visual acuity test in infants

1. VISUAL ACUITY TEST IN
INFANTS
SHAHANA
NETHRADHAMA SCHOOL OF
OPTOMETRY

2. VISUAL ACUITY IN INFANTS
Visual acuity,in preverbal infants
defined as a motor or sensory
responses to a threshold stimulus
of known size at known distance.

3. MEASUREMENT OF VISUAL ACUITY
IN INFANTS
 A child should be aware and responsive to the
surroundings and situation.
 A normal pupillary response , a positive blind response
and an elicitable optokinetic nystagmus indicate good
visual acuity.
 Visual acuity improves rapidly during the 1 year of life
than matures approximately 5 to 6 years of age.
 Fixation behaviour can be determined accurately in this
age group as the fovea develop completely by 3 months
of age
 If the child habitually fixates with one eye , it indicates
poor vision in the non fixating eye.

4. NORMAL VISUAL DEVELOPMENT
 Very soon after birth – can fixate and follow a light
 1 month – fixation is central, steady and
maintained.Can follow a slow target.
 3months- binocular vision and eye coordination.
 6 months- reaches out accurately for toys.
 9 months-looks for hidden toys.
 2 years- picture matching
 3 years- letter matching of single letters.
 5 years – snellen chart by matching or naming.

5. DIFFERENT TYPES OF VISUAL
ACUITY TEST IN INFANTS
 OPTOKINETIC NYSTAGMUS TEST
 PREFERANTIAL LOOKING TEST
 ENHANCED BRUCKNERS TEST
 VESTIBULO OCULAR REFLEX INDUSED NYSTAGMUS
 VISUAL EVOKED POTENTIAL
 CATFORD DRUM TEST
 CARDIFF ACUITY TEST
 INDIRECT ASSESSMENT OF VISUAL ACUITY
 HUNDRED AND THOUSAND SWEET TEST

6. OPTOKINETIC NYSTAGMUS TEST
 Optokinetic nystagmus drum has been proposed
as a method of measuring visual acuity in children.
 In this test , nystagmus is elicited by passing a
succession of black and white stripes through
patient's field of vision.
 When the subject views rotating strip drum
his/her eyes involuntarily follow a strip which slow
eye movement (pursuit movement ) then return
with fast eye movement (saccade movement)to
fixate the new strip.

8. PREFRENTIAL LOOKING TEST
 It is used to access visual acuity in infants and young
children who are unable to identify picture or letter.
 The child is presented with two stimulus fields one
with strips and other with homogeneous grey area of
same average luminous has the striped field.
 Through small peep hole observer judges the
location of strip based on child head and eye
movement.
 The smallest strip the child can identify is
considered to be child‘s visual acuity

10. ENCHANCED BRUCKNERS TEST
 The direct ophthalmoscope is shown to child's eye
from distance of 2-3 feet.
 The bright large color light is used to overlap the
pupil while the child is encouraged to look directly
in direct ophthalmoscope in a dim room.
 The swing in the direct ophthalmoscope from one
eye to other also from back and front observe pupil
reaction.
 For example if retina or optic nerve injured or
affected the eye will have pupil dilation rather then
constriction in both eye which is called marcus gun
pupil or RAPD.

12. VESTIBULO OCULAR REFLEX
INDUSED NYSTAGMUS
 When head is rotated about any axis to certain
distance image eye rotate in opposite direction
which is due to semicircular canals in the vestibule
sends the angular acceleration.
 This send signal to nuclei for the eye movement in
brain from here signal is delay to extra ocular
muscle.
 Nystagmus occur when semicircular canals are
being stimulated while head is not in motion .
 Nystagmus persist for about 5 seconds in blind
child.