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ACKNOWLEDGEMENT

Our thanks are due to our College Medical Officer, Dr. C. Christudoss. But for his assistance and enthusiasm, the survey, in its present form would not have taken place. He brought patients to the class-room and trained our student-investigators as to how to recognize Bitot's spot in children. Messrs S. Govindaraju and M. Chandrasekaran assisted in training the investigators and in organizing the survey. Messrs R. Chandrasekaran, and R. Srinivasan were in charge of processing the data using an IBM 370/155 computer. Our thanks are due to all the student-investigators who collected the data from all over Tamil Nadu and helped in the processing of data.

SUMMARY

Five percent of the children of Tamil Nadu in the 3-7 age group suffer from trachoma. The incidence is clearly higher than the average in the districts of Dharmapuri, South Arcot and Ramnad. Children with night blindness have a greater chance of being attacked by trachoma than normal children. Boys are attacked more often by trachoma than girls. There is no significant difference in the incidence of trachoma between those who had had measles and those who had not. However among the children who had suffered from either jaundice, or chicken pox, or mumps or whooping cough, the incidence of trachoma is significantly higher compared to those who had not suffered from such diseases. There is not very much difference in the incidence of the disease between the rich and the poor, between the educated and the uneducated. Trachoma strikes them all.

Sixteen percent of the children in the 3-7 age group have Bitot's spot and four percent have night blindness. There is a lot of regional variation in the incidence of hypovitaminosis A. Children in the districts of Dharmapuri, Ramnad, Thanjavur and South Arcot are severely affected by Vitamin A deficiency. A higher proportion of boys have hypovitaminosis A in the form of night blindness and Bitot's spot, compared to girls. Children who had suffered from either jaundice or chicken pox or mumps or measles have a higher chance of getting Bitot's spots compared to other children. Children who had had whooping cough have a greater chance of suffering from night blindness and from Bitot's spot. Both night blindness and Bitot's spot occur a little more frequently among the illiterate than among the educated.

To find the extent of refractive errors among children of the 3-7 age-group, each child was asked to read with one eye a Home Eye Test card from a distance of ten feet. A child who could not read the third line was reckoned to have refractive error in that eye. Thirteen percent of the children could not read the chart with the left eye and thirteen percent with the right eye. In nine percent of the children both eyes were affected and in seventeen percent one of the eyes was. Among those children who had had jaundice a higher proportion could not read the chart, compared to the other children.

The proportion of children in the 3-7 age-group who had had chicken pox, whooping cough, measles, jaundice and mumps are eighteen, fifteen, fourteen, eight and eight percent respectively.

INTRODUCTION

"Foresight prevents blindness" is the theme adopted by the World Health Organization for the year 1976. It is well-known that a significant proportion of children suffer from visual impairment and blindness caused by factors associated with protein-calorie malnutrition and Vitamin A deficiency.^{1, 6} The number of people with vision impairment is steadily increasing and there is an urgent need to take quick remedial measures to reverse the trend.

The need for adequate scientific surveys^2,4 to assess the magnitude of the problem in each region has been expressed by doctors and social workers. In a recent editorial⁷ the Journal of the Indian Medical Association has expressed its concern over the problem of prevention of blindness.

It has been pointed out that protein-calorie malnutrition is more widely prevalent in the southern and eastern parts of the country than in other regions.⁵ In order to reduce the incidence of malnutrition and Vitamin A deficiency among children it has been proposed that skim-milk should be fortified with Vitamin A and that large doses of Vitamin A be administered orally to children.⁸

In our country, medical statistics on the incidence of many common diseases have been primarily confined to hospital statistics or of limited regional studies. There is a great need for community health statistics collected directly from the community whether it be in a remote village or in a city slum.

In order to estimate the proportion of children suffering from trachoma, night blindness, Bitot's spot and refractive errors a state-wide survey was organized by the Department of Statistics of the Madras Christian College during the third and fourth weeks of January 1976. A schedule of enquiry was used in the survey and it was first tested in a pilot survey conducted at Tambaram in August 1975.

