituitary

Answer 9

b) The visual nerve fibers terminate into the occipital cortex of the brain. (The eye-related
fibers that terminate in the brain stem, only 10% of all the fibers, are concerned with pupillary action and are not visual.)

Question 10

Conversion of the visual field map into a three-dimensional representation results in:
a) isopters
b) the island of vision profile
c) a comparative analysis
d) threshold gray-tone analysis

Answer 10

b) The island of vision profile is a three-dimensional representation of the visual field. An isopter is a boundary. Comparative analysis and threshold gray-tone analysis are automated perimetry programs.

Question 11

The peak of the island of vision profile corresponds to the:
a) optic nerve
b) center of the crystalline lens
c) nerve fiber layer
d) fovea

Answer 11

d) The peak of the island represents the area of highest visual sensitivity, the fovea.

Question 12

The blind spot would be represented on the island of vision profile as:
a) a bottomless hole
b) a peak
c) a shallow dip
d) a deep pit

Answer 12

a) The blind spot is devoid of light receptor cells and would be represented by a bottomless hole. A peak is the point of highest sensitivity. A dip and a pit have a bottom, indicating that a stimulus could be found to which that area would respond.

Question 13

In the island of vision analogy, vision exists in:
a) a sea of blindness
b) a sea of vision
c) an expanse of vision
d) a time-space continuum

Answer 13

a) The island of vision is afloat in a sea of blindness, because anything that is not seen is in a blind area. (The time-space continuum is a term I borrowed from Star Trek.)

Question 14

The validity of all visual field testing depends on:
a) the technical skill of the operator
b) the patient’s ability to maintain fixation
c) the complexity of the screening program
d) the illumination capabilities of the technique used

Answer 14

b) The validity of any type of field testing depends on the patient’s ability and willingness to maintain fixation. Automated perimetry requires minimal technical skill as compared to the manual Goldmann. Other factors involved (but not listed as responses) are the patient’s response time, vision, and mental capabilities.

Question 15

The Amsler grid is used to document visual field defects:
a) within the central 30 degrees
b) within the central 20 degrees
c) within the central 10 degrees
d) from 30 degrees outward

Answer 15

b) The Amsler grid is used in the central 20 degrees of field.

Question 16

All of the following warrant an Amsler grid exam except:
a) the patient with macular degeneration
b) the patient complaining of a central blot in the vision
c) the patient complaining that letters are distorted when reading
d) the patient with a pituitary tumor

Answer 16

d) The patient with a suspected or known pituitary tumor will have formal fields versus an Amsler grid.

Question 17

When checking a patient with the Amsler grid, it is important to do all of the following
except:
a) cover one eye at a time
b) use good reading light
c) have the patient use his or her regular reading glasses
d) hold the chart 1 meter away

Answer 17

d) The Amsler grid should be held at normal reading distance, 14 to 16 inches. (A meter is
a little over 3 feet.)

Question 18

When checking a patient with the Amsler grid, he or she is told to:
a) look at the upper left corner
b) look at the lower right corner
c) look at the center dot
d) look at the bottom center

Answer 18

c) The patient is to fixate on the central dot on the grid.

Question 19

When checking a patient with the Amsler grid, it is helpful to tell the patient:
a) not to touch the grid because oils from the skin will mar it
b) to outline any missing or distorted areas with a pencil
c) that the test is not conclusive
d) that the test is not very accurate

Answer 19

b) If the patient notices any distorted or blank areas, he or she should outline it on the grid.
This gives the physician an idea of what part of the retina might be affected, as well as
providing a permanent record of the defect.

Question 20

Each of the following is an advantage of the Amsler grid except:
a) it is useful for bedridden patient exams
b) most people easily understand it
c) it is handy for home use by the patient
d) it is useful in monitoring field loss in glaucoma

Answer 20

d) The Amsler grid is not generally used to monitor glaucoma field defects, which occur
outside the inner 20 degree field until very advanced.

Question 21

Each of the following is a standard question to ask when performing an Amsler grid
check except:
a) “Are you aware of the page beyond the grid?”
b) “Are all the lines straight and square?”
c) “Are you aware of all four corners of the grid?”
d) “Is any part of the grid missing?”

Answer 21

a) Answer a moves the testing area off the grid, which is beyond the central 20 degrees of the patient’s field. The other answers are standard Amsler grid questions.

