Conjunctival impression cytology for assessment of vitamin A status

Prevalence of vitamin A deficiency and dietary inadequacy in Indian school-age children and adolescents

PURPOSE

There are no representative estimates of vitamin A deficiency (VAD) and risk of vitamin A (VA) dietary inadequacy in Indian children and adolescents. To evaluate, from national surveys, the prevalence of VAD measured by serum retinol concentrations (< 0.7 µmol/L or < 20 µg/dL), and the risk of VA dietary inadequacy and excess intake beyond the tolerable upper limit (TUL).

METHODS

National and state-level VAD prevalence adjusted for inflammation was estimated in school-age children (5-9 years: 10,298) and adolescents (10-19 years: 9824) from the Comprehensive National Nutrition Survey (CNNS 2016-18). The risk of dietary inadequacy against age-specific average VA requirements, and excess intake against the TUL, was assessed from the National Sample Survey Office (NSSO 2014) data.

RESULTS

Serum retinol concentrations increased with age (5-19 years) in both genders and were significantly lower in school-age children (1.02 µmol/L, CI: 1.01-1.03) compared to adolescents (1.13 µmol/L, CI 1.12-1.15). The inflammation-adjusted prevalence of VAD in school-age children and adolescents was 19.3% (CI 18.8-19.9) and 14.4% (CI 13.9-14.9) respectively, and this was > 20% in seven and four states for children and adolescents, respectively. The prevalence of VAD was significantly higher among children with lower socio-economic status. The risk of dietary VA inadequacy, from the NSSO survey, was 69 and 78% in children and adolescents, respectively. This risk reduced to 6 and 17% with VA fortified oil and milk intake, while the proportion of intakes exceeding the TUL became 6 and 0.5% in children and adolescents, respectively.

CONCLUSIONS

The national prevalence of VAD in school-age children and adolescents in India was just less than 20%. The risk of dietary VA deficiency is likely to decline substantially with VA fortified food intake, but a risk of excessive intake also begins to appear; therefore, a careful assessment of the risk of hypervitaminosis A is required at these ages.

Which blood cutoff value should be used for vitamin A deficiency in children aged 3-10 years? A systematic review

CONTEXT

Blood cutoff values for vitamin A deficiency in children aged 3-10 years have not been addressed in the literature.

OBJECTIVE

To identify blood retinol concentrations for determining severe vitamin A deficiency in children aged 3-10 years.

DATA SOURCES

The MEDLINE, Web of Science, Embase, and Scopus databases were searched.

DATA EXTRACTION

Two reviewers independently extracted article data and assessed quality.

DATA ANALYSIS

The hierarchical summary receiver operating characteristic models were applied for the diagnostic accuracy meta-analysis. This review is registered at PROSPERO (identifier: CRD42020149367).

RESULTS

A total of 15 articles met the eligibility criteria, and 9 were included in the diagnostic accuracy meta-analysis. The summary estimates (95%CI) were: Sensitivity, 0.39 (0.20-0.62); specificity, 0.79 (0.65-0.88); positive likelihood ratio, 1.85 (1.33-2.57); and negative likelihood ratio, 0.77 (0.60-0.99). The area under the curve of the overall analysis was 0.68 (95%CI 0.63-0.72).

CONCLUSIONS

Blood retinol concentrations have low diagnostic accuracy for severe vitamin A deficiency in children aged 3-10 years. Therefore, there is unclear evidence about the preferable cutoff point for determining severe vitamin A deficiency in children in this age group.

Factors associated with childhood ocular morbidity and blindness in three ecological regions of Nepal: Nepal pediatric ocular disease study

Background

Nepal Pediatric Ocular Diseases Study is a three year longitudinal population based study. Here we present the baseline survey report which aims to investigate various risk factors associated with childhood ocular morbidity and blindness in three ecological regions of Nepal.

Method

This baseline survey is a population based cross sectional study. The investigation was conducted in a district from each of the following regions: Terai, Hill and Mountain. The Village Development Committees (VDCs) from each district were selected by random sampling. Three Community health workers were given training on vision screening and identification of abnormal ocular signs in children. They conducted a house to house survey in their respected districts examining the children and gathering a standardized set of data variables. Children with abnormal vision or ocular signs were then further examined by pediatric ophthalmologists.

