bioRxiv preprint doi: https://doi.org/10.1101/532655; this version posted January 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license.
1 Epidemiology of Childhood Blindness: a Community based
2 study in Bangladesh
3 A.H.M Enayet Hussain1, Junnatul Ferdoush2, Saidur Rahman Mashreky2,3, AKM Fazlur
4 Rahman2,3, Nahid Ferdausi4, Koustuv Dalal5,6
5 1Directorate General of Health Services, Bangladesh
6 2Centre for Injury Prevention and Research, Bangladesh
7 3Bangladesh University of Health Sciences, Bangladesh
8 4National Institute of Ophthalmology, Bangladesh
9 5School of Health and Education, University of Skövde, Sweden 10 11 6Higher School of Public Health, Al-Farabi Kazakh National University, Kazakhstan 12 13 [email protected], [email protected], [email protected], [email protected],
14 [email protected], [email protected]
15
16 Corresponding author:
17 A.H.M Enayet Hussain 18 Additional Director General 19 Directorate General of Health Services 20 Mohakhali, Dhaka 21 Phone: +8801711838613 22 E-mail: [email protected] 23
24
25
26
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27 Abstract
28 This study has aimed to detect the prevalence and causes of childhood blindness in rural area of
29 Bangladesh. A cross sectional quantitative study design was adopted for this study which carried-out in
30 three unions (sub- districts) of Raiganj upazila of Sirajganj district of Bangladesh. Using a validated tool
31 a screening program was conducted at household level. After initial screening a team of ophthalmologists
32 confirmed the diagnosis by clinical examinations. The prevalence of childhood blindness found was
33 6.3 per 10,000 children. The rate of uni-ocular blindness was 4.8 per 10,000 children. Congenital
34 problems were the major cause of both uniocular and binocular blindness (UOB: 84% and BB:
35 92% &). For binocular blindness, whole globe was the responsible site (28.0%, CI: 13.1, 47.7)
36 and cornea was for the uni-ocular blindness (57.8%, CI: 35.3, 78.1). Childhood blindness is a
37 public health problem in Bangladesh. Childhood blindness is common irrespective of gender.
38 Major causes of childhood blindness are congenital.
39 Keywords: Childhood Blindness, Uni-ocular Blindness, Binocular Blindness, Bangladesh.
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49 Background
50 Globally, an estimated number of 36 million inhabitants are residing with blindness [1]. The
51 prevalence by age distribution showed that around 1.4 million children aged 0-14 years are living
52 with blindness while about 17.5 million are at risk of low vision [2]. An estimated 70 million
53 blind-person years are caused by blindness among children [3]. Although the actual number of
54 blind children is much lower than the blind adults, but the number of blind years resulting from
55 the blindness is alarmingly high in children which has an immense social and economic impact
56 [4–6].
57 The magnitude and causes of visual impairments and blindness varies from region to region
58 because of socio-developmental diversification [4]. Analysis of global data showed that around
59 90% of the blind people belongs to the developing countries [7]. There is dearth of recent
60 population based studies showing the prevalence as well as factors responsible for childhood
61 blindness in the context of developing countries. However, data found that the burden of
62 childhood blindness higher in African and Asian region which is mainly due to inaccessible
63 primary health care services [5,8,9].
64 Majority of the causes for childhood blindness are avoidable with the available minimal resource
65 settings of the developing countries [7]. Being a lower -middle income country, Bangladesh is
66 not the exception. The situation is more miserable in the rural context. Rural areas in Bangladesh
67 are already facing enormous healthcare delivery problem [10]. With socioeconomic and cultural
68 constraints and with the backdrop of medical poverty-trap, it could be assumed that Bangladesh,
69 especially rural areas have poor healthcare facilities for eye care services [11]. Over the last few
70 years, number of initiatives have been taken to achieve the VISION- 2020. [12,13]. However,
71 there is further scope of improvement in order to achieve the goal. Moreover, there is scarcity of
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72 data from the existing researches related to the burden and capacity of health system regarding
73 childhood blindness. This study aims to detect the prevalence and causes of childhood blindness
74 at community level in rural area of Bangladesh.
