Diagnosis of night blindness through standardized interview and electroretinography.

INTRODUCTION: Objective: To compare the diagnosis of NB through the use of the standardized interview of the World Health Organization/Pan American Health Organization (WHO/PAHO) with electroretinography, and also to evaluate the association of these diagnoses with serum concentrations of retinol in class III obesity individuals. Methods: Adult patients of both genders, in the 20-60 age group, with BMI ≥ 40 kg/m² were studied. NB was diagnosed through electroretinography and the standardized interview validated by the WHO/PAHO. Serum level of retinol was quantified by the HPLC-UV method, and VAD was diagnosed when levels were <1.05 µmol /L, and severity was also evaluated. Statistical analysis was carried out through the Statistical Package for the Social Sciences, version 21.0 (p < 0.05). Results: Mean BMI was 44.9  11.8 kg/m², and a negative correlation was found in serum levels of retinol (p= 0.01). The prevalence of VAD, according to the serum concentrations of retinol, was 14%, and of this percentage 23.3% had NB according to the standardized interview, and 22.0% according to electroretinography. NB diagnosed by both methods showed an association with VAD according to the serum concentrations of retinol. Of these individuals with NB, according to the standardized interview, 6.9% showed severe VAD, 10.3% moderate VAD and 82.8% marginal VAD. Conclusion: The standardized interview for the diagnosis of NB can be a good strategy to evaluate the nutritional status of vitamin A, and it is a simple, non-invasive and low-cost method.

INTRODUCCIÓN: Objetivo: Comparar el diagnóstico de NB mediante el uso de la entrevista estandarizada de la Organización Mundial de la Salud/Organización Panamericana de la Salud (OMS/OPS) con electrorretinografía, y también evaluar la asociación de estos diagnósticos con las concentraciones séricas de retinol en la clase III personas obesas. Métodos: se estudiaron pacientes adultos de ambos sexos, en el grupo de 20 a 60 años de edad, con un IMC ≥ 40 kg/m². La NB se diagnosticó mediante electrorretinografía y la entrevista estandarizada validada por la OMS/OPS. El nivel sérico de retinol se cuantificó mediante el método HPLC-UV, y el DVA se diagnosticó cuando los niveles eran <1.05 µmol / L, y también se evaluó la gravedad. El análisis estadístico se realizó a través del Paquete Estadístico para las Ciencias Sociales, versión 21.0 (p <0.05). Resultados: IMC promedio fue de 44.9 ± 11.8 kg / m², y se encontró una correlación negativa en los niveles séricos de retinol (p = 0.01). La prevalencia de DVA, según las concentraciones séricas de retinol, fue del 14%, y de este porcentaje, el 23,3% tenía NB de acuerdo con la entrevista estandarizada y el 22,0% según la electrorretinografía. La NB diagnosticada por ambos métodos mostró una asociación con VAD según las concentraciones séricas de retinol. De estos individuos con NB, según la entrevista estandarizada, el 6,9% mostró VAD grave, el 10,3% de VAD moderado y el 82,8% de VAD marginal. Conclusión: la entrevista estandarizada para el diagnóstico de NB puede ser una buena estrategia para evaluar el estado nutricional de la vitamina A, y es un método simple, no invasivo y de bajo costo.

Influence of Roux-en-Y Gastric Bypass on the Nutritional Status of Vitamin A in Pregnant Women: a Comparative Study.

OBJECTIVE: The objective of the present study is to evaluate the nutritional status of vitamin A through biochemical and functional indicators of pregnant women who underwent Roux-en-Y gastric bypass (RYGB) surgery compared to pregnant women who did not undergo this surgery. METHODS: The present study is a cross-sectional study of the analytical type with pregnant women paired by age and prepregnancy body mass index (BMI). Group 1 (G1) comprised 80 pregnant women without previous submission to RYGB and group 2 (G2) by 40 pregnant women who previously underwent this surgery. We used high-performance liquid chromatography with UV detector for quantification of retinol and ß-carotene, and the functional evaluation of vitamin A deficiency (VAD) was performed through standardized interview validated for pregnant women. RESULTS: G1 mean age was 29.3 ± 5.3 and 30.8 ± 4.4 in G2. BMI mean prepregnancy found in G1 was 25.7 ± 3.2 and 26.8 ± 3.1 in G2, featuring overweight. Serum retinol and ß-carotene means were significantly higher in G1 (1.8 ± 0.9; 87.4 ± 62.2) compared to G2 (0.99 ± 0.39; 22.7 ± 18.0), respectively (p < 0.001). Regarding the functional indicator for evaluation of VAD, approximately 75.0 % of pregnant women in G2 showed night blindness and 20.0 % in G1, and the percentage of pregnant women with this functional impairment was significantly higher in G2 compared to G1 with p < 0.001. CONCLUSION: Results show that pregnancy after RYGB can represent a high-risk situation for VAD. We recommend interdisciplinary monitoring added to the prenatal routine consultations and the conduction of studies addressed to the investigation of a safe and effective dose of oral supplementation of vitamin A to pregnant women undergoing RYGB.

