The eye begins its development during the fourth week of pregnancy as a thickening of the neural tube called the optic placode. This evaginates from the prosencephalon to form the optic vesicle. During the fifth week, the optic vesicle invaginates to form the optic cup. This occurs at the same time that the branchial pouches are reaching the surface ectoderm. This temporal relation is important in understanding the frequent simultaneous occurrence of malformations of the globe and structures derived from the branchial arches. The classic example of this developmental malformation is the Goldenhar syndrome. This syndrome is also known as the oculoauriculvertebral syndrome. Other problems that result from defects in the structures derived from the branchial arches include ocular malformations (limbal choristomas), preauricular appendages or sinuses, hearing disorders, and vertebral defects.

The ocular lens forms during the sixth week of pregnancy. The optic nerve axons sprout from the retinal ganglion cells and enter the optic stalk during the seventh week. By the eighth week, retinal differentiation begins. At the ninth week, the recognizable eyeball is 1 mm in diameter.

The eyelids open and the retina completes vascular development and tissue differentiation during the eighth month. At full term, the fetus’ eye is 16 mm in diameter and the optic nerve is completing myelination. Children born prematurely experience delays in completing retinal differentiation and vascularization, presumably because of the arrest of growth for some period during the neonatal intensive care stay. Because of the anomalous influences of the preterm environment on the developing retina, retinopathy of prematurity can develop as discussed later in this chapter.

At birth, an infant’s visual system is capable of formed vision. The retinal fovea is the central 1 mm portion of the retina that is used for straight-ahead vision. It completes development during the first year. The globe grows to 22 mm in diameter during the third year and to 24 mm in diameter by the end of adolescence. Most visual improvement noted by parents and clinicians during infancy and childhood is linked to the occipital cortex. This structure undergoes tremendous elaboration and growth during the first 7 years of life.

The development of vision is a dynamic process during childhood. For normal vision to develop, focused, clear visual input is required. If visual input is disrupted—for instance, by scarring, a cataract, or even a refractive error—normal vision does not develop.

Visual development begins shortly before term, proceeding rapidly through the first 2 years of life, then more slowly for the rest of the first decade. After this time, a child’s visual ability remains largely unchanged into adulthood. Thus, any injury or event that negatively affects visual input, even temporarily, has lifelong adverse consequences.

Acuity in children during the first year of life is assessed in terms of corrected age. Visual development is not accelerated by preterm delivery. Acuity testing of young, preverbal children is performed at a distance of 0.5 m using an attractive, colorful toy. A handlight is not used because it is an aversive stimulus for some patients and a too easily seen stimulus for others. Testing is performed monocularly, securely covering the opposite eye with a patch, hand, or a piece of 2-in. tape. By 6 weeks of life, an infant should fixate the target quickly. By 3 months, the patient should be able to follow the target as it moves before the eyes in a 40-degree arc. Many infants can perform these tasks even earlier. Visual function that does not meet these guidelines requires a thorough evaluation. Abnormalities may be present anywhere within the visual system from eye to occipital lobe. A few children have primary delayed visual maturation and eventually become normal. Children with cortical visual impairment respond more favorably to brightly colored objects rather than black and white targets. They may also adopt unusual head positions to place their remaining visual field in the forward direction.

The evaluation of a toddler’s vision should include an assessment of behavior during unstructured play as well as visual function when patched. Children with normal vision appear unimpaired when using either eye after a few moments of distress from the patch. Children who have impaired vision often cry uncontrollably or become withdrawn when trying to use an impaired eye.

Conjunctivitis is the most common cause of a red eye in the pediatric patient. Pain is usually mild. Conjunctivitis, unlike other causes of red eye, is associated with copious discharge. Health care providers are often the unwitting vector of epidemics of viral conjunctivitis. Following contact with a patient who has a red eye, hands must be washed and the areas of the office or clinic visited by the patient must also be thoroughly disinfected.