The survey was conducted in conjunction with a public opinion survey. At the first stage the number of respondents to be selected from each taluk of Tamil Nadu was determined in proportion to the population of that taluk as obtained from the 1971 census. At the second stage each taluk was divided into two strata the rural and the urban in proportion to their corresponding populations. In each stratum a number of villages or town were selected using a probability proportionate sampling procedure. In other words larger villages had a greater chance of being selected compared to smaller villages. This was done to ensure that respondents, whether from larger or smaller villages, had an equal chance of being included in the sample. In the last stage about six respondents were chosen from each village from the voter's list using random number tables. All the children born during the years 1968-72 were chosen from the household of each respondent. If there were no children in a house, children from the next house was selected.

In the tables given in the paper there are apparent differences in total and these are due to the fact that cases with no information were left out.

Data were transferred from field sheets to punch cards in our laboratory. A Fortran program was written by our students and processed in the giant IBM 370/155 computer at the IIT Computer Centre, Madras.

The survey was part of a program of practical field experience for the students of statistics in the collection and analysis of statistical data. A high proportion of the funds for the survey was met by student volunteers who took part in the survey.

1. TRACHOMA

1.1 INTRODUCTION

Trachoma and allied infections are considered to be a preventable major cause of blindness in the country. Children suffering from trachoma have drooping eye-lids and inflammatory granulations on the inner side of the eye-lids. Trachoma³ is a chronic inflammatory eye-disease caused by a large virus called Chlamydia trachomatis and it is very common in the Punjab. In the famous Moghul Miniatures women are depicted with drooping eye-lids, and one wonders whether the beautiful women depicted in the paintings suffered from trachoma.

Trachoma is successfully treated with sulphanomide ointments and antibiotic preparations readily available in the market.

In our sample of about two thousand children, 4.9 percent of the children born during the years 1968-72 suffer from trachoma. Since the survey was conducted in January 1976, children born during 1968-72 correspond to children of the 3-7 age-group.

1.2 TRACHOMA AND REGIONAL VARIATION

The incidence of trachoma varies from district to district and clearly higher than the average in the districts of Dharmapuri (30%), South Arcot (12%) and Ramnad (11%).

1.3 TRACHOMA AND FAMILY BACKGROUND

There is not much difference in the incidence of trachoma between the educated and the uneducated families, between the rich and the poor, and between the children of families with different occupations.

1.4 CHI-SQUARE TEST

While going through the data we found that the incidence of trachoma was higher among children who had suffered earlier from other virus diseases such as jaundice, chicken pox and mumps. To test whether the difference in the incidence was significant or just due to chance we have used the chi-square test. We start with the null hypothesis that there is no association between the incidence of trachoma and the fact that a child had suffered from an attack of certain diseases in the past. The expected values of each category is calculated on this hypothesis of independence. If there is significant difference between the expected values and the observed values, chi-square will have a high value. For a 2X2 table the number of degrees of freedom is one. The values of chi-square at the levels of 5%, 1% and 0.1% are respectively 3.84, 6.63 and 10.83. If for instance we obtain a value higher than 6.63 for chi-square, we conclude that the value is significant at 1% level. In other words the chance of getting such a high value for chi-square purely due to chance is less than one in a hundred. Then we reject the null hypothesis of independence at one percent level.

1.5 TRACHOMA AND VITAMIN A DEFICIENCY

Children with Vitamin A deficiency are prone to get attacked by trachoma. It is quite possible that the general condition of such children is poor. Among the children with night blindness, about thirty percent suffer from trachoma in contrast to only four percent of the group without night blindness (Table I). Vitamin A deficiency often causes night blindness and Bitot's spot. The association between night blindness and trachoma is statistically significant at the 0.1% level as shown by a chi -square test. We also find that there is a significant positive association between trachoma and Bitot's spot. Among those children who have Bitot's spot, twelve percent have trachoma (Table II). This is significantly higher than the incidence of trachoma in the group of children who do not have Bitot's spot. We note that in the districts of Dharmapuri, South Arcot and Ramnad, there is not only high incidence of trachoma but also of Vitamin A deficiency in the form of night blindness arid Bitot's spot (Table X).

