Causes of Corneal Opacities in a 6-Year-Old Child

1. Congenital / Developmental Causes

Anterior Segment Dysgenesis

• Peters anomaly — central corneal opacity with posterior corneal defect, often associated with iridocorneal adhesions ± cataract. One of the most important causes.
• Sclerocornea — all or part of the cornea is opaque and resembles sclera; bilateral or unilateral.
• Aniridia — associated with superficial corneal pannus and eventual opacification.

Birth Trauma

• Forceps injury — vertical Descemet membrane tears (Haab striae) → corneal edema and subsequent scarring. A common cause of unilateral opacity in infancy persisting into childhood.

Congenital Glaucoma

• Elevated IOP → corneal edema (Haab striae) → scarring. Presents with buphthalmos, epiphora, and photophobia.

Corneal Dystrophies

• Congenital hereditary endothelial dystrophy (CHED) — bilateral, diffuse, ground-glass corneal clouding from birth; autosomal recessive (CHED2, SLC4A11 gene) is more common.
• Congenital hereditary stromal dystrophy (CHSD) — bilateral stromal opacification.
• Posterior polymorphous corneal dystrophy (PPCD) — variable presentation, may appear in childhood.

Corneal Dermoid

• Limbal or central choristoma → opacity, astigmatism. Often associated with Goldenhar syndrome.

2. Metabolic / Storage Disorders (Bilateral Opacities)

3. Infectious Causes (Acquired)

• Herpes simplex keratitis — most common cause of infectious corneal scarring in children; dendritic/geographic ulcers → stromal scarring.
• Herpes zoster ophthalmicus — less common in children unless immunocompromised.
• Measles keratoconjunctivitis — especially in vitamin A-deficient children; can be devastating.
• Trachoma (Chlamydia trachomatis) — endemic regions; pannus and corneal scarring (Herbert pits).
• Congenital syphilis — interstitial keratitis is the classic late manifestation (Hutchinson triad: interstitial keratitis + Hutchinson teeth + 8th nerve deafness).
• Congenital rubella — corneal clouding, cataract, glaucoma.
• Bacterial keratitis (post-trauma, contact lens) — scarring from healed ulcers.
• Acanthamoeba keratitis — rare in children, contact lens wearers.

4. Nutritional / Deficiency Causes

• Vitamin A deficiency → Keratomalacia — severe deficiency causes corneal melting and perforation, leading to dense opacities/leucomata. Still a leading cause globally in malnourished children. Preceded by Bitot spots and night blindness.

5. Traumatic Causes (Acquired)

• Corneal laceration/perforation — with scarring
• Chemical injury (alkali > acid) — alkali causes liquefactive necrosis → dense opacity
• Thermal burns
• Foreign body injury
• Non-accidental injury (child abuse) — must be considered

6. Inflammatory / Immune Causes

• Vernal keratoconjunctivitis (VKC) — Shield ulcers → subepithelial scarring; common in atopic boys aged 5–10 years
• Atopic keratoconjunctivitis
• Stevens-Johnson syndrome / Toxic epidermal necrolysis — post-drug reaction; severe bilateral scarring
• Mucous membrane pemphigoid

7. Degenerative / Other

• Band keratopathy — calcium deposition in the interpalpebral zone; associated with JIA (juvenile idiopathic arthritis), hypercalcemia, chronic uveitis
• Keratoconus — thinning and scarring in advanced stages (usually adolescent onset)
• Corneal dermoids (see above)

Quick Reference: Laterality as a Diagnostic Clue

Key Investigations in a 6-Year-Old with Corneal Opacity

1. Slit-lamp examination under GA if needed — morphology of opacity (diffuse, peripheral, central, vascularized)
2. IOP measurement — rule out congenital glaucoma
3. Urine for GAGs — screen for MPS
4. Lysosomal enzyme panel — if metabolic disease suspected
5. TORCH serology / syphilis serology
6. Slit-lamp for crystal deposits (cystinosis), Kayser-Fleischer ring
7. Systemic evaluation — growth, organomegaly, neurodevelopment