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Vitamin A Deficiency

ROUTINE — Systemic

Symptoms

  • night blindness (nyctalopia): the earliest and most common symptom; difficulty seeing in low light
  • dry eyes: a gritty, sandy sensation (xerosis)
  • ocular pain: may occur if the cornea begins to break down
  • severe vision loss: occurs rapidly if "keratomalacia" (corneal melting) develops

Clinical Findings

WHO staging (xerophthalmia)

  • XN (Night Blindness): reversible dysfunction of the rod cells in the retina
  • X1B (Bitot Spots): foamy, triangular, silver-gray plaques on the conjunctiva (pathognomonic)
  • X2 (Corneal Xerosis): the cornea looks hazy, dry, and "lustreless" like wax paper
  • X3B (Keratomalacia): a medical emergency where the cornea physically liquefies and melts

Ocular surface signs

  • white conjunctiva: despite severe dryness, the eye is often not "red" initially
  • rapid TBUT: the tear film breaks up almost instantly (often < 5 seconds)

Fundus signs (XF)

  • yellow-white dots: small deep retinal spots in the periphery; reversible with treatment

Etiology

Primary (dietary)

  • lack of vitamin A-rich foods (liver, carrots, leafy greens, eggs)
  • leading cause of preventable childhood blindness worldwide

Secondary (malabsorption)

  • bariatric surgery: common in developed countries (gastric bypass)
  • gastrointestinal disease: Crohn's, Celiac, or Cystic Fibrosis (pancreatic insufficiency)
  • liver disease: alcoholism or cholestasis

Red Flags

  • foamy spots (Bitot): in a child, this is an emergent warning of impending corneal melt
  • keratomalacia: the cornea can perforate within hours; requires immediate high-dose Vitamin A
  • measles: Vitamin A deficiency significantly increases measles mortality; treatment is mandatory
  • pregnancy: while high-dose Vit A is teratogenic, a corneal threat outweighs fetal risk

Investigations

Clinical exam

  • Slit-lamp exam to stage the disease and check for corneal ulcers
  • Schirmer test to quantify severe dryness

Labs & imaging

  • serum retinol: levels are often the last to drop (liver stores must be empty)
  • RBP (Retinol Binding Protein): more sensitive for early deficiency
  • ERG: can detect rod dysfunction before visible changes appear

Treatment

Systemic replacement (WHO protocol)

  • adults/children >1yr: 200,000 IU orally on Days 1, 2, and 14
  • children 6-12 months: 100,000 IU on the same schedule

Ocular management

  • frequent lubrication with ointment/tears
  • protect the globe if "melting" is present to prevent perforation

Clinical Pearl

Bitot spots and night blindness in a child from a low-resource area or a malabsorbing adult is vitamin A deficiency — keratomalacia melts the cornea within days, so replace vitamin A urgently while working up malabsorption.

Differential Diagnosis

  • • Sjögren syndrome (autoimmune dry eye; usually older females)
  • • chemical burns (scarring and dryness)
  • • congenital stationary night blindness (nyctalopia without the "dryness" findings)
  • • trachoma (causes scarring and dryness but has characteristic lid findings)

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