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Pupillary and visual thresholds in young children as an index of population vitamin A status
Insights
Vitamin A supplementation improved vision in deficient Indonesian children. Retinal sensitivity increased significantly after vitamin A re-dosing, demonstrating its crucial role in maintaining visual function.
Area of Science:
- Ophthalmology
- Nutritional Science
- Public Health
Background:
- Vitamin A deficiency is a significant global health issue, particularly affecting children's vision.
- Early detection and intervention are crucial for preventing irreversible vision impairment.
- Assessing visual function in young children requires specialized, sensitive tools.
Purpose of the Study:
- To evaluate the impact of vitamin A supplementation on pupillary and visual thresholds in vitamin A-deficient Indonesian children.
- To assess the relationship between vitamin A status and visual function over time.
- To determine the efficacy of a second vitamin A dose in improving visual thresholds.
Main Methods:
- A prototype scotopic sensitivity machine was used to test 295 Indonesian children (aged 1-5 years).
- Pupillary and visual thresholds were measured at baseline, 6 months, and 9 months post-initial vitamin A dose.
- Children received a second high dose of vitamin A or placebo, with final testing 2 weeks later.
Main Results:
- Children with abnormal pupillary thresholds showed higher relative dose responses (RDRs) and lower serum retinol.
- Visual thresholds declined (retinal sensitivity fell) as vitamin A status deteriorated between 6 and 9 months.
- Vitamin A re-dosing significantly improved pupillary and visual thresholds compared to placebo.
Conclusions:
- Vitamin A status directly impacts pupillary and visual thresholds in children.
- Timely vitamin A supplementation can reverse vision impairment caused by deficiency.
- Scotopic sensitivity machines are effective tools for monitoring visual function in pediatric populations.
Abstract:
A prototype scotopic sensitivity machine was used to evaluate pupillary and visual thresholds for 295 Indonesian children aged 1-5 y, most of whom were initially vitamin A-deficient. Subjects were tested 6 and 9 mo after receiving a high dose of vitamin A. A group of 136 older children was tested at 6 mo after dosing; all subjects underwent testing at 9 mo. After testing at 9 mo, children randomly received either a second high dose of vitamin A or placebo and were tested a final time 2 wk later. Children with abnormal pupillary thresholds had significantly higher relative dose responses (RDRs) (P < 0.01) and significantly lower serum retinol values (P = 0.05) than did normal children. The mean pupillary threshold rose (eg, retinal sensitivity fell) as vitamin A status deteriorated between 6 and 9 mo after initial dosing, and was significantly different from a group of normal American children tested previously (P < 0.001). After placebo-controlled dosing, the decline in pupillary and visual thresholds (rise in retinal sensitivity) was significant for children receiving vitamin A but not for children receiving placebo.