Question 22

You are assisting the physician during screening eye exams at a nursing home with
minimal equipment. To check a patient’s peripheral vision, you will most likely per-
form a(n):
a) tangent screen
b) confrontation visual field
c) Goldmann visual field
d) automated visual field

Answer 22

b) The confrontation visual field requires no equipment and can be done even on a patient who is lying down.

Question 23

What is the given assumption in confrontation field testing?
a) The patient has 20/20 vision.
b) The fields are tested in the central area.
c) The examiner’s field is normal.
d) The procedure is fully qualitative.

Answer 23

c) In confrontation visual field testing, the assumption is that the examiner’s visual field is normal. The patient need not have 20/20 vision. The peripheral area, rather than the central area, is tested. The test is not qualitative.

Question 24

The confrontation field:
a) requires the use of elaborate equipment
b) will not pick up gross visual field defects
c) can be performed on a patient in any position
d) cannot be performed on children

Answer 24

c) One advantage of the confrontation field is that it can be performed on a patient in any
position (ie, sitting or lying down). Properly done, the test will pick up gross defects. Most
school-aged children can cooperate for a confrontation field test.

Question 25

Which of the following is not true regarding the confrontation visual field test?
a) It is a subjective test.
b) Only the examiner’s fingers should be used as a target.
c) The eye not being tested is occluded.
d) A defect can be either described in words or drawn out in the chart.

Answer 25

b) In some cases, a small test object (frequently, the red cap of an eye drop bottle) is used instead of the more common use of the examiner’s fingers. Confrontation field testing is a subjective test, requiring a response from the patient. The field is checked one eye at a time,
and any defect can be described or drawn.

Question 26

In the standard version of confrontation field testing, one tests the patient’s peripheral vision:
a) in the standard positions of gaze
b) in the center of fixation
c) in the four quadrants
d) superiorly and inferiorly

Answer 26

c) In the standard confrontation field test, the patient is asked to identify the number of
fingers that the examiner holds up in the periphery of each quadrant. If a defect is detected
in this manner, then more meridians may be examined. Other versions of the test involve:

§ moving a target (finger or object) from the periphery inward until the patient
first reports seeing it

§ asking the patient to identify hand motion in each quadrant

§ presenting fingers in two quadrants simultaneously and asking the patient the total

§ presenting a colored target (eg, a red bottle cap) in each quadrant and asking
if there is any difference in color intensity

Question 27

Matching. Match the term to the correct definition:
Terms
constricted, fixation, infrathreshold, meridians, scotoma, step, suprathreshold, threshold

Definitions
a) the central point at which the patient looks during testing
b) diameter lines designated in degrees
c) point where a stimulus is seen 50% of the time
d) a stimulus that is too small or too dim to be seen
e) a stimulus that exceeds threshold and is seen more than 50% of the time
f) internal area where threshold is not seen
g) field is moved inward from expected normal
h) constriction, sometimes very sharp, along the 180-degree meridian

Answer 27

G) constricted
A) fixation
D) infrathreshold
B) meridians
F) scotoma
H) step
E) suprathreshold
C) threshold

Question 28

Maintenance measures for automated perimeters include all of the following except:
a) a surge protector for the electrical outlet
b) initializing (formatting) the hard drive once a week
c) replacing ink and paper when indicated
d) covering the instrument when not in use

Answer 28

b) Initializing or formatting a disk erases all of the information on it. You never will initialize the hard drive. This not only would erase data files but program files as well.

Question 29

Abrasions or marks on the perimeter bowl surface may be treated by:
a) touching up with correction liquid
b) covering with white nylon tape
c) touching up with white enamel paint
d) a new manufacturer-applied coating

Answer 29

d) Only the manufacturer can “treat” the perimeter bowl finish. Answers a through c are blatantly wrong.

Question 30

At the beginning of each day before using an automated perimeter:
a) the background reflectance must be calibrated
b) the stimulus illumination must be calibrated
c) the technician should run a diagnostic test
d) check the amount of printer paper in the machine

Answer 30

d) Check the printer paper supply each day before beginning. Automated perimeters are self-calibrating and run their own internal diagnostic without any prompting, so tasks in answers a through c are not necessary.

