• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

30 Cards in this Set

  • Front
  • Back
Rules for letter chart VA
Use a chart that follows Bailey-Lovie design principles (e.g., ETDRS chart)
Logarithmic size progression, task the same at each level

Have best refractive correction in place

Constant luminance (recommended 160cd/m2 ) 80-320cd/m2 OK

Patient must be able to read ALL letters on top row
and NO letters in the bottom row

Give credit for every letter read correctly

Consistent administration

Do not point to individual letters
If you isolate or underline rows to help place-keeping, be consistent Encourage guessing in a consistent manner
If patient gets 3 of 5 correct (>50%) in their last row
always ask “Can you guess at any letters at all in the next row?”
Why distance VA should be measured at 4m
4 meter viewing distance achievable in most rooms

Convenient to allow +0.25 D for close (4m) viewing distance

Mathematically similar to 40 cm test distance used for near vision

Metric units used for all other ophthalmic measurements
Describe the Berkeley Rudimentary Vision Test. Indicate the kinds of visual acuities it measures, the test distances it uses, and the visual acuity ranges that are achieved.
pairs of 25 cm square cards hinged together
Single tumbling E card pair ( 4 different sizes) 100M, 25M, 63M, 40 M) Grating card pair (4 different sizes) 200M, 50M, 125M, 80M
Basic Vision card pair
White Field Projection (black with white quad field , Black with white hemifield) Black White Discrimination Black card and white card

25 cm for STE, Grating , WFO, BWD

Beyond limit of letter charts (limit LC VA = logMAR 1.6 20/800
( BRVT begins at STE LogMAR = 1.4) Allows acuity scores much less than logMAR = 2,0 (20/2000)
STE acuity to logMAR = 2, .6 (20/8000) Grating acuity to logMAR=2.9 (20/16000)

WFP and BWD do not give a measure of VA. Used if VA not measurable with grating card pair
List 4 different purposes for conducting a visual field examination using a tangent screen. For each, indicate how you select the test target parameters
Screening - for unsuspected disease moderate visibility target
demonstrate blind spot
diagonal sweeps or large zig-zag

Investigation - for suspected disease
test as sensitive as possible
target just visible in region being investigated

Monitoring - for change in known disease
use same conditions as last time
If previous conditions were not appropriate then do second field test with optimal conditions This becomes the new baseline

Functional fields - for predicting practical problems Large easy to see targets)
Might change illumination conditions
Might use white photopic backgroundwith black targets
Describe the Pelli-Robson Test
Large letters all the same size 6 letters across

Contrast varies Each group of three letters has same contrast.

Progressively reduces Viewing distance should not be distant (1 meter recommended, closer is OK)
How do the results from the Pelli Robson chart correspond to the Contrast Sensitvity Function?
The result from the Pelli Robson chart shows the peak of the contrast sensitivity function
List four different purposes for taking VA
Treatment decisions (refraction, magnification)
Checking vision is “normal”
Quantifying effect of ocular disorder or disease
Monitoring stability of vision
Predicting functional abilities at visual tasks
Quantifying loss for compensation or benefits
Standards for eligibility for jobs, privileges
How do spectacle lenses affect the VF?
HIGH PLUS LENS (hyperope)
Blind spot smaller and more central ( less eccentric)
Scotomas smaller. Scotomas less peripheral than retinal lesions
Ring Scotoma
Ring scotoma moves with eye movement.