Impact of different protocols of nutritional supplements on the status of vitamin A in class III obese patients after Roux-en-Y gastric bypass.

BACKGROUND: This study aims to investigate the nutritional status of vitamin A (VA) using biochemical and functional indicators in subjects with class III obesity, before and after RYGB, supplemented with three protocols. METHODS: The sample comprised 90 patients, with BMI ≥40 kg/m(2), divided into three groups: G1 that received routine supplementation containing 5,000 IU of retinol daily; G2 that received 10,000 IU of retinol daily; and G3 that received routine supplementation plus complementary of 50,000 IU of retinol intramuscularly every month. The status of VA was evaluated before (T0), 30 days (T1), and 180 days (T2) after surgery. RESULTS: The vitamin A deficiency (VAD) in G1, G2, and G3 was respectively 20.7, 21.2, and 20.2 % as regards retinol and 37.8, 63.3, and 40 % as regards ß-carotene in T0; 26.7, 10, and 23.4 % as regards retinol and 68, 37, and 32 % as regards ß-carotene in T1; and 21, 8.7, and 20.2 % as regards retinol and 63.3, 20, and 32 % as regards ß-carotene in T2. A reduction of retinol and ß-carotene with increasing BMI and waist circumference was observed in T0. The prevalence of night blindness (XN) in groups 1, 2, and 3 was respectively 23.3, 26.7, and 16.7 % in T0; 56.7, 40, and 60 % in T1; and 70, 43, and 63.3 % in T2. CONCLUSION: The study showed high prevalence of VAD. Among the supplementation protocols used, the one containing 10,000 IU of retinol showed the best impact. However, in cases of more severe VAD, intramuscular supplementation should be considered. The prevalence of XN, justifies attention to this segment of population.

Improvement in S-cone-mediated visual fields and rod function after correction of vitamin A deficiency.

PURPOSE: To evaluate S-cone-mediated visual fields and full-field electroretinograms (ERGs) in a patient with vitamin A deficiency. METHODS: A 65-year-old woman diagnosed with primary sclerosing cholangitis reported experiencing night blindness. The patient underwent comprehensive ophthalmic examination, including funduscopy, ERGs, Humphrey standard automated perimetry (SAP), and short-wavelength automated perimetry (SWAP). Serum vitamin A concentrations were measured. RESULTS: The patient's best-corrected visual acuity was 1.2 in both eyes. The ERG results showed no rod b-waves, reduced combined rod-plus-cone responses (negative type), and normal cone and 30-Hz flicker responses. Serum vitamin A concentration was 18 IU/dL (normal range 97-316 IU/dL). The SAP mean deviation (MD) values were -1.09 dB (OD) and -0.97 dB (OS), whereas the SWAP MD values were -10.10 dB (OD) and -10.50 dB (OS). The rate of sensitivity decreased with increasing eccentricity in SWAP. Four months after starting oral administration of vitamin A, all ERG values were normalized, and SWAP MD values were greatly improved (OD -3.47 dB, OS -4.10 dB) compared with changes in SAP MD values (OD +0.67 dB, OS +0.41 dB). Rod dysfunction and impaired S-cone-mediated pathways were preferentially observed and found to be reversed after the treatment. CONCLUSIONS: The findings in this patient suggest that rods and S cones are more susceptible to vitamin A deficiency than L and M cones. Vitamin A deficiency visual impairment may therefore be reversible with appropriate therapy.

Chromium and manganese levels in biological samples of normal and night blindness children of age groups (3-7) and (8-12) years.

