BMJ Open€¦ · The world Health Organization’s recent report on ‘Universal Eye Health: A global action plan 2014-2019’ highlights the need for regional surveys to generate

For peer review only

Population based assessment of prevalence and causes of visual impairment in the state of Telangana, India – A cross

sectional study using Rapid Assessment of Visual Impairment RAVI) methodology.

Journal: BMJ Open

Manuscript ID bmjopen-2016-012617

Article Type: Research

Date Submitted by the Author: 11-May-2016

Complete List of Authors: Marmamula, Srinivas; L V Prasad Eye Institute, Allen Foster Community Eye Health Research Centre, ICARE Khanna, Rohit; L.V.prasad eye institute, Kunuku, Eswararao; L V Prasad Eye Institute, Allen Foster Community Eye Health Research Centre, ICARE Rao, Gullapalli; LV Prasad Eye Institute

<b>Primary Subject Heading</b>:

Ophthalmology

Secondary Subject Heading: Public health, Research methods

Keywords: Cataract and refractive surgery < OPHTHALMOLOGY, PRIMARY CARE,

EPIDEMIOLOGY

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Research Article

Population based assessment of prevalence and causes of visual impairment in the state

of Telangana, India – A cross sectional study using Rapid Assessment of Visual

Impairment RAVI) methodology.

Srinivas Marmamula 1,2,3, 4

, Rohit C Khanna 1,2, Eswararao Kunkunu

1,2,Gullapalli N Rao

1,2,3

1 Allen Foster Community Eye Health Research Centre, Gullapalli Pratibha Rao -

International Centre for Advancement of Rural Eye care, L V Prasad Eye Institute,

Hyderabad, India

2 Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India

3Brien Holden Institute of Optometry and Vision Science, L V Prasad Eye Institute,

Hyderabad, India

4Wellcome trust / Department of Biotechnology India Alliance research fellow, L V Prasad

Eye Institute, Hyderabad, India

Running Title: Visual Impairment in Telangana, India

Article Type: Research article

Key words: Visual impairment, Cataract, Refractive Errors, India, rapid assessment

Corresponding author:

Dr. Srinivas Marmamula

Gullapalli Pratibha Rao - International Centre for Advancement of Rural Eye care,

L V Prasad Eye Institute,

Hyderabad, India. 500034

Email: [email protected]

Total number of words: 3162 words excluding title page, abstract, acknowledgements,

references, and tables

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Objective: To assess the prevalence and causes of visual impairment (VI) among a rural

population aged 40 years and older in the state of Telangana in India.

Design: Population based cross sectional population

Setting: Districts of Adilabad and Mahbubnagar in south Indian state of Telangana, India

Participants: A sample of 6150 people was selected using cluster random sampling

methodology. A team comprising a trained vision technician and a field worker visited the

households and conducted the eye examination. Presenting, pinhole and aided visual acuity

were assessed. Anterior segment was examined using a torch light. Lens was examined using

distant direct ophthalmoscopy in a semi-dark room. In all, 5881 (95.6%) participants were

examined from 123 study clusters. Among those examined, 2723 (46.3%) were men, 4824

(82%) had no education, 2974 (50.6%) were from Adilabad district and 1694 (28.8%) of

them were using spectacles at the time of eye examination.

Primary Outcome measure: Visual impairment (VI) was defined as presenting visual acuity

worse than 6/18 and it included moderate VI (worse than 6/18 to 6/60) and blindness (worse

than 6/60).

Results: The age and gender adjusted prevalence of VI was 15.0% (95% CI: 14.1 – 15.9). On

applying multiple regression analysis, VI was associated with older age groups. The odds of

having VI was higher among women (OR: 1.2; 95% CI: 1.0 – 1.4). Having any education

(OR: 0.4; 95% CI: 0.3 – 0.6) and current use of glasses (OR: 0.19; 95% CI: 0.1 – 0.2) were

protective. VI was also higher in Mahbubnagar (OR: 1.0 – 1.5) district. Cataract (54.7%) was

the leading cause of VI followed by uncorrected refractive errors (38.6%).

Conclusion: VI continues to remain a challenge in rural Telangana. As over 90% of the VI is

avoidable, massive eye care programmes are required to address the burden of VI in

Telangana.

Article summary:

Strengths and limitations of the study

• Population based study design that achieved a good response rate

• Covered two large districts of Telangana in India

• Provided insights on prevalence and causes of visual impairment that can be used for

program planning

• It was a rapid assessment survey hence posterior segment may have been under

estimated.

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India has a large burden of blindness and moderate and severe visual impairment. It was

estimated that over 8.3 million people are blind in India.[1] Of the total population with

moderate severe visual impairment worldwide, 31% of them are estimated to be in India.[1]

Similar to other regions, a declining trend in the prevalence of visual impairment is reported

in India.[2, 3] Most of the global data are derived from regional population-based surveys

that were carried out in recent years, mostly using rapid assessment methods.[1]

The world Health Organization’s recent report on ‘Universal Eye Health: A global action

plan 2014-2019’ highlights the need for regional surveys to generate evidence on the

magnitude and causes of visual impairment.[4] It also recommends that the member states

target 25% reduction in the prevalence of visual impairment from 2010 baseline.[4] This

underscores the importance of periodic regional surveys as a mechanism to understand both

the burdens and the trends in the prevalence of visual impairment over time and to plan

strategies to address it.[5]

The state of Telangana was separated from Andhra Pradesh as the new 29th state of India in

2014. This newly formed state comprises ten districts and has a population of 35.2 million

people as per the 2011 census.[6] The combined population of the two districts of Adilabad

and Mahbubnagar was 6.8 million.[6] Mahbubnagar is the largest district in the state and is

closer to the capital Hyderabad. It has the highest proportion of rural population (85%)

compared to other districts including Adilabad (72%). The overall proportion of rural

population in Telangana is 69%. The literacy rate in the rural population in Mahbubnagar

district (52%) is lower compared to Adilabad district (55.7%), both of which are lower than

the state average.[6]

