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Evaluation of non seeing infant

BYDR DIWA LAMICHHANE

BIRATNAGAR EYE HOSPITAL, BIRATNAGAR 19 – 05 - 2013

Outline

EpidemiologyVisual development in infantCauses of non seeing infantEvaluation of non seeing infant

The prevalence of blindness increases from less than 0.01 per 100 in preschool- age children to 8.58 per 100 persons over the age of 60 .

Bulletin of the World Health Organization, 63 (2): 375-386 (1985)

Nystagmus is absent in cortical blindness and is not found often in association with unilateral visual defects.

Visual development Complex maturation process Structural changes occur both in the eye & CNS Normal vision develops as a result of both genetic coding &

experience in a normal visual environmentAssessment

Fixation target Blink reflex to bright light 30weeks after birth Pupillary light reflex 29- 31 wks of gestation

Visual development

6 weeks Make and maintain eye contact React with facial expression

2-3mths Interested in bright object

Untill 4mths Disconjugate eye movements

Skew deviation, sunsetting present as a transient deviation in new born

Visual development

Sign of actual poor vision development

Wandering eye movement Lack of response to familiar faces & objects Nystagmus Staring at bright lights Forceful rubbing of the eyes( oculodigital reflex )

Causes

The causes of SVI and blindness may be:

Prenatal Perinatal Postnatal

Causes..

Congenital anomalies Anophthalmos, microphthalmos, coloboma, congenital cataract,

infantile glaucoma, and neuro-ophthalmic lesions

Acquired during the perinatal period Ophthalmia neonatorum, ROP, & cortical visual impairment.

Most common causes

Anterior segment anomalies Glaucoma Cataract Optic nerve hypoplasia Optic atrophy Leber congenital amaurosis Achromatopsia Congenital infection syndrome /

TORCH

Cortical visual impairment Delay in visual maturation ROP X-linked retinoschisis Congenital motor nystagmus Albinism Coloboma

Evaluation of normal infant

General history of the infant

Parents or caretakers are asked routinely Young child’s visual behavior with family members and at playtime Whether the child responds to a silent smile Enjoys silent mobiles Follows objects around the environment.

Pertinent observations include strabismus, nystagmus, persistentstaring, and inattention to objects.

Family history of ocular disease

Such as blindness Poor vision Need for thick glasses Difficulty ambulating in dim Illumination Photophobia

Color vision deficiencies ‘Lazy eye’ or amblyopia Strabismus Nystagmus Leukocoria History of eye surgery.

Family history of systemic disorders

That may be associated with ocular abnormalities Connective tissue Cardiovascular defects associated with

Marfan’s syndromeMidfacial hypoplasia

Arthropathy associated with stickler’s syndrome Dental and umbilical abnormalities in rieger’s syndrome Urinary tract abnormalities in lowe’s syndrome Neurologic and skin abnormalities in the phakomatoses

Family history of systemic disorders

Unusual physical traits, developmental delay, mental retardation, & early death

Denial, illegitimacy, incest, paternal substitutions, & natural variability in expression of inherited disorders make the process even more difficult.

A standard pedigree diagram of nuclear family

Male – X – linked disorder If sibling has similar condition not present in previous generations –

AR disease

Prenatal and perinatal history

About the pregnancy, delivery, birth weight, gestational age, neonatal health.

Maternal Illness, Infection, Radiation, Trauma Teratogenic potential of medications as ethyl alcohol, particularly in

infants or children with dysmorphic features.

The relatively free passage of substances from mother’s circulation into breast milk provides infant with yet another route of ingestion.

The importance of prematurity & its relationship to retinopathy of prematurity is well recognized.

Observing various components of the examination while taking history. Child’s alertness, interaction with parents, head position, fixation &

following ability, steadiness of gaze, gross alignment of eyes can usually be observed .

Attention or crying it is sometimes best to interrupt history & begin more entertaining aspects of examination.

Additional historical information can be obtained either during examination or after examination steps are completed.

History..

General examination

Child’s general physical appearance, alertness, overall size, weight, body structure & interaction with adults accompanying child.

Systemic disorders may be associated with ocular abnormalities, one should undress the child & examine various areas such as head, neck, integument, thorax, abdomen, genitalia, skeletal structure using inspection, palpation, & auscultation.

The child’s head size & shape eg. microcephaly & macrocephaly Unusual skull contours, such as plagiocephaly is related to certain

types of strabismus.

Ocular examinations Position and size of the orbits Position of the globes

which can usually be compared by looking down from over the child’s forehead.

