0:00:00.000,0:00:05.433


0:00:05.433,0:00:08.599
Teller Acuity Cards[br]are used to test visual acuity

0:00:08.600,0:00:11.200
in young children[br]and those with disabilities

0:00:11.200,0:00:13.266
who cannot be tested[br]with standard letter

0:00:13.266,0:00:16.066
or symbol acuity tests.

0:00:16.066,0:00:18.232
The stimulus[br]on a Teller Acuity Card

0:00:18.233,0:00:20.733
is a high contrast black[br]and white pattern

0:00:20.733,0:00:23.099
of stripes called a grating.

0:00:23.100,0:00:25.166


0:00:25.166,0:00:28.466
The gratings range[br]from very coarse to very fine,

0:00:28.466,0:00:30.132
in order to test visual acuity

0:00:30.133,0:00:32.666
from very low vision to normal.

0:00:32.666,0:00:34.166


0:00:34.166,0:00:36.866
Most rectangular cards[br]have a single grating

0:00:36.866,0:00:39.432
printed off to one side[br]of the center.

0:00:39.433,0:00:41.833
Printing the grating[br]to one side of the card

0:00:41.833,0:00:44.666
allows it to be presented either[br]on the left

0:00:44.666,0:00:45.866
or the right.

0:00:45.866,0:00:46.932


0:00:46.933,0:00:47.799
An additional card

0:00:47.800,0:00:51.100
has a grating nearly covering[br]one-half of the card.

0:00:51.100,0:00:54.200
This card[br]is called the low vision card.

0:00:54.200,0:00:56.166


0:00:56.166,0:01:00.266
The final card is a blank, gray card[br]without a grating.

0:01:00.266,0:01:01.332


0:01:01.333,0:01:03.133
Grating values are specified

0:01:03.133,0:01:06.299
by the width[br]of their black and white bars.

0:01:06.300,0:01:10.400
A single black and white pair[br]of bars is called a cycle.

0:01:10.400,0:01:12.000
Grating sizes are specified

0:01:12.000,0:01:15.200
by the number of black[br]and white cycles per centimeter.

0:01:15.200,0:01:16.466


0:01:16.466,0:01:18.366
The metric cycles per centimeter

0:01:18.366,0:01:21.399
is converted to visual acuity based[br]on the distance

0:01:21.400,0:01:24.400
of the Teller Acuity Card grating[br]from the patient,

0:01:24.400,0:01:28.100
and is specified as cycles[br]per degree.

0:01:28.100,0:01:31.333
The cycles per degree measure[br]is the appropriate specification

0:01:31.333,0:01:33.133
for grating acuity.

0:01:33.133,0:01:34.399


0:01:34.400,0:01:37.366
If necessary,[br]grating acuity can be converted

0:01:37.366,0:01:39.699
into conventional Snellen notation,

0:01:39.700,0:01:42.566
which may be more appropriate[br]for certain reporting.

0:01:42.566,0:01:44.466


0:01:44.466,0:01:47.132
Each Teller Acuity Card[br]has labels on the back

0:01:47.133,0:01:49.999
showing the grating size[br]in cycles per centimeter,

0:01:50.000,0:01:54.366
and the conversions to acuity based[br]on three test distances.

0:01:54.366,0:01:56.532
The labels on the back[br]of the card are placed

0:01:56.533,0:01:58.433
so the examiner has no information

0:01:58.433,0:02:00.533
about the right-left position[br]of the grating

0:02:00.533,0:02:03.399
from viewing the back of the card.

0:02:03.400,0:02:05.933
The primary principle[br]of a Teller Acuity Card

0:02:05.933,0:02:08.766
is that if a patient sees a grating[br]on the grey background,

0:02:08.766,0:02:11.199
she will look at the grating.

0:02:11.200,0:02:14.633
If the grating bars cannot be resolved[br]or seen by a patient,

0:02:14.633,0:02:17.199
the grating should match[br]the grey background perfectly,

0:02:17.200,0:02:19.266
mimicking the blank card.

0:02:19.266,0:02:20.466


0:02:20.466,0:02:23.599
The examiner's task[br]in testing Teller Acuity Cards

0:02:23.600,0:02:25.466
is to determine the finest grating

0:02:25.466,0:02:27.832
that the patient sees or detects.

0:02:27.833,0:02:30.699
This gives the patient's[br]visual acuity.