1.6 TRACHOMA AND JAUNDICE

Trachoma is more prevalent among children who have had an attack of jaundice than among the group who have not suffered from jaundice (Table III). A chi-square test shows that the positive association between trachoma and a history of jaundice in the child, is highly significant. It is well known that both jaundice and trachoma are both associated with unhygienic conditions of living.

1.7 TRACHOMA AND CHICKEN POX

A larger percentage of children who have had chicken pox suffer from trachoma compared to the group of children who have not had an attack of chicken pox (Table IV). The difference cannot be attributed to chance. The association between trachoma and a history of chicken pox in a child is positive and is highly significant as shown by a chi-square test.

1.8 TRACHOMA AND MUMPS

The incidence of trachoma is significantly higher among the group of children who had  had an attack of mumps than among the group who had not had mumps (Table V). The association between trachoma and a history of mumps in a child is positive and is statistically significant.

1.9 TRACHOMA AND WHOOPING COUGH

We test the hypothesis that the incidence of trachoma is independent of the fact whether a child had had an attack of whooping cough or not. We reject the hypothesis on the basis of a chi-square test. The value of chi-square is 9 and is significant at the 1% level. We note that the incidence of trachoma is higher among those who have had whooping cough than others (Table VI).

1.10 TRACHOMA AND MEASLES

There is no evidence from our study (Table VII) for any association between trachoma and a history of measles. This is shown by a very low value for chi-square. The incidence of trachoma is slightly less among those who had had measles than those who had not, but we attribute the difference to chance.

1.11 TRACHOMA AND SEX OF CHILDREN

Compared to girls, the incidence of trachoma is higher among boys (Table VIII). The difference is significant at 5% level.

2.HYPOVITAMINOSIS A

2.1 INTRODUCTION

The dreaded disease keratamalacia or the softening of the cornea, leads to irreversible blindness and it is common among children suffering from Vitamin A deficiency (hypovitaminosis A) and protein- calorie malnutrition (PCM). The earliest symptom of the disease is night blindness inability to see in the dark. Mothers often report that such children, after a night meal, fail to locate by themselves tumblers of water and their hands have to be guided by a parent to locate the tumbler. Children in the drought-affected areas must be tested for night blindness and other signs of hypovitaminosis A.

An  early clinical sign of Vitamin A deficiency is the appearance of Bitot's spots greyish triangular raised patches on the white portion of the eye. Children with Bitot's spot and other signs of hypovitaminosis A run a high risk of losing their sight. Conditions of a child suffering from night blindness will improve dramatically with better food and massive doses of Vitamin A in the form of injection or capsules. In the natural diet, milk, carrots, greens, mangoes and papayas are rich in Vitamin A.

In our sample of over two thousand children belonging to the three to seven age-group 3.9 percent suffer from night blindness. Sixteen percent in the same age-group have Bitot's spots in their eyes.

Among those who had night blindness (Table IX) as high as forty eight percent of the children also have Bitot's spot whereas among those who did not have night blindness only fifteen percent had Bitot's spot. Further taking only those children who have Bitot's spot, eleven percent had night blindness in contrast to the average value of 3.9 percent for night blindness. It is not as though every child who had Bitot's spot also had night blindness and vice versa. However the association between night blindness and Bitot's spot is positive and is highly significant.

2.2 VITAMIN A DEFICIENCY AND REGIONAL VARIATION

There is a lot of variation in Vitamin A deficiency from district to district. The incidence of Bitot's spot is very high in the districts of Dharmapuri (32%), Ramnad (30%) and Thanjavur (29%) in contrast to the average value of sixteen percent (Table X). It is also high in Kanyakumari (26%), Tirunelveli (25%) and Madurai (23%) districts and in Madras City (22%).