Results

A total of 10950 children aged 0–10 years (5403 from Terai, 3204 from the hills, 2343 from the mountains) were enrolled in the study. However 681 (6.2%) were non responders. The male to female ratio was 1.03. The overall prevalence of ocular morbidity was 3.7% (95% CI of 3.4%-4%) and blindness was 0.07% (95% CI of 0.02%-0.12%). Ocular morbidity was more prevalent in the mountain region whereas blindness was more prevalent in the Terai region.

Children from the Terai region were more likely to suffer from congenital ocular anomalies compared to the other regions. Children whose mother smoked, drank alcohol, or was illiterate were significantly afflicted with ocular diseases (p < 0.05). In addition,a higher prevalence of ocular disease was related to children with past medical history of systemic illnesses, abnormal postnatal period or missing childhood vaccinations. Blindness was more prevalent in children who suffered from a systemic illness. Females and under-nourished children were more likely to have ocular morbidity and blindness.

Conclusion

It was found that childhood blindness was more prevalent in the Terai region, the undernourished, females and in those with co-morbid systemic illnesses. This study strongly suggests that prevention of childhood blindness requires additional resources to address these disparity.

Vitamin a status in children with diarrhoea

Vitamin A status was measured in 50 pre-school children with acute and persistent diarrhoea. It was measured by (a) Fluorometric micromethod and (b) Conjunctival impression cytology (CIC). The results were compared with 25 normal children. Vitamin A status was lower in children with persistent diarrhoea whereas the results were comparable between the children with acute diarrhoea and control subjects.

Changes in the tear film and ocular surface after cataract surgery

PURPOSE

To evaluate changes in corneal sensitivity, tear film function, and ocular surface stability in patients after cataract surgery.

METHODS

This hospital-based prospective randomized trial included 48 eyes from 30 patients who underwent phacoemulsification. Slit-lamp examination, Schirmer test 1 (ST1), and measurement of corneal sensitivity and tear film breakup time (BUT) were performed for all patients 1 day before and 1 day, 1 month, and 3 months after surgery. In addition, conjunctival impression cytology from the temporal region of the conjunctiva was simultaneously performed.

RESULTS

Corneal sensitivity at the center and temporal incision sites had decreased significantly at 1 day postoperatively (P = .021, P < .001). However, the sensitivity had returned to almost the preoperative level 1 month postoperatively. The mean postoperative ST1 results were no different from preoperative values. On the other hand, BUT results had decreased significantly at 1 day postoperatively (P = .01) but had returned to almost the preoperative level 1 month postoperatively. Mean goblet cell density (GCD) had decreased significantly at 1 day, 1 month, and 3 months postoperatively (P < .001). In addition, decrease in GCD and cataract operative time were highly correlated (r² = 0.65).

CONCLUSIONS

The decrease in GCD, which was correlated with operative time, had not recovered at 3 months after cataract surgery. Therefore, microscopic ocular surface damage during cataract surgery seems to be one of the pathogenic factors that cause ocular discomfort and dry eye syndrome after cataract surgery.

Vitamin A status of pregnant women in Calabar metropolis, Nigeria

The vitamin A status of 101 pregnant women attending clinic at the University of Calabar Teaching Hospital (UCTH), Calabar, Nigeria was assessed based on 24 h dietary recall, serum retinol concentration, history of night blindness, physical appearance and clinical eye signs. The study revealed that the mean dietary vitamin A intake of the respondents (2645.31 +/- 188.91 microg RE) and their mean serum retinol concentration (31.18 +/- 2.94 microg dL(-1)) were significantly (p < 0.05) higher than the FAO/WHO recommended intake and cutoff level for VAD. No case of night blindness, physical signs and symptoms, or clinical eye signs attributable to VAD was observed. There was a significant (p < 0.01) correlation between the amount of 24 h vitamin A intake of the women and their serum retinol concentration (r = 0.31). Also, women who had above 50% of their vitamin A intake from provitamin A sources had a significantly (p < 0.05) lower serum retinol concentration (23.10 +/- 21.12 microg dL(-1)) than those who had above 50% intake from preformed sources (49.54 +/- 42.63 microg dL(-1)) and those with about equal intake from both sources (55.75 +/- 30.80 microg dL(-1)). There was a significant (p < 0.05) and steady decline in serum retinol concentration in the women from the first trimester (37.79 +/- 6.65 microg dL(-1)), through the second trimester (35.12 +/- 4.72 microg dL(-1)), to the third trimester (21.54 +/- 1.46 microg dL(-1)) of pregnancy.

