Crocodile tears (see Chapter 100) occur from congenital aberrant innervation between the fifth and seventh cranial nerves causing tearing with chewing or sucking.³

Dry eyes in children

Congenital causes

Congenital alacrima is rare. It may be due to absence of the lacrimal gland or to it being ectopic in the orbit. Alacrima may be associated with systemic conditions such as the Riley-Day syndrome (familial dysautonomia), anhydrotic ectodermal dysplasia, and Allgrove’s syndrome (familial alacrima, achalasia of the cardia, and adrenal deficiency) (see Chapter 98).

Acquired tear deficiency may be due to pathology of the lacrimal gland, causing failure of tear production, or to conjunctival damage (see Chapter 31), leading to ductule obliteration. The lacrimal gland may be damaged by Epstein-Barr infection, as the result of HIV infection, or in patients with bone marrow transplantation (often associated with graft-versus-host disease). The conjunctiva may be affected by injury (burns), infection, the sequelae of trachoma, Stevens-Johnson syndrome, or toxic epidermal necrolysis.

Sjögren’s syndrome is rare in children. It can be a primary autoimmune event or associated with rheumatoid arthritis or systemic lupus erythematosus. Children with Sjögren’s syndrome often have lacrimal gland enlargement. They may have recurrent parotid gland swelling and salivary gland involvement. Sjögren’s syndrome should be considered in any child with recurrent parotiditis, keratoconjunctivitis sicca, and early tooth decay due to xerostomia.⁴

Chronic blepharitis is uncommon. It usually presents with recurrent chalazia, although the lids may appear normal. The associated poor quality tear film causes patches of dryness and may lead to peripheral corneal vascularization and scarring which can be sight-threatening.

Isotretinoin treatment for acne is a cause of dry eyes in adolescence. This is usually reversible at cessation of the drug.

Children with dry eyes present with irritable, uncomfortable, gritty, red eyes. A reduced tear meniscus is evident with punctate keratopathy, particularly affecting the interpalpebral zone. Staining occurs with fluorescein and Rose Bengal dyes. Severe keratopathy due to concomitant corneal hypoesthesia can be a problem in the Riley-Day syndrome.

Treatment of dry eyes involves copious use of artificial tears and temporary or permanent punctal occlusion in severe cases. Immunomodulation may have a role to play in secondary lacrimal gland failure including that due to infections. Blepharitis should be treated with lid hygiene, lubricants, and systemic antibiotics such as erythromycin or azithromycin. Oral tetracyclines should be avoided in children prior to their second dentition.

Dacryoadenitis

Dacryoadenitis is usually associated with viral infection, mumps, infectious mononucleosis, herpes zoster, tuberculosis, brucella, histoplasmosis, or gonococcal infection. Lacrimal gland swelling may rarely be a sign of childhood Sjögren’s disease.

A primary clinical feature of dacryoadenitis is the “S sign” in which there is drooping of the lateral aspect of the upper lid. In acute inflammatory cases, the overlying skin is inflamed. Neuroimaging confirms enlargement and helps rule out other orbital masses. In the long term, dacryoadenitis may damage the lacrimal gland and cause reduced tear secretion.

Dacryoadenitis must be differentiated from a lacrimal gland infarct, which occurs in children with a sickle cell crisis. The onset is rapid, like acute dacryoadenitis.

Treatment of acute dacryocystitis is aimed at the underlying cause.

Lacrimal tumors (see Chapter 26)

Lacrimal tumors are very rare in children. Pseudotumor causing painful swelling may affect the lacrimal gland.⁵ Malignant epithelial tumors, including mixed cell adenocystic and other carcinomas, have been recorded in childhood.⁶

Lacrimal gland enlargement is also found in conditions such as sarcoidosis or leukemia. Prolapse of the lacrimal gland, which is commonly bilateral, may present as a subconjunctival mass in the upper outer fornix. This may occur with craniofacial anomalies (see Chapter 28) due to reduced orbital volume and increased orbital pressure.

The lacrimal drainage system

Embryology

The lacrimal outflow system develops between the maxilla and the lateral nasal process from surface ectoderm. By the end of the first trimester this tissue begins to canalize. The puncta usually open with the eyelids during the sixth month of gestation. The nasolacrimal duct opens into the inferior meatus of the nose just before or after term birth. There may be a failure of this canalization process at any part of the system, but this is most frequent at the lower end.⁷

Anatomy

Understanding the lacrimal outflow system is important for the pediatric ophthalmologist, especially for performing probing.

The puncta should be in contact with the globe at the medial aspect of the upper and lower lids. The proximal part of the canaliculus, the ampulla, is a slightly dilated vertical portion 1 mm in length in the young child. The canaliculus then turns 90° to run medially in a horizontal direction. The upper and lower canaliculi join to form the common canaliculus that enters the lateral wall of the lacrimal sac. Rosenmüller’s valve prevents reflux of tears from the sac into the canaliculus. The lacrimal sac sits in the bony lacrimal fossa, separated from the middle meatus of the nose by the maxilla and lacrimal bone. The lacrimal sac extends superiorly under the medial canthal ligament to form its fundus. The nasolacrimal duct exits from the lower end of the sac and passes in a downward, lateral, and slightly posterior direction. This duct is surrounded by bone in its upper part but becomes membranous inferiorly. The nasolacrimal duct opens into the medial wall of the inferior meatus of the nose via the valve of Hasner. This ostium is found under the inferior turbinate of the nose, approximately 1 cm directly behind the entrance of the nose in the baby.

Physiology

Tears are actively pumped through the outflow system. During blinking, when the lids close, the canaliculi are shortened and narrowed by contraction of the pretarsal orbicularis muscles. Simultaneously the same muscles pull the lateral sac wall, creating negative pressure inside the sac, sucking fluid into the expanded sac. Further lid closure causes contraction of the orbicularis oculi muscle, which squeezes the tears from the sac into the nasolacrimal duct. At the end of each blink, the sac is empty. As the lids open, the canaliculi and the sac elastically expand. This causes a vacuum within the system into which tears enter via the puncta, and the cycle begins again.

Congenital abnormalities

Common abnormalities, include narrowing (stenosis), blockage (atresia), complete absence (agenesis), or duplication (accessory channels) of any part of the system. A membranous obstruction at the distal end of the nasolacrimal duct is the commonest abnormality, causing congenital nasolacrimal duct obstruction.⁷ Obstruction at other sites is rare, but more relevant in older children.

Children with craniofacial abnormalities (see Chapter 28), particularly clefting syndromes, have complex anomalies of the lacrimal outflow system that may involve large areas being either blocked or absent.

Congenital dacryocystocele

A dacryocystocele is a congenital swelling located at the medial canthus due to trapped fluid inside the lacrimal sac and nasolacrimal duct.⁸ The fluid is unable to escape from either the upper or lower end of the drainage system as both are blocked. This presents as a tense, blue, non-pulsatile swelling below the medial canthus. It is evident at, or shortly after, birth (Fig. 21.1A). The inferior end of the dacryocystocele projects into the nose (Fig. 21.1B) and in some cases may be responsible for breathing difficulties.⁹ If respiratory compromise occurs, urgent treatment is required.