0:02:30.700,0:02:31.833


0:02:31.833,0:02:34.033
This requires testing a series[br]of gratings,

0:02:34.033,0:02:36.733
starting from relatively wide[br]and easily seen

0:02:36.733,0:02:38.699
to progressively finer gratings,

0:02:38.700,0:02:42.433
until the patient[br]no longer responds consistently.

0:02:42.433,0:02:44.566
The recommended clinical method[br]of testing is

0:02:44.566,0:02:46.932
for the examiner[br]to present a single grating

0:02:46.933,0:02:49.733
a sufficient number of times[br]to judge whether the patient

0:02:49.733,0:02:51.733
sees that grating.

0:02:51.733,0:02:54.666
As there are only two locations[br]where the grating can appear,

0:02:54.666,0:02:58.299
an examiner has a 50% chance[br]of guessing the correct location

0:02:58.300,0:03:00.466
without even watching the patient.

0:03:00.466,0:03:01.532
[no audible dialog]

0:03:01.533,0:03:04.699
This means that gratings[br]may need to be shown multiple times

0:03:04.700,0:03:07.933
if the patient's responses[br]are not definitive.

0:03:07.933,0:03:11.266
Typically, the patient's responses[br]will be definitive

0:03:11.266,0:03:14.899
when the grating is coarse[br]and above their acuity level.

0:03:14.900,0:03:17.533
However, a finer grating[br]that is more difficult

0:03:17.533,0:03:20.733
for the patient to see[br]may lead to more subtle responses

0:03:20.733,0:03:22.833
and require more presentations.

0:03:22.833,0:03:23.799


0:03:23.800,0:03:25.700
It is up to the examiner[br]to determine

0:03:25.700,0:03:28.466
how many presentations[br]she needs to be confident

0:03:28.466,0:03:30.799
of the patient's visual acuity.

0:03:30.800,0:03:33.066
[no audible dialog]

0:03:33.066,0:03:34.599


0:03:34.600,0:03:38.033
There is a small hole in the center[br]of the Teller Acuity Card

0:03:38.033,0:03:40.833
through which the examiner[br]or tester can view the patient

0:03:40.833,0:03:44.166
as they look at the gray card[br]and the grating.

0:03:44.166,0:03:46.599
The examiner can also view[br]the patient's responses

0:03:46.600,0:03:49.633
to the gratings[br]by looking over the top of the card.

0:03:49.633,0:03:50.833
[no audible dialog]

0:03:50.833,0:03:53.399
The examiner[br]is able to change the card position

0:03:53.400,0:03:56.700
to judge where the grating[br]is located, right or left,

0:03:56.700,0:03:58.866
based on the patient's[br]visual behaviors,

0:03:58.866,0:04:01.666
such as looking[br]towards the right or left,

0:04:01.666,0:04:04.899
or pointing or other behaviors.

0:04:04.900,0:04:06.433
The card is shown to the patient

0:04:06.433,0:04:09.133
by an examiner holding it[br]along the edges.

0:04:09.133,0:04:12.733
They should not be touching[br]the front surface of the card.

0:04:12.733,0:04:15.066
If the examiner uses fingers[br]to hold the card,

0:04:15.066,0:04:16.999
rather than the palm of the hand,

0:04:17.000,0:04:18.900
fingertips should not touch[br]the front,

0:04:18.900,0:04:22.166
except possibly within one inch[br]of the edge of the card.

0:04:22.166,0:04:23.232


0:04:23.233,0:04:25.633
The examiner shows the card[br]in one position

0:04:25.633,0:04:27.966
and makes a judgment as[br]to where the grating is

0:04:27.966,0:04:30.199
based on the patient's behavior.

0:04:30.200,0:04:33.900
In this case, the examiner[br]judges the grating to be on her left,

0:04:33.900,0:04:35.500
the patient's right.

0:04:35.500,0:04:36.333


0:04:36.333,0:04:40.633
The examiner[br]then rotates the card 180 degrees.

0:04:40.633,0:04:44.266
Now, if the infant's behavior[br]indicates seeing the grating,

0:04:44.266,0:04:48.199
the examiner should judge[br]the grating is on the infant's left.

0:04:48.200,0:04:50.400
The examiner[br]should not always rotate the card

0:04:50.400,0:04:53.100
180 degrees between presentations,

0:04:53.100,0:04:56.866
as some patients[br]may anticipate the gratings position.

