about different chart used to test visual acuity

1. TEST TYPES USED IN
DIFFERENT AGE GROUP
By
praveen p
Optom.praveenmails@gmail.com

2. Visual acuity chart for infants
 Optokinetic nystagmus drum
 Lea paddle.

3. Visual acuity chart for pre-
school children
 Landot ‘c’
 Tumbling ‘E’
 Sheridan Gardiner.
 Stycar visual acuity test .
 Lea symbol .
 Kay picture test.
 Cardiff chart .
 Allen card test .

4. Visual acuity chart for school
going childrens /adults
 Snellen chart
 LogMar chart
These chart are used only to test distance vision
and not used for testing near vision .

5. For infants
 Opto kinetic Nystagmus Drum[OKN]
 It is a gross test and is based on preferential
looking principle .
 It consists of a drum which has alternate
black and white strips .
 The drum is passed through patient field of
vision by rotating the drum and the eye
movement of the patient is seen .

6. Optokinetic Nystagmus Drum

7. Optokinetic Nystagmus Drum
 It is done with both eye open .
 The child makes nystagmus movements if the
stripes are seen as the drum is rotated for
these the patient should fixate the eye on the
drum .
 Black and white stripes are used because it
gives contrast and suppose once the patient
has fixated his eye on one black strip .

8. Optokinetic Nystagmus Drum
 Than immediately at a certain standard
distance he see second black strip and in
these way constant eye movements are seen
.
 It is necessary to attach the childs attention
towards the drum .
 It is done at a close distance .
 The vision we get is only the approximate
value and we cant relay on it .

9. Lea paddle

10. Lea paddle
 It is based on preferential looking and snellen
principle .
 The chart is placed at a distance of 1m from
the patient .
 It is usually used for the age group of 3 to 9
mths .
 There are cards available of various thickness
of lines .

11.  At a time two cards are held infront of the
patient .The blank infront and the one with
lines ie, held behind it .
 Then immediately the second card is flipped
out and we keep on changing the positions.
 The patient should appreciate the card with
lines .
 The test is done at same eye level and the
eye movement of patient is seen .

12.  It is necessary to fixate the patients attention
.
 The thickness of lines varies from 0.25 to 8
cpcm is the measuring unit .
 Cpcm stands for cycle per centimeter .
 It give only approximate value and so we
can’t.

13. Landolt ‘c’ chart

14. For preschool children
Landolt ‘c’ chart
 It is usually used for age group of 3 to 6 yrs
who cannot recognize letters .
 The chart consist of broken circles with each
broken ring subtending an angle of 5 min at
nodal point .
 The chart is shown to the patient at a
distance of 6meter .

15.  The patient has to identify the part from
where the ring is broken by pointing the
direction up ,down ,left,right by finger .
 Landolt ‘c’-chart based on log MAR principle
are also available .
 They consist of 5 rings per line and the size
goes on decreasing as we move a head .

16. Tumbling ‘E’ chart

17. Tumbling ‘E’ chart
 It is similar to landolt ‘c’ except that it consist
of letter ‘E’
 The test is again done at a distance of 6
meter.
 The child is given wooden or plastic letter E
and is asked to point the direction of E as
instructed by the examiner .
 Or the patient is directly told to point the
finger in the direction up down ,left, right as
shown in the main chart .

18. SHERIDAN GARDINER TEST

19. SHERIDAN GARDINER TEST
 It is used for the age group of 2-5yrs .
 It is done at 6 meter and if child can’t read
6/60 we can do it at 3 meter .
 The chart is available in the form of spiral
booklet .
 The main chart consists of letters HOTV of
different size .

20.  These letters are arranged may be in circular
form to give proper orientation so that child
can identify them properly .
 The child is given a key card and is asked to
match with the letter as shown in the main
card.
 The four letter ‘HOTV’ are only used as they
are considered as standard letters for
measuring visual acuity .

21.  More over it is found that these letters are
more child friendly .

22. STYCAR VISUAL ACUITY TEST
 It is done at a distance of 10 to 20 foot
distance .
 The main chart consist of pictures of eating
items or toys .
 The child is given a key card and is asked to
match with the pictures as shown in the main
chart by the examiner .