Investigation of dry eye disease and analysis of the pathogenic factors in patients after cataract surgery

PURPOSE

To study dry eye and analyze pathogenic factors in patients after cataract surgery.

METHODS

A total of 37 patients (50 eyes) were studied by using a 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ25) and Ocular Surface Disease Index (OSDI) 3 days before and 1 week, 1 month, and 3 months after cataract surgery. Slit-lamp microscope examination, cornea and conjunctiva fluorescein staining, tear breakup time (BUT), Schirmer test I (STI), and impression cytology (IC) were carried out at the same time. Cytologic specimens for IC were obtained from the upper lid-covered region, explosive region, and lower lid-covered region of the globe conjunctiva. The average density of goblet cells on these 3 regions was measured, and the pathogenic factors of dry eye after cataract surgery were analyzed.

RESULTS

After cataract surgery, the incidence of dry eye increased dramatically; NEI-VFQ25 and OSDI indicated that most patients developed this symptom after surgery. The lacrimal river line became narrow, and BUT and STI decreased in patients after cataract surgery. IC suggested the presence of serious squamous metaplasia in the epithelial layer of the globe conjunctiva, especially the lower lid region.

CONCLUSIONS

Dry eye can develop or deteriorate after cataract surgery if not treated in time. Misuse of eyedrops is one of the major pathogenic factors that causes dry eye after cataract surgery. Eyedrops should be carefully administered before and after cataract surgery to avoid or reduce the occurrence of dry eye postoperatively.

Conjunctival epithelial changes induced by cilia in patients with epiblepharon or entropion

PURPOSE

To evaluate the effect of mechanical trauma induced by cilia on the conjunctival epithelium in patients with epiblepharon or entropion and to evaluate changes in epithelium after surgical correction in patients with entropion.

DESIGN

Case-control study.

METHODS

One hundred and seven eyes of 61 patients were enrolled in this study and were divided into three groups: the epiblepharon group (n = 59), the entropion group (n = 17), and the age-matched control group for the epiblepharon group (n = 31). Impression cytologic specimens were obtained from nasal and temporal bulbar conjunctiva of the epiblepharon and control groups immediately after the induction of general anesthesia. In the entropion group, these were obtained before and one month after surgical correction. Conjunctival changes were graded using the Tseng method and goblet cell densities were compared.

RESULTS

Cytologic scores were significantly higher in the epiblepharon group than in the control group (P < .001), and goblet cell densities of nasal and temporal conjunctiva were significantly lower in the epiblepharon group than in the control group (P = .044 and P = .018, respectively). In the entropion group, postoperative scores were significantly lower than preoperative scores in both conjunctival areas (P = .033 and P = .003, respectively). No statistically significant difference was found between nasal and temporal conjunctiva in the three groups.

CONCLUSIONS

The persistent mechanical trauma by cilia in patients with epiblepharon or entropion can induce squamous metaplasia of the conjunctival epithelium. However, these conjunctival changes can be reversed by surgical correction.

Vitamin A deficiency and xerophthalmia among school-aged children in Southeastern Asia

OBJECTIVE

To determine provisional estimates of the extent of vitamin A (VA) deficiency and xerophthalmia among school-aged children.

DESIGN

Literature search of published, unpublished and website-based population survey and study reports, with country-specific imputation of prevalence rates and numbers of children affected by: (1) VA deficiency based on measured or imputed distributions of serum retinol concentration < 0.70 micromol/l (equivalent to < 20 microg/dl) and (2) xerophthalmia, by country.

SETTING

Countries within the WHO South-East Asian Region.

SUBJECTS

The target group for estimation was children 5-15 y of age.

INTERVENTIONS

None.

RESULTS

The estimated prevalence of VA deficiency is 23.4%, suggesting that there are approximately 83 million VA-deficient school-aged children in the region, of whom 10.9% (9 million, at an overall prevalence of 2.6%) have mild xerophthalmia (night blindness or Bitot's spot). Potentially blinding corneal xerophthalmia appears to be negligible at this age.