Like other districts in the state, the health care facilities in general, and eye care facilities in

particular are confined to large towns.[7] A few non-governmental organizations provide eye

care services through ‘outreach’ screening camps in Mahbubnagar district and the

government run hospital at Adilabad also provides eye care including cataract surgeries. L V

Prasad Eye institute (LVPEI), a major eye care service provider based in Hyderabad has

established a rural network of eye care centres in both these districts.[8] In Adilabad, two

secondary eye care centres (the first in 1996 and the second in 2005), followed by 19 primary

eye care centres (vision centres) were established. In Mahbubnagar, a secondary centre was

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established in 1998 followed by the establishment of ten primary eye care centres. In both the

districts, the LVPEI rural eye care network is one of the largest eye care service providers,

offering cataract surgeries.[9]

We undertook a population based study using Rapid Assessment of Visual Impairment

(RAVI) methodology among the population aged 40 years and older in the two districts of

Telangana - Adilabad and Mahbubnagar (Figure 1) with the following objectives; a) to assess

the prevalence, causes and risk factors for visual impairment, b) to assess the prevalence and

patterns of spectacles use, c) to assess the visual outcomes following cataract surgery and d)

to understand the barriers for the uptake of services among those with avoidable causes of

visual impairment. In this paper, we report on the prevalence, causes and risk factors of visual

impairment in these two districts.

METHODS

The Institutional Review Board (IRB) of Hyderabad Eye Research Foundation, L V Prasad

Eye Institute, Hyderabad, India, approved the study protocol. This study adhered to the tenets

of the Declaration of Helsinki. Verbal informed consent was obtained from each subject after

explaining the study procedures and before starting the eye examination.[10] Permission was

obtained from the head of the each village before starting the data collection. At the

household level, the study procedures were explained to each individual, and oral consent

was obtained in the presence of fellow family members and another individual who did not

belong to the same family, or was a neighbor.

IRB gave the approval for oral consent for two reasons: a) The study procedures were non -

invasive and did not involve any physical contact with the subjects or administration of any

medication. The procedures are a part of regular eye screening protocols used as a part of

door-to-door screening at the primary level in India, and b) The literacy levels in the

geographical location where the study was conducted was not very high and there was

general apprehension in the community towards providing a thumb impression on the consent

form, which in turn may lead to poor response rate. The provision of verbal consent was

documented by taking photographs to illustrate the process in the selected villages and by

random visits to the villages by the Principal investigator, for cross verification with the

participants, as a part of the quality control measures. Data collection for the project was

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carried out from February to April in Adilabad, and October to December 2014 in

Mahbubnagar district.

Definitions

The Indian definitions for categories of visual impairment (VI) were used.[11] According to

this, blindness is defined as presenting VA worse than 6/60 in the better eye. Moderate Visual

Impairment (MVI) was defined as presenting VA worse than 6/18 to 6/60 in the better eye.

VI is used as generic term which includes both blindness and MVI. We used the same case

definitions for the causes of VI as reported in our previous studies.[10, 12] In short, cataract

was defined as the presence of white opacity in the pupillary area on torch light examination

and/or presence of dark shadow on distance direct ophthalmoscopy in dim light causing a VI.

Refractive error is defined as presence of presenting VA worse than 6/18 and improving to

6/18 or better with a pinhole. Posterior segment disease is considered as the cause of VI in

cases where there was no media opacity and visual acuity did not improve with a pinhole.

The causes of VI were first recorded for each eye separately and then mapped to the person.

Where there was more than once cause, the condition that could be most easily corrected or

treatable was considered as the cause for visual impairment.

Sampling method

The Rapid Assessment of Visual Impairment (RAVI) methodology was used in this study.[10

12] The sample size was calculated based on an estimated prevalence of visual impairment of

6%, with 20% precision, 95% confidence intervals and a design effect of 1.5 for cluster size

of 50. The minimum sample size needed, including an inflation of 20% to account for non-

response, was 2800 subjects in each district.

In total, 123 study clusters (villages) within a distance of 60 kilometers from the two

secondary centres of LVPEI in Mudhol (sub-district) in Adilabad district and Thoodukurthy

(Nagarkurnool sub-district) in Mahbubnagar district were selected using the cluster random

sampling method. In the first stage, study clusters were randomly selected based on

population proportionate to size. In the second stage, in each of the randomly selected

clusters, compact segment sampling method was used to select the households. In each

cluster 50 participants aged 40 years and older were enumerated and also those available

were examined by trained teams of vision technicians. The visits to the clusters were made

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during the time when the most number of people were likely to be available, as in early

mornings and evenings. At least two attempts were made for those who were not available at

first visit. The participants who were not available after multiple visits were marked as ‘non

available’ participants and were not substituted.

Eye Examination

In total, three study teams, each comprising one trained vision technician and a community

eye health worker, participated in the data collection. All three teams underwent rigorous

training in the study procedures. A reliability study was set-up before the data collection

where 40 subjects were examined by the gold standard optometrist and the three vision

technicians. A minimum agreement of 0.7 kappa was achieved for distance and near vision

testing and lens examination. After the training, the teams visited the selected households and

conducted eye examinations. The detailed examination procedure is described in our previous

publication.[10] In short, the eye examination included demographic and ocular history,

visual acuity (unaided, pinhole and aided, if applicable) for distance and near, anterior

segment examination and distant direct ophthalmoscopy. All the participants who had visual

impairment were referred to the nearest secondary centre for management and services.

Data Management

Data were initially collected on RAVI data collection forms and entered into a database

created in Microsoft Access. Regular consistency checks were performed. Data analysis was

performed using Stata Statistical software v12. Chicago, IL.[13] Student’s t test was used to

compare means and chi-squared test was used to compare proportions. The prevalence

estimates are presented with 95% confidence intervals (CI). The prevalence estimates were

adjusted to the age and gender population distribution of rural Andhra Pradesh as per 2011

census.[6] The demographic associations of VI with age, gender, education, area of residence

were assessed using multiple logistic regression analysis. The model fit was assessed using

Hosmer-Lemeshow test for goodness of fit.

