Eye Evaluation of the Newborn
David S. Walton
Garyfallia Katsavounidou
Congenital or acquired ocular defects in neonates unfortunately are not rare. In the best interests of both child and family, it is of extreme importance that the neonatologist be well prepared for the eye evaluation of the newborn. The optimum preparation for such an evaluation is acquired through a multiplicity of avenues. Experience is gained from the evaluation of newborns with normal visual systems, and familiarity with the common neonatal ocular problems and an appreciation for the potential occurrence of unusual problems is helpful. Obtaining a preliminary history of any familial congenital ocular disorders and of adverse prenatal or perinatal conditions (intrauterine problems, prematurity or difficult delivery events) can be very directive and helpful. It is indispensable to perform an informative eye examination, completed as early as
possible, to recognize suspected or unexpected neonatal ocular abnormalities.
possible, to recognize suspected or unexpected neonatal ocular abnormalities.
Following the initial examination, if an ocular abnormality is recognized—or when parents express concerns about the baby’s visual system that cannot be explained by normal developmental phenomena—the infant should be promptly examined by an ophthalmologist. Generally, this further evaluation will determine the medical or surgical management of any significant neonatal ocular abnormality. Some conditions, such as infections, glaucoma, or evidence of intraocular abnormalities, are more urgent than others. Communicating the findings of an adverse examination to the child’s family, and especially to the mother, must be made attentively to lessen the potential shock and disappointment. Parents may be reassured by learning about their infant’s condition and the potential advantages (or not) of early treatment.
OCULAR ASSESSMENT IN THE NEWBORN
The ocular system assessment of the newborn is an essential component of a complete neonatal physical examination. This can be performed quickly. A few specialized pediatric eye examination instruments are helpful and include an ophthalmoscope, a penlight, an optional magnification loupe, and an eyelid speculum. The magnification loupe can be especially helpful for studying anterior segment structures. The use of topical anesthetic and dilating eye drops may be indicated. This examination should be performed while the infant is kept comfortable and warm, and optimally while sleeping or being fed. It is advisable that the least upsetting maneuvers are performed first. The results should all be recorded carefully. The newborn eye examination should include an evaluation of the following:
Pupillary light responses
Eyelid position and movement
Basic tear composition
Eye position and movements
Conjunctiva
Corneal size and transparency
Iris appearance and symmetry
Pupillary size, position, and shape
Lens transparency
Quality and symmetry of the retinal red reflexes
Vision testing of the newborn lacks precision. Laboratory testing methods reveal that a term newborn possesses a visual acuity of approximately 20/200 and begins to focus (accommodate) by 3 months of age. When presented with an object or light stimulus, the normal newborn may show no response, stare, halt movement of the extremities, or rarely, follow briefly. Blinking or blepharospasm is an expected response to bright light, but its presence is not evidence of intact cortical function. Pupillary constriction to light is the most reliable evidence of neonatal sensory ocular function; it may be present by the postconceptional age of 28 weeks and is consistently present by 32 weeks’ gestational age. It increases in amplitude during the last 8 weeks of gestation and is best studied in a somewhat darkened room. The direct pupillary responses of each eye should be compared. The term newborn’s pupils are small compared to the larger and variably sized pupils of a preterm neonate of less than 30 weeks’ gestational age. A slight difference of pupillary size is present in a small percent of normal newborns. Nystagmus always is a significant observation; it may be secondary to decreased vision, or may be indicative of seizure activity.
The condition of the eyelids and the presence of normal tears can be appraised by observation. Term newborns have basal and reflux tear secretion similar to adults. Preterm infants have less production of tears. This examination may be made uncertain due to postpartum eyelid swelling or irritation caused by silver nitrate prophylaxis. The superior eyelid crease is indicative of levator (elevator) muscle function and should be similar in each lid, but may be absent in the case of congenital ptosis. A slight asymmetry in palpebral fissure width usually is insignificant. Congenital turning out (ectropion) or turning in (entropion) of the eyelid margins towards the cornea should be ruled out because of the risk of corneal exposure and secondary eyelash-related injury.
The extraocular movements and eye position are assessed next. Observe the eye in the straight-ahead primary position. The presence of symmetrical corneal light reflexes is an indication of straight eyes. Whereas an eye deviation during sleep is common, the occurrence of a constant and large deviation when the neonate is awake is significant. Vertical and horizontal conjugate eye movements can be stimulated by head rotation. It is especially important to confirm the presence of abduction (sixth nerve function) in each eye. Vestibular nystagmus, with both fast and slow phases, is expected in the term newborn and is best induced by rotation of the baby and examiner while the infant is held facing the examiner. The slow phase during rotation and the fast phase after rotation occur in the direction of rotation. An optokinetic tape or drum also can be used to stimulate eye movements and to estimate vision.
The inspection of the conjunctiva is done by viewing the white bulbar region of each globe and by everting the eyelids to expose each fornix. Increased redness (injection) and discharge are common indicators of conjunctival inflammation. Familiarity with the normal conjunctiva and its appearance after silver nitrate application can be helpful in assessing a newborn for an infectious conjunctivitis.