75 Methods
76 Study Design
77 A cross sectional quantitative design was adopted for this study, carried-out during January and
78 April 2017 in three unions of Raiganj, a sub-district (Upazila) of Sirajganj District in the Rajshahi
79 Division of northern Bangladesh.
80 Study Population
81 The whole area of the targeted upazila is 259.74 sq. km with an established population density of
82 223 per sq. km. About 317,666 people are inhabiting in the upazila where male and female
83 proportion were 51.1% and 49.9% respectively [14]. The Upazila comprises of nine unions. A
84 union is the lowest administrative unit comprising of 20,000-50,000 population. The survey was
85 conducted among three unions where Center for Injury Prevention and Research Bangladesh
86 (CIPRB) is maintaining an injury and demographic surveillance system. Entire population of those
87 three unions are included in this surveillance system of the current study. It comprised 31,971
88 households with a population of 147,072 where total number of children aged ≤15 years was
89 39,351. The survey was conducted among whole child populations of the indicated study areas.
90 The target population was below or of 15 years of old child included according to the operational
91 definition.
92 Data Collection Procedure
93 A household level screening was conducted to identify the suspected childhood blindness, visual
94 impairment and other ocular morbidities. In the screening, data collectors conducted face-to-face
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95 interview along with some simple examinations using a validated structured questionnaire with
96 pictorial charts. Each data collector was provided training on measuring visual acuity using age
97 specific vision chart and performing of a basic ocular examination. A day long comprehensive
98 training was provided by a team of both the researchers and ophthalmologists. Socio-demographic
99 information of the respondents was collected from the database of CIPRB surveillance system. All
100 individuals in the surveillance area have their own unique identification number. After collecting
101 specific information, it was merged with the required socio-demographic variables of the existing
102 population database.
103 Total 18 field workers (3 field supervisors and 15 data collectors) conducted the survey. If any
104 household member was not available during the period of data collection, field workers collected
105 their contact number and visited them again as per their convenience. Data collectors identified
106 570 suspected cases blindness, visual impairment and other ocular morbidities.
107 All the suspected children were then invited to visit the eye camp for the confirmation of their
108 diseases and further management advice. Field workers invited all the parents/ caregivers of the
109 suspected children through mobile phone, those who were not reached out over phone in-person
110 meeting was carried out to ensure presence in the eye camp. Transportation cost were given to all
111 families. Day-long eye camp was carried out in three phases to examine all suspected cases. Team
112 was consisting of five ophthalmologists, two health assistants and five supporting staffs.
113 All children were examined as per the standard clinical guideline after having written consent from
114 their legal guardian. Ophthalmologists used Snellen chart, slit lamp, retinoscope, direct
115 ophthalmoscope and indirect ophthalmoscope to confirm the cases. Out of 570 screened cases
116 finally, 198 cases of blindness and different kind of eye morbidities were confirmed by the team.
117 The ophthalmologist kept the record of both the principal reason as well as the contributing reasons
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118 for their blindness and visual impairment. Among the confirmed cases, total nine children were
119 referred to the specialized hospitals for carrying out their indicative surgery. Other confirmed cases
120 were referred to different health care facilities for definitive treatment (Fig 1).
121 Fig 1: Methodological protocol of this study
122 Statistical Analysis
123 Descriptive analysis was carried out to describe the population by gender, age and socioeconomic
124 status. Similar analysis was made to estimate the prevalence of childhood blindness and its
125 associated risk factors. The prevalence rate of all types of blindness were calculated per 10,000
126 children with 95% confidence interval (CI). Prevalence of childhood blindness was described by
127 gender, age, wealth index and classification of the blindness. WHO standard anatomical and
128 aetiological classification used to do the analysis [15]. For analysis purpose, child age group was
129 categorized as under-five and 5 to 15 years where wealth index categorized as poor, middle and
130 rich. The wealth index was categorized using some selective assets of the household which
131 included unit of land ownership; availability of amenities i.e. electricity, refrigerator, television,
132 radio, bicycle, motorcycle, wardrobe, table, chair, clock, bed, sewing machine, mobile, car, water,
133 toilet; daily used fuels; household income along with expenditure and the materials used for
134 building roof, floor and wall of the household. Bi-variate analysis was carried out to analysis the
135 relationship between childhood blindness and the independent variables such as sex, age group,
136 wealth index and classification of blindness. Construction of all variables and estimations were
137 ascertained using the statistical software SPSS version 24.