Compared to the average value of about four percent, the incidence of night blindness is quite high in the districts of Thanjavur (14%), South Arcot (12%) and Dharmapuri (9%).

We have shown clearly that the regional differences within Tamil Nadu are significant. Further work is needed to get better estimates at the district and the taluk level so that concerted efforts may be made to remove pockets of malnutrition and Vitamin A deficiency which are breeding grounds of preventable blindness among children.

2.3 VITAMIN A DEFICIENCY AND SEX OF CHILDREN

Boys are more prone to get Bitot's spot than girls. In contrast to the thirteen percent of girls who have Bitot's spot, nineteen percent of the boys in our sample have the ailment (Table XI). There is clear association between sex of a child and Bitot's spot. The value of chi-square is 12.5 and it is significant at the 0.1 percent level. A higher proportion of boys suffer from night blindness compared to girls (Table XII). On the basis of a chi-square test we reject the null hypothesis that the sex of child is independent of its having night blindness. The value of chi-square is 7.2 and it is significant at one percent level. The difference may be attributed to genetic factors or to possible difference in diet supplied at home to boys and girls.

2.4 VITAMIN A DEFICIENCY IN FAMILIES USING MILK

Seventy four percent of the families surveyed use milk (We exclude from this study the availability of mother's milk). In other words, one fourth of the households in Tamil Nadu are not able to afford to use milk. Vitamin A deficiency, as to be expected, is significantly higher among the children of such poor families compared to other children. For instance in the families that use milk, three percent of the children have night blindness in contrast to six percent of the children belonging to families who do not use milk who suffer from night blindness. In poor families who consume milk, children in the three to seven age-group may not get much milk. One hopes that more milk will become available in Tamil Nadu and more children will be able to get either fresh milk or skim-milk fortified with Vitamin A.

2.5 HYPOVITAMINOSIS A  AND OTHER DISEASES

It is seen from our study that children who had suffered from either jaundice or chicken pox or mumps or measles have a higher chance of getting Bitot's spot. It is quite possible that their general condition may be poor and they may be more susceptible to Bitot's spot. We do not have sufficient evidence to establish any association between night blindness and a history of either chicken pox or mumps or measles. Children who had had whooping cough have a greater chance of suffering from Vitamin A deficiency in the form of night blindness or Bitot's spot.

2.6 NIGHT BLINDNESS AMONG THOSE WHO HAVE HAD JAUNDICE

Among those who had suffered from jaundice 12.5 percent have night blindness whereas among those who had not had jaundice only 3.1% had night blindness (Table XIII). The value of chi-square is thirty five and is significant at 0.1% level. The association between night blindness arid a history of jaundice is statistically significant. We get similar results for Bitot's spot.

2.7 BITOT'S SPOT AMONG CHILDREN WHO HAD HAD WHOOPING COUGH

Among children who had had whooping cough (which is a bacillary infection), twenty seven percent have Bitot's spot compared to only fifteen percent among those who had not had whooping cough (Table XIV). The association between Bitot's spot and a history of whooping cough in the child, is significant at the 0.1% level. We get similar results for night blindness among those who had suffered from whooping cough.

2.8 VlTAMIN A DEFICIENCY AND FAMILY BACKGROUND

Both night blindness and Bitot's spot are found a little more among the illiterate than among the educated (Table XV). Children are classified into five groups on the basis of the occupation of their father. If we take all the children from the group where the fathers are illiterate, 21.7 percent of the children have Bitot's spot. On the other hand in the group where the father is college educated, 9.4 percent of children have Bitot's spot. Similarly in the illiterate group, 5.4 percent of the children suffer from night blindness whereas in the college-educated group, 2.8 percent of the children suffer from night blindness.