23. LEA SYMBOL CHART

24. LEA SYMBOL CHART

25. LEA SYMBOL CHART
 It is done at a distance of 3meter.
 The chart is available in simple as well as
spiral booklet form .
 The main card consist of 5 symbols with one
symbols in centre and the rest 4 are located in
circular form around the central symbol .
 These arrangement is done in particular to
develop both crowding and confusing
phenomenon for the child difficulty .

26.  The examiner shows normally centre symbol
but at the same time he can ask for other
symbols too.
 The patient is given a key card to point out
the symbol .
 These symbols are fixed and are kept a
standard like apple ,house ,circle ,square etc
..

27.  The size of pictures goes on decreasing from
3/9.5 to 3/2.4 and there are four cards for
each size .

28. KAY PICTURE TEST

29. KAY PICTURE TEST
 It is used for children of 2-3 yrs .
 The test is done at distance of 6 meter .
 It is based on snellen principle .
 The chart is in the form of spiral booklets .
 Each page has a single picture .
 The size goes on decreasing from 6/60 to 6/6
with each size having 3 cards.
 Again the patient is given a key card and is asked
to match with the picture as shown in the main
chart .

30.  The picture are set up as standard like house
,train ,shoe etc

31. CARDIFF TEST CHART

32. CARDIFF TEST CHART
 It is done at a distance of 1 meter and if
patient can’t appreciate than the chart
workup can be done at 1/2meter also.
 The chart consist of a single picture object .
 The patient is shown the first object and than
the second card having the same object but
at different position is shown or the same first
card is rotated and shown to the patient .

33.  The test is done at same eye level and the
patients eye movement is seen .
 It is a gross test and based on preferential
looking .
 It is the most common chart used for
screening , visual acuity for pediatric patient .
 The charts are changed fast so that patients
eye movement can be seen.

34.  The pictures are of fish, house ,boat ,duck
etc…
 Another advantage of these chart is that the
conversions in foot ,metre, decimal and
logMAR for 1meter and ½ meter are given
itself behind the card so that vision can be
recorded accurately.


35. ALLEN CARD TEST/ALLEN
PRESCHOOL VISION TEST
 It is done at a distance of 3 meter .
 It consist of a set of seven card with each card
containing a single picture .
 It is usually used for 2 yrs old child and older .
 The child is first shown cards at close range
with both eyes open and is asked to name
each picture .
 Then one eye of patient is occluded the
examiner shuffles the cards and presents
them individually over greater distances.

36.  The picture are of familiar objects so that the
child can name them properly .

37. FOR SCHOOL GOING
CHILDREN/ADULTS
 SNELLEN CHART
 It was introduced in 1862 by snellen .
 The chart consist of seven row namely
6/60,6/36,6/24,6/18,6/12,6/9,6/6. and sometimes
6/5 ,6/4 also will be there.
 These is the most common chart used to measure
the vision.
 The patient is told to occlude one eye and is asked
to read the chart from top until the last line or letter
that he can read and the vision is recored as vn OD
,OS .,

38.  It consist of letters of varying size .
 It is done at 6 meter and we can take it as
3meter also.

39. DISADVANTAGE
 It has 100% contrast level same all over the
chart .
 If the patients visual acuity is in between 6/60
and 6/36 or 6/36 and 6/24 than it cannot be
measured by these chart .
 It cannot be used for low vision patients.

40. LOGMAR CHART

41. LOGMAR CHART
 It was given by Bailey and lovie in 1916 and so
it also called as Bailey lovie chart.
 The production was done by light house .
 The measurements are based on logarithm
principle .
 Bailey Lovie also gave another logMAR chart
which had decreasing contrast as we move a
head to measure the contrast level.

42. Advantage of logMAR chart
over snellen’s chart
 It is used to find minimum visual acuity .
 It can be used for low vision patients.
 The rate of progression is slow .Each line
consists of 5 letters .
 If the patient cant read the side letters ,this
will give the motivation level to the patient .
 It is measured at a distance of 3 meter the
chart work up can also be done at a distance
1/2 meter .

43.  The spacing between two lines is equal to the
width of the letter presented in earlier line
and the spacing between two letter symbol
present in the same line ,it gives accurate
readings.

44. Disadvantages
 It is very costly.
 Care should be taken .

45. Thanks to all