RESULTS

Sample characteristics

In all, 5881/6150 (95.6%) enumerated participants were examined from 123 study clusters in

Adilabad and Mahbubnagar districts. Among those examined, 2723 (46.3%) were men, 4824

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them were using spectacles at the time of eye examination. The mean age of those examined

in Mahbubnagar was higher when compared to those at Adilabad (53.7 years versus 51.9;

p<0.01). In Adilabad district, 47.9% of those examined were in 40 to 49 years age group

compared to 42.9% in Mahbubnagar. Except for those in 50-59 year age groups, the

proportion of subjects in other age groups varied significantly in both the districts.

Participation of men and women was similar in both the districts (p=0.272); however, a

higher proportion of those examined were educated in Mahbubnagar district (23.6%)

compared to Adilabad district (12.4) (p<0.01) (Table 1).

Table 1: Personal and demographic characteristics of the participants stratified by

districts

Adilabad

district

Mahbubnagar

district Total

p

value*

Age group (years)

40 - 49 1424 (47.9) 1247 (42.9) 2671 (45.4) <0.01

50 - 59 796 (26.8) 732 (25.2) 1528 (26.0) 0.166

60 - 69 526 (17.7) 605 (20.8) 1131 (19.2) <0.01

70 & above 228 (7.7) 323 (11.1) 551 (9.4) <0.01

Gender

Male 1356 (45.6) 1367 (47.0) 2723 (46.3) 0.272

Female 1618 (54.4) 1540 (53.0) 3158 (53.7)

Education level

No education 2604 (87.6) 2220 (76.4) 4824 (82.0) <0.01

Any education 370 (12.4) 687 (23.6) 1057 (18.0)

Total 2974 (100.0) 2907 (100.0) 5881 (100.0)

*Significance test comparing the proportions in Adilabad and Mahbubnagar districts

Visual impairment

Overall, VI was present in 741 individuals. The age and gender adjusted prevalence of VI

was 15.0% (95% CI: 14.1 – 15.9). The prevalence of VI was16.2% (95% CI: 14.9 - 17.6) in

Mahbubnagar compared to 13.7% (95% CI: 12.5 - 15.0) in Adilabad district. Both MVI and

blindness were higher in Mahbubnagar district compared to Adilabad but the difference was

not statistically significant (Table 2).

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Among the sub-sample of those aged 50 and older, the age and gender adjusted prevalence of

VI was 23.5% (95% CI: 22.1 – 25.0). It was 25.1% (95% CI: 23.0 – 27.3) in Mahbubnagar

compared 21.9% (95% CI: 19.8 – 24.0) in Adilabad district. Similar to those aged 40 years

and older, both MVI and blindness were higher in Mahbubnagar compared to Adilabad;

however this was not statistically significant (Table 2).

Table 2: Age and gender adjusted prevalence of visual impairment in Adilabad and

Mahbubnagar districts in Indian state of Telangana

MVI Blindness All Visual

impairment

Prevalence (95%

CI)

Prevalence (95%

CI)

Prevalence (95%

CI)

People ≥ 40 years

Adilabad 10.4 (9.3 - 11.5) 3.3 (2.7 - 4.0) 13.7 (12.5 - 15.0)

Mahbubnagar 12.1 (10.9 - 13.3) 4.1 (3.5 - 5.0) 16.2 (14.9 - 17.6)

Both areas combined 11.3 (10.5 - 12.1) 3.7 (3.2 - 4.2) 15.0 (14.1 - 15.9)

People ≥50 years

Adilabad 16.6 (14.8 - 18.5) 5.3 (4.2- 6.5) 21.9 (19.8 - 24.0)

Mahbubnagar 18.6 (16.8 - 20.5) 6.5 (5.4 - 7.8) 25.1 (23.0 - 27.3)


On applying multiple regression analysis, VI increased with increasing age. Compared to

those aged 40 – 49 years, the odds of VI increased to 8.3 (95%CI: 5.7 – 11.9) in 50 – 59 years

age group, 32.3 (95% CI: 22.7 – 46.0) in 60 – 69 year age group and 96.4 (95% CI: 66.0 –

140.6) in those aged 70 years and older. The odds of having VI was higher among women

(OR:1.2; 95% CI: 1.0 – 1.4) compared to men though it was of borderline significance.

Having any education (OR: 0.4; 95% CI: 0.3 – 0.6) and current use of glasses (OR: 0.19;

95% CI: 0.1 – 0.2) were protective.VI was also higher in Mahbubnagar (OR: 1.0 – 1.5)

compared to Adilabad district (Table 3).

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Table 3: Effect of socio-demographic variables on prevalence of visual impairment

using multiple logistic regression analysis

Adjusted Odds

Ratio 95% CI P value

Age group (years)

40 - 49 1.0

50 - 59 8.3 5.8–12.0 <0.01

60 - 69 32.3 22.7– 46.0 <0.01

70 & above 96.4 66.1 - 140.6 <0.01

Gender

Male 1.0

Female 1.2 1.0 - 1.4 0.06

Education

No Education 1.0

Any Education 0.4 0.3 - 0.6 <0.01

Spectacles use for distance

No 1.0

Yes 0.2 0.1 - 0.2 <0.01

Area

Adilabad district 1.0

Mahbubnagar district 1.2 1.0 - 1.5 0.02

Table 4 shows the causes of VI stratified by districts. Overall, cataract (54.7%) was the

leading cause of VI followed by uncorrected refractive errors (38.6%). The causes of VI

differed significantly in both the districts. The VI caused due to cataract was 59.2% in

Adilabad district compared to 51.4% in Mahbubnagar (p=0.04). Similarly, VI due to

refractive errors was 32.7% in Adilabad against 42.8% in Mahbubnagar (p=0.01). Other

causes of VI were similar in both the regions.

