Transcript Clinical VS Functional Assessments

Session 1: Wednesday, September 9, 2015:
Clinical versus Functional Assessments of
Vision



Introductions
Discussion of Course Syllabus
Clinical versus Functional Assessments of
Vision
◦ Clinical Assessments (Rhiannon)
◦ Functional Assessments (Sheree)
Any Questions/Comments?

This is detective work for clinician!








Chief complaint
Ophthalmic History
General Health
Family Ocular History
Family Medical History
Medications
Allergies
Goal is for us to have a working diagnosis






Definition: The ability to distinguish object
details and shape
Is assessed by the smallest identifiable object
that can be seen at a specified distance.
Can be recorded in feet (i.e. 20/20) or in
meters (i.e. 6/6)
Legal blindness is 20/200 (6/60)
What does 20/40 vision mean?
What does 10/200 vision mean?

Testing Vision
◦ Adults read letter charts (Snellen, ETDRS)
◦ If a patient cannot see any lines on the chart:







Use a low vision chart
Move chart closer to patient
Count Fingers (CF)
Hand Motion (HM)
Light Projection (LProj)
Light Perception (LP)
No Light Perception (NLP)
◦ Children are a little more difficult!!!

Testing Vision in Children
◦ Some older children can recognize letters, and can
be tested with adult vision charts
◦ Children who cannot read letters can be tested with
various tests
 HOTV (usually matching)
 LH (Lea) Symbols (matching or naming)
 Heart, Square, Circle, House
 Fix and Follow
 Face, light, toy
 Heidi Paddles
 Fixation Pattern (with penlight)
 Central, Steady, Maintained
CSM
CUSM
CSUM

Testing Vision in Children
◦ Teller Acuity
 Preferential Looking Test
 Can be used on infants and children with cognitive
delays
 Can over estimate vision



Definition: Binocular perception of depth
Is caused by horizontally disparate retinal
images
The Phi Phenomenon
◦ Hold out your finger at arms length and close your
eyes alternately.
◦ Your finger will appear to “jump”
◦ This demonstrates how each eye has a slightly
different view of the same object, which is how
stereopsis is produced.



It’s important for clinicians (especially
orthoptists and pediatric ophthalmologists) to
measure this, because it tells us about a
patient’s binocularity (how their eyes are
working together).
It’s measured in seconds of arc or (’’)
There are a variety of tests
◦
◦
◦
◦
Random Dot Stereograms
Lang Test
Titmus Test (fly)
Frisbee Test


Strabismus is a misalignment of the eyes.
Detected by using light reflexes or a cover
test.

Types of Strabismus
◦
◦
◦
◦

Exotropia
Esotropia
Hypertropia
Hypotropia
Is always identified by which eye is
misaligned
◦ Right
◦ Left
◦ Alternating

Strabismus can be constant or intermittent.
RXT RX(T)
AXT
LHT



Is measured with prisms and recorded in
prism diopters
Eye muscle movements are also recorded on
each visit
These will help the clinician to monitor
changes, or to compare pre- and postoperative measurements


Definition: Ability to perceive and
discriminate between light on the basis of
wavelength composition.
Color is detected by the photoreceptors in the
retina
◦ Red, blue and green cones

Color vision defects can be inherited (Xlinked recessive) or acquired (side effect of
medication, retinal disease, optic nerve
problems, etc.)

Color vision is tested under specific
conditions
◦ Controlled lighting
◦ Proper correction must be worn
◦ Tested one eye at a time

There are a large variety of tests
◦ Farnsworth D-15
◦ Ishihara


Definition: The portion of space that is visible
to the steadily fixing eye.
Total binocular field is about 180-200
degrees.

The image formed on the retina is upside
down and reversed, but everything becomes
upright when the “message” reaches the
brain.
◦ If the retina looks abnormal at the top of the eye,
then the visual field defect would be in the lower
part of the field.

Visual fields are always tested one eye at a
time.
◦ There will be a blind spot at the site of the optic
nerve.

