Vitamin A Deficiency Among Children

Impact indicator

Indicator Phrasing

% of children aged 24–71 months experiencing night blindness
% d’enfants âgés de 24 à 71 mois souffrant de cécité nocturne
% dětí ve věku 24-71 měsíců postižených noční slepotou

Indicator Phrasing

English: % of children aged 24–71 months experiencing night blindness

French: % d’enfants âgés de 24 à 71 mois souffrant de cécité nocturne

Czech: % dětí ve věku 24-71 měsíců postižených noční slepotou

What is its purpose?

The indicator measures the proportion of children experiencing night blindness, a condition in which they cannot see in dim light. It is the earliest and easiest-to-measure sign of vitamin A deficiency (VAD). VAD is the single most important cause of childhood blindness in developing countries and significantly contributes to child morbidity and mortality. According to WHO, up to 500,000 vitamin A-deficient children become blind every year.

How to Collect and Analyse the Required Data

Collect the following data by conducting individual interviews with mothers of (a representative sample of) children aged 24-71.99 months:

 

RECOMMENDED SURVEY QUESTIONS (Q) AND POSSIBLE ANSWERS (A)
Q1 for data collector: if you have not done so earlier, ask for the name of the youngest child aged 24-71.99 months

 

Q2: Does [specify the child's name] have any problem seeing in the daytime?

A2: yes / no / I do not know

 

(ask the next question only if the previous answer is NO)

 

Q3: Does [specify the child's name] have any problem seeing at nighttime?

A3: yes / no / I do not know

 

(ask the next question only if the previous answer is YES)

 

Q4: Is this problem different from the problems many other children in your community have? (use this question only in areas where vitamin A deficiency is not very prevalent)

A4: yes / no / I do not know

 

(ask the next question only if the previous answer is YES)

 

Q5: Does [specify the child's name] have night blindness? (use local term that describes the symptom)

A5: yes / no / I do not know


 

A child can be counted as experiencing night blindness if the response to Q2 is no, to Q3 yes, to Q4 (if used) yes, and to Q5 yes. Calculate the indicator’s value by dividing the number of children aged 24-71 months who experience night blindness by the total number of surveyed children (exclude all whose mothers replied “I do not know”). Multiply the result by 100.

Important Comments

1) The provided set of four questions is based on WHO’s recommendation.

 

2) Since the prevalence of night blindness is relatively low, the margin of error must be very low (preferably 0.5); otherwise, it is unlikely that you will be able to objectively assess the impact of your intervention. This requires using a very large sample of children (ranging from 8,000 to 30,000 children) and makes assessing vitamin A deficiency (VAD) quite demanding. 

 

3) According to WHO, the prevalence of night blindness among children aged 24-71 months should be interpreted as:

   0.01 – 0.99%: mild

   1 – 4.99%: moderate

   above 5%: severe

 

4) Consult and ideally co-implement the survey with the relevant health authorities, so that you increase the chances of the results being officially recognized (and ideally also acted upon). 

 

5) Since interviewing such a large number of respondents is fairly demanding, before you conduct a new survey, first review the availability of existing data – you might be able to use it for your baseline (however, ensure that you will be able to gain comparable endline data).

 

6) Do not survey children younger than 24 months – they are not usually very mobile at dusk or after dark and night blindness can therefore go unnoticed. 

 

7) Whenever possible, find and use a local name for night blindness (for example, in Ethiopia, it is known as dafint in Amhara, hema in Oromiya, and gahami in Tigray).

 

8) This indicator relies on accurate age assessment. Since people often do not remember the exact dates of their children’s birth, the data collectors should never rely solely on the information provided by caregivers and should always verify the child’s age. This can be done by reviewing the child’s birth certificate or other documents. However, since many caregivers do not have such documents, it is essential that your data collectors are able to determine the child’s age by using local events calendars. Read FAO’s Guidelines (see below) to learn how to prepare local events calendars and how to train data collectors in their correct use.

 

9) Disaggregate the data by sex and age groups. 

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