5 Pediatrics / Strabismus
Anatomy
At birth, diameter of eye is 66% that of adult eye
Eye enlarges until 2 years of age, then further growth in puberty (Table 5-1)
Ocular dimensions | Infant (mm) | Adult (mm) |
---|---|---|
Axial length | 17 | 24 |
Corneal diameter | 9.5–10.5 | 12 |
Corneal radius of curvature | 6.6–7.4 | 7.4–8.4 |
Scleral thickness | Half of adult |
Infants have variable levels of astigmatism
Majority of children are hyperopic; increases up to 7 years of age, then diminishes
Eye color darkens during first few months of life
Dilator pupillae poorly developed at birth
Physiology
Visual acuity levels (see Strabismus section)
Decreased vision in infants and children
History
family history, complications in pregnancy, perinatal problems
Orbital Disorders
Congenital Anomalies
Anophthalmos
Bilateral absence of eye due to failure of primary optic vesicle to form; extremely rare
Cryptophthalmos
Failure of differentiation of lid and anterior eye structures
Partial or complete absence of the eyebrow, palpebral fissure, eyelashes, and conjunctiva
Attenuation of the levator, orbicularis, tarsus, and conjunctiva
Infections
Benign Lesions
Dermoid Cyst (Choristoma)
Arises from dermal elements (neural crest origin)
Lined by keratinizing epithelium with dermal appendages
Most common orbital mass in childhood
Usually located in superotemporal quadrant near brow, often adjacent to bony suture
Epidermoid Cyst (Choristoma)
Arises from epidermal elements
Lipodermoid
Solid tumor usually located beneath the conjunctiva over lateral surface of globe
May appear similar to prolapsed orbital fat, prolapsed lacrimal gland, or lymphoma
Teratoma
Rare, cystic tumor arising from 2 or more germinal layers
Usually composed of ectoderm along with either endoderm or mesoderm (or both)
Capillary Hemangioma
Most common benign tumor of the orbit in children
Spontaneous involution over the next few years
Predilection for the superior nasal quadrant of the orbit and medial upper eyelid
Diffuse irregular mass of plump endothelial cells and small vascular channels
Findings
Pathology
numerous blood-filled channels lined by endothelium; little contribution from larger vessels or stroma; unencapsulated (Figure 5-1)
Complications
High-output congestive heart failure can occur with multiple visceral capillary hemangiomas
Lymphangioma
Rare, lymphatic-filled choristoma
Appears in first decade of life
Involves the eyelids, conjunctiva, and deeper orbital tissues
Fibrous Dysplasia
Tumor of fibrous connective tissue, cartilage, and bone
Progressive disease of childhood and young adulthood
Monostotic (in young adults) or polyostotic
Polyostotic
multiple bones involved; can cause narrowing of optic canal and lacrimal drainage system
Neurofibroma
18% have neurofibromatosis (NF) type 1
Nearly all adults with NF 1 have neurofibromas
Plexiform neurofibroma
most commonly involves the upper lid; tortuous, fibrous cords infiltrate orbital tissues
Optic Nerve Glioma (Grade I Astrocytoma)
Considered pilocytic astrocytoma of the juvenile type
Slow-growing hamartoma derived from interstitial cells, astroglia, and oligodendroglia
Usually appears during first decade of life
Malignant Neoplasms
Rhabdomyosarcoma
Most common primary orbital malignancy of children
Most common soft tissue malignancy of childhood
Most common mesenchymal tumor of orbit
Malignant spindle cell tumor with loose myxomatous matrix
Average age at diagnosis is 8 years old (90% before age 16)
Unilateral; tends to involve superonasal portion of orbit
Types
Neuroblastoma
Most common metastatic orbital tumor of childhood
Usually originates in the adrenal gland or sympathetic ganglion chain, also mediastinum or neck
40% develop orbital metastases
Average age of presentation with metastatic neuroblastoma to orbit is 2 years old
Ewing’s Sarcoma
Second most frequent metastatic tumor to the orbit
Primary intermedullary malignancy of bone; originates in long bones of extremities or axial skeleton
Histiocytosis X
Children under age 2 with multifocal disease have a poor prognosis (50% survival rate)
Findings
most frequent orbital presentation is lytic defect of orbital roof causing progressive proptosis
Craniofacial Disorders
Structural development of head and face occur during 4th–8th week of gestation
Ocular motility disturbances occur in 75% of patients with craniofacial disorders
Syndromes
Crouzon’s Syndrome (Craniofacial Dysostosis) (autosomal dominant [AD] or Sporadic)
Absence of forward development of the cranium and midface
Lid Disorders
Ankyloblepharon
Partial or complete fusion of lid margins; usually temporal, often bilateral
Blepharophimosis
Horizontally and vertically shortened palpebral fissures with poor levator function
Coloboma
Embryologic cleft involving lid margin; unilateral or bilateral; partial or full thickness
Congenital Blepharoptosis
Droopy eyelid; 75% unilateral; nonhereditary
Congenital Ectropion
Eversion of eyelid margin due to vertical shortening of anterior lamella
Congenital Entropion
Distichiasis
Partial or complete accessory row of eyelashes growing from or posterior to meibomian orifices
Epiblepharon
Usually occurs in lower lid and resolves spontaneously
Rarely requires surgery (excision of skin and muscle for significant trichiasis)
Lacrimal Disorders
Dacryocystocele
Presents at birth as bluish swelling inferior and nasal to medial canthus
Infection (dacryocystitis) develops if condition does not resolve spontaneously
Nasolacrimal Duct Obstruction (NLDO)
Up to 5% of infants have obstruction of the NLD, usually due to membrane covering valve of Hasner
Most open spontaneously within 4–6 weeks of birth; are bilateral
Conjunctival Disorders
Conjunctivitis
Ophthalmia Neonatorum
Conjunctivitis within first month of life
Papillary conjunctivitis (no follicular reaction in neonate due to immaturity of immune system)
Etiology
Other Infections
Age dependent; more common in younger children (<3 years old)
Vernal Keratoconjunctivitis
Form of seasonal (warm months), allergic conjunctivitis
Male > female (2 : 1); onset by age 10 years, lasts 2–10 years, usually resolves by puberty
Associated with atopic dermatitis (75%) or family history of atopy (66%)