f unctional v ision a ssessment duncan mcgregor july 2015
TRANSCRIPT
FUNCTIONAL VISION ASSESSMENT
Duncan McGregor
July 2015
FUNCTIONAL VISION ASSESSMENT
A functional vision assessment examines how a student who is visually impaired uses his or her vision in day-to-day activities in school, home and community.
Twofold purpose:- to determine what the student sees- to identify what helps or hinders the student’s visual performance (Anthony, 2000) (accommodations, ECC goals)
WHOSE JOB IS IT ANYWAY?
A teacher of students who are visually impaired can:
Determine how a student who is visually impaired uses his or her vision in real-life activities.
Recommend accommodations or adaptations to- the educational environment- educational materials- teaching methods- etc.
Recommend programming in ECC areas Determine eligibility for TVI service
WHERE DO WE START?
Preparation for assessment
Review the file, esp. medical eye reports Interviews/questionnaires for teachers,
parents Classroom observation (sample checklists)
INTERPRETING AN EYE REPORT
Eye report forms: Looking to Learn, p. 29-30 YRDSB form Sometimes doctor will provide written report
and/or clinical notes
GUIDING QUESTIONSWHEN INTERPRETING EYE REPORT
Diagnosis, symptoms (nystagmus)? Implications
Stable/progressive? Additional disabilities? Acuity? Distance vs. near vision? Visual fields? Glasses? For near or distance? Do they help? Colour vision? Lighting? What materials will I bring to assess?Looking to Learn, p. 26
EYE REPORTS:WHAT THE DOCTOR TELLS US
Acuity measures: Distance:
- Snellen notation (20/, 6/, etc.)- LogMAR (Log Minimum Angle of Resolution)
Near:- Snellen equivalents- M size (distance in metres at which LC letter subtends 5° of arc)- Jaeger- point size
LOGMAR NOTATION
LogMAR eye charts have the same number of characters per line and same relative spacing.
Snellen Angle LogMAR
20/200 10° 1.00
20/160 8° 0.90
20/100 5° 0.70
20/80 4° 0.60
20/40 2° 0.30
20/20 1° 0.00
NEAR ACUITY EQUIVALENTS*FROM LOOKING TO LEARN, P. 20
M size Snellen equivalent
Jaeger Point size (Lower Case)
0.4 20/20 or 6/6 3
0.5 20/25 or 6/8 J1-J2 4
0.8 20/40 or 6/12 J4-J5 6
1.0 20/50 or 6/15 J6 8
1.2 20/60 or 6/18 J8 10
1.6 20/80 or 6/24 J9-J11 14
2.0 20/100 or 6/30
J11-J12 18
4.0 20/200 or 6/60
J17 36
5.0 20/250 or 6/80
J18
10.0 20/500 or 6/150
J19
20.0 20/100sss0 or 6/300
COMPONENTS OF A FUNCTIONAL VISION ASSESSMENT
VISUAL CAPACITIES
1. Visual acuity- distance- near
2. Visual fields- peripheral- upper and lower- (central)
COMPONENTS OF A FUNCTIONAL VISION ASSESSMENT
3. Motility - alignment - tracking
verticalhorizontaldiagonalcrossing midline
- scanning- convergence- nystagmus
4. Light and colour perception- colour vision- contrast sensitivity- light sensitivity- light/dark adaptation
CONDUCTING THE ASSESSMENT
blink reflex pupillary response muscle balance cover/uncover eye preference tracking convergence scanning peripheral fields (confrontation field test) then look at distance and near-point acuities
COLOUR AND CONTRAST SENSITIVITY
Colour vision testing (Waggoner video)- Farnsworth- Ishihara- Color Vision Testing Made Easy
Contrast sensitivity testing- flip charts: Lea numbers, Lea symbols- Hiding Heidi