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Table 4: Causes of visual impairment stratified by district

Adilabad

(n=309)

Mahbubnagar

(n=432)

Both areas

combined

(n=741)

p values

% % %

Cataract 59.2 51.4 54.7 0.04

Refractive Error 32.7 42.8 38.6 0.01

Posterior segment disorders 5.2 3.2 4.0 0.19

Corneal opacity 1.9 0.9 1.3 0.23

Cataract Surgical

complications 0.3 1.2 0.8 0.21

Phthisis or absent globe 0.6 0.5 0.5 0.74

Total 100.0 100.0 100.0

Discussion

We reported the prevalence and causes of VI from two large districts in the newly formed

state of Telangana in India. Telangana has witnessed few population based studies in the last

decade and half, some of which were conducted using rapid assessment survey methods. The

prevalence of MVI and blindness across various rapid assessment studies carried out in the

state of Telangana are shown in Table 5.

Table 5: Prevalence of visual impairment in various rapid assessment studies in

Telangana

Study / Area Year Sample

size

Moderate

Visual

Impairment

Blindness All visual

impairment

RACSS, Adilabad[2] 2007 2160 13.6% 8.0% 21.6%

RAVI (Warangal)[10] 2011 - 12 1357 12.5% 9.7% 22.2%

RAVI (Khammam)[10] 2011 - 12 1191 17.1% 9.2% 26.3%

Present study - Adilabad 2014 1550 16.6% 5.3% 21.9%

Present study - 2014 1660 18.6% 6.5% 25.1%

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Mahbubnagar

The overall prevalence of VI found in the present study were comparable with the earlier

studies in Warangal and Khammam districts; however the proportion of MVI and blindness,

which by definition sum up to the given VI, differed.[10] In the present study, the prevalence

of MVI and blindness were 11.3% and 3.7% respectively whereas the corresponding

prevalence of MVI and blindness in the previous study was 8.5% and 5.1% respectively.[10]

While the prevalence of MVI was higher, the prevalence of blindness was lower.

These differences in the contribution of MVI and blindness towards VI can be attributed to

differences in demographic profiles, availability and accessibility of services across the

districts. We also found differences in the prevalence of VI in Adilabad and Mahbubnagar

districts, again suggesting a difference in availability and uptake of services. Other socio-

demographic factors may also be influencing this. For example, high levels of migration were

found in Mahbubnagar compared to Adilabad district.[14] And also the proportion of rural

population is higher in Mahbubnagar compared to Adilabad district. A higher prevalence of

MVI and lower prevalence of blindness may also reflect an early trend where people with

more severe levels of VI (blindness) are utilizing the services more than that in the past. This

trend may also be attributed to the availability of good quality services in the form of

secondary centres and vision centres in the vicinity as these are the largest service providers

in the region.[6]

The nation-wide survey conducted in 2008 in India found the prevalence of blindness and

moderate VI as 8% and 16.8% respectively.[3] Another study from two districts in Telangana

found 9.5% blindness and 14.7% moderate visual impairment.[10] Both those studies

included only those who were aged 50 years and older. In the same age group (≥50 years), we

found blindness and moderate VI as 5.8% and 17.2% respectively. There seem to be a large

variation in prevalence of VI across the country and also within the districts in the state of

Telangana as noted in the preceding discussion.[10]

It is well known that the prevalence of VI is higher in older age groups and we had similar

findings in our study.[15] The association between gender and VI varied across the studies in

India. In our study, the association between gender and VI were of borderline significance.

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Earlier studies found a significantly higher proportion of VI among women.[3, 15, 16]

Another recent study from the same state reported a similar prevalence of VI in both the

genders.[10] The varied association can be attributed to issues related to access and uptake of

services among women in the state of Telangana. There is some evidence for this from other

studies where utilization of eye care services is reported. The studies on barriers have shown

a decline in the proportion of people who reported accessibility as a barrier for the uptake of

eye care services in Andhra Pradesh.[17] Studies have also reported a higher prevalence of

spectacles among rural women compared to men, suggestive of higher uptake of services.[18]

In many community settings, literacy can be considered as a surrogate measure for the socio-

economic status of an individual. We found that those who were educated had lower odds of

having VI. It is possible that those who were educated had better awareness, affordability and

access to eye care services compared to their uneducated counterparts.[17] This can also

partly be attributed to higher visual demands among those who were educated. It also may be

due to varying levels of perception of ‘felt need’ among those with and without any

education. We found that those who were using spectacles at the time of examination were

less likely to have VI which was an expected finding.

The national programme for the prevention of blindness (NPCB) in India has been proactive

in providing cataract surgery through various non-government organizations across the

country.[11, 19, 20] There has been a steady increase in the number of cataract surgeries over

the years;[21] however, the proportion of surgeries that are sight restoring is not known. Also

the regional disparities in availability and accessibility of services could be the possible

reasons for the huge burden of VI despite numerous efforts.[22, 23] There is also an

increasing proportion of the elderly population that offsets the blindness prevention

efforts.[22, 23]

A majority of the VI in Telangana is avoidable. Cataract and refractive errors continue to

remain the leading causes of visual impairment in the region though there are regional

variations in the proportion of VI caused due to these two conditions.[10]. Together, cataract

and refractive errors contribute to over 90% of the total VI. From the planning of eye care

services perspective, nine out of every ten people with VI may benefit from either cataract

surgery and/or spectacles in rural Telangana, both of which can be addressed through primary

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and secondary eye care. If these two levels of care are integrated and provide services of high

quality, most of blindness and visual impairment can be eliminated in rural Telangana. A

recent report by the World Bank has identified cataract surgery as one of the essential

surgeries which is cost-effective and feasible for implementation with a significant impact on

an individual.[24]

A large randomly selected representative sample and a high response rate are the strengths of

this study which provides decent external validity to the findings of this study. Extrapolating

the data from this study to the 6.8 million people in the two districts of Mahbubnagar and

Adilabad, there could be at least 300,000 people with VI among those aged 40 years and

older, of whom 270,000 can be helped either by providing cataract surgery or spectacles.