Blind spot larger and less central (more peripheral)
Scotomas larger than retinal lesion. Scotomas more peripheral than retinal lesions Unable to stimulate peripheral retina through spec lens
Contrast sensitivity.is often assessed by comparing high-contrast letter-chart acuity and low-contrast letter-chart acuity.
How are these measurements be related to the CSF?
Differences in letters seen for high and low contrast gives info about the slope of the CSF as it approaches the cut off spatial frequency
Hi contrast VA = cut off SF
Low contrast VA gives Spat Freq limit at a certain height up the slope.
Height up the slope is determined by the contrast of the low contrast chart Join these two points and it gives slope of CSF curve in right side
The United States law that defines Statutory Blindness, gives the visual acuity requirement as
best corrected visual acuity in the better eye must be
worse than 20/200
The United States law that defines Statutory Blindness, gives the visual field requirement that, for the field in the better eye.
maximum diameter is equal to or less than 20 degrees in all 8 major meridians
The visual acuity criterion for “blindness” used by the World Health Organization (WHO) is that best corrected acuity is
worse than 20/400
In 2007, The Social Security Administration issue new rules so that now an acceptable criterion for Statutory Blindness
worse than 20/100
How many people would you expect to be legally blind?
How many people would you expect to be totally or functionally blind?
15%-20% of the legally blind
How many people would you expect to be visually impaired?
2% total
List the reasons for preferring to trial lenses, rather than a phoropter
when refracting low vision patients
Better to use trial lens system than phoropter
Observe eye movements and viewing strategies
Observe nystagmus, change with monocularity, fixation etc
Observe closing eyelids, actively or passively
Allows patient to alter head and eye posture
Allows abrupt changes in large steps of power Avoids vignetting of pupil by phoropter aperture
On the Bailey Lovie Chart, the visual task is essentially the same at each size level so that size is the only significant variable from one level to the next.
List the chart design features required to bring about this standardization of the task on letter charts
Charts should have task the same at each size level
ie., size only significant variable from one level to the next
a. Same number of letters at each size level
b. Logarithmic size progression (constant ratio)
c. Spacing between-letters and between-rows proportional to letter size d. Letters balanced for legibility (rows equally difficult)
How many mm in 1M
List the advantages of doing an over-refraction using Halberg Clips (or similar) rather than using a trial frame
In high powers, better control of positioning and aberrations
Old Rx and New Rx expected to have
-Similar vertex distance
-Similar lens tilt
-Similar aberration distribution and field properties

Changes in Rx are of usually of modest magnitude
-Work with lower power lenses (available in 0.25D steps)
-Less precision needed positioning lenses
-Less precision needed for axis (of over-refraction cyl)

Easier demonstration of the effect of changes
-Verify changes Patient sees the impact
What are the differences between the Bailey Lovie Chart and the ETDRS
4x5 letters in BL (British non serif) 5x5 letters in ETDRS Sloan letters) 4 meter test dist for ETDRS
How to make the a chart as good as the Bailey Lovie Chart
Log size progression

Same number of optotypes per row

Spacing between rows and between letters proportional to size

Mix of optotypes about equally difficult in each row
Many visually impaired patients report that their visual abilities are especially sensitive to lighting levels. Describe a methodology for systematically assessing the effects of retinal illuminance on visual acuity and contrast sensitivity, and when would you use such a method.
Use dark gray filters
Test VA and CS with and without filters
Note differences due to filter.

Neutral NOIR U23 (1.6% or 2% neutral) or other very dark filter

VA drops by 10 letters, CS by 0.12 log units
What is the major difference between square wave gratings and sine wave gratings for the Contrast Sensitivity Function?
there is no low frequency roll off for square wave grating
For VA = 20/20, what is the expected “cut-off spatial frequency ” in cycles per degree?
30 cpd
What is the spatial frequency at the peak of the normal CSF?
What do measurements of low contrast visual acuity tell you about the CSF?
Diff in VA at two different contrasts indicates slope of curve on right side of CSF
Describe the Berkeley Discs Test of Contrast Sensitivity, and comment on the potential advantages of this test. You do not need to specify contrast levels.
3 cards, 6 sides

A 3x2 grid (6 cells) on each card face.
Some cells have a disc of selected contrast (actually 3 discs on each side) and subjects task is to locate the discs. (Cells about 3” or 75 cm square and discs 2” or 50mm in diam)

First card is screening card (S card 0.0, 0.6, 1.2 and 0.3, 0.9 and 1,5) Two other cards. One for high CS, the other for medium and low CS
One card does in-between steps at medium &low CS end,
(A card 0.15, 0.75, 1.35 and 0.45, 1.05 and 1.65)
The third card does extra contrast at the good CS end
(B card 0.75, 1.85 and 1.80 and 1.05, 1.65 and 1.95)
What are the parameters for testing Legal Blindness?
Goldmann III 4e on white background of 10 cd/m2
What are the four color vision tests you can use?
D15 Panel

Portnoy Test for RG defects

Bernson Achromatopsia

Sloan achromatopsia test