Final Exam Flashcards
Do you take into account Eccentric viewing position with VA exam?
NO! Do not assess them with eccentric viewing. Looking for central fixation.
what correction to use with VA
conventional like cl or spectacles but no lv devices.
VF blindness
20 degrees central limitation with Goldman III4e or -22 db mean deviation with automated.
Blind Defintion in US and Canada
20/200 or worse on normal or 20/125 or worse on logMAR or less than 20 degrees using goldman III4e stimulus.
WHO blind definition
20/400 or worse
Visual impairment in US and Canada
20/70 or worse. Peripheral vision loss in a sector or similar to glaucoma or RP.
Visual impairment defintion
a limitation in the vision
visual disablity
a limitation in abilities of the individual
visual handicap
a lack of personal and socioeconomic freedom.
Causes of blindness in adults
Cataracts (developing), ARMD (developed), glaucoma, diabetic retinopathy.
Which problem causing blindness is growing the most rapidly
diabetic retinopathy.
How many of kids with vision impairments are multiply handicapped?
75%
Central Vision loss
Hereditary foveal conditions/ARMD, foveal hyperplasia. i.e. albinism, aniridia.
Peripheral vision loss
RP, glaucoma, CVA, TBIs.
Central and peripheral vision loss
ON problems, late stage dystrophies, , ROP, diabetic reg
Conditions resulting in photosensitivity
aniridia, albinism, achromtopsia, retinal dystrophies, corneal dystrophies/scaring, congenital glaucoma.
Conditions affecting color vision
achromtopsia, cone dystrophies, ON conditions.
Conditions affecting contrast
glaucoma, cataracts, retinal dystrophies, corneal dystrophies/scaring.
Conditions causing nystagmus
any condition affecting the foveal pathway early on.
Vision where you can get by with just an add
20/100 or better (child) and 20/50 or better (adult)
Vision where you need mag 2-5x
20/100-20/250 (child) 20/60-20/100 (adult)
Vision where you need low vision
20/300-20/800 (child) 20/100-20/400 (adult)
Vision where brail is best
20/1,000 (child) or 20/400 (adult)
Development of a child with vision loss
Still develop but more slowly.
What areas are affected in development of a child with vision loss
Fine and gross motor development, social and communication development, cognitive develop (lacking visual information for some concepts)
Age for walking independently for low vision child
18-24 months.
Fine motor development in visual impiared
Need extra encouragement to tactile to explore their environment. Vision leads tactile and tactile reinforces vision normal.
Language development of visually impiared
Develop language acquisition at the same rate but descriptive vocabulary lacks.
Hearing in visual impairment
Can be increasing in congenital blindness or early on but acquired vision impairment can decrease hearing as no visual cues.
Cognitive development of the visual impairement
Severely impaired can have difficulty with concepts such as colors, figure ground, objects in 3d space, size and shape char.
Who has the greatest challenge with literacy
Moderate VI. 20/100-20/400.
Bioptic Driving laws
Can drive in the daytime if vision 20/70-20/200.
New preferred locus in older
Have difficulty findings a new locus with conditions like ARMD. This is why normal magnifiers do not work as expected.
Good outcome for LV
good cognitive development, self motivated, good image of self, 20/800 or better, longstanding, stable conditions, previous success with other LV devices.
Refraction of LV
Use retinoscopy and trial frame (allows eccentric viewing)
Retinoscopy of LV
scope on the axis of viewing if doing eccentric viewing.
JND
20 feet denomitor/100
Prescribing for near
Want 2x magnification above threshold.
Contrast reserve
contrast of objects/contrast threshold
what level of contrast reserve affects reading
10/1
Bailey Lovie Chart
One chart at high contrast (90) and one chart at low contrast (10). Normal difference is two lines. Significant if 4.
Bailey Lovie Chart
Same contrast but the size of the optotypes change.
Pelli-Robison
Same size letters and contrast changes. Perform at twice the threshold acuity. i.e. if 20/100 threshold perform at 20/200.
Functional deficient for contrast threshold
when 5% or greater
Which contrast is better
Peli-robison good for LV. Bailey love good for cataracts or recent disease.
Improving contrast with magnification
Often need much more magnification than predicted off of VAs
How to help with binocular vision at near
Plus lens with BI.
Stereopsis testing in lv
use a local test as global test is very rare.
VF testing in LV
Goldman III4e or HVF 30-2 or 24-2.
Arc perimeters
can be used to record the vf
Tangent Screen and campimeter
Test response with 9mm target at 1m Test again at 18mm object at 2m. The field should respond by 2 times. If not it is non physiological and nonorganic.
Macular testing in low vision
black on white best.
Macular testing with psuedomacular
Fixate with this location.
Position of PRL
To the right make it hard to saccade. The the left can make it hard to go to beginning of line.
Increase difficulty of VAs
- Minimal detection 2. resolution 3. recognition 4. hyperacuity
Levels of VA
NLP or total blindness, LP, LP with projection, hand motion, quantifiable VA.
Do you take into account a patient’s eccentric viewing position
NO
Visual field definition of blindness when no Goldman available
Mean deviation of -22 db or worse.
Hyperacuity
10x finer than resolution. 3-8 arc seconds. An improvement in hyperacidity vs resolution indicates that there is at least some macular function retained.
What to code for first
Medical or pathological condtions
What code to use regarding vision
H54.8 code for legal blindness before other vision impairment code.
What are most LogMar Charts calibrated for
4m
Fein bloom Calibration
In feet. Can get very high VAs.
FrACT Test
Must say the position of the landolt C. Can get up to very high VA. Similar to fienbloom
BRVT
Goes from tumbling E to grating to black vs white. At 100 or 25 cm.
Contrast for near charts standard
Should not be more than 15% of the background luminance. Correlates to 73.9% contrast.
Background luminance for near charts
80-320
what does improved performance on color contrast VA chart indiacte
Need for tinted lenses.
VA Measured with Landolt C
Can be 20-25% better than recognition.
Snellen
Denominator is the distance that the full letter subtends 5 arc minutes.
Half JND
Sphere bracketing lens, cylinder test lens, Cross cylinder lens
Full JND
Cyl bracketing lens
sine waves
gradual change in brightness
square wave
line waves. what is seen with a letter. 2.5 on the E.
M notion
the distance in M that the target subtest 5 arc minutes.
Preferred notion for near testing of low vision patients
M notion
RIM
RSM, RDM, LIM
afocal telescope
changes the angular subtense without changing the mergence.
Focal lengths of magnifying devices
stated relative to the principal planes.
Principal plane in plano convex lens
At the front of the surface
Principal plane in equiconvex lens
In the midpoint of the lens.