Massive efforts are required to address this huge burden of avoidable VI.

The study protocol and the definitions used to assign causes in this study have a tendency to

over-estimate the prevalence of cataract and refractive errors and underestimate the

prevalence of posterior segment diseases such as glaucoma and diabetic retinopathy. Though

the causes of VI may be prone for misclassification of causes due to the use of these

definitions, the prevalence of VI in itself may not be influenced by this methodology. Despite

this limitation, the data from this study can be used for planning eye care services in the

region. The low cost of the surveys and the use of local resources make such studies

repeatable at regular intervals to access the changing trends in burden of VI over time.

In conclusion, VI continues to remain a challenge in Adilabad and Mahbubnagar districts in

the newly formed state of Telangana, most of which can be addressed by cataract surgery and

spectacles. A multi-pronged approach that can provide quality eye care in rural Telangana

and also remain affordable and accessible is needed to comprehensively address this

challenge of VI in the state of Telangana.

Acknowledgements:

The authors thank the volunteers for their participation in the study. The authors acknowledge

the assistance for Rajesh Challa (vision technicians) in data collection, and thank Mr. D.

Sandeep Rao and Mr. Devichander Chowdry for their logistic support for the study. Prof. Jill

Keeffe is acknowledged for her scientific inputs on the earlier versions of the manuscript.

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The authors also thank Dr. Sreedevi Yadavalli for her language inputs on earlier versions of

the manuscript.

Competing interests:

“We have read and understood BMJ policy on declaration of interests and declare that we

have no competing interests.”.

Funding Support: This work was supported by by Hyderabad Eye Research Foundation,

India and Christoffel Blindenmission (CBM), Germany.

Contributorship Statement: The financial support for this study was provided by

Hyderabad Eye Research Foundation, India. SM conceived the idea, designed and conducted

the study, analysed the data and wrote the manuscript. EK assisted in data collection and

supervised the field activities. RCK and GNR reviewed the earlier version of the manuscripts

and provide the intellectual inputs.

Data Sharing: It is a small study. No additional data available.

REFERENCES

1. Stevens GA, White RA, Flaxman SR, et al. Global prevalence of vision impairment

and blindness: magnitude and temporal trends, 1990-2010. Ophthalmology

2013;120(12):2377-84.

2. Khanna RC, Marmamula S, Krishnaiah S, et al. Changing trends in the prevalence of

blindness and visual impairment in a rural district of India: Systematic observations

over a decade. Indian J Ophthalmol 2012;60(5):492-7

3. Neena J, Rachel J, Praveen V, et al. Rapid Assessment of Avoidable Blindness in

India. PLoS ONE 2008;3(8)

4. WHO. Universal Eye Health: A global action plan 2014-2019, 2013:28.

5. Dandona L. Blindness-control policy and population-based surveys in India, Lancet

1999. 356 Suppl:s25

6. Census. Registrar General and Census Commissioner, Census of India 2011. In:

Ministry of Home Affairs, Government of India, eds. New Delhi, 2011.

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7. Thomas R, Paul P, Rao GN, et al. Present status of eye care in India. Surv

Ophthalmol 2005;50(1):85-101.

8. Rao GN, Khanna RC, Athota SM, et al. Integrated model of primary and secondary

eye care for underserved rural areas: the L V Prasad Eye Institute experience. Indian J

Ophthalmol 2012;60(5):396-400.

9. Rao GN. The Barrie Jones Lecture-Eye care for the neglected population: challenges

and solutions. Eye (Lond) 2015;29(1):30-45.

10. Marmamula S, Narsaiah S, Shekhar K, et al. Visual Impairment in the South Indian

State of Andhra Pradesh: Andhra Pradesh - Rapid Assessment of Visual Impairment

(AP-RAVI) Project. PLoS One 2013;8(7):e70120.

11. Bhaduri G. National Programme for Control of Blindness--a review. Indian journal of

public health 1997;41(1):25-30, 32.

12. Marmamula S, Madala SR, Rao GN. Rapid assessment of visual impairment (RAVI)

in marine fishing communities in South India--study protocol and main findings.

BMC Ophthalmol 2011;11:26.

13. StataCorp. Stata Statistical Software: Release 12. College Station, TX: StataCorp LP.,

2011.

14. Khanna RC, Murthy GV, Giridhar P, et al. Cataract, visual impairment and long-term

mortality in a rural cohort in India: the Andhra Pradesh Eye Disease Study. PLoS One

2013;8(10):e78002

15. Dandona L, Dandona R, Srinivas M, et al. Blindness in the Indian state of Andhra

Pradesh. Invest Ophthalmol Vis Sci 2001;42(5):908-16

16. Dandona R, Dandona L, Srinivas M, et al. Moderate visual impairment in India: the

Andhra Pradesh Eye Disease Study. Br J Ophthalmol 2002;86(4):373-7

17. Marmamula S, Khanna RC, Shekhar K, et al. A population-based cross-sectional

study of barriers to uptake of eye care services in South India: the Rapid Assessment

of Visual Impairment (RAVI) project. BMJ open 2014;4(6):e005125

18. Marmamula S, Khanna RC, Narsaiah S, et al. Prevalence of spectacles use in Andhra

Pradesh, India: rapid assessment of visual impairment project. Clin Experiment

Ophthalmol 2014;42(3):227-34

19. Murthy G, Gupta SK, John N, et al. Current status of cataract blindness and Vision

2020: The right to sight initiative in India. Indian J Ophthalmol 2008;56(6):489-94

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20. Jose R. Present Status of the National Programme for Control of Blindness in India.

Community Eye Health J (India Supplement) 2008;21(65):103 - 04

21. Murthy G, John N, Shamanna BR, et al. Elimination of avoidable blindness due to

cataract: where do we prioritize and how should we monitor this decade? Indian J

Ophthalmol 2012;60(5):438-45.

22. Murthy GV, Gupta SK, Bachani D, et al. Current estimates of blindness in India. Br J

Ophthalmol 2005;89(3):257-60

23. Debas HT, Donkor P, Gawande A, et al. Essential Surgery. Disease Control Priorities,

third edition. Third Edition ed. Washington, DC: World Bank, 2015.