Question 31

Regarding data entry on an automated perimeter:
a) one may use all the data from a previous test
b) the computer automatically makes changes from one test to another
c) the computer automatically saves displayed data, even if the machine is shut off
d) it must be entered in the prescribed manner or the computer will not find it later

Answer 31

d) Data must be entered the same way every time. If you enter Charles Aaron for one test and Aaron Charles for the next, the computer will not know they are the same patient. Data from a previous test needs to be updated. For example, the lens prescription might have changed. The computer only knows what you tell it. Data are lost if the instrument is turned off before the information is saved.

Question 32

All of the following are true regarding the floppy disks used in an automated perimeter except:
a) they are sensitive to magnetic fields
b) they should be left in the computer at all times
c) an extra copy should be stored apart from the testing site
d) a log book should be kept to cross-reference files

Answer 32

b) Floppy disks should be removed from the instrument before the computer is turned off.

Question 33

Before starting automated fields, it is a good idea to perform a confrontation field on the patient. In addition to providing the examiner general information about possible gross defects, this also serves to:
a) locate the blind spot
b) educate the patient about fixation and response
c) quantitate possible defects
d) evaluate the patient’s visual acuity

Answer 33

b) Performing a confrontation field on the patient prior to formal perimetry serves to rein-
force the idea that “you will not be looking directly at the target” and “you need to look straight ahead during the entire test.” Confrontation fields will not quantitate defects or give visual acuity.

Question 34

The best type of lens to use for the near add during automated perimetry is:
a) the patient’s own glasses
b) a lens from any trial lens set
c) sphere only
d) a lens with a thin rim

Answer 34

d) A lens with a thin rim is the best type of trial lens to use. The patient’s glasses, or a trial lens with a thick rim, will most likely cause artifactual field losses because the edge of the frame or the lens rim will block off part of the patient’s side vision. Cylinder correction for astigmatism may sometimes be required, so “sphere only” is not a correct answer.

Question 35

Calculation of the add for automated perimetry includes the factors of:
a) full distance correction and age-related add
b) full distance correction and habitual add
c) full distance correction, age-related add, and bowl depth
d) full distance correction and a 30-cm bowl depth

Answer 35

c) In automated perimetry, the near add calculation must include the patient’s full distance correction, an age-related add, and the bowl depth. Bowl depth can range from 30 cm (equal to a Goldmann perimeter) to 50 cm. Most computerized perimeters calculate the add for you once you input the distance prescription and the patient’s age.

Question 36

The trial lens(es) should be placed:
a) with the sphere closest to the eye and as close to the eye as possible
b) with the cylinder closest to the eye and as close to the eye as possible
c) with the sphere closest to the eye at the patient’s habitual vertex distance
d) with the cylinder closest to the eye at the patient’s habitual vertex distance

Answer 36

a) The near add should be placed with the sphere closest to the patient’s eye (if cylinder is also required) and as close to the patient’s eye as possible. Vertex distance is not usually considered when going from glasses to trial lens.

Question 37

The trial lens is used when testing:
a) the entire visual field
b) the central 30 degrees
c) the central 40 degrees
d) the peripheral field

Answer 37

b) The trial lens is used to compensate for the patient’s need for a near add and is thus used for the central 30 degrees. Most automated perimeters will prompt you when to insert/remove a trial lens if the test chosen evaluates the field beyond 30 degrees.

Question 38

The smallest size pupil diameter for adequate mapping of the periphery is:
a) 0.5 to 1.5 mm
b) 2.5 to 3.0 mm
c) 3.5 to 5.0 mm
d) 6.0 to 7.0 mm

Answer 38

b) If the pupil is smaller than 2.5 to 3.0 mm, consider dilating the patient before proceeding
with the test.

Question 39

Occlusion of the eye not being tested for visual fields is best done by:
a) having the patient close his or her eye
b) the patient’s hand
c) a piece of tape running from upper to lower lid
d) a “pirate patch” that can be disinfected

Answer 39

d) A patch that can be disinfected (such as a plastic “pirate” patch) should be used. It is not advisable to use a patch and place a tissue under it because this may cause a corneal abrasion. Some clinics use a flesh-toned stick-on occlusion patch. This is a good option because there is no strap to potentially interfere with testing on the other eye, and a fresh one would be used for each patient. (Note: In the past, a white patch was recommended. However, when researching for this edition, I was unable to find any printed reference to this. Several of my colleagues had heard of the white patch rule, but none of us had the same logic for using one. I had been taught that it would keep the eye from dark-adapting, which would be a
problem when that eye was uncovered and tested. Another technician had heard it was to avoid affecting reflectivity from the bowl. Yet another thought it was an issue of cleanliness.)