This study was designed to compare the levels of chromium (Cr) and manganese (Mn) in scalp hair, blood, and urine of night blindness in children age ranged (3-7) and (8-12) years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure, was developed as a sample pretreatment, for the determination of Cr and Mn in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood and urine. The digests of all biological samples were analyzed for Cr and Mn by electrothermal atomic absorption spectrometry. The results indicated significantly higher levels of Cr, whilst low level of Mn in the biological samples (blood and scalp hair) of male and female night blindness children, compared with control subjects of both genders. These data present guidance to clinicians and other professional investigating deficiency of Mn and excessive level of Cr in biological samples (scalp hair and blood) of night blindness children.

Evaluation of status of cadmium, lead, and nickel levels in biological samples of normal and night blindness children of age groups 3-7 and 8-12 years.

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood trace metals toxicity, which is the most common problem found in underdeveloped countries. This study was designed to compare the levels of cadmium (Cd), lead (Pb), and nickel (Ni) in scalp hair, blood, and urine of night blindness children age ranged 3-7 and 8-12 years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of Cd, Pb, and Ni in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cd, Pb, and Ni by electrothermal atomic absorption spectrometry. The results indicated significantly higher levels of Cd, Pb, and Ni in the biological samples (blood, scalp hair, and urine) of male and female night blindness children, compared with control subjects of both genders. These data present guidance to clinicians and other professional investigating toxicity of trace metals in biological samples of night blindness children.

Prevalence of vitamin A deficiency and its determinants among the rural pre-school children of Madhya Pradesh, India.

BACKGROUND: Vitamin A deficiency (VAD) continues to be a major public health nutritional problem in India, even though the National Vitamin A Prophylaxis Programme has been in operation for more than three decades. AIM: To assess the prevalence of vitamin A deficiency among rural pre-school children. SUBJECTS AND METHODS: A community-based cross-sectional study was carried out in rural Madhya Pradesh. A total of 8777 pre-school children were clinically examined for VAD and blood vitamin A levels were estimated in a sub-sample by dried blood spot method. RESULTS: Prevalence of night blindness and Bitot's spot, an objective sign of VAD, was 0.8% and 1.4%, respectively, and prevalence increased significantly (p < 0.001) with age. The proportion of children with blood vitamin A deficiency ( < 20 µg/dL) was 88% (95% CI: 84.8-91.2).The prevalence of Bitot's spot was significantly (p < 0.001) higher among children of lower socio-economic communities, 3-5-year age group and those of illiterate mothers. CONCLUSIONS: VAD is a major public health problem among rural children of Madhya Pradesh. Children of 3-5 years and those belonging to lower socio-economic communities are at high risk of VAD. Therefore, appropriate intervention measures are to be initiated to improve the vitamin A status of children.

Evaluation of status of zinc, copper, and iron levels in biological samples of normal children and children with night blindness with age groups of 3-7 and 8-12 years.

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition. This study was designed to compare the levels of zinc (Zn), copper (Cu), and iron (Fe) in scalp hair, blood, and urine of both genders of children with night blindness with age range of 3-7 and 8-12 years, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of zinc, copper, and iron in biological samples of children with night blindness. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cu, Fe, and Zn by flame atomic absorption spectrometry using an air/acetylene flame. The results indicated significantly lower levels of Fe, Cu, and Zn in the biological samples (blood and scalp hair) of male and female children with night blindness, compared with control subjects of both genders. These data present guidance to clinicians and other professionals investigating the deficiency of essential trace metals in biological samples (scalp hair and blood) of children with night blindness.

Evaluation of essential trace and toxic elements in biological samples of normal and night blindness children of age groups 3-7 and 8-12 years.

The most common cause of blindness in developing countries is vitamin A deficiency. The World Health Organization estimates 13.8 million children to have some degree of visual loss related to vitamin A deficiency. The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence biological samples composition. Vitamin and mineral deficiency prevents more than two billion people from achieving their full intellectual and physical potential. This study was designed to compare the levels of Zn, Mg, Ca, K, Na, As, Cd, and Pb in scalp hair, blood, and urine of night blindness children age ranged 3-7 and 8-12 years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of As, Ca, Cd, K, Pb, Mg, Na, and Zn in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The concentrations of trace and toxic elements were measured by atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The results of this study showed that the mean values of As, Cd, Na, and Pb were significantly higher in scalp hair, blood, and urine samples of male and female night blindness children than in referents (p < 0.001), whereas the concentrations of Zn, Ca, K, and Mg were lower in the scalp hair and blood but higher in the urine samples of night blindness children. These data present guidance to clinicians and other professional investigating deficiency of essential mineral elements in biological samples (scalp hair and blood) of night blindness children.