138 Operational Definitions
139 Children: In this study, cases at or below 15 years of age were considered as children.
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140 Blindness: Blindness definition of ICD- 10 considered for this study. Blindness is the corrected
141 visual acuity of less than 3/60 in the better eye or a central field of less than 10 degrees [16].
142 Binocular and Uniocular Blindness (BB & UOB): ICD- 10 standard definition of Binocular and
143 Mono/Uni ocular blindness considered for this study [16].
144 Reversible Blindness: The temporary loss of eye sight which could be treatable through surgical
145 intervention is termed as reversible blindness.
146 Irreversible Blindness: Irreversible blindness where the eye sight can be restored either medical
147 or surgical intervention.
148 Ethical Consideration
149 Ethical clearance of this study was received from the Ethical Review Committee of Centre for
150 Injury Prevention and Research Bangladesh. We have taken written consent of all legal
151 guardians of the respective suspected cases during the screening and for the ophthalmologist
152 visit.
153 Results
154 In this study, the proportion of male (51%) and female (49%) population was almost similar. Two
155 categories of age group for the study population were generated and majority of the children were
156 from age group 5 to 15 years (70%) and rest were below 5 years old. Four categories of wealth
157 index were generated for the study population and majority of the children have fallen into the
158 poor category (50%) (Table 1).
159
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160 Insert table 1 about here
161 Table 1: Population characteristics (N= 39,351)
Variables Frequency Percentage
Gender
Male 20211 51.3
Female 19140 48.6
Age (in years)
< 5 years 11806 30.0
5 to 15 years 27545 70.0
Wealth index
Poor 19678 50.0
Middle-class 9843 25.0
Rich 9830 25.0
162
163 The prevalence of binocular blindness among study population found was 6.3 per 10,000
164 children whereas the rate for uni-ocular blindness found was 4.8 per 10, 000 children. Both uni-
165 ocular and binocular rate was found higher among male, however difference was not statistically
166 significant. Significantly higher rate of binocular was found among the under 5 aged children.
167 The rates were 19.4 (CI: 12.6 - 28.7) and 0.7 (CI: 0.1 - 2.3) in under-five and 5 years and above
168 age group children. Compared to rich higher rate of binocular blind was found among poor.
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169 However, difference was not statistically significant. The rates were 8.1 (CI: 4.7 - 12.9) and 2.0
170 (CI: 0.3 - 6.7) among rich and poor respectively (Table 2).
