Corneal abnormalities in childhood

Chapter 33 Corneal abnormalities in childhood




The broad spectrum of disorders that affect the clarity and optical regularity of the cornea are represented in children but developmental and genetic anomalies comprise a larger proportion than in adults. However, many degenerative and dystrophic conditions may not be apparent until adolescence and beyond.


Corneal abnormalities, particularly if monocular or asymmetrical, have the potential to be amblyogenic; in management we should consider not only restoration of optical clarity, but the role that amblyopia might play.


The white cornea at birth poses an important differential diagnosis. The first consideration is congenital glaucoma (see Chapter 37). Intraocular pressure is elevated and the corneal diameter is large. Ruptures in Descemet’s membrane may be present. The optic nerves show increasing cupping, often reversible with intraocular pressure control. Urgent intervention is usually indicated.


Forceps injury is another cause of corneal clouding apparent at birth. Forceps marks may be visible on the lids or cheek. A linear, usually vertical, rupture of Descemet’s membrane is present causing corneal edema which always resolves leaving astigmatism. Late corneal decompensation is possible. Metabolic disorders that may cause congenital corneal clouding such as the mucopolysaccharidoses are discussed in Chapter 62; congenital hereditary endothelial and stromal dystrophies are discussed in Chapter 34.



Developmental defects




Genetic syndromes





Corneal opacities associated with dermatologic conditions



Ichthyosis


The ichthyosiform dermatoses are a group of disorders characterized by scaling. “Harlequin baby” and “collodion baby” are extreme congenital forms that may have congenital ectropion.16 They frequently succumb to skin infections in the neonatal period. Ichthyosis vulgaris is the most common form, inherited as an autosomal dominant trait, with scaling of the extensor surfaces and back. No eye problems occur.


X-linked ichthyosis is congenital and occurs in 1 in 6000 males.17 Afflicted individuals suffer scaling of the scalp, face and neck, abdomen, and limbs; palms and soles are spared. Corneal nerves may be thickened and band keratopathy occurs as an isolated abnormality.18 Superficial corneal lesions, which stain with fluorescein (Fig. 33.4A), occur; they are usually transient but recur and eventually cause superficial scarring. The scarring and superficial lesions may be caused by eyelid abnormalities, or may occur independently.



Small posterior corneal opacities are located in deep corneal stroma or Descemet’s membrane and are not visually significant.18


Lamellar ichthyosis and ichthyosis linearis circumflexa are severe autosomal recessive disorders giving rise to ectropion and keratoconjunctivitis mainly due to exposure.19 This can be so severe as to lead to corneal scarring, infection, and perforation.20 Epidermolytic hyperkeratosis and erythrokeratoderma variabilis are two autosomal dominant varieties. Ichthyosis occurs in the Sjögren-Larsson syndrome, Netherton’s syndrome (ichthyosis, sparse hair, eyebrows, and eyelashes, and atopic diathesis), Refsum’s disease, chondrodysplasia punctata, IBIDS syndrome (ichthyosis, brittle hair, impaired intelligence, decreased fertility, and short stature), and the KID syndrome of ichthyosis, deafness, and keratitis21 (Fig. 33.4B). The keratitis of KID syndrome is attributed to ocular surface drying due to obstruction of the lacrimal gland ductules by shed hyperkeratinized corneal epithelial cells or alternatively to limbal stem cell deficiency.22 Treatment with lubrication, topical corticosteroids, and antibiotics have been advocated with variable success.




Erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis


Erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis (see Chapter 15) are self-limited eruptions of the skin and mucous membranes that are due to a hypersensitivity reaction to environmental factors including drugs and infections.24 Since the long-term ocular surface compromise and corneal scarring are considered to be a consequence of the severity of the acute event, initial management is directed toward attenuating local inflammation. Amniotic membrane to the eyelid margins, palpebral conjunctiva, bulbar conjunctiva, and cornea is sometimes successsful.25





Vitamin A deficiency and measles (see Chapter 31)


In patients with long-term vitamin A deficiency, the ocular surface can become involved with conjunctival and corneal xerosis, keratinization, severe punctate keratitis, vascularization, and edema. When vitamin A deficiency is accompanied by malnourishment and protein deficiency, keratomalacia, an acute liquefactive necrosis of the cornea can occur (Fig. 33.6), especially when associated with measles infection, herpes simplex, or the use of traditional eye medicines.29 When diagnosed early, some of these problems are reversible with vitamin A replacement. It may be prevented by diet, vitamin A replacement, and measles vaccination.30 Higher doses of vitamin A are necessary when the child has worm infestation or diarrhea.31 Bitot’s spot is a triangular foamy-appearing lesion of keratinized tissue that occurs over the conjunctiva in vitamin A deficiency; its presence on the temporal side of the eye suggests active deficiency.32 Vitamin A deficiency also causes night-blindness.




Infectious keratitis (see Chapter 15)


Infectious keratitis is one of the most vision-threatening consequences of trauma, trachoma, and vitamin A deficiency and related ocular surface disease. It becomes the common denominator leading to blindness associated with numerous ocular and systemic conditions. Traumatic corneal injury is a leading predisposing factor,33,34,35,36 but the nature of the trauma and the microbiology of subsequent infection varies based on geography. Recently, corneal trauma due to contact lens wear including orthokeratology has emerged as a distinct risk in regions such as Asia with a high prevalence of pediatric contact lens wear.3739


Infections following traumatic injury are most commonly caused by bacteria, but a relatively high rate of fungal infection occurs in areas where filamentous fungal corneal infection is more common, such as South India and China.33,36 Whether the leading risk factor is traumatic injury or contact lens wear, the most common organisms include both Gram-positive species (staphylococcal and streptococcal species)33,34,35,37 and Gram-negative species.36,38


Infectious keratitis associated with orthokeratology carries an elevated risk for infection with destructive organisms such as Acanthamoeba.39 Aggressive topical treatment with the appropriate antimicrobial agent offers the best chance of a good optical outcome, but amblyopia due to residual corneal scarring and irregular astigmatism after this unilateral condition can have a significant impact on vision.






Cogan’s syndrome


Cogan’s syndrome consists of interstitial keratitis and audiovestibular disease.49 Commonly a disease of adulthood, Cogan’s syndrome has been recognized in children.50 The keratitis is usually bilateral, peripheral subepithelial stromal inflammation that can progress to nummular lesions. Deep stromal keratitis can lead to deep stromal neovascularization.The eighth nerve impairment may precede or follow corneal involvement. An association with polyarteritis nodosa and other systemic associations has been described.51 The cause is unknown although immunologic factors,52 viral agents,53 and vasculitis54 have been implicated. In atypical disease, uveitis replaces corneal inflammation,55 but the anterior segment inflammation responds well to topical corticosteroids. Although sometimes reversible, hearing loss56 is more commonly persistent; cochlear implants may provide successful rehabilitation.57



Corneal trauma




Corneal anesthesia and hypoesthesia


Defective corneal sensation may give rise to a chronic, recurrent, and severe keratitis. Although termed neurotropic, the main etiologic factors are drying, reduced blinking, and repeated trivial trauma. Defective corneal sensation may arise from any cause of fifth nerve damage. It occurs with trauma, herpes zoster ophthalmicus, developmental or acquired brain stem lesions, and tumors, in particular cerebellopontine angle or pontine tumors. It may occur with herpes simplex keratitis.59 Corneal hypoesthesia occurs in leprosy, Goldenhar’s syndrome,60 and other oculofacial syndromes.61 It has been reported in a family of Navajo Indians with an acromutilating neuropathy.62 It can be found in a subclinical form in Adie’s pupil,63 and is characteristic in the Riley-Day syndrome (Fig. 33.9). It occurs in the MURCS association − Mullerian duct aplasia/hypoplasia, renal agenesis or ectopy, and cervicothoracic somite dysplasia.64


Jun 4, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Corneal abnormalities in childhood
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