While preparing for the survey we found two of our student investigators had Bitot's spot. We note that even in educated families children suffer from Vitamin A deficiency.

Vitamin A deficiency is a little more common among the poorer sections than among the well-to-do (Table XVI). Whether the parents are agricultural workers, or traders or professionals the children run the same risk of getting Bitot's spot.

3. REFRACTIVE ERRORS

3.1 INTRODUCTION

Many young children have vision problems, which if left uncorrected might cause visual impairment. A child often imagines that everyone sees the way it does and does not complain of its vision problems. Such children should be identified and given proper treatment. To enable parents to identify such children with vision problems, a simple chart with the letter E in different sizes and orientations, was brought out in 1974 by the U.S. National Society for the Prevention of Blindness.

The author came across this interesting Home Eye Test card during his visit to the U.S. in 1974. A number of these cards were brought home to conduct field studies in Tambaram.

During August 1975, the Home Eye Test card was tried out on children in and around Tambaram. More cards were made and students were trained to use the cards, on both literate and illiterate children. The chart has to be read from a distance of ten feet and if a child cannot read the third line of symbols then we classify the child as having refractive errors. Each eye was tested separately.

Thirteen percent of the children could not read the chart with the left eye and thirteen percent with the right eye. In nine percent of the children both eyes were affected and in seventeen percent one of the eyes was affected.

3.2 REGIONAL VARIATION

There is a lot of regional variation. The percentage of children who cannot read with the left eye is quite high in the districts of Ramnad (30%), Madurai (24%), South Arcot (20%) and the Nilgiris. Since this is the first survey of this kind further work is necessary to get more accurate estimates at the district level. The fact that the districts of Ramnad and South Arcot also have a high incidence of Vitamin A deficiency, makes one wonder whether the vision problems of children who cannot read the eye chart could be attributed to refractive errors alone.

One of the reasons for high proportion of dropouts in village schools night be due to defective vision and massive program must be launched to supply spectacles to village children.

3.3 REFRACTIVE ERRORS AND JAUNDICE

Among those children who had had jaundice a higher proportion are not able to read the third line of the vision chart compared to those who had not had an attack of jaundice. Whether we take the right-eye vision or left-eye vision the results are very close. Among those who had had an attack of jaundice, twenty three percent cannot read the third line with their left eye compared to twelve percent in the group that did not have a history of jaundice (Table XVII). The value of chi-square is 16 and is significant at 0.1 percent level. We reject the null hypothesis that refractive errors are independent of the fact whether a child had suffered from jaundice or not. There is significant positive association between refractive error and a history of jaundice.

4 . OTHER DISEASES

Eighteen percent of the children in the sample are reported to have had an attack of chicken pox, fifteen percent had suffered from whooping cough, fourteen percent had had measles, eight percent had come down with jaundice and eighteen percent with mumps (Table XVIII). These figures are likely to be under estimates since mild attacks of some of these diseases could have been overlooked by parents and respondents might not have recalled all the diseases. 

We note that the figures for the common diseases refer to the percentages of children who had contracted the diseases some time or other in the past. The figures for the diseases refer to the prevalence of eye-diseases at the time of the survey. Further work is needed to get more accurate estimates of the prevalence of the common diseases among children.

REFERENCES

1. AGARWAL, L.P., " National plan of action in India for prevention and control of visual impairment", Paper presented at the Sixth Afro-Asian Congress in Ophthalmology, Madras, 1976.
2. AGARWAL, L.P., " Endemic eye diseases", Paper presented at the Sixth Afro-Asian Congress in Ophthalmology, Madras, 1976.
3. DUKE-ELDER, S., Parson's Diseases of the Eye, The English Language Book Society, 1964.
4. GOPALAN, C. et al, Studies on Pre-School Children , ICMR Technical Report Series No.26, 1974.
5. GOPALAN, C. and RAGHAVAN K.V., Nutrition Atlas of India, Hyderabad, 1971.
6. GUPTA, U. C., and AGARWAL, L. P., "Endemic eye diseases in India", Paper presented at the Sixth Afro-Asian Congress in Ophthalmology, Madras, 1976.
7. MUKERJI R., " Prevention of blindness", Journal of the Indian Medical Association, Vol. 66, No.8, April 1976, pp.187-188.
8. WHO, The Prevention of Blindness, Technical Report Series No. 518, 1973.

