Night blindness, medically known as nyctalopia, is a condition where an individual finds it difficult to see in dim lighting or darkness. This visual impairment primarily stems from a deficiency of vitamin A, a fat-soluble vitamin essential for maintaining healthy vision and proper functioning of the retina. Understanding the connection between vitamin A and night blindness can highlight the importance of this nutrient in eye health and guide effective treatment.

The Role of Vitamin A in Vision

Vitamin A is critical for the formation of rhodopsin, a photopigment found in the rod cells of the retina. Rod cells are specialized for vision in low-light conditions and are essential for night vision.

• Rhodopsin Synthesis:
  Vitamin A is a precursor of retinal, a component of rhodopsin. Adequate vitamin A ensures the production and regeneration of rhodopsin, allowing rod cells to function properly during darkness.

• Maintaining Eye Surface Health:
  Vitamin A also supports the health of the cornea and conjunctiva, preventing dryness and maintaining the integrity of the ocular surface.

Vitamin A Deficiency and Night Blindness

When vitamin A levels drop, the production of rhodopsin decreases, compromising the eye’s ability to adapt to dark environments, resulting in night blindness. Early symptoms include difficulty seeing in low light and gradual loss of peripheral vision.

Treatment and Prevention

Supplementing with vitamin A is effective in curing and preventing night blindness, especially when deficiency is identified early.

• Supplementation:
  Oral or intramuscular vitamin A supplements can restore vitamin A levels, improve rhodopsin regeneration, and consequently improve night vision.

• Diet:
  Consuming foods rich in vitamin A such as liver, dairy products, fish, green leafy vegetables, and orange-colored fruits can prevent deficiency.

• Healthcare Interventions:
  In regions where vitamin A deficiency is common, public health programs provide high-dose vitamin A supplements to vulnerable populations.

Why Other Vitamins Don’t Cure Night Blindness

• Vitamin B: Primarily involved in metabolic processes but not directly linked to night vision.

• Vitamin C: Functions as an antioxidant but does not influence rhodopsin or night vision.

• Vitamin E: Antioxidant properties without a direct role in correcting night blindness.

Conclusion

The vitamin essential for curing night blindness is Vitamin A due to its vital role in synthesizing rhodopsin necessary for vision under low-light conditions. Supplementation and adequate dietary intake of vitamin A help restore night vision and protect against the progression of visual impairment.

Therefore, the correct answer is:
(4) Vitamin A