Fig. 1: Map showing the study areas in Adilabad and Mahbubnagar districts in the state

of Telangana

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354x140mm (300 x 300 DPI)

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STROBE 2007 (v4) Statement—Checklist of items that should be included in reports of cross-sectional studies

Section/Topic Item

# Recommendation Reported on page #

Title and abstract 1 (a) Indicate the study’s design with a commonly used term in the title or the abstract 1

(b) Provide in the abstract an informative and balanced summary of what was done and what was found 1

Introduction

Background/rationale 2 Explain the scientific background and rationale for the investigation being reported 2

Objectives 3 State specific objectives, including any prespecified hypotheses 3

Methods

Study design 4 Present key elements of study design early in the paper 3

Setting 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data

collection

3,4

Participants

6

(a) Give the eligibility criteria, and the sources and methods of selection of participants 3,4

Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if

applicable

3,4

Data sources/

measurement

8* For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe

comparability of assessment methods if there is more than one group

4

Bias 9 Describe any efforts to address potential sources of bias 4

Study size 10 Explain how the study size was arrived at 4

Quantitative variables 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and

why

4

Statistical methods 12 (a) Describe all statistical methods, including those used to control for confounding 6

(b) Describe any methods used to examine subgroups and interactions 6

(c) Explain how missing data were addressed 6

(d) If applicable, describe analytical methods taking account of sampling strategy 6

(e) Describe any sensitivity analyses NA

Results

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Participants 13* (a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility,

confirmed eligible, included in the study, completing follow-up, and analysed

NA

(b) Give reasons for non-participation at each stage 7

(c) Consider use of a flow diagram

Descriptive data 14* (a) Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential

confounders

(b) Indicate number of participants with missing data for each variable of interest

Outcome data 15* Report numbers of outcome events or summary measures 7

Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence

interval). Make clear which confounders were adjusted for and why they were included

7

(b) Report category boundaries when continuous variables were categorized 7

(c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period 7

Other analyses 17 Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses 7,8,9

Discussion

Key results 18 Summarise key results with reference to study objectives 10

Limitations 19 Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and

magnitude of any potential bias

12

Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from

similar studies, and other relevant evidence

12

Generalisability 21 Discuss the generalisability (external validity) of the study results 12

Other information

Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on

which the present article is based

14

*Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.

Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE

checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at

http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org.

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Population based assessment of prevalence and causes of visual impairment in the state of Telangana, India – A cross

sectional study using Rapid Assessment of Visual Impairment RAVI) methodology.

Journal: BMJ Open

Manuscript ID bmjopen-2016-012617.R1

Article Type: Research

Date Submitted by the Author: 28-Sep-2016

Complete List of Authors: Marmamula, Srinivas; L V Prasad Eye Institute, Allen Foster Community Eye Health Research Centre, ICARE Khanna, Rohit; L.V.prasad eye institute, Kunuku, Eswararao; L V Prasad Eye Institute, Allen Foster Community Eye Health Research Centre, ICARE Rao, Gullapalli; LV Prasad Eye Institute

<b>Primary Subject Heading</b>:

Ophthalmology

Secondary Subject Heading: Public health, Research methods

Keywords: Cataract and refractive surgery < OPHTHALMOLOGY, PRIMARY CARE,

EPIDEMIOLOGY


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Research Article

Population based assessment of prevalence and causes of visual impairment in the state

of Telangana, India – A cross sectional study using Rapid Assessment of Visual

Impairment RAVI) methodology.

Srinivas Marmamula 1,2,3, 4

, Rohit C Khanna 1,2, Eswararao Kunkunu

1,2,Gullapalli N Rao

1,2,3

1 Allen Foster Community Eye Health Research Centre, Gullapalli Pratibha Rao -

International Centre for Advancement of Rural Eye care, L V Prasad Eye Institute,

Hyderabad, India

2 Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India

3Brien Holden Institute of Optometry and Vision Science, L V Prasad Eye Institute,

Hyderabad, India

4Wellcome trust / Department of Biotechnology India Alliance research fellow, L V Prasad

Eye Institute, Hyderabad, India

Running Title: Visual Impairment in Telangana, India

Article Type: Research article

Key words: Visual impairment, Cataract, Refractive Errors, India, rapid assessment

Corresponding author:

Dr. Srinivas Marmamula

Gullapalli Pratibha Rao - International Centre for Advancement of Rural Eye care,

L V Prasad Eye Institute,

Hyderabad, India. 500034

Email: [email protected]

Total number of words: 3162 words excluding title page, abstract, acknowledgements,

references, and tables

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Objective: To assess the prevalence and causes of visual impairment (VI) among a rural

population aged 40 years and older in the state of Telangana in India.

Design: Population based cross sectional study

Setting: Districts of Adilabad and Mahbubnagar in south Indian state of Telangana, India

Participants: A sample of 6150 people was selected using cluster random sampling

methodology. A team comprising a trained vision technician and a field worker visited the

households and conducted the eye examination. Presenting, pinhole and aided visual acuity

were assessed. Anterior segment was examined using a torchlight. Lens was examined using

distant direct ophthalmoscopy in a semi-dark room. In all, 5881 (95.6%) participants were

examined from 123 study clusters. Among those examined, 2723 (46.3%) were men, 4824


them were using spectacles at the time of eye examination.

Primary Outcome measure: Visual impairment (VI) was defined as presenting visual acuity

< 6/18 in the better eye and it included moderate VI (< 6/18 to 6/60) and blindness (< 6/60).

Results: The age and gender adjusted prevalence of VI was 15.0% (95% CI: 14.1 – 15.9). On

applying binary logistic regression analysis, VI was associated with older age groups. The

odds of having VI was higher among women (OR: 1.2; 95% CI: 1.0 – 1.4). Having any

education (OR: 0.4; 95% CI: 0.3 – 0.6) and current use of glasses (OR: 0.19; 95% CI: 0.1 –

0.2) were protective. VI was also higher in Mahbubnagar (OR: 1.0 – 1.5) district. Cataract

(54.7%) was the leading cause of VI followed by uncorrected refractive errors (38.6%).