CONCLUSIONS

VA deficiency, including mild xerophthalmia, appears to affect large numbers of school-aged children in South-East Asia. However, nationally representative data on the prevalence, risk factors and health consequences of VA deficiency among school-aged children are lacking within the region and globally, representing a future public health research priority.

Ocular surface impression cytology

Impression cytology, either using cellulose acetate strips or the Biopore membrane device, is a simple, noninvasive technique that aids in the diagnosis of several disorders of the ocular surface. These disorders include ocular surface squamous neoplasia, dry eye syndrome, limbal stem-cell deficiency, specific viral infections, vitamin A deficiency, allergic disorders, conjunctival melanosis, and malignant melanoma. Another advantage is the preservation of limbal stem cells, which occur in the basal layer of the limbal epithelium and are responsible for renewal of the corneal epithelium. The Biopore membrane device is particularly user friendly, with little expertise required and adequate specimens obtained in a very high percentage of cases. The most common applications in diagnostic ocular pathology are:(i) primary diagnosis and follow-up of ocular surface squamous neoplasia, including after therapy with topical mitomycin C. The sensitivity is high (78-87%); and (ii) dry eye syndrome where squamous metaplasia and/ or hyperkeratosis are noted. Certain limitations of the technique for diagnosis of squamous neoplasia include the fact that dysplasias are often keratinizing and may yield very few or even no dysplastic cells with impression cytology. Secondly, no definite cytologic criteria reliably distinguish invasive SCC of ocular surface from in situ disease. Other applications include the rapid specific diagnosis of ocular surface infections with herpes simplex, adeno-, and varicella zoster viruses. Impression cytology samples may also be used to obtain mRNA, cells for phenotyping by flow cytometry, and proteins for Western blotting for research studies.

Helicobacter pylori infection and micronutrient deficiencies

It is known that deficiencies of micronutrients due to infections increase morbidity and mortality. This phenomenon depicts itself conspicuously in developing countries. Deficiencies of iron, vitamins A, E, C, B12, etc are widely prevalent among populations living in the third world countries. Helicobacter pylori (H pylori) infection has a high prevalence throughout the world. Deficiencies of several micronutrients due to H pylori infection may be concomitantly present and vary from subtle sub-clinical states to severe clinical disorders. These essential trace elements/micronutrients are involved in host defense mechanisms, maintaining epithelial cell integrity, glycoprotein synthesis, transport mechanisms, myocardial contractility, brain development, cholesterol and glucose metabolism. In this paper H pylori infection in associaed with various micronutrients deficiencies is briefly reviewed.

Extent of vitamin A deficiency among preschool children and women of reproductive age

Knowledge of the extent of vitamin A (VA) deficiency (D) is critical for identifying high-risk populations and mobilizing resources for prevention. Yet, all estimates are necessarily imperfect, often based on assumptions in the absence of data. In 1995, the World Health Organization estimated 254 million children to be VA-deficient and 2.8 million to have xerophthalmia. Subsequently, estimates were changed to 75-140 million and 3.3 million, respectively. Although both sets are consistent with a problem of enormous magnitude, the discrepancies also created uncertainty. The present analysis indicates there are approximately 127 million and 4.4 million preschool children with VAD (serum retinol < 0.70 micro mol/L or displaying abnormal impression cytology) and xerophthalmia, respectively. More than 7.2 million pregnant women in the developing world are VA-deficient (serum or breast-milk vitamin A concentrations < 0.70 micro mol/L), and another 13.5 million have low VA status (0.70-1.05 micro mol/L); >6 million women develop night blindness (XN) during pregnancy annually. Roughly 45% of VA-deficient and xerophthalmic children and pregnant women with low-to-deficient VA status live in South and Southeast Asia. These regions harbor >60% of all cases of maternal XN, three fourths of whom seem to live in India. Africa accounts for 25-35% of the global cases of child and maternal VAD; about 10% of all deficient persons live in the eastern Mediterranean region, 5-15% live in the Western Pacific and approximately 5% live in the Region of the Americas. VA prophylaxis seems to be preventing the number of deficient preschool children from increasing while probably reducing rates of blindness and mortality. Greater effort is needed to assess and prevent VAD and its disorders, particularly among pregnant and lactating women.

