As elucidated by Alfred Sommer, even mild, subclinical deficiency can also be a problem, as it may increase childrens risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness.VAD is estimated to affect about one-third of children under the age of five around the world. It is estimated to claim the lives of 670,000 children under five annually. Around 250,000–500,000 children in developing countries become blind each year owing to VAD, with the highest prevalence in Southeast Asia and Africa. According to the World Health Organization (WHO), VAD is under control in the United States, but in developing countries, VAD is a significant concern. Globally, 65% of all children aged 6 to 59 months received two doses of vitamin A in 2013, fully protecting them against VAD (80% in the least developed countries). Signs and symptoms
The most common cause of blindness in developing countries is Vitamin A deficiency. The WHO estimated in 1995 that 13.8 million children had some degree of visual loss related to VAD. Night blindness and its worsened condition, xerophthalmia, are markers of Vitamin A deficiency, collections of keratin in the conjunctiva, known as Bitots spots, and ulceration and necrosis of cornea keratomalacia can be seen. Conjunctival epithelial defects occur around lateral aspect of the limbus in the subclinical stage of VAD. These conjunctival epithelial defects are not visible on a biomicroscope, but they take up black stain and become readily visible after instillation of kajal (surma); this is called "Imtiazs sign".
Brachymetacarpia is a medical condition in which the metacarpals of the hands are shortened, the foot equivalent to this condition is brachymetatarsia. This condition is one of the causes of brachydactyly.