Eye lids Palpebral fissures compared with respect to contour, size, location position & movement of the upper & lower eyelids, presence of epicanthal folds. Intercanthal & interpupillary distances is measured & compared with

standard nomograms such as those listed in Smith’s recognizable patterns of human malformation

Lacrimal system Size of tear meniscus, presence of epiphora, patency of lacrimalpuncta, appearance of areas overlying lacrimal drainage system& lacrimal gland.

Orbital structures Should be palpated & auscultated, with emphasis on areas ofspecial concern.

Ocular examinations

Visual acquity

Infants & children up to the age of 2.5 to 3 years are generally unable to accomplish recognition visual acuity tests.

It is evaluated by using objective techniques, such testing in clinical office setting is performed by observing eye movements that are produced in response to visual stimulation.

The ability to ‘fixate and follow’ a target is the principal clinical acuity test used to assess central visual function in infants & young children.

Ocular examinations

Normal motor responses to visual stimulation in child consist of fast, voluntary, refixation saccades & slow, smooth pursuit movements that occur as eyes follow a moving target.

Human face is generally strongest visual stimulus for young infant, even newborn infants intermittently attempt to fixate on a human face placed in proximity.

The innate visual interest in the human face may well be related to infant-mother bonding. Visually induced motor response may be enhanced by holding the infant in a comfortable but upright position and placing the examiner’s face close to the infant while examiner slowly moves from side to side. If there is no reaction, test should be repeated with mother

holding child using her own face as test

Ocular examinations

Young infants are not capable of producing normal slow, smooth pursuit movements seen in older children and adults. Instead, young infants display jerky, hypometric saccades in the same direction as target moves.

The examiner must also be careful not to rotate the infant duringacuity testing, because rotation induces vestibuloocular

reflex (VOR), which is a powerful non visual stimulus for eyemovement.

The status of visual motor system must be appropriately evaluated before concluding that the lack of eye movement

Ocular examinations

However, in neonates, tonic phase predominates, whereas fast component may be observed intermittently. By 4 weeks of age, both slow & fast phases of vestibular nystagmus are easily elicited in

almost all normal infants. The young infant who appears to be blind but in whom a VOR fast

phase also fails to develop may simply be unable to generate normal hypometric, saccadic following movements in response to visual

stimulation. This may occur in children with CNS damage, such as cerebral palsy, & congenital oculomotor apraxia.

Truly blind child also fails to visually suppress VOR in usual 3–5 s after cessation of Rotation.Instead, blind children may have nystagmus that persists for 15–30.

By 2 or 3 months of age, most normal infants quite consistently fixate on & follow a nearby human face, as well as small toys such as finger puppets.

Motor responses to visual stimulation should be evaluated at both near and distance

By 6 months of age, most infants fixate on moving toys or cartoons at the end of a 20-ft examining room.

In the office setting, pediatric ophthalmologists commonly use a vertical array of two or three electrically operated mechanical toys located at the end of the examining room.

the left as the left eye,

Each toy is individually illuminated & controlled by a foot pedal. The normal child fixates on toy that is illuminated & moving, & small vertical refixation saccades are easily observed as the child’s attention is directed from one toy to another when the foot pedal is pressed. The noise generated by the toys is not sufficiently directional to elicit refixation saccades, because the toys are spaced about 1 ft apart.

Assessment visual acuity using fixation responses is generallyrecorded using the CSM method. C – central fixation, implying that fixation is foveal. S – steady fixation, the eye being tested is steadily fixating on a stationary or slowly moving target. Wandering eye movements or nystagmus indicates that fixation is not

steady. M - eye maintains fixation after cover is removed from opposite eye.

Determining whether

The CSM method may not adequately describe the reduced acuity in a child with a severe visual disability. In this situation, it may be appropriate to employ a narrative description of the level of visual responses, such as

Visual acuity both eyes = No ‘fixation’ or ‘following’ effortswith human face, toys, or hand light at 1 ft distance. Mild photoaversion to bright halogen indirect ophthalmoscope light.

Evaluation of non seeing infants

Evaluation..

1. History.. Perinatal problems including prematurity, IUGR, Fetal distress,

bradycardia, meconium staning, & oxygen deprivation.

Systemic abnormalities Delayed mild stones

Evaluation..

2. Examination

Fixation target OKN VEP Preferential looking Blink reflex to bright light several days after birth Pupillary light reflex 29- 31 wks of gestation

Evaluation..