0:04:56.866,0:04:59.899
Instead, the examiner[br]should show the grating frequently

0:04:59.900,0:05:02.100
in the same location.

0:05:02.100,0:05:04.300
The examiner is being shown[br]holding the cards

0:05:04.300,0:05:06.200
in a horizontal orientation,

0:05:06.200,0:05:08.000
which is the standard[br]and most common way

0:05:08.000,0:05:10.133
of presenting Teller Acuity Cards.

0:05:10.133,0:05:13.633
However, the cards may be held[br]in a vertical orientation,

0:05:13.633,0:05:17.133
with the grating either on the upper[br]or lower part of the card.

0:05:17.133,0:05:19.366
This can be a useful method[br]for testing patients

0:05:19.366,0:05:22.999
with nystagmus or strabismus.

0:05:23.000,0:05:24.500


0:05:24.500,0:05:27.200
During testing,[br]patients may wish to touch the grating

0:05:27.200,0:05:30.866
or may invertently touch it[br]when trying to point to the grating.

0:05:30.866,0:05:33.732
This should be avoided[br]by giving the child a soft toy to hold

0:05:33.733,0:05:36.199
and point toward the grating.

0:05:36.200,0:05:38.200
To keep the patient's attention,

0:05:38.200,0:05:41.733
the examiner can interact with[br]and reinforce the patient

0:05:41.733,0:05:44.066
for finding the grating location.

0:05:44.066,0:05:45.366
[no audible dialog]

0:05:45.366,0:05:46.832


0:05:46.833,0:05:49.866
Presenting a grating that has been[br]seen previously by the patient

0:05:49.866,0:05:52.232
can reestablish interest[br]in the testing

0:05:52.233,0:05:54.433
and also reassure the examiner[br]that the infant

0:05:54.433,0:05:56.433
is still attending[br]to the gratings.

0:05:56.433,0:05:57.499
[no audible dialog]

0:05:57.500,0:05:59.433


0:05:59.433,0:06:01.633
What behaviors[br]does the examiner use

0:06:01.633,0:06:04.933
to judge whether the patient[br]sees a grating?

0:06:04.933,0:06:06.666
The examiner must be aware of any

0:06:06.666,0:06:08.799
and all patient cues and behaviors

0:06:08.800,0:06:12.100
that indicate the location[br]of the grating.

0:06:12.100,0:06:15.700
Typically, in young infants,[br]a strong fixation response

0:06:15.700,0:06:18.933
to one side of the card,[br]presumably at the grating,

0:06:18.933,0:06:23.199
and then to the other side[br]when the card is rotated 180 degrees,

0:06:23.200,0:06:26.433
indicates the infant detects[br]that grating.

0:06:26.433,0:06:29.199
Finer gratings may not be[br]as strongly fixated,

0:06:29.200,0:06:33.633
yet will still elicit a consistent gaze[br]from the young infant.

0:06:33.633,0:06:37.133
Older infants and toddlers[br]may give brief glances to each side,

0:06:37.133,0:06:38.833
which are accepted as detection,

0:06:38.833,0:06:40.999
because the glance[br]is direct and clear,

0:06:41.000,0:06:44.200
and repeated[br]on subsequent presentations.

0:06:44.200,0:06:46.500
Some mature toddlers[br]and young children

0:06:46.500,0:06:48.100
may point to one side,

0:06:48.100,0:06:50.766
especially if prompted by the examiner,[br]such as,

0:06:50.766,0:06:52.732
"Where did the stripes go?"

0:06:52.733,0:06:54.266


0:06:54.266,0:06:56.766
This section illustrates[br]the complete sequence

0:06:56.766,0:07:01.299
of testing a child's visual acuity[br]with Teller Acuity Cards.

0:07:01.300,0:07:04.633
Young patients are usually seated[br]on their parent's lap,

0:07:04.633,0:07:06.999
and the parent or holder[br]should be cautioned

0:07:07.000,0:07:10.066
not to give the child any guidance[br]during testing.

0:07:10.066,0:07:11.199


0:07:11.200,0:07:15.333
Based on the patient's age,[br]determine the start card for testing.

0:07:15.333,0:07:18.933
Consult the Teller Acuity Card[br]Reference and Instruction Manual.

