Nutritional Blindness

• Loss of useful vision resulting from vitamin deficiency.

Vitamin A Deficiency (VAD)

• VAD is a common form of micronutrient deficiency.
• VAD is among the leading causes of blindness worldwide, estimated to blind half a million children each year.

Vitamin A Functions

• Vitamin A (a fat-soluble vitamin) performs essential functions in the body, including:
• Cell development
• Metabolism
• Immune function
• Vision
• Reproductive function

Vitamin A is essential for maintaining conjunctival, corneal epithelia, and night vision.

• The most common cause of VAD is malnutrition complicated by chronic inflammation from regular GI infections.
• Other causes include liver and intestinal pathologies (in the developed world).

• VAD causes metaplasia and keratinization of mucus-secreting epithelium, leading to:
• Conjunctival and corneal xerosis
• Corneal ulcers
• Keratomalacia
• Corneal scarring
• Retinol is a vitamin A-derived cofactor required for the formation of rhodopsin (rod’s pigment).
• VAD leads to impairment of rod function and causes nyctalopia (night blindness).

Synergy between VAD and Infections:

• Poor vitamin A status prolongs the course of illness by impairing the immune system.
• Increased susceptibility to mucosal infections: diarrhea, RTI, measles are common in VAD.
• Infections reduce the intestinal absorption of vitamin A.

• Low socioeconomic status
• Malnutrition
• Maternal malnourishment (affects Vitamin A concentration in breastmilk)
• Zinc deficiency: depresses the hepatic synthesis of retinol-binding protein, which is required for the metabolism of retinol from the liver. Zinc may also play a role in the conversion of beta-carotene to retinol.
• Co-existing measles or other respiratory or diarrheal illness

• Animal Foods:
• Liver
• Eggs
• Cheese
• Fish
• Plant Foods - Most important sources are:
• Yellow, yellow-red, and dark green leafy vegetables
• Red oil
• Fruits: mango, papaya, carrots

• Xerophthalmia is the clinical spectrum of ocular manifestations of vitamin A deficiency.
• It ranges from the milder stages of night blindness and Bitot spots to the potentially blinding stages of corneal xerosis, ulceration, and necrosis (keratomalacia).
• Vitamin A is essential for the synthesis of retinal photopigments, particularly rhodopsin.
• Visual cycle - delayed dark-adaptation, Night Blindness.
• Conjunctival epithelial dysfunction.
• Ocular-surface dryness.

World Health Organization Re-classification of Xerophthalmia Signs

Classification	Ocular Signs
XN	Night blindness
X1A	Conjunctival xerosis
X1B	Bitot's spots
X2	Corneal xerosis
X3A	Corneal ulceration-keratomalacia involving one-third or less of the cornea
X3B	Corneal ulceration-keratomalacia involving one-half or more of the cornea
XS	Corneal scar
XF	Xerophthalmic fundus

XN: NIGHT BLINDNESS

• Earliest symptom.
• Due to impairment in dark adaptation.
• Defective rhodopsin function.
• Responds rapidly to vitamin A therapy within 24-48 hours.

X1A: CONJUNCTIVAL XEROSIS

• The conjunctival epithelium undergoes keratinization, i.e., the normal columnar epithelium is transformed into stratified squamous epithelium.
• Dull and dry appearance of the conjunctiva with slight wrinkling.
• Goblet cells are lost.

X1B: BITOT’S SPOT

• Accumulate on the xerotic surface, giving a foamy appearance (BITOT’S SPOT).
• Begin to resolve within 2-5 days and disappear by 2 weeks of treatment.
• In chronic cases, the spots will not disappear.

X2: CORNEAL XEROSIS

• Lustreless dry appearance of the cornea.
• Responds within 2-5 days, disappears within 2 weeks of treatment.

X3A & X3B: KERATOMALACIA

• Liquefactive necrosis/sterile corneal melting.
• Corneal ulcers, perforation.

XS: Corneal Scarring

• Corneal scarring.

XF: Xerophthalmic Fundus

• Prolonged VAD can lead to structural changes in the retina.
• Small, white, deep retinal lesions scattered throughout the posterior pole of the retina.

• Vitamin A: (3 doses)
• 200,000 I.U - orally or
• 100,000 I.U – I.M
• 1st day, 2nd day & day 14
• Children within 6 to 11 months- half dose
• For ocular lesions:
• Lubricants
• Antibiotics
• Fortified diet

• Consume dark green leafy vegetables and other Vitamin A-rich foods.
• Cultivation of a variety of food with high vitamin and mineral content.
• Promotion of breastfeeding.
• Immunization.
• Development of low-cost weaning food.

Measures to Improve Family Diet

• Nutrition education.
• Home economics.
• Family planning & spacing of births.

Additional Information on Vitamin B Deficiency

• Vitamin B deficiency may result in optic neuropathy and optic neuritis.
• Chronic alcoholism.