The inspection of the anterior segment of the eyes begins with an estimation of the corneal size and transparency. Clarity of the cornea and anterior chamber is suggested by a clear view of the iris and pupils. With practice, the examiner can perform this assessment confidently. A 2× magnification loupe can be used advantageously for this examination. The normal newborn corneal diameters are equal and approximately 10.5 mm in size. Corneas of unequal size, or possessing a measurement 12.5 mm or more, are abnormal. Fluorescein dye may be used topically to help confirm the presence a superficial corneal epithelial defect.
When a total cataract is present, the pupil will appear white, and the normal red reflex obtained by focusing an ophthalmoscope on the pupillary border will be absent. A small lens opacity can be seen as a dark defect against the red reflex background. Diffuse, less dense cataracts will cause the red reflex to be of poor quality and will prevent a clear view of the ocular fundi.
The fundus examination, although not a mandatory part of the examination, should include, when indicated, inspection of the disks, retinal vessels, and macular regions. Small pupils make this evaluation difficult, so it is usually adequate to be reassured by an equal red reflex from each fundus. More pigmented patients possess a darker red reflex. This color variation is proportional to the amount of pigment in the choroid. Neonatal pupils dilate well with the use of mydriatics, which are required when complete funduscopy is indicated.
DISORDERS OF THE EYE IN THE NEWBORN
Abnormal Vision
Congenital disorders associated with poor vision are rarely detected in the newborn period. Even anencephalic infants may
exhibit pupillary responses and demonstrate blepharospasm in response to light. Visual behavior develops rapidly, and parents often observe its absence by 1 to 2 months of age. Parental concern that their child “does not see” must be treated attentively and indicates the need for ophthalmologic consultation. A family history of infant blindness, as well as the effects of unfavorable prenatal and perinatal conditions, must be considered. The cause of the visual unresponsiveness may be apparent on inspection of the eyes by the presence of microphthalmos, signs of glaucoma, cataracts, or cloudy corneas. Internal examination of the eyes may detect abnormalities such as vitreous hemorrhage, optic nerve atrophy, or hypoplasia, or may reveal normal findings. Congenital retinal dystrophies may manifest normal fundi and require electroretinography for identification. Poor vision secondary to cortical defects may be associated with minimal eye abnormalities and require neuroimaging for recognition. Delayed visual development and apparent blindness related to abnormal eye movement also must be taken into consideration.
exhibit pupillary responses and demonstrate blepharospasm in response to light. Visual behavior develops rapidly, and parents often observe its absence by 1 to 2 months of age. Parental concern that their child “does not see” must be treated attentively and indicates the need for ophthalmologic consultation. A family history of infant blindness, as well as the effects of unfavorable prenatal and perinatal conditions, must be considered. The cause of the visual unresponsiveness may be apparent on inspection of the eyes by the presence of microphthalmos, signs of glaucoma, cataracts, or cloudy corneas. Internal examination of the eyes may detect abnormalities such as vitreous hemorrhage, optic nerve atrophy, or hypoplasia, or may reveal normal findings. Congenital retinal dystrophies may manifest normal fundi and require electroretinography for identification. Poor vision secondary to cortical defects may be associated with minimal eye abnormalities and require neuroimaging for recognition. Delayed visual development and apparent blindness related to abnormal eye movement also must be taken into consideration.
Eyelid Abnormalities
Ptosis is a common eyelid abnormality caused by weakness of the elevator muscle, and it can be unilateral or bilateral. Moderate ptosis may be evidence of Horner syndrome and be associated with homolateral upper-extremity paralysis caused by a birth injury. Widening of the palpebral fissure can be a sign of a congenital facial nerve palsy or be caused by proptosis, which in the newborn can result from a retrobulbar tumor or hemorrhage secondary to birth trauma. A congenital entropion positions the eyelashes against the cornea and requires prompt attention. Colobomatous defects of the eyelids are seen in Goldenhar and Treacher-Collins syndromes.
Tear Abnormalities
The excessive presence of tears suggests common congenital tear duct obstruction; it usually is noticed promptly by parents when it becomes complicated by a discharge. Epiphora (excessive tearing) also may be caused by corneal abnormalities, including corneal ulceration and defects secondary to glaucoma. A deficiency of tears may be isolated or associated with corneal hypesthesia; this places the corneal surface and eyes at jeopardy, as is seen in newborns with familial dysautonomia.
DISORDERS OF EYE POSITION AND MOVEMENT
An intermittent eye deviation in infancy is common and usually observed during periods of drowsiness. A congenital esotropia is seen in approximately 1% of infants; it is typically large and may be associated with impaired abduction of both eyes. Congenital exotropia is unusual. A sixth-nerve palsy may occur with birth, is usually unilateral, and often resolves spontaneously. A congenital fourth-nerve paralysis also can occur, but it is typically recognized after infancy. Congenital third-nerve palsies are rare; they cause ptosis, pupillary abnormalities, external ophthalmoplegia, an exotropia, and are frequently associated with other evidence of central nervous system abnormalities, such as hemiplegia.
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