Abstract
Vitamin A deficiency is the leading cause of preventable childhood blindness in developing countries. Each year, an estimated 13.5 million children world-wide are unable to adapt to the dark and half a million children progress to complete blindness annually from lack of vitamin A. Most of the currently available methods for assessing vitamin A status are expensive, require sophisticated instrumentation and are not efficacious in field conditions. A simple, inexpensive method was developed to identify children with defective dark-adaptability, thereby providing a reflection of marginal vitamin A stores. The purpose of this preliminary study was to test the field-efficacy of the Night Vision Threshold Tester (NVTT). Thirty-nine middle-school children with a mean age of 13.5 ± 1.37 years were initially tested for their ability to adapt to the dark using the NVTT and were retested 3 weeks after vitamin A supplementation. A modified retinol dose response (MRDR) test was also conducted before and after vitamin A supplementation. Among those who initially failed the NVTT test, 93 per cent (14/15) passed the test after supplementation. All of those who initially passed the NVTT test passed it upon subsequent testing. Those who failed the NVTT test had an odds ratio of 2.3 (95 per cent CI, 0.51-9.95) for having low vitamin A levels according to the MRDR test but this did not reach statistical significance due to the small sample size. The NVTT is a prime example of 'appropriate technology' for developing nations as it has the potential to be used as a survey tool for assessing functional vitamin A status of individuals and communities with vitamin A deficiency. It would then be possible to target vitamin A distribution programs more judiciously, resulting in improved allocation of scarce resources. Large-scale, double-blind placebo trials are needed to assess further the sensitivity and specificity of the NVTT.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 352-356 |
| Number of pages | 5 |
| Journal | Journal of Tropical Pediatrics |
| Volume | 46 |
| Issue number | 6 |
| DOIs | |
| State | Published - 2000 |
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ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Public Health, Environmental and Occupational Health
- Immunology
Cite this
A new, simple, inexpensive means of testing functional vitamin A status : The night vision threshold test (NVTT). A preliminary field-test report. / Shrestha, A. K.; Duncan, Burris R; Taren, Douglas L; Canfield, L. M.; Greivenkamp, John E; Shrestha, N.; Shrestha, K. K.
In: Journal of Tropical Pediatrics, Vol. 46, No. 6, 2000, p. 352-356.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A new, simple, inexpensive means of testing functional vitamin A status
T2 - The night vision threshold test (NVTT). A preliminary field-test report
AU - Shrestha, A. K.
AU - Duncan, Burris R
AU - Taren, Douglas L
AU - Canfield, L. M.
AU - Greivenkamp, John E
AU - Shrestha, N.
AU - Shrestha, K. K.
PY - 2000
Y1 - 2000
N2 - Vitamin A deficiency is the leading cause of preventable childhood blindness in developing countries. Each year, an estimated 13.5 million children world-wide are unable to adapt to the dark and half a million children progress to complete blindness annually from lack of vitamin A. Most of the currently available methods for assessing vitamin A status are expensive, require sophisticated instrumentation and are not efficacious in field conditions. A simple, inexpensive method was developed to identify children with defective dark-adaptability, thereby providing a reflection of marginal vitamin A stores. The purpose of this preliminary study was to test the field-efficacy of the Night Vision Threshold Tester (NVTT). Thirty-nine middle-school children with a mean age of 13.5 ± 1.37 years were initially tested for their ability to adapt to the dark using the NVTT and were retested 3 weeks after vitamin A supplementation. A modified retinol dose response (MRDR) test was also conducted before and after vitamin A supplementation. Among those who initially failed the NVTT test, 93 per cent (14/15) passed the test after supplementation. All of those who initially passed the NVTT test passed it upon subsequent testing. Those who failed the NVTT test had an odds ratio of 2.3 (95 per cent CI, 0.51-9.95) for having low vitamin A levels according to the MRDR test but this did not reach statistical significance due to the small sample size. The NVTT is a prime example of 'appropriate technology' for developing nations as it has the potential to be used as a survey tool for assessing functional vitamin A status of individuals and communities with vitamin A deficiency. It would then be possible to target vitamin A distribution programs more judiciously, resulting in improved allocation of scarce resources. Large-scale, double-blind placebo trials are needed to assess further the sensitivity and specificity of the NVTT.
AB - Vitamin A deficiency is the leading cause of preventable childhood blindness in developing countries. Each year, an estimated 13.5 million children world-wide are unable to adapt to the dark and half a million children progress to complete blindness annually from lack of vitamin A. Most of the currently available methods for assessing vitamin A status are expensive, require sophisticated instrumentation and are not efficacious in field conditions. A simple, inexpensive method was developed to identify children with defective dark-adaptability, thereby providing a reflection of marginal vitamin A stores. The purpose of this preliminary study was to test the field-efficacy of the Night Vision Threshold Tester (NVTT). Thirty-nine middle-school children with a mean age of 13.5 ± 1.37 years were initially tested for their ability to adapt to the dark using the NVTT and were retested 3 weeks after vitamin A supplementation. A modified retinol dose response (MRDR) test was also conducted before and after vitamin A supplementation. Among those who initially failed the NVTT test, 93 per cent (14/15) passed the test after supplementation. All of those who initially passed the NVTT test passed it upon subsequent testing. Those who failed the NVTT test had an odds ratio of 2.3 (95 per cent CI, 0.51-9.95) for having low vitamin A levels according to the MRDR test but this did not reach statistical significance due to the small sample size. The NVTT is a prime example of 'appropriate technology' for developing nations as it has the potential to be used as a survey tool for assessing functional vitamin A status of individuals and communities with vitamin A deficiency. It would then be possible to target vitamin A distribution programs more judiciously, resulting in improved allocation of scarce resources. Large-scale, double-blind placebo trials are needed to assess further the sensitivity and specificity of the NVTT.
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UR - http://www.scopus.com/inward/citedby.url?scp=0034517212&partnerID=8YFLogxK
U2 - 10.1093/tropej/46.6.352
DO - 10.1093/tropej/46.6.352
M3 - Article
VL - 46
SP - 352
EP - 356
JO - Journal of Tropical Pediatrics
JF - Journal of Tropical Pediatrics
SN - 0142-6338
IS - 6
ER -