Pacific Acuity Test - 360000 - Good-Lite Company

Pacific Acuity Test - 360000
The Pacific Acuity Test is a vanishing optotype test designed
with opposing figures to provide a simple forced-choice testing
format appropriate for nonverbal children and individuals with
developmental disabilities who are unable to respond to standard
optotype recognition tests. Each card has two figures, a
simple face, and an opposing oval target of the same overall size
but with interior details that allow discrimination from the face at
the threshold of acuity. The vanishing optotype design significantly
reduces the difference in the threshold between detection
and recognition acuity. However, by using a similar opposing figure,
the Pacific Acuity Test requires contour analysis and visual
discrimination. This format yields a more accurate measure of
acuity than traditional preferential looking tests, particularly with
children who have significant visual impairment.
The Pacific Acuity Test is appropriate for preschool children aged
6 months and older. While developing the test, we found many
children between 6 and18 months will respond to the standard
test paradigm showing a clear preference for the face. However,
most children over age 18 months can respond well to this testing
format to yield reliable and accurate results. For children under
18 months better testability can be achieved by using the
mask provided to present only one optotype (face).
It is important to understand that the Pacific Acuity Test is not
equivalent to a standard optotype recognition test like LEA Symbols
or Snellen. However, it does provide an acuity measure that
is close to isolated single symbol tests and can be used to detect
significant visual impairment and inter-ocular difference in cases
of suspected amblyopia or unilateral pathology in children who
are cooperative for monocular acuity assessment.
Test Administration
The full test kit consists of 18 cards with two cards at each level.
The cards at each acuity level have a different position of the
face target compared to the opposing oval figure. Each card
can be presented at either 50 cm or 1 meter but the 1 meter test
distance is recommended for greater accuracy and comparison
to distance visual acuity tests. The test range from 1.3 LogMAR
(20/400) down to 0 LogMAR (20/20) allows for testing a broad
range of visual acuity. (see chart below)
It is important to have adequate lighting but be careful to avoid
direct lighting at an angle that creates glare on the card surface.
The clear coat used on each card improves durability but can
create glare with direct lighting positioned behind and above the
patient.
1. For most children, we recommend starting with the 1.0 Log-
MAR (20/200) card and use that level to introduce the child to
the test paradigm. If the child has visual impairment, the 1.3
LogMAR(20/400) level card can be used.
2. The test administrator should shuffle the cards at each level
so that they are not aware of the position of the face prior to
presenting each card.
3. Present a card at 1 meter and ask the patient, “Where is the
boy”? We have found that testability improves if the examiner
gives the face a name. It is important to be consistent since it
is the same face used on each card. Observe the child’s fixation.
The child should respond by looking at each figure before
making a “decision” and either fixating preferentially on the
face, pointing or saying up or down if verbal. Encourage the
patient to point to the face and reward the child for responding.
Positive reinforcement is critical to testability. As the child
reaches the threshold of acuity, even incorrect responses
should be rewarded.
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Pacific Acuity Test Continued
4. If the patient responds easily to the 20/200 card level (both
cards), we recommend moving to the 20/100 level next. If the
child is able to respond to 2 successive cards at any level,
move on to the next. When the child begins to have difficulty
discriminating the targets (near threshold), it is important to
perform at least 3 card presentations at that level. Threshold
should be the last level in which the child is able to get at least
2 out of 3 card presentations correct but more presentations
can be done to increase certainty at and below threshold.
Make sure to shuffle the cards after each presentation so that
the patient nor the examiner can guess the position of the face.
5. For children below age 18 months, we recommend using the
mask provided to create a single optotype (face only) presentation.
Although this will yield a detection acuity without a
recognition component, infants and toddlers respond much
better to a single optotype. It is possible to use the 2-optotype
recognition task with children younger than 18 months
as many will respond by clearly showing a gaze preference for
the face. The clinician should evaluate the child’s responses
and use the test paradigm that will yield the most success in
reaching a clear threshold.
Snellen Equivalent
at 50 cm
LogMAR
Snellen Equivalent
at 1 meter
LogMAR
400 1.3 200 1.0
200 1.0 100 0.7
160 0.9 80 0.6
127 0.8 63 0.5
100 0.7 50 0.4
80 0.6 40 0.3
63 0.5 32 0.2
50 0.4 25 0.1
40 0.3 20 0
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