The most common cause of conjunctivitis is viral. These cases are termed pink eye by families. Many viruses are implicated, but the most common are the adenoviruses. These are responsible for numerous outbreaks in the spring and summer. The conjunctiva is pink and slightly thickened, especially the palpebral conjunctiva. This tissue loses its smooth surface, becoming bumpy and resembling a cobblestone road. There is intense photophobia. The discharge is copious and clear, and there is a prominent painless preauricular lymph node.

Although many cases of conjunctivitis are isolated, some types are associated with fever, pharyngitis, and other symptoms of an upper respiratory infection (pharyngeal conjunctival fever). The disease is self-limited, resolving in 7 to 10 days. Cultures are usually not necessary.

Supportive therapy includes cool compresses, artificial tears, topical and systemic antihistamines, and topical mast-cell stabilizers (e.g., ketorolac, levocabastine, lodoxamide). Topical corticosteroids should not be used without ophthalmologist supervision because these drugs adversely affect a herpetic infection.

The first exposure to herpes simplex virus produces a viral conjunctivitis indistinguishable from any other type of viral conjunctivitis. This infection is self-limited. The presence of clear vesicles on the eyelids is usually secondary to a herpes simplex infection and confirms the diagnosis without the need for culture.

Unlike the other causes of viral conjunctivitis, this virus becomes latent in the trigeminal nerve ganglion. Once there, the herpes simplex virus is responsible for recurrent conjunctivitis and keratitis, the latter a major cause of blindness in the United States. The recurrent inflammation and ulceration of the cornea leads to scarring and vascularization. These changes in the cornea reduce clarity and eventually reduce vision. Many patients eventually require corneal transplantation to restore vision.

When the diagnosis of a herpes simplex infection—whether primary or secondary—is made, a topical antiviral agent is administered (e.g., trifluridine). Most clinicians suggest systemic acyclovir for treating infant herpetic ocular disease or any case involving the eyelids or cornea because of the high frequency of systemic infection.

Patients with herpetic disease or its history should be treated cautiously with topical steroids because they can cause the disease to dramatically worsen. Such a deleterious effect may also be seen with the use of systemic corticosteroids. For this reason, the use of steroids should be avoided by nonophthalmologists in treating conjunctivitis and all other causes of a red eye.

The signs of bacterial conjunctivitis include an injected conjunctiva, both bulbar and palpebral, associated with a purulent discharge. There is no preauricular lymphadenopathy. The causative organisms include Neisseria, Haemophilus, Staphylococcus, and Streptococcus. A Gram stain and culture should be performed to assist in selecting the appropriate antibiotic therapy. A broad-spectrum topical agent (e.g., a combination of trimethoprim and polymyxin B sulfate) is used initially if the Gram stain does not suggest Neisseria gonorrhea. Pseudomonas can have a devastating effect on the cornea in patients using contact lenses due to its quick invasion, and sometimes even perforation, of the cornea. Redness or pain in a contact lens wearing patient should elicit emergent ophthalmologic consultation, removal of the lens, and culture of any discharge. Many organisms are resistant to common topical antimicrobials. Quinolone antibiotics have become the drug of choice for initial therapy of these ulcers.

Conjunctival infection and destruction with subsequent corneal scarring from chlamydia is one of the most common causes of blindness in the world. This blinding form of chlamydia is trachoma. In the United States, chlamydia presents as either neonatal or inclusion conjunctivitis. These forms of the disease are not associated with visual loss.

Inclusion conjunctivitis presents as a prolonged follicular conjunctivitis with mild mucopurulent discharge. The diagnosis is made by Giemsa stain, culture, or most rapidly by fluorescent antibody test of conjunctival swab. The diagnosis of chlamydia in older children suggests child abuse and should be appropriately reported. Therapy for all forms of the disease is systemic.

Ophthalmia neonatorum is conjunctivitis seen in the first 2 weeks after birth due to chemical irritation, bacteria, chlamydia, or herpes simplex. With the discontinuation of silver nitrate drops, the single topical application of erythromycin or tetracycline ointment has replaced silver nitrate in the delivery room as prophylaxsis. A diluted solution of povidone-iodine has been found very effective in clinical trials.

