This document provides information about visual acuity and how it is assessed. It defines visual acuity as the ability to see fine detail and distinguish shapes. Visual acuity is measured using charts with letters, numbers, or symbols of decreasing size. It discusses different charts used to test visual acuity in infants, children, and adults. The document also describes procedures for assessing visual acuity and what is recorded if a patient cannot read the smallest line of a chart.

1. What is he
writing , why
can’t I see?

2. VISUAL ACUITY
Presented by : Dr Nikhil Agrawal , 1ST Year DOMS
Moderated by : Dr Pushkar Dhir
DHIR HOSPITAL AND POSTGRADUATE INSTITUTE OF OPTHALMOLOGY

3. VISION
VISUAL
ACUITY
COLOUR
VISION
CONTRAST
VISUAL
FIELD
STEREOPSIS

4. VISUAL ACUITY

5. What is Visual Acuity ?
• Visual acuity is a measure of the ability of the eyes
to distinguish shapes and the details of the object
at a given distance .
• It is measure of spatial resolution of the visual
processing system
• It is quantified by the minimum dimension that an
object must have in order for the observer to be
able to identify, distinguish or simply detect it.

6. Visual Angle
• It is the angle subtended at the nodal point of the eye by an object in the visual field.
• It is useful and convenient mode of specifying the spatial
(size, position , area)extent of an object.

7. COMPONENTS
MINIMUM VISIBLE RESOLUTION RECOGNITION
Presence/absence of stimulus Identify the spatial characteristics of
target
Resolution + Cognition

8. Visual Milestones
Age Visual Milestone Visual Acuity
3 Months Reaches towards interesting objects
Prefers photographs to patterns
Bifoveal fixation
6/120
6 Months Accommodation well developed
Fusional vergence well developed
Development of fixation to moving objects
6/90-6/24
9 Months Visual differentiation of objects 6/48-6/12
3 Years VA approaches near adult level
Can recognize picture and some letters
6/12-6/6
5 Years Stereopsis fully developed 6/6
3
Years

9. Birth- 3 MONTHS 3-6 MONTHS 6-12 MONTHS 1-3 YEAR 3-5 YEAR SCHOOL GOING
• Blink reflex
• Pupillary light
reflex
• Vestibulo-ocular
reflex
• Eye popping test
• OKN
• VER
• Fixation and
following
• CMS fixation
• Cover test
• Bruckner’s red
reflex test
• Menace reflex
test
• Preferential
looking test
• Catford drum
test
• Cardiff acuity
tests
• Lea’s symbol
• Marble game
test
• STYCAR
• Miniature toy
test
• Boeck candy
test
• Landolt’s C test
• Broken wheel
test
• Pictorial vision
chart test
• Tumbling E test
• HOTV test
• Snellen’s letters
and numbers
• Snellen’s
number and
letters
• LogMAR CHART

10. VA Assessment in Infants
(Birth – 3 months)
• Blink Reflex Test
• Pupillary Light Reflex Test
• Vestibulo-Ocular Reflex: Dolls eye response
• Eye Popping Test
• OKN Test : Optokinetic Nystagmus
• VER :Visually Evoked Response
OKN TEST :10x8 inches diameter , slow phase 0.2s , fast phase 0.1s VER : Only clinically objective test
3 MONTHS OLD ANAYA

11. VA ASSESSMENT FROM
3-6 MONTHS
• Fixation Behavior Test: Infant fixates habitually with better
eye , resists its occlusion .
• CSM Method : Central( corneal light reflex )
Steady (eye movements are smooth)
Maintained( alignment is correct when either
eye is covered )
• Bruckner’s Red Reflex Test
• Cover Test
6 MONTHS OLD ANAYA

12. VA ASSESSMENT IN
6-12 MONTHS
PLT: Preferential Looking Test , Tellers Acuity Card test
Leas Paddles TAC CARDS
12 MONTHS OLD ANANYA

13. • Child prefers to look at a
patterned background .
• VA determined with PLT ranges
from approximately 6/240 in
newborn to 6/60 at 3 months
and 6/6 at 36 months .
Baby can you see me !!
TELLERS ACUITY CARD TEST

14. VA ASSESSMENT IN 6-12 MONTHS
Catford Drum Test:
 It is a detection acuity test.
 Oscillating drum with black dots of various size is
observed .
 Rotation of disc at 60cm evokes pendular
movement .
 Unreliable , as it overestimates the VA.