Chi-square equals 114 and is highly significant at 0.1% level


TABLE II- Comparative study of incidence of trachoma between
children who have Bitot's spot and children who have not.

Bitot's Spot	Trachoma
		Yes	No	Total
	Yes	40 (12.0%)	292 (88.0%)	332 (100%)
	No	59 ( 3.5%)	1630 (96.5%)	1689 (100%)
	Total	99	1922	2021

Chi-square equals 44 and is highly significant at 0.1% level.


TABLE III: Comparative study of incidence of trachoma between
children who had suffered from jaundice and those who had not.

Trachoma
	Yes	No	Total
Children who had suffered from jaundice	27 (17%)	132 (83%)	159 (100%)
Children who had not suffered from jaundice	71 ( 4%)	1780 (96%)	1851 (100%)
Total	98	1912	2010

Chi-square equals 55 and is highly significant at 0.1% level.


TABLE IV: Comparative study of incidence of trachoma between
children who had suffered from chicken pox and those who had not.

Trachoma
	Yes	No	Total
Children who had suffered from chicken pox	34 (9%)	333 (91%)	366 (100%)
Children who had not suffered from chicken pox	64 (4%)	1577 (96%)	1641 (100%)
Total	98	1909	2007

Chi-square equals 19 and is highly significant at 0.1% level.


TABLE V: Comparative study of incidence of trachoma between
children who had suffered from mumps and children who had not

Trachoma
	Yes	No	Total
Children who had suffered from mumps	18 (11%)	140 (89%)	158(100%)
Children who had not suffered from mumps	78 (4%)	1769 (96%)	1847(100%)
Total	96	1909	2005

Chi-square is 16 and is highly significant at 0.1% level


TABLE VI: Comparative study of incidence of trachoma between
children who had suffered from whooping cough and those who had not

Trachoma
	Yes	No	Total
Children who had suffered from Whooping cough	26 (8%)	285 (92%)	311 (100%)
Children who had not suffered from Whooping cough	73 (4%)	1628 (96%)	1701 (100%)
Total	99	1913	2012

Chi-square equals 9 and is significant at 1% level


TABLE VII: Comparative study of incidence of trachoma between
children who had had an attack of measles and those who had not.

Trachoma
	Yes	No	Total
Children who had suffered from measles	11 (3.9%)	271 (96.1%)	282 (100%)
Children who had not suffered from measles	85 (5.0%)	1634 (95.0%)	1719 (100%)
Total	96	1905	2001

Chi-square equals 0.58 and is not significant at 5% level


TABLE VIII: Comparative study of incidence of trachoma among
boys and girls in the three to seven age-group

Trachoma
	Yes	No	Total
Boys	65 (5.9%)	1033 (94.1%)	1098 (100%)
Girls	32 (3.5%)	889 (96.5%)	921 (100%)
Total	97	1922	2019

Chi-square is 6.55 and is significant at 5% level.


TABLE IX: Night blindness and Bitot's spot

Night Blindness	Bitot's spot
		Yes	No	Total
	Yes	38 (48%)	41 (52%)	79 (100%)
	No	294 (15%)	1647 (85%)	1941 (100%)
	Total	332	1688	2020

Chi-Square equals 60 and is highly significant at 0.1% level.