Question 40

The visual field patient should be told all of the following except:
a) you will not see every light
b) some of the lights will be dimmer or smaller than others
c) be sure to look at the light once you see it
d) press the button as soon as you are aware of the light

Answer 40

c) Patients should be told not to look at the stimulus. Telling patients up front that they will not see every light reduces a lot of stress, because normally they think, “I must be doing terribly because I do not see anything.” Tell them that they may go for a while without seeing anything. They also should know that they are to respond regardless of the size or brightness of the stimulus. Patients should respond as soon as they are aware of the light and not wait for it to get crystal clear.

Question 41

The visual field patient should be positioned so that he or she:
a) is not leaning forward at all
b) is on an eye level with the fixation target
c) has his or her chin jutted forward as far as possible
d) has his or her forehead tilted forward as far as possible

Answer 41

b) The eye should be level with the fixation area. It is okay if the patient has to lean forward a little as long as the back is straight and not hyperextended or hunched over. The plane of the face should be parallel to the plane of the back of the bowl or screen. If the chin is jutted forward, this will minimize the lower field. If the forehead is jutted out, the size of the superior field is reduced.

Question 42

What is the best way for a visual field patient who is physically unable to push the buzzer button with the thumb to indicate his or her response?
a) The test cannot be done.
b) Have him or her push the upside-down buzzer against the tabletop.
c) Have him or her give a verbal response.
d) Have him or her nod when the stimulus is seen.

Answer 42

b) Patients who cannot press the buzzer may turn the buzzer upside down and press the button into his or her knee, leg, armrest, or tabletop. Giving a verbal response or a nod will interfere with fixation and positioning and, of course, will not register on an automated perimeter.

Question 43

If the visual field patient’s head is tucked into a chin-down position:
a) the brow may obstruct the upper field
b) the cheek bone may obstruct the lower field
c) the eye cannot be aligned properly
d) fixation will be impossible

Answer 43

a) A patient with the chin tucked down has a reduction of the superior field because of interference by the brow. You must visually check the head position, because it still is possible to align the eye and for the patient to fixate even if the head is malpositioned.

Question 44

If a male visual field patient has a beard:
a) tape the facial hair back out of the way
b) request that he shave before the test
c) position him so there is as little hair as possible in the chinrest
d) no special modifications are necessary

Answer 44

c) If a man has a full beard, have him put his chin beyond the chinrest, then slide back into the chin cup. Then, the hair can be parted to either side of the chin cup so as not to interfere with the lower field. A beard can cushion the chin in the cup, making it difficult to maintain
alignment.

Question 45

Which of the following is the most comfortable position during the visual field exam?
a) The feet should not touch the floor.
b) The back should be curved gently.
c) The patient should not have to lean forward at all.
d) The back should be straight, with feet flat on floor.

Answer 45

d) The patient’s back should be straight, not hyperextended, even if he or she has to lean
forward a little. Feet should be flat on the floor, thighs parallel to the floor.

Question 46

Adaptations that might allow a wheelchair-bound patient to be positioned at the perimeter include all of the following except:
a) placing a sturdy board across the wheelchair armrests and having the patient sit on the
board
b) raising the table so the chair will fit under it, and using pillows to help prop the patient
c) removing the wheelchair armrests so that the chair will slide under the table
d) removing the footrests so the chair will fit closer to the table

Answer 46

a) Perching the wheelchair-bound (or any) patient on a board for the test would be uncomfortable and probably dangerous. Remove parts of the wheelchair, if possible, in order to accommodate. If you remove the armrests, be sure the patient is not going to fall out of the chair. Propping with pillows may help with comfort and positioning.

Question 47

In general, the longer the test time:
a) the less reliable the patient becomes
b) the more reproducible the test
c) the more accurate the test because more data are provided
d) the more reliable the patient becomes

Answer 47

a) The longer the test continues, the greater the patient’s fatigue, boredom, and “hypnosis.” These all lower reliability. The test may stretch on because the program does not find that the data are reliable.