Conclusion: Visual Impairment continues to remain a challenge in rural Telangana. As over

90% of the VI is avoidable, massive eye care programmes are required to address the burden

of VI in Telangana.

Article summary:

Strengths and limitations of the study

• Population based study design that achieved a good response rate

• Covered two large districts of Telangana in India

• Provided insights on prevalence and causes of visual impairment that can be used for

program planning

• It was a rapid assessment survey hence posterior segment may have been under

estimated.

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India has a large burden of blindness and moderate and severe visual impairment. It was

estimated that over 8.3 million people are blind in India.[1] Of the total population with

moderate and severe visual impairment worldwide, 31% of them are estimated to be in

India.[1] Similar to other regions, a declining trend in the prevalence of visual impairment is

reported in India.[2 3] Most of the global data are derived from regional population-based

surveys that were carried out in recent years, mostly using rapid assessment methods.[1]

The world Health Organization’s recent report on ‘Universal Eye Health: A global action

plan 2014-2019’ highlights the need for regional surveys to generate evidence on the

magnitude and causes of visual impairment.[4] It also recommends that the member states

target 25% reduction in the prevalence of visual impairment from 2010 baseline.[4] This

underscores the importance of periodic regional surveys as a mechanism to understand both

the burdens and the trends in the prevalence of visual impairment over time and to plan

strategies to address it.[5]

The state of Telangana was separated from Andhra Pradesh as the new 29th state of India in

2014. This newly formed state comprises ten districts and has a population of 35.2 million

people as per the 2011 census.[6] The combined population of the two districts of Adilabad

and Mahbubnagar was 6.8 million.[6] Mahbubnagar is the largest district in the state and is

closer to the capital Hyderabad. It has the highest proportion of rural population (85%)

compared to other districts including Adilabad (72%). The overall proportion of rural

population in Telangana is 69%. The literacy rate in the rural population in Mahbubnagar

district (52%) is lower compared to Adilabad district (55.7%), both of which are lower than

the state average.[6]

Like other districts in the state, the health care facilities in general, and eye care facilities in

particular are confined to large towns.[7] A few non-governmental organizations provide eye

care services through ‘outreach’ screening camps in Mahbubnagar district and the

government run hospital at Adilabad also provides eye care including cataract surgeries. L V

Prasad Eye institute (LVPEI), a major eye care service provider based in Hyderabad has

established a rural network of eye care centres in both these districts.[8] In Adilabad, two

secondary eye care centres (the first in 1996 and the second in 2005), followed by 19 primary

eye care centres (vision centres) were established. In Mahbubnagar, a secondary centre was

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established in 1998 followed by the establishment of ten primary eye care centres. In both the

districts, the LVPEI rural eye care network is one of the largest eye care service providers,

offering cataract surgeries.[9]

We undertook a population based study using Rapid Assessment of Visual Impairment

(RAVI) methodology among the population aged 40 years and older in the two districts of

Telangana - Adilabad and Mahbubnagar (Figure 1) to assess the prevalence, causes and risk

factors for visual impairment in these districts These two districts were also sites for

population based studies in the past. We also plan to repeat the survey in the same districts

every 5-10 years to assess the trends in the prevalence of visual impairment over time.

METHODS

The Institutional Review Board (IRB) of Hyderabad Eye Research Foundation, L V Prasad

Eye Institute, Hyderabad, India, approved the study protocol. This study adhered to the tenets

of the Declaration of Helsinki. Verbal informed consent was obtained from each subject after

explaining the study procedures and before starting the eye examination.[10] Permission was

obtained from the head of the each village before starting the data collection. At the

household level, the study procedures were explained to each individual, and oral consent

was obtained in the presence of fellow family members and another individual who did not

belong to the same family, or was a neighbor. Data collection for the project was carried out

from February to April in Adilabad, and October to December 2014 in Mahbubnagar district.

Definitions

The Indian definitions for categories of visual impairment (VI) were used.[11] According to

this, blindness is defined as presenting VA worse than 6/60 in the better eye. Moderate Visual

Impairment (MVI) was defined as presenting VA worse than 6/18 to 6/60 in the better eye.

VI is used as generic term which includes both blindness and MVI. We used the same case

definitions for the causes of VI as reported in our previous studies.[10 12] In short, cataract

was defined as the presence of white opacity in the pupillary area on torch light examination

and/or presence of dark shadow on distance direct ophthalmoscopy in dim light causing a VI.

Refractive error is defined as presence of presenting VA worse than 6/18 and improving to

6/18 or better with a pinhole. Posterior segment disease is considered as the cause of VI in

cases where there was no media opacity and visual acuity did not improve with a pinhole.

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The causes of VI were first recorded for each eye separately and then mapped to the person.

Where there was more than once cause, the condition that could be most easily corrected or

treatable was considered as the cause for visual impairment.

Sampling method

The Rapid Assessment of Visual Impairment (RAVI) methodology was used in this study.[10

12] The sample size was calculated based on an estimated prevalence of blindness of 6%,

with 20% precision, 95% confidence intervals and a design effect of 1.5 for cluster size of

50.[10] The minimum sample size needed, including an inflation of 20% to account for non-

response, was 2800 subjects in each district.

In total, 123 study clusters within a distance of 60 kilometers from the two secondary centres

of LVPEI in Mudhol (sub-district) in Adilabad district and Thoodukurthy (Nagarkurnool sub-

district) in Mahbubnagar district were selected using the cluster random sampling method.

[10] In the first stage, study clusters were randomly selected based on population

proportionate to size. In the second stage, in each of the randomly selected clusters, compact

segment sampling method was used to select the households. In each cluster 50 participants

aged 40 years and older were enumerated and also those available were examined by trained

teams of vision technicians. The visits to the clusters were made during the time when the

most number of people were likely to be available, as in early mornings and evenings. At

least two attempts were made for those who were not available at first visit. The participants

who were not available after multiple visits were marked as ‘non available’ participants and

were not substituted.

