Visual Assessment 5% Flashcards
The normal human eye can distinguish 2 points separated by an angle of __________
1 arc minute
Each section of the letter E subtends ____________
1 minute of arc
The whole letter E subtends _______________
5 minutes of arc
In recording VA (US measurements) Numerator=
Top number, Distance (in feet) pt is from chart
*In recording VA (US measurements) Demominator=
Bottom number. Distance (in feet) that someone with normal vision could correctly read the letters.
When checking VA, the larger the number___________
the worse the vision.
How to convert feet to meters
3:1 ratio
6m=20ft
1m=3.28
Divide denominator by 3 to get approx meters. (Or drop the 0 and multiply the first number by 3. Ex. 20/40=6/12(2x3 is 6 and 4x3 is 12))
Convert to meters…
20/60
6/18
Convert to meters…
20/400
6/120
Convert to meters….
20/30
6/9
What do you do if pt can’t see 20/400 E?
Have pt move toward the chart until he can read 20/400E
Example charting 4/400 (pt 4’ away from screen, read 400 line)
If pt cannot distinguish the 20/400 E even from close distance what are the next steps?
Hold you one or two fingers up in from a distance of 5’
Move 1’-2’ closer until pt can accurately count your fingers
Record as CF(count fingers) @_______
If pt cannot count fingers…….
Move your hand side to side or up and down in front of eye.
Ask..”am I moving my hand up and down or side to side?”
If s/he can accurately perceive your hand moving record HM(hand motion) @___
If pt can’t accurately detect HM…….
Darken Room
Project transillumintor from 1”(be sure to keep fellow eye covered). Check all 4 quadrants.
If pt can’t see transilluminator, use indirect ophthalmoscope and try again.
Record as LP with proj or Light percetion with projection.
If pt can’t accurately detect the position of the light but CAN perceive the light record as LP or Light perception.
If pt is unable to perceive light…..
Record….Absent Light perception, No light perception, or NLP
When checking VA 3 month old should be able to _________
4-6 mos old should be able to _________
Follow light
Reach for toy
When checking VA of Pre-verbal Pts…..
3 mos to 2 years old
-observe patient’s gaze
-Cover each eye seperately and see if pt focuses on a light. (Fixates & Follows)
-Eccentric fixation but steady+Probably ,NL
-Unsteady and eccentric fixation=VA probably extremely poor and eye defective.
What does CSM stand for when evaluating fixation in infants?
CSM=Central, Steady, Maintained
What does CSUM stand for when evaluating fixation in infants?
CSUM=Central, Steady, Un-Maintained
What does CUSUM stand for when evaluating fixation in infants?
CUSUM=Central, UnSteady, Un-Maintained
What does UCUSUM stand for when evaluating fixation in infants?
UCUSUM=UnCentral, UnSteady, Un-Maintained
What vision chart is best for pre school children age 2+ and mentally challenged older children or illiterate adults, used in school screenings, 30’ denominator, shows pictures at close range with OU open then one eye, pictures presented while backing away. You record greatest distance at which 3 pictures are accurately identified in each eye. If difference of VA is >5’ refer to doctor for eval.
Allen Picture Chart
This vision chart is for Pre school children an 2+ and illiterate adults. Pt points their finger or plastic E in the direction of the E on the chart. Pt should practice before beginning.
Tumbling E’s
This vision chart is good for illiterate and pre school children. Pt identifies where the break is in the letter C.
Landolt’s Broken Ring Test
*This vision chart is good for young or mentally challenged children or adults with a language barrier. Measures Near and Distance VA. Used at 10’ or 20’. Pt is given corresponding key chart and asked to hold the chart to identify the corresponding letter.
Sheridan-Gardiner Test (Matching Test)
*PAM uses ________light source.
Pinpoint
PAM uses an illuminated __________chart.
Snellen
_____________test uses pattern of stripes. Red or white separated by black stripes of equal width. Width of stripes can be changed. Present vertical & horizontal lines first assess VA, then present oblique lines. Pt is asked to state orientation of each grid while the width of stripes are changes. This test is similar to PAM but uses stripes.
Laser Inferometer Test.
Visual Acuity________. Is standard eye chart accepted in studies sponsored by the National Eye Institute. Adopted from Early Treatment of Diabetic Retinopathy Study. Designed for use in clinical studies and low vision evaluations where accurate and repeatable visual acuity measurements are required. Geometric progression in letter size from line to line, each line is of equal difficulty.
ETDRS
This vision chart is used for Pre school ages 3-7. Has video Acuity Tester with monitor, software and hand controller. Is calibrated at 3 meters. Uses high contrast black and white letter ( H O T & V). Single letters are framed with crowding bars spaced a letter width around the letter.
EVA (Electronic Visual Acuity)
Children should be able to follow light by age….
3mos
Children should be able to reach for you by age…..
4-6 mos
Used to check VA in infants and pre verbal patients. Uses vertical black and white stripes. High contrast images.
Teller Acuity Cards
Measurement of VA in poor contrast conditions.
Contrast sensitivity testing
Test that uses charts and machines, stripes of varied contrast, size, orientation, done at near and distance, and is more reliable than Snellen.
Contrast sensitivity test
When should contrast sensitivity testing be done?
With cataracts, refractive sx, glaucoma, AMD, CL fitting.