Question 48

To provide for patient comfort and rest during an automated visual field, the patient
should be:
a) told to hold down the button to pause the test after every couple of stimuli
b) told to close his or her eye whenever needed
c) encouraged periodically to continue, then allowed to rest between testing eyes
d) allowed to take a break every 5 minutes

Answer 48

c) Give patients verbal encouragement. This helps them stay alert and motivated. For example, tell patients they are doing well, or that they are halfway through. Answer a might be considered correct by some. My opinion is that if you tell patients to hold down the button and pause whenever they want to, it will lengthen the test and add to the stress, instead of helping the patient. It is better to let pauses remain in the control of the technician. A patient should not be allowed to sit at the machine with his or her eyes closed during the test. Resting every 5 minutes might be allowed in extreme cases, but not as a general rule.

Question 49

Which of the following is true regarding visual field screening techniques?
a) they are difficult for patients because of the time required
b) they are not practical for evaluating large groups
c) the main purpose is to rule out pathology
d) they cannot be used to confirm changes in prior fields

Answer 49

c) The main purpose of screening techniques is to give a yes/no answer to the question: Is this patient’s peripheral vision grossly normal? In general, screening techniques are quicker and practical for evaluating large groups of people. (Not all at once, of course!) They also are useful in comparing a patient’s screening results from one test to the next.

Question 50

When testing a return patient for an annual automated field exam, it is important to:
a) use the same test parameters as the previous test
b) use the same correcting lens as before
c) not fatigue the patient with test instructions
d) save the results on the same floppy disk

Answer 50

a) In order for tests to be comparable, they must be run with the same parameters. Otherwise, you are trying to compare apples and stones. The correcting lens used for one test may not be appropriate for the next, however. The patient always should be instructed, even if he or she has done numerous field tests. There is no need to back up files on the same floppy disk.

Question 51

You are halfway through the field when your patient begins to complain that her eye is stinging and watering. This might indicate that you forgot to instruct the patient to:
a) maintain fixation
b) use artificial tears before the test
c) blink often during the test
d) take her allergy medication before the test

Answer 51

c) Burning, watery eyes are symptoms of dryness. In the case of a visual field exam, dryness is usually caused by staring. Before starting the test and sometime during the test, remind the patient to blink. You can stop the test and instill artificial tear drops, if necessary.

Question 52

Once the automated visual field test has begun, the technician should:
a) encourage the patient frequently
b) be totally quiet
c) leave the room
d) speak only if the patient repeatedly loses fixation

Answer 52

a) Communication during an automated field is almost constant. The droning of the machine and rhythm of responses can be tiring for even the most alert patients. Automated fields are taxing; therefore, reinforce the patient often. Leaving the room is not a good idea.
Even the best patient can slip out of alignment.

Question 53

Fixation losses may be minimized by:
a) telling the patient where the next kinetic stimulus is going to appear
b) telling the patient that you can see his or her eye during testing
c) using the correct near add
d) enlarging the fixation point for every patient

Answer 53

b) Just knowing that you are watching makes the patient more motivated to hold fixation. A few Goldmann perimeter advocates tell the patient where the next kinetic stimulus is coming from, but most technicians do not feel this is a good idea. Using the near add may clear the fixation target, but cannot be used to plot the outer isopter. The fixation point needs be enlarged only for low-vision patients. Fixation in a visually and mentally capable
patient is a matter of willpower.

Question 54

Match the automated field terms with the definitions. Each will be used more than once:
Terms
fixation loss, false-positive, false-negative, fluctuation

Definitions
a) evaluates the patient’s understanding of the test
b) the patient does not respond to the brightest target available in an area where he or she previously responded to a dimmer light
c) the patient responds to a target that appears within the
previously designated blind spot
d) the patient responds to the sound of the perimeter when no stimulus was presented
e) a measure of the patient’s consistency
f) evaluates the patient’s alertness
g) some perimeters will retest the points that were evaluated just before this occurred
h) this factor can be affected by certain eye diseases
i) a higher number indicates that the patient is giving
varying responses to the same point
j) may be detected continually by a photoelectric sensor

Answer 54

C), G), J) - fixation loss
A), D) - false-positive
B), F) - false-negative
E), H), I) - fluctuation

Question 55

During automated visual fields, if the patient repeatedly responds to the blind spot check, yet seems to be maintaining fixation:
a) encourage the patient to continue to fixate
b) relocate the blind spot
c) pause the test and allow the patient to rest
d) turn off the fixation monitor

Answer 55

b) If the patient seems to be fixating, yet the instrument is registering fixation losses, have the program relocate the blind spot or reduce the fixation stimulus. If the blind spot is not placed accurately, the patient will respond when the light is flashed in that area. Reducing the intensity of the stimulus may help, as well.

