How a Vitamin A deficiency causes vision loss

Diet can impact vision
When a young boy began losing his sight, Professor Stephanie Watson immediately recognised the signs of Vitamin A deficiency. Caused by the patient's diet, the deficiency led to the loss of vision in one eye.

Cian, a young teenager from Perth, started to lose his vision at 14. He visited many specialists, and was tested for a range of diseases. No one found a cause. At a loss, a family member flew Cian from Perth to Sydney to see the Save Sight Institute's Professor Stephanie Watson.

Professor Watson immediately diagnosed Cian with Vitamin A deficiency. Vitamin A deficiency is a rare diagnosis in developed countries like Australia. In the developed world, Vitamin A deficiency usually occurs after other medical complications. Cian’s Vitamin A deficiency was due to his diet. Cian was a fussy eater; since the age of 5, he had been living on chicken, bread, chips, and coke.

Vitamin A deficiency can lead to blindness, infections and death. Today, 228 million children lack enough Vitamin A. That makes Vitamin A deficiency the most common form of childhood blindness. Vitamin A deficiency causes eye diseases in 5 to 10 million children a year. Of those, five hundred thousand go blind because of a lack of Vitamin A.

Vitamin A, a fat-soluble vitamin, is found in dairy products. Vitamin A also occurs in some fruits and green leafy vegetables. It has two roles in the eye; it helps the retina convert light to a visual signal in the retina. It also ensures correct maturation of the ocular surface cells.

The first sign of vitamin A deficiency is an eye condition called ‘xerophthalmia’. The effects on the eyes of xerophthalmia follow a predictable pattern. The first stage is night blindness (nyctalopia). That’s where retinal rhodopsin (sight pigments) stop regenerating.

The second stage is drying (conjunctival xerosis). Corneal drying can lead to ulceration, scarring and keratomalacia. Keratomalacia is a rapidly progressive and irreversible disease that can lead to rupture of the cornea with loss of the eye’s content.

Vitamin A deficiency also affects mood and general health with anaemia a frequent association.

In many of these cases, prompt treatment with high doses of Vitamin A can reverse the effects. In Cian’s case, he improved his nutrition and regained sight in his right eye but not his left eye.

In Australia, doctors should examine a patient’s diet if there is an unexplained visual loss.

Cian's story opens the film ‘Vitamania’, for which Professor Watson was an advisor.

Facts & figures

Vitamin A deficiency

  • 228 million children are affected
  • 5-10 million children have eye disease as a result
  • 500,000 children go blind as a result