Active clinical trials for "Night Blindness"

The primary purpose of this study is to determine whether daily consumption of orange-fleshed sweet potatoes increases the vitamin A status of Bangladeshi women of reproductive age. Secondary purposes of the study are to determine whether consumption of orange-fleshed sweet potatoes has an effect on the intestinal absorption of dietary iron or dietary zinc in Bangladeshi women of reproductive age.

Iron, zinc and vitamin A deficiencies are particularly common among children and young women in the developing countries of South and Southeast Asia resulting in important adverse health effects. Simultaneous fortification of rice with iron, zinc and vitamin A could be a novel and sustainable approach to control these deficiencies. Recently conducted extrusion trials have demonstrated that extruded rice grains containing iron, zinc and vitamin A show acceptable stability during production and storage and good sensory properties. The grains were produced using a twin-screw extruder equipped with a special cutter and a rice shaping die. The Fe, Zn and vitamin A content of the extruded product is 10 mg, 9 mg and 1050 μg per g of rice, respectively. In this study the investigators plan to test the efficacy of the extruded triple fortified rice in Satun, Thailand, an area where rice is the staple food. Preliminary data from this area show that zinc and vitamin A intakes are low. Biochemical indicators have confirmed zinc deficiency and suboptimal vitamin A status in 1/3 of school aged children. The efficacy of the fortified rice will be evaluated in a 9 months, controlled, double-blind intervention trial in 7-12 y-old children. Children will be selected from primary schools in Satun Province based on low serum zinc values as the primary goal is to investigate Zn efficacy. As secondary outcome the effect on iron and vitamin A status will be investigated. The children will be randomized into two groups: a control group will receive a daily non-fortified rice lunch meal at school, while the second group will receive a daily rice meal containing the triple fortified rice. The rice meals will be given 5 days a week. At baseline, weight and height will be measured and determination of hemoglobin, serum ferritin, zinc protoporphyrin, serum zinc, serum retinol and C-reactive protein will be done. At mid-point and at 9 months, the baseline measurements will be repeated to judge the efficacy of the triple fortified rice.

To assess the effect of oral administration of the alga Dunaliella bardawil containing approximately 50% all-trans beta-carotene and 50% 9-cis beta-carotene isomers on visual functions patients with Congenital Stationary Night Blindness {Fundus albipunctatus).

Breast milk is the best food during the first 6mo of life because it offers multiple benefits for the mother-infant pair. An inadequate maternal diet during pregnancy can lead to excess weight gain, leading to negative health consequences for the dyad. In Mexico, an excess of body weight coexists with micronutrient deficiencies (double burden of malnutrition). Low vitamin A concentration has been observed in northwest Mexico, which can affect the human milk composition and increase the risk of VAD in breastfed babies. An individualized dietary intervention in the lactating woman will reduce body weight and improve vitamin A status. The objective is to assess the effect of an individualized dietary intervention during 3 months postpartum on body composition and vitamin A status of lactating women.

This is a study to evaluate the effects of vitamin A supplementation program on the vitamin A status of preschool children. All children aged 3-5 years who do not have severe illness and are not planning to move from the study area are eligible. Children whose caregivers agree to sign the consent form will be enrolled in their community and submitted to a longitudinal evaluation of vitamin A status before and after vitamin A supplementation campaign. Vitamin A status will be assessed by measuring serum retinol, retinol binding protein and vitamin A total body pool size using stable isotope dilution methodology.

The study comprises an open-label randomized controlled trial investigating the efficacy of consuming a daily ration of pro-vitamin A biofortified cassava on vitamin A status of Nigerian children, aged 3-4 years old (n=200).

For assessing body retinol pools in preschool children, it is recommended that a blood sample is taken 14-21 days after isotope dosing. During this period, dietary intake of vitamin A should be controlled. Shortening of this period as has been validated for adults would reduce the burden for the children as well as improve research efficiency. The aim is to validate a 4-day protocol for assessing body retinol pools in preschool children by modelling data derived by retinol isotope dilution (RID) method. Venous blood samples will be collected of 60 children 4 days after dosing of 0.4 mg 13C-labeled retinyl acetate. A second venous blood sample will be collected at 6, 8, 12 hrs; and 1, 2, 4, 7, 11, 16, 22 and 28 days after dosing in subgroups of 6 children, randomly divided over the 10 additional time points. Body retinol pools will be modelled, and the time point at which a parsimonious model applies (presumably at day 4) will be assessed.

This pilot study will evaluate the visual response to infrared (IR) in humans after dark adaptation. The investigators plan to determine which wavelength and intensity the human eye is most sensitive too, using a broad spectrum light source and wavelength-specific bandpass filters. The investigators will then evaluate the electrophysiologic response in healthy humans to IR, followed by studies in those with specific retinal diseases. The long-term goal of this research is to better understand the role that IR plays in visual function, and whether this can be manipulated to allow for vision in certain retinal pathologies that result from loss of photoreceptor cells. The investigators central objective is to test the electrophysiologic response to IR in the dark-adapted retinal and visual pathways. The investigators central hypothesis is that IR evokes a visual response in humans after dark adaptation, and the characteristics of this response suggest transient receptor potential (TRP) channel involvement. The investigators rationale is that a better understanding of how IR impacts vision may allow for an alternative mechanism for vision in a number of diseases that cause blindness from the degradation or loss of function of photoreceptor cells. The investigators will test the investigators hypothesis with the following Aims: Aim 1: To determine the optimal IR wavelength for visual perception in dark-adapted human participants. The investigators hypothesize that the healthy human eye will detect IR irradiation, with a maximum sensitivity at a specific wavelength. Using a broad-spectrum light source with wavelength-specific bandpass filters, the spectral range of visual perception to IR will be evaluated. The same will be done on colorblind participants. Aim 2: To test the electrophysiologic response to IR in healthy humans after dark adaptation. The investigators hypothesize that IR will elicit an amplitude change on electroretinography (ERG) and visual evoked potential (VEP) responses after dark adaptation in healthy human participants. Participants will be tested with both test modalities to evaluate their response to IR. Aim 3: To test the electrophysiologic response to IR after dark adaptation in humans with certain retinal diseases. Participants with retinitis pigmentosa, age related macular degeneration and congenital stationary night blindness, will be tested. Results will be compared to baselines and to those of healthy participants. The investigators hypothesize that there will be a response to IR on ERG and VEP, which will provide clues to the retinal cell layer location of the response to IR and the nature of potential TRP channel involvement.

The overall aim of the project is to provide proof-of-principle that biofortification of cassava with vitamin A is a viable strategy to improve vitamin A status of deficient populations.

The purpose of this cluster-randomized trial is to examine whether daily consumption of β-carotene biofortified maize flour can reduce the prevalence of vitamin A deficiency and improve the vitamin A status and among 4-8 year old children in rural Zambia.