Question 56

All of the following could cause the perimeter to be unable to find the blind spot except:
a) the other eye is not adequately occluded
b) the patient is not fixating
c) you have selected the wrong eye to be tested
d) the presence of a scotoma

Answer 56

d) The presence of a scotoma anywhere in the field would not affect the instrument’s ability to find the blind spot. The other three situations would. Even technicians experienced in doing fields occasionally forget to patch the untested eye. If the patch is on and the instrument cannot locate the blind spot, you should double-check the patch placement: it could have slipped enough to let the patient “peek.” If the patient is looking around and not fixating, he or she may respond to every stimulus, and the machine will be unable to find the blind spot. Alternately, if you accidentally tell the perimeter to check the right eye and then patch the right as if testing the left, the blind spot will be on the opposite side from what the instrument expects, and the perimeter will be unable to find it.

Question 57

Target exposure time on an automated perimeter is usually:
a) 0.1 to 0.4 seconds
b) 0.5 to 0.7 seconds
c) 0.9 to 1.0 seconds
d) 1.5 to 2.0 seconds

Answer 57

a) Most automated perimeters present the target for somewhere between 0.1 and 0.4 seconds.

Question 58

Your patient seems to have a slow response time. In order to get the most accurate results possible, you should:
a) change the stimulus presentation interval
b) let the patient rest frequently
c) use a different testing strategy
d) turn off the gaze monitor

Answer 58

a) Some perimeters will automatically change the presentation rate to accommodate a “slower” patient. Alternately, the time interval can be increased by manually changing the testing speed.

Question 59

“At threshold” means that the patient responds to a given stimulus at the same location:
a) 25% of the time
b) 50% of the time
c) 75% of the time
d) 100% of the time

Answer 59

b) Threshold refers to a response to a given stimulus, at a given location, 50% of the time.

Question 60

In automated perimetry, threshold is dependent on all of the following except:
a) background and stimulus intensity
b) patients’ age
c) patients’ level of stereopsis
d) distance of stimulus from the fovea

Answer 60

c) Stereopsis is a binocular phenomenon. Visual field testing is monocular. The intensity of the background and stimulus affects threshold, in that a dimmer background increases contrast and a brighter stimulus is easier to see. Threshold decreases with age and with distance from the fovea.

Question 61

A patient might not respond to a suprathreshold stimuli:
a) by chance
b) because it is too dim
c) because it is too small
d) because it is too large

Answer 61

a) A suprathreshold stimulus is not seen 100% of the time, but rather is considered to be seen only 95% of the time. It is extrapolated that suprathreshold could be missed 5% of the time, in part by chance alone.

Question 62

The main challenge in testing the visual fields of low-vision patients is:
a) patients’ inability to understand the test
b) patients’ inability to see the fixation area
c) finding the appropriate threshold
d) finding the appropriate correcting lens

Answer 62

b) Because of poor vision, many low-vision patients have difficulty seeing the fixation area and maintaining fixation on it. Many automated perimeters have an alternate fixation area made up of several lights instead of just one that may be used in low-vision testing situations.

Question 63

If the patient has poor vision and cannot see the fixation target in the center of the automated perimeter:
a) activate an alternate/eccentric fixation pattern
b) turn off the fixation monitor
c) increase the size of the stimulus
d) use a +3.00 correcting lens to provide more magnification

Answer 63

a) Most automated perimeters have an alternate fixation pattern that can be used for low-vision patients. This pattern is offset from normal fixation, so you may hear it called an eccentric fixation pattern. If the eccentric fixation pattern is activated, the instrument automatically adjusts the blind spot and other points to coincide. Turning off the fixation monitor will not help the patient see the fixation point any better, nor will using a larger target. The correcting lens must be calculated for each patient; a +3.00 lens used across the board is unacceptable.

