Low vision techniques Flashcards
What are the differences in vision rehab exam and general eye exam
- detailed functional case history
- obtain VA differently
- trial frame refraction
- central field test
- contrast sensitivity
- optical device testing
What do you do if the patient fails to read even the largest target
- Reduce the test distance
- wiggle your hand
- use a light and ask where?
- use a light and ask, can you see it turn on or off. If patient cant determine if room lights are on or off –> no light perception
WHat are the benefits of a standard projector chart
- doesnt require room lighting
2. lines can be isolated
What are the disadvantages of a standard projector chart
- poor measurement of <20/100 vision
- no uniform spacing and amount of letters per line
- set distance
- variable contrast and illumination
What are the benefits of a computerized acuity system
- many choices of optotypes
- eleminates patient memorization
- high contrast optotypes
What are the disadvantages of computerized acuity systems
- poor measurement of <20/100 vision
- less optotypes per line
- Set test distance
- limited by size of screen.
Why is the ETDRS chart the most benefiical
- Same number of optotypes per row
- equal spacing of optotypes and rows on a log scale
- variable test distance
- equal optotype difficulty
- high contrast optotypes
What are the benefits of a feinbloom chart (handheld)
- portable
- test at any distance
- high contrast numbers
- large optotypes
- can measure <20/800
What are the disadvantages of a feinbloom chart
- variable number of optotypes per page
2. variable spacing between optotypes
ETDRS chart measures VA in ____whereas, feinbloom measures in ______
meters; feet
Recording Distance VA
- Always record the exact test distance you used and actual letter size
- extrapolations are noted in parenthesis (20 feet equiv)
- note the chart you used
Why do we record VA diff in vision reha
- more accurate measure of visual acuities = can alter test distance and can obtain VA for severe to profound vision loss
- can repeat the same testing conditions as the previous clinician
- easily determine if any changes in VA
- avoids confusion about which testing conditions were used
Near VA is recorded in ___units NOT reduced snellen
meter
1M = ____ min arc @ 1 meter
5
To go from snellen to point notation you would ____by ____:
divide; 6
To go from point to meters you would ____ by ____
divide; 8
To go from meters to snellen you would ____ by ____
multiply; 50
What is spot acuity
Limit of acuity to be able to recognize print; quick reading
What is sustained reading acuity
limit of acuity for reading print for a longer period of time (~10 mins or more); ex reading books, mags, or newspapers
What is the static visual field testing for
peripheral field; stimulus changes in brightness; techniques are confrontation field, humprey automated perimetry, and octopus perimetry
what is the kinetic visual field testing for
points tested are moving from an unseen area to a seeing area. stimulus brightness is the same; techniques include tangent screen, humphrey SSA kinetic test, goldmann perimetry, octopus perimetry
central field tests:
asses the central 20-30 degrees of the visual field; techniques include the amsler grid, humphrey automated perimetry, california central visual field test, octopus perimetry
What is the California Central Visual Field Test
Several laser brightness intensities allow for more sensitivity in plotting clinically significant scotomas. Examiner views patients fixation and eye movements better. Can be done monocularly and binoclularly
What is the test distance for CCVFT and what does 1 cm = to
57 cm. 1 cm= 1 degree