0:07:18.933,0:07:19.999


0:07:20.000,0:07:22.166
If the patient[br]is visually impaired,

0:07:22.166,0:07:24.499
a coarser grating than[br]that based on age

0:07:24.500,0:07:26.700
may be needed for the start card.

0:07:26.700,0:07:28.000


0:07:28.000,0:07:30.066
Distance of the card[br]from the patient's face

0:07:30.066,0:07:32.299
also depends upon age.

0:07:32.300,0:07:36.366
Consult the Teller Acuity Card[br]Reference and Instruction Manual.

0:07:36.366,0:07:41.266


0:07:41.266,0:07:43.199
The examiner[br]measures the test distance

0:07:43.200,0:07:46.666
from the patient's eyes[br]to the position the card is held.

0:07:46.666,0:07:49.699
For the 55-centimeter distance,[br]the length of the card

0:07:49.700,0:07:51.200
is an exact measure.

0:07:51.200,0:07:52.366


0:07:52.366,0:07:55.732
For the 38-centimeter distance,[br]used with young infants

0:07:55.733,0:07:57.999
and patients with limited vision,

0:07:58.000,0:08:00.466
a measuring tape can be used.

0:08:00.466,0:08:02.699
Or, a convenient measure[br]is the distance

0:08:02.700,0:08:05.433
between the examiner's elbow[br]and fingers,

0:08:05.433,0:08:07.499
with fingers either close or open,

0:08:07.500,0:08:10.266
depending[br]on the examiner's arm length.

0:08:10.266,0:08:13.599
This needs to be measured[br]before testing.

0:08:13.600,0:08:15.533
For 84-centimeter distance,

0:08:15.533,0:08:18.999
used with older children,[br]a measuring tape is needed.

0:08:19.000,0:08:21.400
Alternatively,[br]a measuring tape can be placed

0:08:21.400,0:08:24.800
on a table surface, adjacent[br]to the patient and the examiner,

0:08:24.800,0:08:27.600
with marks for each distance.

0:08:27.600,0:08:29.966
The examiner should check[br]the test distance periodically

0:08:29.966,0:08:32.632
during the testing,[br]as some patients will lean forward

0:08:32.633,0:08:34.499
to get closer to the gratings,

0:08:34.500,0:08:37.800
especially when they[br]become finer and more difficult to see.

0:08:37.800,0:08:39.100


0:08:39.100,0:08:42.200
Set up the cards in two stacks[br]with the grading face down

0:08:42.200,0:08:44.933
on a soft, clean surface.

0:08:44.933,0:08:47.233
The card labels are up.

0:08:47.233,0:08:49.833
One stack is for gratings[br]the patient has not seen,

0:08:49.833,0:08:51.833
or will not be tested on,

0:08:51.833,0:08:54.699
and the other stack is[br]for cards the patient has seen

0:08:54.700,0:08:57.600
or are larger[br]than need to be presented.

0:08:57.600,0:08:59.700
Stacking the cards[br]with the grating face down

0:08:59.700,0:09:01.733
keeps the examiner unaware[br]of the position

0:09:01.733,0:09:03.866
of the grading before testing.

0:09:03.866,0:09:07.632
It also minimizes damage[br]to the grating face of the card.

0:09:07.633,0:09:09.633
Papers can be inserted[br]between each card

0:09:09.633,0:09:12.666
in order to minimize marks[br]or blemishes.

0:09:12.666,0:09:15.832
The not-seen stack[br]has the start card top-most,

0:09:15.833,0:09:17.433
with progressively fine gratings

0:09:17.433,0:09:19.733
in series below the top card.

0:09:19.733,0:09:22.499


0:09:22.500,0:09:24.866
The seen stack[br]has the gratings that are coarser

0:09:24.866,0:09:25.999
than the start card,

0:09:26.000,0:09:29.600
in a series of progressively[br]wider stripes below the top card.

0:09:29.600,0:09:31.433


0:09:31.433,0:09:35.133
The examiner picks up the top card[br]from the not-seen stack,

0:09:35.133,0:09:37.866
and tests the infant[br]with this grating.

0:09:37.866,0:09:40.232
If she judges the infant[br]detects the grating,

0:09:40.233,0:09:42.699
she places it on the seen stack.

0:09:42.700,0:09:46.000


0:09:46.000,0:09:49.233
At some point, the series[br]of judgments will become difficult,

0:09:49.233,0:09:50.566
and the examiner may be unsure

0:09:50.566,0:09:52.866
whether the patient detects[br]that grating.