Question 64

A “normal” screening test means that:

a) the patient has no visual field defect
b) the patient has no field defect detectable by this test
c) confrontation visual fields are adequate for future testing
d) the patient does not have glaucoma

Answer 64

b) Normal for a screening test does not necessarily mean that there is no field loss. It means that there is no field loss detected at this time by this particular instrument and this particular testing strategy. Screening programs can miss shallow defects that indicate the early stages of disease. The need for future formal visual field tests depends on the patient’s diagnosis and complaints. Screening tests are not adequate in glaucoma evaluation. Diagnosis of glaucoma requires elevated pressures, nerve damage, and consideration of central corneal thickness, in addition to field loss.

Question 65

Which of the following is not true regarding test results found with an automated perimeter?
a) The data can be rearranged into a variety of printouts.
b) It is valid only if the same person performs the test each time.
c) The data can be compared with the patient’s previous test(s).
d) The data can be compared to normal age-related values.

Answer 65

b) One of the beauties of automated perimetry is that it is largely independent of operator
bias and expertise.

Question 66

On the numeric printout of an automated field, the number zero indicates that:
a) the stimulus was seen 100% of the time
b) the stimulus was below threshold
c) the dimmest stimulus was used
d) the brightest stimulus was not seen

Answer 66

d) The numbers represent retinal sensitivity. A zero means that the brightest stimulus on the unit was shown and not seen. Lower numbers indicate that the target had to be made brighter before it was seen and are more commonly elicited in the periphery. The higher numbers around the fovea represent dimmer lights and greater retinal sensitivity.

Question 67

A point that is not seen is represented on a gray-scale printout by:
a) a white area
b) a dot
c) a black area
d) an X

Answer 67

c) A point that is not seen would appear as a black area on the gray-scale printout.

Question 68

The comparison printout on an automated perimeter is designed to:
a) compare the patient’s results to normal
b) compare the patient’s test with and without a correcting lens
c) compare the patient’s current results to a previous test
d) compare the patient’s responses to one stimulus with another

Answer 68

c) The comparison printout is designed to compare a patient’s previous test to the present test.

Question 69

Which of the following ocular disorders is frequently followed by visual field testing on a regular basis (every 6 to 12 months)?
a) cataracts
b) macular degeneration
c) glaucoma
d) retinal detachment

Answer 69

c) Routine visual field testing is standard of care for the patient with glaucoma. Many clinicians will alternate visual field testing and retinal scanning every 6 months. While the other disorders will exhibit visual field changes, they are not monitored on a routine basis like glaucoma.

Question 70

The physician has requested an automated visual field to be performed “taped and untaped.” Most likely, this patient is being evaluated for:
a) blepharoplasty
b) cataract surgery
c) driver’s license renewal
d) glaucoma

Answer 70

a) Before agreeing to pay for a blepharoplasty, most insurance companies will want a visual field test. This is performed twice: once with the lids in their relaxed, drooped position (possibly showing a loss of the upper visual field) and another with the upper lids taped up, out of the way (simulating how much upper field would be restored if the surgery was done). Correction of a field loss moves the surgery from cosmetic to functional.

Question 71

The visual field in a high hyperope will be:
a) compressed, with a blind spot closer to fixation than normal
b) expanded, with a blind spot farther from fixation than normal
c) compressed, with a smaller blind spot than normal
d) expanded, with a larger blind spot than usual

Answer 71

a) A high hyperope will exhibit a compressed field with a blind spot displaced closer to fixation than normal. This happens because the prismatic effect of a plus-diopter lens changes the image location.

Question 72

A high myope will have a field that is:
a) compressed, with a blind spot closer to fixation than normal
b) expanded, with a blind spot further from fixation than normal
c) compressed, with a smaller blind spot than normal
d) expanded, with a larger blind spot than usual

Answer 72

b) By contrast, a high myope will have an expanded field with a blind spot further away from fixation than normal. This happens because the prismatic effect of a minus-diopter lens changes the image location (in an opposite manner to the plus-diopter lens, as in answer 71).

ANSWER 71: A high hyperope will exhibit a compressed field with a blind spot displaced closer to fixation than normal. This happens because the prismatic effect of a plus-diopter lens changes the image location.