One of the common causes of ophthalmia neonatorum is N. gonorrheae. Although the incidence has been reduced through the use of postnatal prophylaxis, the disease occurs and can lead to blindness if untreated. Unlike other bacteria that require an epithelial defect to infect the cornea, N. gonorrheae may invade through an intact epithelium. Infections with this pathogen must be treated with systemic antibiotics, usually ceftriaxone. Topical therapy, such as erythromycin ointment, may be used but is much less important to the success of the therapy.

Chlamydia trachomatis conjunctivitis is probably the most common cause of neonatal conjunctivitis, occurring in 4 of every 1,000 births. It involves a moderate
mucopurulent conjunctivitis with onset 7 to 14 days after vaginal delivery. Diagnosis is made with a fluorescent antibody test or a Giemsa stain of a conjunctival swab. Cultures can also be obtained. Treatment is a 10-day course of oral erythromycin. Topical agents are not necessary.

Glaucoma, a disease characterized by elevated intraocular pressure, is an infrequent cause of a red eye in childhood. Compared with conjunctivitis, an eye with glaucoma is minimally injected, but much more painful. The triad of ocular signs that should alert the physician to the diagnosis of congenital or infantile glaucoma include red conjunctiva of the bulbar surface, enlarged and cloudy cornea, and tearing. There may also be photophobia and blepharospasm. Older children may present with pain in the eye and vomiting.

Most childhood glaucoma presents within the first year of life. Ocular involvement is often bilateral. The congenital disease may present alone, as part of an ocular syndrome, or as part of a systemic syndrome. The systemic syndromes include aniridia, the congenital rubella syndrome (cataract, hearing, cardiac), Lowe syndrome (renal, cataract), Sturge-Weber syndrome, and neurofibromatosis type 1. Glaucoma may also occur following ocular injuries, especially blunt trauma to the eye, and as a postoperative complication following intraocular ophthalmologic surgery.

The elevated pressure within the eye that causes congenital, infantile, and juvenile forms of glaucoma is usually produced by impaired drainage of fluid from the eye. The pressure is responsible for producing the enlargement of the eye and the destruction of the optic nerve. Prompt institution of pressure-reducing treatment may prevent optic nerve damage. Emergent treatment includes acetazolamide, β-blockers, and filtration surgery. Therapy is needed for life, and many of these patients suffer severe visual impairment.

Childhood iritis, or inflammation of the iris, may follow trauma, be associated with juvenile rheumatoid arthritis, or be idiopathic. The most common cause is blunt trauma to the eye. The patient presents with a red eye, pain, photophobia, and reduced vision. Iritis is treated with cycloplegic and steroid drops.

Any patient with iritis in the absence of trauma should be tested for rheumatoid arthritis and antinuclear antibodies. Most cases are idiopathic, but a few patients have arthritis. The morphology of the inflammation may suggest the etiology. Patients with juvenile rheumatoid arthritis should be carefully followed for the development of glaucoma and cataract. Iritis may precede or follow the diagnosis of the arthritis. Once the diagnosis is made, ongoing ophthalmologic observation is recommended.

Nasolacrimal blockage should be suspected in the presence of an unremitting ocular discharge despite the use of topical antibiotics and the absence of upper respiratory infection and congestion. An intermittent discharge likely represents a partial obstruction. This situation occurs when there is mild swelling of the nasal mucosa. The discharge can be clear or purulent. With growth, this problem generally disappears.

Simple testing of the patency of the drainage system may be performed with a dye disappearance test. This test is performed by adding a drop of 2% fluorescein to each eye. Normally, all traces of the dye in the tear film disappear in 5 minutes. If the dye remains in the tear film, this is confirmatory evidence of an obstruction. Comparison of the rate of dye disappearance between a symptomatic eye and an asymptomatic eye is very reliable. Alternatively, a cotton applicator can be placed under the inferior turbinate in the very cooperative patient. If the applicator is stained yellow from the dye, patency is confirmed.

More complex testing involves computed tomography (CT) views with contrast media placed in the tear film or injected into the lacrimal sac.