Pediatric Ophthalmology

Screening the child's eyes

Red reflex. The red reflex test is the basic eye screen, done in the nursery and at every well-child visit. With a direct ophthalmoscope focused on both pupils from about 30–45 cm, each should glow a bright, symmetric red-orange; an absent, white, dull, dark-spotted, or unequal reflex needs ophthalmology referral. Viewing both eyes together (Brückner test) also exposes strabismus, since the deviating eye usually gives the brighter reflex.

Vision screening. Photoscreening detects amblyopia risk factors from about 1 year, and acuity charts are added by 3–4 years; the USPSTF recommends screening at least once between ages 3 and 5. Tearing, photophobia, and a large, hazy cornea point instead to congenital glaucoma, a surgical problem.

Leukocoria: retinoblastoma and congenital cataract

Leukocoria. A white pupillary reflex, often first noticed in flash photographs, requires urgent pediatric ophthalmology evaluation because retinoblastoma must be excluded first.

Retinoblastoma genetics. The most common primary intraocular malignancy of childhood arises when both copies of RB1, a tumor suppressor on 13q14 that restrains the G1-to-S transition, are lost (Knudson two-hit model). About 40% of cases are heritable: every bilateral case and about 15% of unilateral cases carry a germline hit, so one somatic hit suffices and tumors are bilateral or multifocal and appear earlier (around 1 year). Inheritance is autosomal dominant with high penetrance, giving each child of a carrier a 50% chance of the mutation. Nonheritable tumors need two somatic hits and present as unilateral, unifocal disease around 2 years. Most children are diagnosed before age 3, usually with leukocoria and next most often with strabismus.

Workup and treatment. Diagnosis rests on dilated examination under anesthesia, ultrasound showing a calcified mass, and MRI of the orbits and brain to assess optic nerve invasion and a pineal tumor (trilateral retinoblastoma); CT radiation is avoided. Options include intra-arterial or systemic chemotherapy, laser or cryotherapy, and enucleation for advanced disease. All patients are offered germline testing, and siblings and offspring get screening exams. Heritable survivors carry a lifelong excess of second cancers (osteosarcoma first, then soft-tissue sarcomas and melanoma), highest inside radiation fields.

Never biopsy a suspected retinoblastoma: needle sampling can seed tumor outside the globe.

Congenital cataract. A dense lens opacity blocks the visual axis during the critical period, causing deprivation amblyopia and nystagmus unless removed early, ideally within the first 6–8 weeks, followed by an aphakic contact lens or glasses and patching. Bilateral cataracts prompt evaluation for congenital rubella and other TORCH infections, galactosemia, and trisomy 21; oil-droplet cataracts in a vomiting, jaundiced newborn with E. coli sepsis indicate classic galactosemia (GALT deficiency), treated by stopping lactose-containing feeds.

Strabismus and amblyopia

Checking alignment. In the Hirschberg test the corneal light reflex should sit at the same spot in both pupils; temporal displacement means esotropia and nasal displacement exotropia. In the cover–uncover test, covering the fixing eye makes a deviated fellow eye shift to take up fixation, confirming a manifest tropia. Pseudostrabismus (broad nasal bridge and epicanthal folds hiding the nasal sclera) has symmetric reflexes and a normal cover test and needs only reassurance.

When to refer. Intermittent misalignment is normal only until about 4–6 months. A constant deviation at any age, or any misalignment beyond that window, needs referral for cycloplegic refraction and a dilated fundus exam, since retinoblastoma can present as an eye turn. Infantile esotropia (onset before 6 months, large angle) is corrected surgically; accommodative esotropia (around 2–3 years, hyperopia) responds to full-time glasses. New esotropia with headache suggests an abducens palsy from raised intracranial pressure.

Amblyopia. Amblyopia is reduced best-corrected acuity from abnormal visual input during the critical period (to about 7–8 years) in a structurally normal eye. Its mechanisms are strabismic (suppression of the deviating eye), refractive (anisometropia or high bilateral error), and deprivation (cataract, ptosis over the pupil, corneal opacity), the most severe.

The patch goes on the better-seeing eye; covering the amblyopic (often deviating) eye deepens the amblyopia. Gains are greatest before about 7–8 years.

Retinopathy of prematurity

Pathogenesis. Retinal vessels reach the periphery only near term, so preterm infants have an avascular peripheral retina. Hyperoxia, including supplemental oxygen, halts vessel growth; the avascular retina then becomes hypoxic, VEGF surges, and neovascularization at the vascular–avascular junction can progress to fibrovascular proliferation and tractional detachment. Stages run from a demarcation line (1) and ridge (2) to extraretinal proliferation (3) and partial (4) or total (5) detachment; plus disease (dilated, tortuous posterior vessels) marks severe activity.

Screening and treatment. Infants born at ≤30 weeks or ≤1500 g, plus unstable larger infants, get serial dilated exams. Treatment-requiring disease receives laser ablation of the avascular retina or intravitreal anti-VEGF such as bevacizumab. Survivors have more myopia, strabismus, amblyopia, and late retinal detachment.

Neonatal conjunctivitis

Timing is the clue. Conjunctivitis in the first month (ophthalmia neonatorum) is sorted by day of onset and confirmed with Gram stain, culture, and NAAT of conjunctival swabs.

Gonococcal ophthalmia. Gram stain shows gram-negative intracellular diplococci, and the organism can penetrate intact corneal epithelium and perforate the cornea within days. Management is admission, single-dose IM or IV ceftriaxone, frequent saline irrigation, evaluation for disseminated infection, testing for chlamydia, and treatment of the mother and partners; topical antibiotics alone are inadequate.

Give ceftriaxone cautiously to hyperbilirubinemic or preterm neonates (it displaces bilirubin), and never with calcium-containing IV fluids.

Chlamydial conjunctivitis. Chlamydia trachomatis is the most common infectious cause in the United States. Treatment is systemic because topical therapy neither clears nasopharyngeal carriage nor prevents pneumonia (afebrile, staccato cough, tachypnea, eosinophilia at 1–3 months); the mother and partner are treated too. Macrolides before 6 weeks of age raise the risk of infantile hypertrophic pyloric stenosis.

Prophylaxis. Every newborn receives erythromycin 0.5% ophthalmic ointment soon after delivery to prevent gonococcal ophthalmia (silver nitrate was abandoned because it caused chemical conjunctivitis). It does not reliably prevent chlamydial disease, which is prevented by prenatal screening and treatment of the mother.