Visual Fields are tested with various machines
◦ Goldman
◦ Humphrey

A confrontation visual field is a simplified
visual field screening tool


Determines the retina’s ability to detect
subtle differences in brightness between
targets and their backgrounds
It measures the minimum contrast necessary
for resolution of a target




The “non-invasive” measurement of
intraocular pressure (IOP)
Measured in mmHg
Normal range is 10-21mmHg
Tested with various devices
◦ Can be contact (requiring anesthetic eye drops) or
non-contact (puff of air)

Slit lamp exam
◦ Look at outer parts of the eye under high
magnification

Refraction (+/- dilation)
◦ Determine what prescription is required

Dilated eye exam
◦ Look at the inside of the eye through the pupil


Everything done during a clinical assessment
is meant to help the ophthalmologist assess
the health of the eye, and to determine a
diagnosis.
All testing is done under specific testing
conditions, and in a very “scientific” way

“The major goal of these evaluations [FVA] is
to obtain detailed information about an
individual’s current visual performance on
functional tasks carried out in the home,
school, workplace, and community in order to
determine the most effective compensatory
methods to improve performance and, as a
consequence, increase his or her independent
participation in those tasks” (Amanda Hall
Lueck, Functional Vision: A practitioner’s
Guide to Evualtion and Intervention).



Many of the areas of a FVA will look similar to
a clinical evaluation, however the information
being gathered is used in a very different
way.
A clinical evaluation looks at diagnosing and
treatment.
A FVA looks at accommodations and
supporting vision loss.
Before assessing:
 Gathering medical information
 Interview parents, teachers or other people
involved in the students life to see how they
function with their vision loss and where/if there
are areas of need.
 Interview student about their own concerns and
understanding of their vision loss.
*Students need to understand their own vision in
order to self advocate and find/use appropriate
accommodations.


Clinical charts are used to find functional
information e.g. print size, eye fatigue, visual
fields, head postures, tracking, lighting, etc.
The charts are always used in combination
with other informal tests such as reading
books, magazines, looking at pictures, sitting
at a computer and general observations made
while having a snack/lunch, talking with the
assessor.


Clinical charts are used to look at functional
tasks e.g. distance for seeing the board,
lighting, head postures, crowding, etc.
The charts are always used in combination
with other informal assessments such as
observations while travelling, ability to
recognize people, ability to read from the
board or recognize posters.


Clinical charts such as the Lea Symbols low
contrast flip chart are used to find functional
information i.e. lighting, distance, glare, etc
Charts are always used in combination with
informal assessment such as looking at low
contrast pictures, light or low contrast print
(magazines, sidebars in text books).



How students react to different lighting can
be discovered through interviews with family
and teachers as well as with the student.
Assessors can look at lighting in different
environments and how they perform the
same task in different lighting i.e. looking at
charts or reading a book.
Glare can also be assessed through
observation. i.e. magazines, graphic novels or
shiny plastic toys.
Many formal tests can be used to look at colour
discrimination during a FVA:
 Waggoner: Colour Vision Made Easy
 Farnsworth Colour Vision test
These tests can help pick out a colour
deficiency, but should be used in
combination with other informal tests such as
colour labeling and looking at books or maps,
etc where colour is intricate to
understanding.

Visual Fields can not be formally assessed
during a FVA. Observation is the best way to
see if there is a field loss i.e. bumping into
objects on one side, dropping letters on one
side of the chart, missing words when
reading, missing objects on the desk,
head/eye movements, etc.

Confrontational testing of visual fields
involves moving objects in and out of a
child’s visual field in order to determine if
there is a loss.



Clinical tests can be used, such as the Stereo
Butterfly Test or the Stereo Fly Test. However,
with these tests we are looking for difficulty in
perceiving depth or 3D images.
For functional reasons, we also observe actions
such as missing curbs or changes in ground
level, over under reaching, inaccurate pointing,
etc.
The clinical test should always be combined with
informal testing or observation.
Why can’t I see the 3D movie?

Tracking is informally assessed by having the
student read from a book or a chart, find
objects in an eye spy or follow a moving
object. Watching a students eyes while
following a moving object can give insight
into difficulty tracking print or troubles in
O&M.


What is most important about a FVA are the
recommendations or Functional Implications
that come at the end of the report. The
purpose of the report is to determine where
the student is functioning visually and then to
find ways to support their functioning.
Functional Vision assessments should be
done often in the field and should be the
driving force for programming.
Next week we explore the eye….stay tuned!