How does a lack of vitamin A impact vision?

A lack of vitamin A can lead to night blindness and, in severe cases, complete vision loss.

Vitamin A is crucial for maintaining healthy vision. It plays a significant role in the conversion of light into a signal that can be transmitted to the brain, a process known as visual transduction. This vitamin is a key component of a protein called rhodopsin, found in the retina of the eye, which is responsible for detecting low-light conditions. When there is a deficiency of vitamin A, the production of rhodopsin is affected, leading to difficulties in seeing in dim light or at night, a condition known as night blindness.

Moreover, vitamin A is essential for the health and maintenance of the cornea, the clear front surface of the eye. A prolonged deficiency of this vitamin can lead to a condition called xerophthalmia, which is characterised by dryness, thickening, and clouding of the cornea. In severe cases, this can progress to corneal ulcers and scarring, ultimately leading to complete vision loss.

Additionally, vitamin A deficiency can also affect the conjunctiva, the membrane that covers the front of the eye and the inside of the eyelids. This can result in a condition called Bitot's spots, which are foamy patches on the conjunctiva.

In summary, vitamin A is vital for various aspects of eye health, including visual transduction and the maintenance of the cornea and conjunctiva. A deficiency in this vitamin can lead to serious vision problems, including night blindness, xerophthalmia, and Bitot's spots. Therefore, maintaining an adequate intake of vitamin A is crucial for preserving good vision.