0:09:52.866,0:09:54.899
The examiner does not look[br]at the front of the card

0:09:54.900,0:09:57.266
for this grating location.

0:09:57.266,0:10:00.566
The examiner places the card[br]the infant does not detect

0:10:00.566,0:10:03.166
on top of the not-seen stack.

0:10:03.166,0:10:05.399


0:10:05.400,0:10:08.733
The examiner then retests[br]the previously seen grating.

0:10:08.733,0:10:11.033
And if she judges the infant[br]detects it,

0:10:11.033,0:10:14.333
she places the card on top[br]of the seen stack again.

0:10:14.333,0:10:15.366
[no audible dialog]

0:10:15.366,0:10:18.299


0:10:18.300,0:10:20.466
If the examiner still cannot determine[br]that the patient

0:10:20.466,0:10:21.666
detects the grating,

0:10:21.666,0:10:24.732
this indicates that a below-threshold[br]grating has been found,

0:10:24.733,0:10:26.633
and testing is completed.

0:10:26.633,0:10:28.033
The next-coarser grating,

0:10:28.033,0:10:30.833
the finest the patient[br]responds positively to,

0:10:30.833,0:10:33.833
is recorded[br]as the patient's acuity.

0:10:33.833,0:10:36.666
Sometimes, retesting results[br]in different decisions

0:10:36.666,0:10:38.099
on the patient's detection,

0:10:38.100,0:10:40.966
and the examiner must go back[br]and forth between several cards

0:10:40.966,0:10:43.166
to determine the patient's acuity.

0:10:43.166,0:10:44.566


0:10:44.566,0:10:45.966
After testing a patient,

0:10:45.966,0:10:49.099
the cards can be placed[br]in a single stack, ready for storage.

0:10:49.100,0:10:50.133


0:10:50.133,0:10:52.833
We recommend randomly[br]reordering the right-left locations

0:10:52.833,0:10:55.633
of the gratings to avoid[br]biasing the grating locations

0:10:55.633,0:10:57.466
to one side.

0:10:57.466,0:11:00.666
As indicated,[br]the finest or smallest grating size

0:11:00.666,0:11:03.332
that the patient is judged to see[br]by the examiner

0:11:03.333,0:11:05.999
defines their visual acuity.

0:11:06.000,0:11:08.166
The recording form shown[br]in the handbook

0:11:08.166,0:11:10.766
can be used to record information[br]about the patient,

0:11:10.766,0:11:12.399
such as name,

0:11:12.400,0:11:14.000
date of birth,

0:11:14.000,0:11:15.333
test date,

0:11:15.333,0:11:16.999
and age.

0:11:17.000,0:11:19.133
It is also used[br]to record the important results

0:11:19.133,0:11:20.733
of the acuity test,

0:11:20.733,0:11:24.399
including the acuity card[br]at threshold in cycles per centimeter,

0:11:24.400,0:11:27.366
test distance, and acuity conversion.

0:11:27.366,0:11:29.166
The examiner can take the value

0:11:29.166,0:11:32.532
from the "Teller Acuity Card Handbook,[br]Appendix D,"

0:11:32.533,0:11:35.199
showing conversions[br]from cycles per centimeter

0:11:35.200,0:11:38.933
to cycles per degree, Table 1,

0:11:38.933,0:11:42.333
and from cycles per centimeter[br]to Snellen equivalents.

0:11:42.333,0:11:46.333


0:11:46.333,0:11:49.233
The patient's acuity can be shown[br]on an age-norm graph

0:11:49.233,0:11:51.866
from the "Teller Acuity Card[br]Handbook."

0:11:51.866,0:11:54.866
The patient's age is noted[br]at the bottom of the graph.

0:11:54.866,0:11:56.732
The test distance is circled,

0:11:56.733,0:11:58.366
and the grating[br]in cycles per centimeter

0:11:58.366,0:12:02.032
in the column[br]under the test distance is also circled.

0:12:02.033,0:12:05.699
A line is drawn from this value[br]across to the patient's age.

0:12:05.700,0:12:07.266
This shows[br]where the patient's acuity

0:12:07.266,0:12:10.799
falls relative to the normal range[br]for that age.

0:12:10.800,0:12:12.300
All values are then recorded

0:12:12.300,0:12:15.000
in the results section[br]of the recording form.