15. VAASSESSMENTIN
1-3 YEAR OLD
• Cardiff Acuity Card Test: Vanishing optotype test.
11 set of cards are available.
By observing the child’s eye movements and fixations.
• Lea’ Symbols: consists of 4 optotypes arranged
in combination of five per line.
Based on same principle as logMAR

16. VA ASSESSMENT IN 3-5 YEARS
At this age child is able to verbalize and recognize well
• Landolt’s C Test
• Broken Wheel Test
• Tumbling E Test
• HOTV Test
• Pictorical Vision Charts
• Isolated Hand –Fingur Test

17. VA ASSESSMENT IN SCHOOL
CHILDREN AND ADULTS
• SNELLEN’S VISUAL ACUITY CHARTS
• LogMAR CHARTS

19. SNELLEN’S CHART
• Starts with single letter at 6/60 with additional letters on each line progressing
to the 6/4 level.
• Fixed spacing between the lines .
• Nonuniform decrease in size of letters .
• Evenly illuminated
• Measures distance central acuity.
Dr Herman Snellen

20. SNELLEN’S CHART

21. LogMAR CHART
• Logarithm of the Minimum Angle of
Resolution
• Each step indicates increase of 25% in letter
size.
• Letter sizes ratio as we move up is a
constant value of 1.26(0.1log unit steps).
• Incorporated 5 letters in every row.
• Spacing b/w 2 adjacent letters = width of 1
letter.
• Spacing b/w 2 horizontal rows = height of
the letter on lower row.
Designed by Ian Bailey and Jan E. Lovie

22. • Used at a distance of 4 meters .
• 1min of visual angle scores LogMAR of 0 (Log of 1 is
0)
• 2min of visual angle scores LogMAR of 0.3
• As each letter size changes by 0.1logMAR units per
row & there are 5 letters on each row ,therefore
each letter can be assigned value of 0.02.
• LogMAR takes account of every letter that has been
correctly read.

23. VE Equivalents in Different Notation
MAR(min.) Snellen’s VA (ft) Snellen’s VA (m) LogMAR
1.00 20/20 6/6 0
1.5 20/30 6/9 -0.18
2.0 20/40 6/12 -0.3
3.0 20/60 6/18 -0.5
4.0 20/80 6/24 -0.6
6.0 20/120 6/36 -0.78
10.0 20/200 6/60 -1.0
20.0 20/400 6/120 -1.3

24. Early Treatment Diabetic
Retinopathy Study (ETDRS) charts
• Randomized clinical trial designed
to evaluate argon laser
photocoagulation and aspirin
treatment in the management of
patients with early proliferative
diabetic retinopathy(Based on
LogMAR).
• ETDRS equipment and testing have
evolved into what is considered the
gold standard of current-day clinical
trials involving vision testing.

25. Freiburg Visual Acuity Test (FrACT)
• “FrACT” is a visual test battery in
form of a free computer program.
It uses psychometric methods to
provide automated, self-paced
assessment of visual acuity and
contrast sensitivity
• For low vision it can reproducibly
assess CF and even HM.

26. Procedure
• Ensure good natural light or illumination.
• Explain the procedure to the patient.
• Position the patient, sitting or standing, at a distance of 6 meters or adjust
the optotypes according to the available distance .
• Test the eyes one at a time, at first without any spectacles
• The smallest line read is expressed as a fraction, e.g. 6/18.
• If the patient cannot read the top letter at 6m , move him/her closer, 1m at a
time, until the top letter can be seen – the VA will then be recorded as 5/60
or 4/60, etc.

27. Procedure
• If the top letter cannot be read at 1m (1/60), hold up your fingers at varying
distances of less than 1m and check whether the patient can count them. This
is recorded as counting fingers (CF): VA = CF
• If the patient cannot count fingers, wave your hand and check if he/she can see
this. This is recorded as hand movements (HM): VA = HM
• If the patient cannot see hand movements, shine a torch toward the eye and
ask if they can see the light. If they can, record ‘perception of light’ (VA = PL). If
they cannot, record ‘no perception of light’ (VA = NPL).
• Now test the patient while wearing any current distance spectacles or pinhole
occluder and record the VA in each eye separately.
• If the vision improves, it indicates the visual impairment is due to irregularities
in the cornea, a problem in the lens, or refractive error, which is correctable
with spectacles or a new prescription.

28. Having problem reading our discharge
tickets!! You need a near vision
assessment

29. Near Vision Assessment
• Near vision is tested by asking the pt. to
read a near vision chart kept at a distance of
25cm to 35cm.
• Each eye should be tested separately.
• The near vision is recorded as the smallest
type which the pt. can read comfortably.

30. Jaeger’s Chart
Prints are marked from 1 to 7 and
accordingly patient’s acuity is labelled as J1-
J7 .
Eduard Jäger von Jaxtthal

31. Roman Test Types
• Consists of Times Roman fonts
with standard spacing.
• The near vision is recorded as
N5, N6, N8, N10, N12, N18,
N36 and N48.

32. Snellen’s Near Vision Test Types
• Constructed on the same principles as of the distant
types.
• The graded thickness of the letters is about 1/17 of the
distant vision chart letter.
• The letter equivalent to 6/6 line subtend an angle of 5
min. at the average reading distance.

33. References
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4069781/#:~:text=Visual%20
acuity%20(VA)%20is%20a,is%20tested%20at%20a%20time.
• https://www.aao.org/eye-health/tips-prevention/eye-chart-facts-history
• https://michaelbach.de/fract
• https://www.precision-vision.com/articles/what-is-etdrs/
• Khurana – Optics and Refraction

34. That’s how I passed .