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OP10.4 | Vitamin A Deficiency: Ocular Manifestations, Management and Referral — SDL Guide (Part 2)

Examination and Investigation of Xerophthalmia

Clinical examination of the child with suspected xerophthalmia proceeds systematically from observation to targeted testing. The examination is primarily clinical — laboratory investigations confirm the diagnosis but should not delay treatment. This is a critical principle: in a resource-limited community setting, a child with night blindness and Bitot's spots does not need to wait for a serum retinol result before receiving vitamin A supplementation. The serum retinol level is a negative acute-phase reactant that can be falsely normal during concurrent infection, making it an unreliable sole gatekeeper for treatment initiation. The clinical examination is therefore both the diagnostic tool and the treatment trigger. Understanding each examination component — what it detects, why it matters, and how it differs from similar-appearing conditions — enables you to function as an effective first-contact provider even without laboratory backup. The examination sequence described below moves logically from general observation (to establish the nutritional context), to the external eye (conjunctiva, then cornea in order of severity), to specific investigations that add diagnostic precision where available. Remember that the goal of the examination is not merely to confirm xerophthalmia but to stage it precisely — because the WHO stage determines the urgency of referral and whether the child needs same-day ophthalmology review.

Observation: Look for general features of malnutrition (wasting, oedema, pallor). Note the child's behaviour in the examination room — a child who functions normally in a bright room but becomes fearful or inactive in dimmer lighting should trigger suspicion of night blindness.

Slit-lamp examination (or loupe + torch in a field setting):
- Inspect the CONJUNCTIVA: note lustre, moisture, texture. A normal conjunctiva is glistening and reflects light; a xerotic conjunctiva appears dull and wrinkled. Look specifically at the TEMPORAL bulbar conjunctiva for Bitot's spots — the foamy triangular plaque.
- Inspect the CORNEA: note brilliance (mirror-like = normal), haziness (xerosis = X2), or areas of softening/melting (keratomalacia = X3).
- Rose bengal staining highlights devitalised epithelial cells on the conjunctiva and cornea — the xerotic areas stain intensely.

Dark adaptometry: A formal test of rod function under controlled low-light conditions; rod adaptation is significantly impaired even at the XN stage before any structural sign appears. This test is rarely available at primary care level but is the gold standard functional test for early VAD.

Serum retinol: Normal serum retinol is ≥0.70 μmol/L (20 μg/dL). A level below 0.35 μmol/L indicates deficiency; below 0.70 μmol/L indicates sub-optimal status. However, serum retinol does not accurately reflect liver stores in acute illness (it is a negative acute-phase reactant) — a low level confirms deficiency but a normal level does not exclude it in the context of acute infection.

Conjunctival impression cytology (CIC): A small piece of cellulose acetate filter paper is pressed onto the bulbar conjunctiva and peeled off, taking a superficial impression of the epithelium. In VAD, goblet cells are absent and the epithelial cells show squamous metaplasia — a finding visible on light microscopy. CIC is a sensitive, non-invasive research and epidemiological tool.

Nutritional assessment: Weight, height, mid-upper arm circumference; dietary history (frequency of vitamin A-rich foods — liver, egg, dark leafy vegetables, yellow/orange fruits); history of malabsorption, chronic diarrhoea, or recent measles.

Diagnosis and Differential Diagnosis

The diagnosis of xerophthalmia is primarily clinical in the appropriate demographic context — a malnourished child from a low-income, rice-dependent diet background with night blindness and Bitot's spots does not require laboratory confirmation before treatment is initiated. However, several conditions must be distinguished.

Differential diagnoses for Bitot's spots: In adults and older patients, Bitot's spots may represent inactive scarring from previous vitamin A deficiency or may be associated with pinguecula. Unlike active VAD-associated Bitot's spots in children, these lesions do not respond to vitamin A supplementation. However, in a child aged 1–6 years from a high-risk area, Bitot's spots should be presumed to represent active deficiency and treated accordingly.

Differential diagnoses for night blindness: Retinitis pigmentosa (RP) causes progressive night blindness from early childhood (congenital rod dystrophy); VA is usually normal; fundus shows the classic 'bone-spicule' pigmentation, attenuated vessels, and waxy disc — quite different from the normal or pale fundus of VAD. Advanced glaucoma (loss of peripheral fields including scotopic field) and certain drug toxicities (chloroquine, quinine) also impair night vision.