Incidence of low vitamin A levels and ocular symptoms after Roux-en-Y gastric bypass.

BACKGROUND: Previous reports have demonstrated a significant incidence of fat-soluble vitamin deficiency after bariatric surgery. The purpose of the present study was to determine the incidence of vitamin A deficiency after Roux-en-Y gastric bypass and to correlate the laboratory findings with ocular symptoms potentially related to vitamin A deficiency. METHODS: All patients who had undergone Roux-en-Y gastric bypass were invited to participate in a nutritional screening. The patients completed a detailed survey concerning ocular symptoms and had their vitamin A level evaluated. RESULTS: A low vitamin A level was identified in 7 (11%) of 64 RYBG patients. Ocular xerosis was present in 18 patients (27%), with night vision changes reported in 45 (68%). Visual disturbances were present in 7 patients (11%) found to have low vitamin A levels, with hypovitaminosis A present in 22% of patients with xerosis (P <.05). CONCLUSION: Low vitamin A levels and frequent ocular complaints that might be associated with decreased vitamin A are common findings in the post-RYBG patient population. Additional study is needed to assess the role of routine vitamin A screening and replacement in the postbariatric surgery patient.

Magnitude and distribution of vitamin A deficiency in Ethiopia.

BACKGROUND: Several surveys conducted over a period of 40 years have shown that vitamin A deficiency is a serious public health problem in Ethiopia. To address the problem effectively, up-to-date, comprehensive information on the magnitude and distribution of vitamin A deficiency is needed. OBJECTIVE: A national vitamin A survey was conducted to assess the national and regional prevalence rates of vitamin A deficiency in Ethiopia. METHODS: The survey employed a multistage, cluster-sampling approach and a cross-sectional study design. A total of 23,148 children aged 6 to 71 months and their respective mothers were examined for clinical signs and symptoms, and blood samples were collected from 1200 systematically selected children for serum retinol analysis. RESULTS: The findings indicated national prevalence rates of 1.7% for Bitot's spots among children. 0.8% for night-blindness among children, and 1.8% for night-blindness among mothers. Nationally, 37.7% of children (95% CI, 35.6% to 39.9%) had deficient serum retinol levels, 50.7% had been sick in the previous 15 days, and 22.6% had received vitamin A supplements in the previous 6 months. The prevalence of clinical vitamin A deficiency was significantly (p < .05) higher among children who were male, older, or rural residents. CONCLUSIONS: The study confirmed that vitamin A deficiency is a serious public health problem in Ethiopia. Intensification of the ongoing vitamin A supplementation program, postpartum vitamin A supplementation for mothers, intensifying efforts to improve the health status of preschool age children, and promotion of production and consumption of fruits and vegetables are recommended.

Supplementation with iron and riboflavin enhances dark adaptation response to vitamin A-fortified rice in iron-deficient, pregnant, nightblind Nepali women.

BACKGROUND: Nightblindness affects 16-52% of pregnant women in areas of Nepal and in some cases persists after vitamin A treatment. Iron and riboflavin affect vitamin A utilization and photoreceptor function, respectively, and pilot data in the study population showed a high prevalence of iron and riboflavin deficiencies. OBJECTIVE: The objective was to assess the effect of supplemental iron and riboflavin on pupillary threshold (PT) and plasma retinol in nightblind, pregnant Nepali women given vitamin A-fortified rice. DESIGN: Nightblind pregnant women were randomly assigned to receive, 6 d/wk under supervision for 6 wk, a vitamin A-fortified rice curry dish providing 850 microg retinal activity equivalents/d with either a 30-mg Fe and 6-mg riboflavin (FeR + VA) capsule or a placebo control (VA only) capsule. Hemoglobin, erythrocyte riboflavin, and plasma ferritin and retinol were measured before and after the intervention. Dark adaptation was assessed by PT score. RESULTS: Women who were iron deficient at baseline (n=38) had significantly greater improvement in PT score with iron and riboflavin supplementation than without (P=0.05). Iron and riboflavin supplements significantly reduced the prevalences of riboflavin deficiency (from 60% to 6%; P<0.0001), iron deficiency anemia (from 35% to 15%; P<0.007), and abnormal PT (from 87% to 30%; P<0.05) from baseline. Mean increases in erythrocyte riboflavin (P<0.0001) and plasma ferritin (P=0.01) were greater in the FeR + VA group than in the VA only group. CONCLUSIONS: Iron deficiency may limit the efficacy of vitamin A to normalize dark adaptation in pregnant Nepali women. Further studies are needed to assess the effect of simultaneous delivery of iron and vitamin A for the treatment of nightblindness.