FIXATION TARGETS Such as a human face Stripes, dots, or checkerboards are preferred Infants younger than 3months of age follow by means of hypometric

saccades when the target is small Term infants may generate smooth pursuit movements to a large

target such as an opticokinetic drum. Because saccadic palsies are common in young children who have

central nervous system damage, spinning an upright child demonstrates the presence of saccades as the rapid recovery phase of the spin-induced nystagmus

Estimated visual acuity at different ages from Dabson and Teller and Hoyat et al

Age OKN Preferential looking

VEP

1 M 6/120 6/120 6/120

2M 6/60 6/60 6/60

6M 6/30 6/30 6/6-6/12

Age at which6/6 is achieved

20-30M 24-36M 6-12M

Evaluation..

OPTICOKINETIC NYSTAGMUS

Visual angle subtended by the smallest

strip width that elicits an eye movement.

Measures acuity by means of a motor

response technique (eye movement ).

Subcortical areas of the occipital cortex

may generate opticokinetic responses.

Binocular acuity 20/400(6/120) at birth

and reach 20/20(6/6) by 26-30 months.

Evaluation..

VISUALLY EVOKED RESPONSE

Used to evaluate acuity in Aphakic Amblyopic Strabismic large refractive errors Although the test directly evaluates vision by means of a sensory

process, a waveform of normal appearance has been recorded in the occasional decorticate infant who later behaves as if blind, which implies a subcortical contribution

Evaluation

Forced choice preferential looking

Based on observation that infants prefer to view a pattern stimulus

rather than a homogeneous field.

Using flat, calibrated, square-wave gratings

Observed by a trained individual.

Term newborn differentially responds to 20/400 (6/120) gratings; the

response to 20/20 (6/6) gratings occurs at 18–24months

Evaluation

Infant exposed to pair of stimuli consisting

of field of black and white stripes and

indentically sized gray field of equal

luminance.

Location of stripes shifted randomly from

right to left

Fineness of stripes reduced till infant can

no longer differentiate stripe and

background.

VA in infant..

Forced choice prefential looking device Teller acuity cards

Evaluation..

2. Examination Visual fixation Crispness and equality of pupillary light responses Ocular alignment & motility Nystagmus or roving eye movements Detailed fundus examination Infant with normal but immature visual system may be unresponsive

to even very bright light that is indistinguishable from blindness Fixation & follow response can be elicited with moving red light

horizontally /vertically in front of infant in otherwise unresponsive baby

Examination with hand held slit lamp

Evaluation..

2. Examination.. Pupillary response

Sluggish in ant visual pathway disease such as ON hypoplasia or atrophy, ON coloboma, morning glory disc anomaly

Paradoxical pupillary phenomenon ( constriction to darkness) – diiffuse retinal disease eg ON hypoplasia, cone dystrophy

Pupillary responses are normal in infant with cortical visual impairment

Evaluation..

2. Examination.. Nystagmus Begins at 2-3 mths, not at birth Nystagmus implies presence of at least some visual function.

Roving eye movements Total or near total blindness Congenital motor nystagmus No organic eye abnormality, mild to moderate reduction in visual

acuity.

Evaluation..

2. Examination..

Abnormal binocular alignment < 1 yr - Exotropia > 1 yr - Esotropia

Evaluation..

3. Investigation Electrophysiological tests ERG Poor vision with normal appearing ocular structure: Leber congenital amaurosis Achromatopsia Blue-cone monochromatism X-linked or AR CSNB VEP

Evaluation..

3. Investigation.. Imagings CT MRI Specialized laboratory studies based on consultation with:

Paediatric neurologist Endocrinologist Neurosurgeon Geneticist

Take home message.. Childhood blindness has an adverse effect on

growth, development, social, and economic opportunities.

Severe visual impairment (SVI) and blindness in infants must be detected as early as possible to initiate immediate treatment to prevent deep

amblyopia.

References… AAO Section 6 Paediatric Ophthalmoloy and strabismus.

Yanoff and Duker Ophthalmology 3rd edition.

Jakobiec Principles and practice of ophthalmology vol 4, 3rd edition.

THANK YOU

FIXATION TARGETS

Targets: mother’s face, flashlight

CSM method

Vertical prism or induced tropia test

• Catford drum test

• child is made to observe an oscillating drum with black dots of

varying sizes

• Smallest dot that evokes pendular eye movements denotes

visual acuity

Indirect assessment of VA

I. Blink response

II. Menace reflex

III. Test based on fixation reflex

Fixation behaviour test

Binocular fixation pattern

Central, steady and maintained (CSM)