Differential diagnoses for corneal ulceration (X2, X3): Corneal xerosis and keratomalacia must be distinguished from:
- Bacterial keratitis: Rapid-onset hypopyon ulcer, significant pain, mucopurulent discharge — the cornea is white and opaque rather than softened and gelatinous.
- Fungal keratitis: Feathery margins, satellite lesions, history of agricultural injury — typically unilateral.
- Herpes simplex keratitis: Dendritic ulcer staining with fluorescein; unilateral; herpetic vesicles or history.
- Neonatal ophthalmia: Gonococcal or chlamydial — neonatal age, purulent discharge.
In VAD keratomalacia, the bilateral distribution, the context of malnutrition, and the gelatinous rather than inflammatory appearance of the cornea are the distinguishing features.

Management: Vitamin A Supplementation and Supportive Care

Treatment of xerophthalmia is based on high-dose oral vitamin A supplementation according to the WHO protocol, combined with nutritional rehabilitation and treatment of any underlying precipitating illness. The rationale for high-dose supplementation rather than simply recommending dietary improvement is pharmacokinetic: dietary vitamin A is absorbed slowly over weeks, and a child with active corneal xerosis or keratomalacia cannot afford to wait for dietary sources to replenish depleted liver stores. The three-dose schedule (Day 1, Day 2, Day 14) saturates hepatic stores rapidly over the first two days, then consolidates them at day 14, providing a sustained therapeutic concentration during the critical period when the ocular surface is regenerating goblet cells and the rhodopsin cycle is recovering. Without the Day 14 top-up dose, liver stores may fall again before dietary intake has improved sufficiently to maintain them. Oral administration is preferred over intramuscular injection because retinyl palmitate is poorly water-soluble and IM administration is painful and less reliably absorbed. The protocol is age-stratified because high-dose vitamin A is teratogenic and must not be given to pregnant women; in children the doses are carefully calibrated to avoid hypervitaminosis A (which causes raised intracranial pressure, irritability, and vomiting at excessive doses). Treatment must always be accompanied by nutritional rehabilitation — without addressing the underlying dietary deficiency, deficiency will recur within months.

WHO oral vitamin A treatment protocol (for xerophthalmia):
- Children >1 year and adults: 200,000 IU (200 mg retinol palmitate) orally on Day 1, Day 2, and Day 14.
- Infants 6–12 months: 100,000 IU on Day 1, Day 2, and Day 14.
- Infants <6 months: 50,000 IU on Day 1, Day 2, and Day 14.

The three-dose schedule (Day 1, 2, 14) saturates liver stores rapidly (days 1 and 2) and then tops up the store two weeks later. The rationale for the repeat dose at day 14 is to maintain therapeutic levels while the retinol-binding protein system recovers.

Vitamin A for measles (WHO recommendation): All children with measles should receive vitamin A: 200,000 IU on day 1 and day 2 (children >1 year), regardless of their nutritional status or country, because measles causes rapid depletion of vitamin A stores and the two doses prevent vision loss in children with subclinical deficiency.

Topical ocular treatment:
- Lubricating eye drops (artificial tears — carboxymethylcellulose or hypromellose) provide symptomatic relief and protect the ocular surface.
- Antibiotic eye drops (chloramphenicol or ciprofloxacin) may be added if secondary bacterial infection of the cornea is suspected.
- The eyes may need to be padded (closed with moist pads) in severe keratomalacia to prevent further desiccation of the softened cornea.

Nutritional rehabilitation:
- Address the underlying dietary deficiency. Vitamin A-rich foods: liver (highest density), egg yolk, dairy products (fat-containing), dark leafy green vegetables (spinach, methi, drumstick leaves — beta-carotene precursor), and yellow-orange fruits and vegetables (carrots, papaya, mango).
- Ensure adequate dietary fat for retinol absorption.
- Treat concurrent protein-energy malnutrition, iron deficiency, and zinc deficiency (zinc is required for retinol-binding protein synthesis and transport of vitamin A from the liver).
- Treat any precipitating illness (measles, diarrhoea, respiratory infection).