Improvement of scotopic electroretinograms and night blindness with recovery of serum zinc levels.

BACKGROUND: We sought to determine the cause of reduced scotopic and photopic electroretinograms (ERGs) and night blindness in a 46-year-old man with liver dysfunction but no history of alcoholism. CASE: A 46-year-old Japanese man with a complaint of visual difficulties in dim light for 1 month. OBSERVATIONS: By electrophysiological investigation, the patient was found to have low levels of serum zinc and vitamin A on admission. The rod b wave was unrecordable, and the bright-flash ERGs were reduced, with the a wave > b wave. The amplitudes of the cone and 30-Hz flicker responses were also reduced, and their implicit times were prolonged. Three weeks after admission, the patient's serum zinc level recovered to normal levels, but his serum vitamin A level was still low. The symptoms of night blindness were gone, and the rod ERGs and single bright-flash responses were within normal limits. However, the cone ERGs and 30-Hz flicker responses were still depressed. CONCLUSIONS: The recovery of scotopic function together with the recovery of zinc but not vitamin A levels suggests that the ERG changes were most likely related to low zinc levels.

Association between gestational night blindness and serum retinol in mother/newborn pairs in the city of Rio de Janeiro, Brazil.

OBJECTIVE: Gestational night blindness (XN) is associated with increased risk of reproductive morbidity and mortality. This study investigated the prevalence of gestational XN among postpartum women treated in a public maternity hospital in the city of Rio de Janeiro, Brazil and evaluated its association with maternal and neonatal (cord blood) serum retinol concentrations. METHODS: XN was evaluated retrospectively, using an interview according to guidelines of the World Health Organization, in 222 postpartum women (< or = 6 h after delivery) after singleton births who had low obstetric risk. Serum retinol concentrations were measured according to the modified Bessey method, with a cutoff point lower than 1.05 micromol/L for inadequate serum retinol concentration. RESULTS: Prevalence of gestational XN was 18%, and inadequate maternal and cord blood serum retinol concentrations were found in 24.4% and 45.5% of samples, respectively. The results associated gestational XN with inadequate maternal serum retinol concentration (P = 0.000), and an association was observed between maternal and neonatal serum retinol concentrations (P = 0.000). A poor association was observed between maternal XN and serum levels of retinol in newborn children (P = 0.06). CONCLUSIONS: The results suggest that prevalence of gestational XN and inadequate serum retinol concentration among postpartum women and newborns is a concern, calling attention to the need for studies in other parts of Brazil. In addition, the risk of inadequate serum retinol in newborns was significantly higher among infants of postpartum women with serum retinol levels below 1.05 micromol/L. Gestational XN was associated with inadequate levels of maternal serum retinol, and the results suggest a poor relation between maternal XN and vitamin A nutritional status of newborns.

The night vision threshold test is a better predictor of low serum vitamin A concentration than self-reported night blindness in pregnant urban Nepalese women.

This study was conducted to validate the night vision threshold test (NVTT) as an indicator of night blindness. A total of 1401 pregnant women from the National Maternity Hospital participated in this study. Women were queried about night blindness and took the NVTT using standardized procedures after 10 min of dark adaptation. Sixteen percent failed the NVTT, but only 6.4% reported having night blindness. Blood samples from women who failed the NVTT (cases) and matched controls indicated the serum vitamin A (SVA) concentration was lower (P < 0.05) in cases (1.19 +/- 0.03 micromol/L) than in controls (1.29 +/- 0.03 micromol/L). The SVA concentrations did not differ between women who reported and did not report night blindness. The SVA concentration was correlated (r = 0.22, P < 0.001) with the NVTT scores. Twenty-five percent of women with an SVA < 0.35 micromol/L reported night blindness while 100% failed the NVTT. Nineteen percent of women with an SVA < 0.70 micromol/L reported night blindness while 73% failed the NVTT. A receiver operating characteristics analysis indicated that the NVTT had greater sensitivity (0.73 vs. 0.19) and less specificity (0.51 vs. 0.87) compared with reported night blindness for women with SVA < 0.70 micromol/L and greater sensitivity (100.0 vs. 0.73) and similar specificity (0.51 vs. 0.50) for women with SVA < 0.35 micromol/L. The NVTT identified women with low SVA and self-reported night blindness was misleading. We provide a preliminary algorithm to predict the population of women with low SVA concentrations.

