Hypovitaminosis deficiency, Xerophthalmia

Figure 6 Foods that protect against hypovitaminosis A (xerophthalmia), based on numerous studies. Dark line, strong evidence dashed line, suggestive evidence. From Sommer A and West KP Jr (1996) Vitamin A Deficiency Health, Survival and Vision. New York Oxford University Press.

Corneal scars may be indicative of past severe vitamin A deficiency but they may be due to other etiologies as well. When observed, a careful history must be taken for evidence of trauma rather than xerophthalmia as causative. The prevalence of scars that partially or totally obstruct vision (see Fig. 12) are associated with high mortality rates and thus underestimate the prevalence of xerophthalmia when they are used as the sole clinical indicator of hypovitaminosis A prevalence. The reason for the high mortality is likely a combination of factors associated with being blind and living under circumstances of deprivation, e.g., accidents, family neglect, and continued undemutrition and exposure. 

This brief accounting of the current situation in south and east Asia leaves little doubt that clinical vitamin A deficiency currently (1982) is a serious public health problem in several countries. Sommer et al, (1981) estimated that in India, Bangladesh, the Philippines, and Indonesia, 500,000 new cases of xerophthalmia occur annually, half of which lead to blindness. Hypovitaminosis A of lesser severity affects many more and is a likely contributor to compromised health throughout the region. 

A disease resulting from a deficiency of one or more vitamins is hypovitaminosis (if vitamin is supplied in insufficient quantity) or avitaminosis (complete lack of vitamin manifested by some biochemical processes disorder). Deficiency of vitamins was formerly one of the main causes of many diseases and deaths. Pellagra (deficiency of some B-complex vitamins), scurvy (vitamin C), beriberi (thiamine), rickets (vitamin D), pernicious anaemia associated with reduced ability to absorb vitamin Bj2 (corrinoids) and xerophthalmia (vitamin A) are now well-known diseases caused by vitamin deficiency. Excessive intake of one or more vitamins (especially of lipophilic vitamins A and D) also causes an abnormal state resulting from disturbances of biochemical processes and can lead to severe diseases known as hypervitaminosis. 

Infection A bidirectional relationship exists between hypovitaminosis A and infection, each exacerbating the other, representing a classic vicious cycle. Thus, infection may be considered both a cause of VA deficiency and, in terms of severity and sequellae, a disorder as well. Cross-sectionally, xerophthalmia... 

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