TABLE X: Comparative study of Vitamin A deficiency among
children from different districts (in percentages)

District	Bitot's spot			Night blindness
	Yes	No	Blank	Yes	No	Blank
Madras City	21.8	74.7	3 .5	1.1	92.0	6.9
Chinglepet	8.7	91.3	-	0.7	99.3	-
North Arcot	2.8	97.2	-	1.1	98.9	-
South Arcot	14.4	85.1	0 .5	12.2	87.2	0.6
Dharmapuri	31.6	68.4	-	8.8	91.2	-
Madurai	22.7	77.3	-	2.7	97.3	-
Salem	3.7	96.3	-	-	100.0	-
Tiruchy	9.6	89.6	0 .8	2.9	96.2	0.9
Thanjavur	29.3	69.6	1 .1	13.8	85.1	1.1
The Nilgiris	11.8	88.2	-	5.8	94.1	0.1
Kanyakumari	25.9	70.7	3 .4	-	100.0	-
Coimbatore	8.0	90.5	1.5	0.4	98.2	1.4
Ramnad	30.1	69.9	-	3.8	96.2	-
Tirunelveli	25.0	75.0	-	1.2	98.8	-

TABLE X1: Incidence of Bitot's spot among boys and girls

Bitot's spot
	Yes	No	Total
Boys	210 (19.1%)	888 (80.1%)	1098 (100%)
Girls	122 (13.2%)	798 (86.7%)	920 (100%)
Total	322	1686	2018

Chi-squire equals 12.5 and is significant at 0.1% level


TABLE XII: Incidence of night blindness among boys and girls.

Night Blindness
	Yes	No	Total
Boys	54 (4.9%)	1042 (95.1%)	1096 (100%)
Girls	24 (2.6%)	896 (97.4%)	920 (100%)
Total	78	1938	2016

Chi-square equals 7.2 and is significant at 1% level.


TABLE XIII: Comparative study of incidence of night blindness among
children who had had jaundice and those who had not.

Night Blindness
	Yes	No	Total
Children who had suffered from jaundice	20(12.5%)	140(87.5%)	160(100%)
Children who had not suffered from jaundice	57(3.1%)	1792(96.9%)	1849(100%)
Total	77	1932	2009

Chi-square is 35.4 and is highly significant at 0.1% level.


TABLE XIV: Comparative study of incidence of Bitot's spot between children
who had had whooping cough and those who had not

Bitot's spot
	Yes	No	Total
Children who had suffered from whooping cough	83 (27%)	228 (73%)	311 (100%)
Children who had not suffered from whooping cough	249 (15%)	1451 (85%)	1700 (100%)
Total	332	1679	2011

Chi-square is 27.7 and is highly significant at 0.1% level


TABLE XV: Incidence of Vitamin A deficiency and levels of education of father (percentages).

Level of education of father	Bitot's spot	Night blindness
Illiterate	21.7	5.4
Standards I to V	17.6	3.6
Standards VI to XIII	16.9	2.9
Standards IX to XI	11.9	3.7
College educated	9.4	2.8

TABLE XVI: Incidence of Vitamin A deficiency and levels of income of father (percentages)

Level of annual income of parent in rupees	Bitot's spot	Night blindness	Sample size
Less than 1000	22.0	3.9	337
1001 to 3500	14.8	3.5	913
3501 to 6000	10.6	2.2	369
6001 to 12000	17.4	2.8	109
Above  12000	0.0	0.0	35

TABLE XVII: Comparative study of incidence of refractive error (left eye) between
children who had had jaundice and those who had not

Ability to read with left eye
	Yes	No	Total
Children who had suffered from jaundice	121 (77.1%)	36 (22.9%)	157 (100%)
Children who had not suffered from jaundice	1607 (88.2%)	215 (11.8%)	1822 (100%)
Total	1728	251	1979

Chi-square equals 16.2 and is significant at 0.1% level


TABLE XVIII: Percentages of children in the three to seven age-group
who had suffered from common diseases at some time or other

Name of disease	Percentage of children who had suffered from the disease
Chicken pox	18.0
Whooping cough	15.3
Measles	13.8
Jaundice	8.0
Mumps	7.8