Validation of night blindness reports among children and women in a vitamin A deficient population in rural Tanzania.

OBJECTIVE: This study validates different definitions of reported night blindness (XN) in a vitamin A deficient African population with no local term for XN. DESIGN: Case-control study with follow-up after treatment. SETTING: Eight primary schools and health centres in rural Tanzania. SUBJECTS: A total of 1214 participants were screened for reported XN and other eye signs of xerophthalmia: 461 children aged 24-71 months, 562 primary school-age children and 191 pregnant or breast-feeding women. All 152 cases of reported XN were selected for the validation study and group matched with 321 controls who did not complain of XN. XN reports were validated against serum retinol concentrations and pupillary dark adaptation measurements in cases and controls. INTERVENTION: All children and women who reported XN or had other signs of active xerophthalmia were treated with vitamin A and followed up 3-4 weeks later. Half of the untreated control group who had their serum retinol examined in the baseline examination were also followed up. RESULTS: The overall prevalence of reported XN was 12.5%. At baseline, mean pupillary threshold (-1.52 vs -1.55 log cd/m(2), P=0.501) and median serum retinol concentrations (0.95 vs 0.93 micromol/l, P=0.734) were not significantly different in cases and controls either overall or in each population group. More restricted case definitions reduced the prevalence of reported XN to 5.5% (P<0.001), but there was still no significant difference between cases and controls although the results were in the expected direction. After treatment, the median serum retinol concentration improved significantly only in the most deficient group, the young children. Dark adaptation improved in all the subgroups but the difference was only significant for young children and primary school-age children when the restricted case definitions were used. CONCLUSIONS: XN reports are a poor indicator of vitamin A deficiency in this population. SPONSORSHIP: Task Force Sight and Life, Basel, Switzerland.

Current status of vitamin A deficiency and the National Vitamin A Control Program in Nepal: results of the 1998 National Micronutrient Status Survey.

The overall objective of the Nepal Micronutrient Status Survey (NMSS) was to assess the distribution and severity of micronutrient malnutrition, and to measure the progress achieved by different interventions. Data presented in this paper concern the prevalence of vitamin A deficiency (VAD) and the outreach and coverage of the National Vitamin A Supplementation activity. A multi-stage cluster sample design was employed that provided statistically representative data for each of thirteen eco-development strata (because of low population density, the West Mountains, Mid-west Mountains and Far-west Mountains were combined into a single stratum). The design allowed for aggregate estimates to be made at the national and ecological zone level. The survey showed a significant improvement in the status of clinical vitamin A deficiency in Nepal. The prevalence of both Bitot's spots and night-blindness among preschool children decreased from levels observed in surveys conducted in the previous twenty years. However, the prevalence of night-blindness was found to be 5% among women, and over 1% among school-aged children, which indicates that the entire population is vulnerable to VAD. These observations support findings from other surveys that have noted a high prevalence of maternal night-blindness in Nepal. Biochemical data collected as part of the survey indicated a high prevalence of low serum retinol (< 0.70 mumol/l), particularly among preschool children. Almost one of every three children (32.3%) and one of every six women (16.6%) had low serum retinol values. Low serum retinol among preschool children was associated with young age (6-11 months), rural location, wasting, presence of night-blindness and Bitot's spots, and residence in the Terai or Mountains. Similarly, sub-clinical VAD in women was associated with age (less than 20 years), pregnancy, the presence of night-blindness and residence in the Terai or Mountains. In the 42 districts covered by the National Vitamin A Programme (NVAP), more than 87% of preschool children were reached with vitamin A capsules. In addition to this, the National Immunisation Day (NID) provided oral polio vaccine drops to an estimated 95.7% of children 12-59 months. Awareness of the importance of vitamin A was, however, much higher in the NVAP districts than in non-programme districts. As would be expected, clinical VAD was most prevalent among children who had not received vitamin A during the most recent vitamin A capsule distribution. Indeed, the data show that vitamin A capsule receipt among children conferred a 59% protective effect for night-blindness and a 51% effect for Bitot's spots. These results point to significant progress having been achieved by the NVAP and NID capsule distribution activities.