Physiologic indicators of vitamin A status

Physiologic indicators reflect the functional consequences of vitamin A deficiency and may be particularly useful for detecting early perturbations in vitamin A status. In conjunctival impression cytology (CIC), epithelial morphology and the presence or absence of mucin spots and goblet cells allow samples, obtained by applying filter paper to the temporal conjunctiva, to be characterized as normal or typical of vitamin A-deficient keratinizing metaplasia. The validity of CIC has been established with reference to other indicators of vitamin A status, and a prevalence of > or =20% abnormal results has been suggested as indicative of a public health problem. However, interpretation of specimens requires considerable training, and nonresponsiveness to supplementation is a frequent problem, which limits the utility of CIC as a method for evaluating the impact of intervention programs. Several simplified field protocols for dark adaptation have been developed, including one in which dark adaptation is assessed by the responsiveness of the pupil to light. Night blind subjects have consistently shown abnormal results on this test, and a significant response to placebo-controlled dosing has been demonstrated for children and pregnant women. Scores have correlated significantly with serum retinol and relative dose response. Pupillary dark adaptation testing is acceptable to most children as young as 2 y old. Limitations of this technique include a time course for recovery after dosing as long as 4-6 wk, a testing time of 20 min, and the need for 1-3 d of training. Given its low cost, noninvasive nature, and lack of the need to transport samples, pupillary dark adaptation offers advantages over other techniques for assessing a population's vitamin A status.

Immunobiology of mild micronutrient deficiencies

Nutrition is a critical determinant of the outcome of host microbe interactions through a modulation of the immune response. Besides macronutrient malnutrition, deficiencies of several macronutrients also influence immune homeostasis and thus affect infection-related morbidity and mortality. Deficiencies of micronutrients like vitamin A, iron and zinc are widely prevalent among populations living in developing countries. Besides their severe deficiencies, subclinical deficiencies are known to impair biological functions in the host, immune function being one of them. The effects of these micronutrients on various immune mechanisms are briefly reviewed in this article.

The effect of vitamin A on epithelial integrity

Vitamin A is the generic term for a variety of fat-soluble substances including retinol, retinyl palmitate and the provitamin A carotenoids such as all-trans-beta-carotene. Vitamin A is commonly known as the anti-infective vitamin and has an essential role in vision and cellular differentiation, the latter providing a unique core mechanism helping to explain the influence of vitamin A on epithelial barriers. Alterations in the epithelial lining of vital organs occur early in deficiency, suggesting a potentially important role for the barrier function. Vitamin A deficiency (VAD) is most commonly recognized in the eye. The conjunctival-impression cytology test detects the presence of larger irregular keratinized cells and the absence of mucous-secreting goblet cells, indicative of VAD. The method is simple, quick and sensitive in populations where VAD is present. In the respiratory tract, observational studies all show an association with VAD, although vitamin A supplementation studies appear to have little effect on respiratory disease. Organ-specific targeting may improve success rates. The dual-sugar intestinal-permeability test allows the effect of vitamin A supplementation to be monitored on the gastrointestinal tract. Two vitamin A supplementation studies were carried out recently in Orissa State, India. Healthy infants of weaning age were administered orally eight weekly doses of 5.0 mg retinol equivalents and hospitalized infants received one large oral dose 60 mg retinol equivalents in the form of retinyl palmitate. Improvements in gut integrity and haematological status were observed in both studies. In summary, the response of the eye to vitamin A supplementation is well established; the present review highlights some of the more recent observations examining the effects of vitamin A.

Conjunctival impression cytology with transfer (CICT) to detect pre-clinical vitamin A deficiency among slum children in India

In order to establish a method usable in the field for diagnosis of pre-clinical vitamin A deficiency, conjunctival impression cytology with transfer (CICT) was used in 200 normal slum children aged 6-120 months in Chandigarh, India. Conjunctival impressions taken on cellulose acetate paper were transferred to glass slides which were fixed in ethanol and stained with alcian blue and carbol fuchsin. Sixty samples of cellulose acetate paper were preserved after transfer of impression and were stained later. Transfer was complete in forty-eight samples and in the other twelve it was incomplete. Conjunctival impressions on paper and slide of these twelve cases were comparable. At a plasma retinol concentration of < 0.70 mumol/l measured by HPLC the sensitivity, specificity and positive predictive values of CICT were 90.59%, 100% and 100% respectively. Compared with conventional conjunctival impression cytology, CICT is less time consuming, cheaper and comparable in validity. It is thus more suitable than the conventional method for mass screening.