171 Insert table 2 about here
172 Table 2: Distribution of BB & UOB by Age, Sex and Socio-economic Status
Variable Binocular Blindness Total Uni-ocular Total (BB) Blindness(UOB)
Reversible Irreversible Reversible Irreversible
Rate per 10,000 children (95% CI)
Gender
Male 0.9 6.4 7.4 4.9 0.4 5.4 (n=20211) (0.1,3.2) (3.5,10.7) (4.3,11.9) (2.5,8.7) (0.03,2.4) (2.8,9.4)
Female 3.1 2.0 5.2 2.0 2.0 4.1 (n=19140) (1.2,6.5) (0.6,5.0) (2.6,9.3) (0.6,5.0) (0.6,5.0) (1.9,7.9)
Total 2.0 4.3 6.3 3.5 1.2 4.8 (n=39351) (0.9,3.8) (2.5,6.7) (4.2,9.2) (2.0,5.8) (0.4,2.8) (2.9,7.3)
Age group
Under-5 5.9 13.5 19.4 5.0 2.5 7.6 (n=11806) (2.5,11.7) (8.0,21.5) (12.6,28.7) (2.0,10.5) (0.6,6.9) (3.7,13.9)
5-15 years 0.3 0.3 0.7 2.9 0.7 3.6 (n=27545) (0.04,1.7) (0.04,1.7) (0.1,2.3) (1.3,5.5) (0.1,2.3) (1.8,6.4)
Total 2.0 4.3 6.3 3.5 1.2 4.8 (n=39351) (0.9,3.8) (2.5,6.7) (4.2,9.2) (2.0,5.8) (0.4,2.8) (2.9,7.3)
Wealth index
Poor 2.5 5.5 8.1 1.5 1.5 3.0
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(n=19678) (0.9,5.6) (2.9,9.7) (4.7,12.9) (0.4,4.1) (0.4,4.1) (1.1,6.3)
Middle class 3.0 4.0 7.1 7.1 1.0 8.1 (n=9843) (0.8,8.2) (1.3,9.8) (3.0,14.0) (3.0,14.0) (0.03,5.0) (3.7,15.4)
173
174 Congenital diseases are found as the major reason for both the uniocular and binocular blindness
175 (BB: 92% & UOB: 84%). For binocular blindness, whole globe was the responsible site for
176 structural origination with the proportion of 28.0 (CI: 13.1 - 47.7) where cornea was for uni-
177 ocular blindness (57.8%, CI: 35.3 - 78.1) (Table 3).
178 Insert table 3 about here
179 Table 3: Distribution of BB & UOB by anatomical & aetiological classification
Binocular blindness Uni-ocular blindness (N=25) (N=19)
Proportion (95% CI)
Main Site
Whole globe 28.0 (13.1, 47.7) 0 Cornea 4.0 (0.1, 18.1) 57.8 (35.3, 78.1) Lens 16.0 (5.2, 34.2) 0 Uvea 0 0 Retina 12.0 (3.1, 29.2) 15.7 (4.1, 37.2) Optic Nerve 8.0 (1.3, 24.0) 15.7 (4.1, 37.2) Glucoma 4.0 (0.1, 18.1) 5.2 (0.2, 23.3) CNS 20.0 (7.7, 38.9) 5.2 (0.2, 23.3) Other (Angle of Ant. Chamber) 8.0 (1.3, 24.0) 0
Aetilogical
Hereditary 92.0 (76.0, 98.6) 84.2 (62.7, 95.8) Acquired 8.0 (1.3, 24.0) 15.7 (4.1, 37.2)
180
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181 Discussion
182 This is the first household level survey in a rural community of Bangladesh showing the prevalence
183 of childhood blindness. The rate was 6.3 per 10,000. By extrapolating this number into the national
184 target group, it is found that around 35,000 children in Bangladesh is living with blindness. While
185 another extrapolation of the data found from a study of Muhit et al. in 2007 claimed that the
186 estimated children with blindness/ severe visual impairments could be 26,000 [17]. Both studies
187 followed a different methodology where the former screened out the cases through house to house
188 community based survey and the latter followed a combination of the inclusion of special child
189 from the institution along with capturing of blind cases through key informant method. Moreover,
190 another assumption made that around 40,000 children of Bangladesh are breathing their lives with
191 blindness [18]. It is mentionable that the information of the current study was extracted from the
192 rural context only, warranting further rigorous research in both rural and urban context.
193 This is the very first study which estimated the prevalence and causes of uni-ocular reversible and
194 irreversible blindness among children. There was almost no previous research found in terms of
195 Bangladesh that examined the burden and etiology of uni-ocular blindness. Data from a
196 community based study of Oman showed that the rate of uni-ocular blindness is 9 per 10,000
197 children [19]. The estimation of blindness will be double if the contributory number of uni-ocular
198 blindness dropped into the bucket of binocular blindness [19]. So, this piece of information might
199 be helpful for the policy makers to set their priorities. Study stated that the persistent untreated
200 unilateral blindness particularly due to ocular trauma eventually leads to blindness [20] . Although
201 the prevalence of uni-ocular blindness does not directly contribute to the burden of total blindness,
202 but early diagnosis and treatment of reversible uni-ocular blindness will eventually contribute in
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203 reducing the burden of total blindness. By that means, the burden of uni-ocular blindness is also
204 an emerging public health concern for Bangladesh.
