Vitamin A deficiency and measles infection are important poverty-related causes of blindness
Gilbert et al’s study apparently under-emphasized the importance of
vitamin A deficiency and measles infection as important poverty-related
causes of blindness in poor countries. There are at least two likely
reasons for this under-emphasis. First, the focus of the WHO adult
blindness classification system used by most authors conducting national
blindness surveys is understandably biased towards treatable causes, and
this is likely to lead to classification of the majority of cases of
blindness and visual impairment due to measles/vitamin A-related corneal
scarring (which is very difficult to treat) as due to other causes.1,2
Second, given that childhood blindness is second only to cataract in the
magnitude of world blindness when “blind years” (the number of years a
person lives with blindness) are considered, and that at least half of all
cases of childhood blindness in developing countries are caused by measles
and vitamin A deficiency, perhaps corneal scarring is a cause of only
11.8% of blindness in the authors’ study because of a high childhood
mortality among Pakistan’s blind children.3 While studies indicate that
corneal opacity account for less than 10% of all blindness globally4, in
developing countries, the proportion of blindness due to corneal opacity
caused by measles and vitamin A deficiency is much higher. Apart from
addressing structural factors to alleviate poverty itself, these poverty-
related causes of blindness and visual impairment are preventable and, if
detected early, treatable.5
1) Gilbert et al. Poverty and blindness in Pakistan: results from the
Pakistan national blindness and visual impairment survey. British Medical
Journal, 2008; 336: 29-32.
2) Dineen et al. Prevalence and causes of blindness and visual impairment
in Bangladesh adults: results of the national blindness and low vision
survey of Bangladesh. Bri. J. Opthalmology, 2003; 87: 820-828.
3) World Health Organization. Preventing blindness in children: report of
WHO/IAPB scientific meeting. Geneva: WHO, 2000. (WHO/PBL/00.77.).
4) Resnikoff S et al. Global data on visual impairment in the year 2002.
Bulleting of WHO, 2004; 84: 844-851.
5) Rabiu MM, Kyari F. Vitamin A deficiency in Nigeria. Niger. J. Med.,
2002; 11: 6-8.
Competing interests: No competing interests