Which vitamin deficiency is associated with vision changes such as night blindness and Bitot spots?

Vitamin A Deficiency Causes Night Blindness and Bitot Spots

Vitamin A deficiency is the vitamin deficiency associated with vision changes including night blindness and Bitot spots, which are pathognomonic early clinical signs of this deficiency 1.

Clinical Manifestations of Vitamin A Deficiency

The ocular manifestations follow a predictable progression:

Early Signs

• Night blindness (nyctalopia): The earliest and most characteristic symptom, resulting from insufficient rhodopsin synthesis in retinal photoreceptors 1
• Conjunctival xerosis: Dryness and keratinization of the conjunctival surface
• Bitot spots: Grey/white foamy patches on the conjunctiva, appearing as keratinized epithelial debris 1, 2

Advanced Manifestations (If Untreated)

• Corneal xerosis: Drying and clouding of the cornea
• Keratomalacia: Corneal softening with inflammatory centers spreading to iris and lens
• Xerophthalmia: Complete corneal maceration leading to secondary infection and irreversible blindness 1

The progression from night blindness to blindness can be prevented with prompt recognition and treatment, making early detection critical for preserving vision.

High-Risk Populations Requiring Screening

Based on the ESPEN 2022 guidelines, actively screen for vitamin A deficiency in 1:

• Chronic liver disease patients: Prevalence increases with disease severity due to impaired retinol storage and RBP synthesis
• Chronic alcohol consumption: Depletes hepatic vitamin A stores even when serum levels appear normal
• Short bowel syndrome/malabsorption disorders: Including cystic fibrosis, celiac disease, chronic diarrhea 2
• Post-bariatric surgery patients: Particularly after malabsorptive procedures 3
• Restrictive dietary practices: Vegan diets, eating disorders, autism with food selectivity 4
• Chronic kidney disease: Paradoxically may show elevated serum retinol initially, but liver stores become depleted over time requiring regular monitoring 1

Diagnostic Approach

Measure serum retinol levels when clinical signs are present 3. Key considerations:

• Normal serum retinol: >20 µg/dL
• Deficiency confirmed: <20 µg/dL (severe deficiency may show levels as low as 4.2 µg/dL) 2
• Important caveat: Inflammation decreases serum retinol concentrations independent of true vitamin A status, so adjust for CRP or AGP when elevated 1
• Consider ophthalmology referral when visual symptoms are present 3

Treatment Protocol

For Adults with Confirmed Deficiency 3:

• Oral vitamin A 10,000-25,000 IU daily for 1-2 weeks for clinical improvement
• Recheck vitamin A levels at 3 months
• If night blindness is present or oral treatment fails: Consider intramuscular vitamin A injections and refer to specialist 3

For Severe Cases with Malabsorption 2:

• Intramuscular administration of 100,000 IU on days 1,2, and again after 2 weeks has been effective in documented cases with short bowel syndrome

Critical Treatment Considerations:

• Light-sensitive vitamin requires light-protecting administration materials 1
• Monitor for toxicity: acute toxicity occurs above 300,000 IU in adults or >60,000 IU in children 1
• In adolescents with deficiency, always refer for specialist support 3

Common Pitfalls to Avoid

1. Misdiagnosis in developed countries: Xerophthalmia cases in high-income countries are frequently misdiagnosed, causing treatment delays and adverse visual outcomes 4. Maintain high clinical suspicion in at-risk populations.

2. Relying solely on serum levels in inflammation: Serum retinol drops during inflammatory states independent of true deficiency status—adjust interpretation accordingly 1.

3. Inadequate monitoring in chronic kidney disease: These patients may initially show elevated retinol levels that mask progressive depletion of hepatic stores 1.

4. Overlooking dietary history: Particularly important in children with autism or restrictive eating patterns who may develop severe deficiency despite living in resource-rich settings 4, 5.

5. Delayed recognition of associated infections: Vitamin A deficiency increases susceptibility to respiratory and gastrointestinal infections, which may present before obvious ocular signs 1, 5.

The key to preventing irreversible blindness is recognizing that night blindness represents a medical emergency requiring immediate vitamin A supplementation, as progression to corneal involvement can occur rapidly and result in permanent vision loss 1, 6.