visual acuity estimation in children in Optometry

Here is a summary of different methods of visual acuity estimation in children. After reading you will the basic idea about this

1. PEDIATRIC VISUAL ACUITY ESTIMATION
Name : Halima Khatun
Student Code : BWU/BSO/21/014
Course Name : Clinical Examination of Visual System
Course Code : BOPTOC405
Programme Name : Bachelor of Optometry
Department : Allied Health Sciences

2. Content
◦Visual acuity
◦Measurement of visual acuity in infants
◦Assessment of visual acuity from 1-3 years
◦Measurement of visual acuity in preschool children (3-5years)
◦Measurement of visual acuity in school children (above 5 years)

3. Visual Acuity
◦Visual acuity consists if the following :
◦Minimum visible : detection of presence or absence of stimulus
◦Recognition : to identify the object
◦Minimum discriminable : the minimum separation required between two dark bars
to discriminate
◦Resolution : measurement of the threshold of discrimination . The normal angular
threshold of discrimination for resolution measures approx. 30-60s of an arc which
is known as MAR.

4. Measurementof visual acuity in infants
◦From birth up to 3 months :
1.Blink reflex test –Present since birth .When bright light is shown ,a normal infant
should respond by blinking.
2.Pupillary light reflex test : presence of this reflex determines that patient is
having vision.
3.Vestibulo-ocular reflex : tested by turning the newborn’s head on his/her axis
and observing doll’s eyes response .
4.OKN test : here nystagmus is elicited by passing a succession of black and white
strips by means of OKN drum (size 10*8 inches),rotated at 8-10 rpm through the
patient’s field of vision.

6. Assessment of visual acuity in infants
◦From 3 to 6 months :
1.CSM method : asked to fixate on pen light ; A small target is coupled with light
held in front of the child and moved slowly . Nystagmus results in unsteady
fixation . Check the ability to keep the eye fixed when other eye is covered.
2.Bruckner red reflex test : evaluate strabismus

7. Assessment of visual acuity in infants
◦6 to 12 months
Catford drum test : child is made to observe an oscillating drum with black dots
varying sizes ranges from 0.5 to 15mm in diameter representing vision between 6/6
and 2/60. Rotation of disc at a distance of 60 cm evokes pendular movements. The
smallest dot that evokes pendular eye movements denotes the level of visual acuity.

8. Assessment of visual acuity from 1 to 3 years
1.Cardiff acuity card tests : vanishing optotype .Target –line drawings of pictures
of fish, car etc. The black and white lines forming the pictures become finer with
each set of 3 cards until picture the picture is lost. A total 11 set of cards are
available from 20/400 to 20/20 .
2.Coin test: Coins of different sizes are shown to child and child is asked to
identify the two faces of coins held in different distances .
3.Miniature toy test : in this test, the child is shown a miniature toy from a distance
of 10ft and is asked to name or pick the pair from the assortment.

10. Measurement of visual acuity in preschool
children
◦3 to 5 years :
◦Landolt‘s C test :use to test minimum separable acuity.
Landolt‘s Cs are presented with the opening of the optotype at
3,6,9,12 o’clock clock. The child has to tell where the opening
is. The separation at the break in the C represents 1min of arc
and the entire C subtends 5min of arc at the eye for 20/20 .
◦Lea symbols test : optotypes are read at a distance of 10-
20ft.This is a good way to test individuals who do not use the
Western alphabet. Hence, it eliminates the problem with
language barriers.

11. Measurement of visual acuity in school children
◦5 years and above
1.Snellen’s visual acuity chart:
The visual acuity test is used to
determine the smallest letters you can
read on a Snellen chart held 6 meters
away.
2. LogMAR chart : comprises rows of letters and
has equal number of letters in each line. It is
used at a distance of 4m. It is designed to enable
a more accurate estimate of acuity as compared
to other charts.

12. Thank you