1. GEPY 6911: Functional Implications of Visual Impairment
Session 1: Wednesday, September 9, 2015:
Clinical versus Functional Assessments of Vision

2. Agenda Introductions Discussion of Course Syllabus
Clinical versus Functional Assessments of Vision
Clinical Assessments (Rhiannon)
Functional Assessments (Sheree)

3. Introductions

4. Any Questions/Comments?
Course Syllabus
Any Questions/Comments?

5. Part I: Clinical Assessments of Vision

6. Clinical Assessments: History Taking
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

7. Clinical Assessments: Visual Acuity
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?
Numerator is the testing distance
Trying to determine the smallest identifiable object at a distance.
20/200 in the better seeing eye.
20/40: testing at 20 feet
10/200 chart is at 10 feet

8. 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!!!
Low vision chart: more lines of vision on it. More accurately determine vision.

9. CSM CUSM CSUM 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
HOTV are reversible
¼ chance of guessing correctly
Crowding
ETDRS and Logmar
CUSUM: Central, unsteady, unmaintained
CSM
CUSM
CSUM

10. Testing Vision in Children
Teller Acuity
Preferential Looking Test
Can be used on infants and children with cognitive delays
Can over estimate vision
Black dot in centre of gray card is a small hole. Tester looks through the card to see where she/he is looking. They should look at the black lines. Then move on to the next card. Lines get thinner and closer together. Harder to see it. Something to make comparisons from time to time.

11. Clinical Assessments: Stereopsis
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.
FIE Phenomenon
Each eye sees a slightly different picture. That allows us to have depth perception.

12. It’s measured in seconds of arc or (’’) There are a variety of tests
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
Smaller the number the better the depth perception.
Frisbee test: different thickness of glass
Measured in seconds or arc is measuring depth perception

13. Clinical Assessments: Measuring Strabismus
Strabismus is a misalignment of the eyes.
Detected by using light reflexes or a cover test.

14. Is always identified by which eye is misaligned
Types of Strabismus
Exotropia
Esotropia
Hypertropia
Hypotropia
Is always identified by which eye is misaligned
Right
Left
Alternating
Strabismus can be constant or intermittent.
Hyper: upward
Hypo: downward
Right eye turned in: right Esotropia

15. RXT RX(T) AXT LHT Right Exotropia: RXT
Intermittent right exotropia: RX(T)
Alternate exotropia:AXT
LHT: left hypertropia
LHT

16. 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 post- operative measurements
40 little triangle off to the side measures strabismus

17. Clinical Assessments: Color Vision
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 (X- linked recessive) or acquired (side effect of medication, retinal disease, optic nerve problems, etc.)
Congenital defects have few mistakes in some parts of the color wheel, whereas acquired defects have mistakes all over.
Cones pick up wave length and give picture to brain

18. 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
Specific bulbs, room lights out.
Farnsworth: place colors in order
Ishihara: pictures using dots

19. Clinical Assessments: Visual Fields
Definition: The portion of space that is visible to the steadily fixing eye.
Total binocular field is about degrees.
Test one eye at a time. Gives a better picture of what each eye is doing. Everyone has one blind spot when one eye is closed.

20. Visual fields are always tested one eye at a time.
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.

21. Visual Fields are tested with various machines
Goldman
Humphrey
Difficult to use with children

22. Right eye
Goldman visual field. Girl sitting at machine. Blacked out spot=blind spot

23. Left homonymous hemianopsia
Lost part of visual left field

24. RP
Goldman
Can see in patches
A different looking field

25. A confrontation visual field is a simplified visual field screening tool

26. Clinical Assessments: Contrast Sensitivity
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

27. Clinical Assessments: Tonometry
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)
Holding breath or eyelids closed can raise pressure!
Checking for glaucoma. Prof hates the puff of air test. Not a very accurate test. Need drops to freeze cornea. They press on the cornea to determine intraocular pressure.

28. Clinical Assessments: Ophthalmologist Exam
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
What looks better?

29. Clinical Assessments: Summary
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

30. Functional Assessments of Vision

31. Functional Vision Assessment
“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).
Used to find accommodations in the classroom. Not used as medical diagnosis. Functional tasks not medical info.

32. FVA and Clinical Assessment
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.

33. Areas of a FVA 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.

34. Assessing near visual acuity
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.
Not used in perfect lighting. Usually what the classroom lighting is. Pointing on a chart can take away from the visual acuity so you have to document that. Record acuity and in different environments and times during the day. A lot of students read on a computer or ipad. Use it to check their vision and see if we can make it easier for them or increase acuity. Make observations: move face close to book or snack.

35. Assessing Distance Visual Acuity
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.
Reading from the board, a poster, what concerns do they have, what do they see not can they see. Do it during the O&M session. Look at the distance acuity. Using a smart viewer, take pics with ipad/phone to zoom and make bigger.

36. Assessing Contrast Sensitivity
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).
Math/science text book can have poor contrast. As well as comic books. What do you see in this picture if low contrast picture.

37. What do you see?
Chris Van Alsburg. Kids make up stories based on the picture. Low contrast. Some see rock, water, trees.
Can you read text on your phone, ipad etc?

38. Assessing Light Sensitivity
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.
Observe outside and in. doing a lot of different activities. Some see better with dimmed light.

39. Assessing Colour Discrimination
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.

40. Assessing Visual Fields
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.

41. Assessing Visual Fields
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.
Have a deficit on left or right. Careful that the visual field you are testing is supported by a medical diagnosis as well.

42. Assessing Depth Perception
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?
Pick up fly by wings. Touch top of pen when placed infront of them. Will have difficulty if depth perception deficit.

43. Assessing Tracking
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.
Stick with bug on the end of it. Or use a pen. They track it and we watch their eyes. Difficulty: jumpy eyes, nistagmus will get worse. So difficulty tracking print. They need to follow with their fingers.

44. Functional Implications
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.
May have same acuity but each student is different..light sensitivity, etc.

45. Next week we explore the eye….stay tuned!
Questions/Comments?
Next week we explore the eye….stay tuned!