A randomised controlled trial to test equivalence between retinyl palmitate and beta carotene for vitamin A deficiency

OBJECTIVES

To determine whether beta carotene is therapeutically equivalent to retinyl palmitate in the formulation currently recommended by the World Health Organisation.

DESIGN

Randomised blind equivalence trial.

SETTING

Rural area in Senegal.

SUBJECTS

Children aged 2-15 years suffering from vitamin A deficiency as defined by abnormal results on eye cytology were randomly allocated treatment with retinyl palmitate (n = 256) and beta carotene (n = 254).

MAIN OUTCOME MEASURE

Reversion to normal results on eye cytology as defined by the reappearance of goblet cells and normalisation of the epithelial cells.

RESULTS

Seven weeks after the supplement was given the percentages were 51.2% (124/242) children taking retinyl palmitate and 50.0% (123/246) of those taking beta carotene, who had reverted to normal eye cytology, a difference of 1.2% (95% confidence interval 6.2% to 8.6%) [corrected]. According to an equivalence testing procedure, the two treatments were statistically equivalent; the null hypothesis of non-equivalence was rejected (one tailed p value = 0.03).

CONCLUSIONS

beta Carotene supplementation seems to be a promising candidate for the alleviation of vitamin A deficiency. It could be given either as high dose capsule or through increased dietary intake. The challenge now is to improve dietary intake of vitamin A in programmes that are effective and sustainable at the community level.

Efficacy of massive oral doses of retinyl palmitate and mango (Mangifera indica L.) consumption to correct an existing vitamin A deficiency in Senegalese children

Administration of large oral doses of retinyl palmitate has become the most widely practised vitamin A deficiency prevention strategy in developing countries. We conducted a follow-up study among 220 Senegalese children aged 2-7 years suffering from moderate undernutrition to determine the efficacy of vitamin A treatment on their vitamin A status assessed by biochemical and cytological (impression cytology with transfer) methods. The first examination (T = 0 m[onth]) was carried out during April 1989, before the mango (Mangifera indica L,) harvest. The second examination (T = 2 m) was carried out 2 months after vitamin A treatment during June 1989 when ripe mangoes become widely available. Conjunctival cells of the eyes of the children with or without ocular inflammation were responsive to vitamin A administration (P < 0.01). There was a significant increase (P < 0.001) in mean serum retinol and beta-carotene levels between T = 0 m and T = 2 m. Mean serum retinol-binding protein (RBP) and transthyretin (TTR) levels did not differ significantly (P > 0.05) at T = 0 m and T = 2 m. Despite the intake of vitamin A, 54% of the children who had abnormal cytology at T = 0 m remained abnormal at T = 2 m. This was due to inadequate levels of TTR and RBP, presumably due to the cereal diet eaten by the Senegalese population. children with abnormal eye cytology had lower serum retinol levels than those with normal eyes at T = 0 m, and beta-carotene values did not correlate with eye cytological abnormalities at T = 0 m. Children with normal cytology had higher serum retinol and also beta-carotene levels than those with abnormal cytology after massive oral doses of vitamin A and consumption of mangoes at T = 2 m. Retinyl palmitate may, therefore, only lead to partial cytological improvement due to a lack of retinol-carrier proteins but dietary beta-carotene may also be involved.

Carotenoids and retinoids in human nutrition

Since the discovery of vitamin A as a fat-soluble growth factor in the early part of the century, research into carotenoids and retinoids has attracted the attention of many scientists. These two groups of compounds are still being actively studied all over the world since many gaps in knowledge exist and new frontiers are being pursued. Recent developments in studies into the possible roles of carotenoids and retinoids beyond their classical functions in vision have created a great deal of excitement in the biomedical community. This review covers a wide range of topics pertaining to these two closely related compounds. Particular emphasis is given to the functions of these compounds and their roles in human nutrition. Various aspects of vitamin A deficiency and studies on carotenoids and retinoids in cancer development and prevention are reviewed in some detail.