205 Study stated majority of blind children are female as found in t population-based study at two
206 areas of Andhra Pradesh, India which was published in 2003 [21] In our study, we found higher
207 rate among male however it is not statistically significant. . The relative small sample size should
208 keep in consideration while doing the interpretation of this study finding. Though many studies
209 showed that blindness is highest among poor group than the richest but this study does not resemble
210 such pattern [22]. Study finding of this study showed the similar trend although the difference was
211 not statistically significance.
212 Congenital causes were found as the most common reason for both uni-ocular and binocular
213 childhood blindness. Additionally, whole globe was the responsible site in terms of binocular
214 blindness whereas cornea found as the accountable for mono ocular blindness. A previous
215 nationwide study stated that lens as the commonest anatomical site where unoperated cataract
216 cases were the responsible reason [23]. Improved maternal and child care initiatives taken by the
217 Bangladesh Govt. might help in reducing national burden of cataract in children. A study
218 conducted in school going children of China also found whole globe as the accountable anatomical
219 site [24]. Previous study result showed Vitamin A deficiency as the major attributable acquired
220 reason for childhood vision loss [23]. Nevertheless, this study did not find these acquired reasons
221 to be as mentionable which might be due to continuous spectacular progress in the sector of health
222 and nutrition in Bangladesh. The National Vitamin-A plus campaign is a successful program held
223 each year in Bangladesh which contributed tremendously to control night blindness [25].
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224 Strength and limitation
225 This study has performed screening of the cases at community level through house to house
226 survey following another study published in 2003 done by Nirmalan et al in Southern India [26].
227 Investigators suggest that community door to door approach is credible to determine the extent of
228 childhood blindness as there is less chance of case dropping. Moreover, this survey was
229 conducted within an established Health and Demographic Surveillance System which covered
230 more than 150,000 population. All the children aged below and 15 years of the study area were
231 included in this study. It minimized the sampling error of the study. A group of senior
232 ophthalmologists were involved in the diagnostic procedure. An experienced ophthalmologist
233 leaded the diagnostic team. It might minimize the error related to the misclassification of
234 diseases. The study was conducted in a rural area of Bangladesh, which may not represent the
235 urban situation of the country.
236 Conclusion
237 Childhood blindness is a significant public health concern in Bangladesh. Childhood blindness is
238 common irrespective of gender. Major causes of childhood blindness are congenital.
239 Recommendation
240 This study finding indicates that necessary measures are needed to be considered for the reduction
241 of childhood blindness in Bangladesh. Raising social awareness is important so that the reversible
242 childhood blindness can be identified and treated early. A strategy need to be developed with
243 proper strengthening of six building blocks of the health system for the prevention of childhood
244 blindness in Bangladesh.
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245 Acknowledgements
246 This study was conducted in the surveillance area of Centre for Injury Prevention and Research
247 Bangladesh (CIPRB). CIPRB provided administrative and technical support in the data
248 collection and data management procedure. Disabled Rehabilitation Research Association
249 (DRRA), Bangladesh provided financial support for this study. We are also grateful to the
250 ophthalmologists who took part in the visits to detect the confirmed cases. We are thankful to
251 Director General of Health Services (DGHS) for providing their technical support in validating
252 the materials.
253 Authors Contributions:
254 Conceptualization: EH, SRM, KD
255 Formal Analysis: EH, JF, SRM, KD
256 Writing (original draft): EH, JF, SRM, NF, KD
257 Writing (review and editing): EH, SRM, FR, KD
258
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