Eye Examination

In total, three study teams, each comprising one trained vision technician and a community

eye health worker, participated in the data collection. All three teams underwent rigorous

training in the study procedures. A reliability study was set-up before the data collection

where 40 subjects were examined by the gold standard optometrist and the three vision

technicians. A minimum agreement of 0.7 kappa was achieved for distance and near vision

testing and lens examination. After the training, the teams visited the selected households and

conducted eye examinations. The detailed examination procedure is described in our previous

publication.[10]

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In short, the eye examination included demographic and ocular history, visual acuity

(unaided, pinhole and aided, if applicable) for distance and near, anterior segment

examination and distant direct ophthalmoscopy. All the participants who had visual

impairment were referred to the nearest secondary centre for management and services.

Visual acuity was assessed at a distance of six meters using a standard Snellen chart with

tumbling E Optotypes in ambient lighting conditions, usually in shade outdoors. Unaided

visual acuity was recorded first, if VA is worse than 6/12, VA assessment was repeated with

a pinhole. Aided visual acuity was recorded, if a subject reported using spectacles. Right eye

was assessed first. After VA assessment, anterior segment was examined using oblique

illumination with a torch light. Distant direct ophthalmoscopy was done from a distance of

one meter in semi dark conditions (indoors) to assess the media opacities such as corneal

scars covering the pupil, cataract and posterior capsular opacification, if cases operated for

cataract.

Data Analysis

Data were initially collected on RAVI data collection forms and entered into a database

created in Microsoft Access. Regular consistency checks were performed. Data analysis was

performed using Stata Statistical software v12. Chicago, IL.[13] Student’s t test was used to

compare means and chi-squared test was used to compare proportions. The prevalence

estimates are presented with 95% confidence intervals (CI). The prevalence estimates were

adjusted to the age and gender population distribution of rural Andhra Pradesh as per 2011

census.[6] Indirect method of adjustment was used. The demographic associations of VI with

age, gender, education, area of residence were assessed using binary logistic regression

analysis. The model fit was assessed using Hosmer-Lemeshow test for goodness of fit.

RESULTS

Sample characteristics

In all, 5881/6150 (95.6%) enumerated participants were examined from 123 study clusters in

Adilabad and Mahbubnagar districts. Among those examined, 2723 (46.3%) were men, 4824


them were using spectacles at the time of eye examination. Among those not examined, 108

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(40.1%) were men, 142 (52.8%) were women and data were not available for 19 (0.3%)

participants. The mean age of those examined in Mahbubnagar was higher when compared

to those at Adilabad (53.7 years versus 51.9; p<0.01). In Adilabad district, 47.9% of those

examined were in 40 to 49 years age group compared to 42.9% in Mahbubnagar. Except for

those in 50-59 year age groups, the proportion of subjects in other age groups varied

significantly in both the districts. Participation of men and women was similar in both the

districts (p=0.272); however, a higher proportion of those examined were educated in

Mahbubnagar district (23.6%) compared to Adilabad district (12.4) (p<0.01) (Table 1).

Table 1: Personal and demographic characteristics of the participants stratified by

districts

Adilabad

district

Mahbubnagar

district Total

p

value*

Age group (years)

40 - 49 1424 (47.9) 1247 (42.9) 2671 (45.4) <0.01

50 - 59 796 (26.8) 732 (25.2) 1528 (26.0) 0.166

60 - 69 526 (17.7) 605 (20.8) 1131 (19.2) <0.01

70 & above 228 (7.7) 323 (11.1) 551 (9.4) <0.01

Gender

Male 1356 (45.6) 1367 (47.0) 2723 (46.3) 0.272

Female 1618 (54.4) 1540 (53.0) 3158 (53.7)

Education level

No education 2604 (87.6) 2220 (76.4) 4824 (82.0) <0.01

Any education 370 (12.4) 687 (23.6) 1057 (18.0)

Total 2974 (100.0) 2907 (100.0) 5881 (100.0)

*Significance test comparing the proportions in Adilabad and Mahbubnagar districts

Visual impairment

Overall, VI was present in 741 individuals. The age and gender adjusted prevalence of VI

was 15.0% (95% CI: 14.1 – 15.9). The prevalence of VI was16.2% (95% CI: 14.9 - 17.6) in

Mahbubnagar compared to 13.7% (95% CI: 12.5 - 15.0) in Adilabad district. Both MVI and

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blindness were higher in Mahbubnagar district compared to Adilabad but the difference was

not statistically significant (Table 2). Based on World Health Organization definition, the

prevalence of blindness defined as presenting visual acuity worse than 3/60 in the better eye

was 1.7% (95%: 1.4 – 2.1).

Among the sub-sample of those aged 50 and older, the age and gender adjusted prevalence of

VI was 23.5% (95% CI: 22.1 – 25.0). It was 25.1% (95% CI: 23.0 – 27.3) in Mahbubnagar

compared 21.9% (95% CI: 19.8 – 24.0) in Adilabad district. Similar to those aged 40 years

and older, both MVI and blindness were higher in Mahbubnagar compared to Adilabad;

however this was not statistically significant (Table 2).

Table 2: Age and gender adjusted prevalence of visual impairment in Adilabad and

Mahbubnagar districts in Indian state of Telangana

MVI Blindness All Visual

impairment

Prevalence (95%

CI)

Prevalence (95%

CI)

Prevalence (95%

CI)

People ≥ 40 years

Adilabad 10.4 (9.3 - 11.5) 3.3 (2.7 - 4.0) 13.7 (12.5 - 15.0)

Mahbubnagar 12.1 (10.9 - 13.3) 4.1 (3.5 - 5.0) 16.2 (14.9 - 17.6)


People ≥50 years

Adilabad 16.6 (14.8 - 18.5) 5.3 (4.2- 6.5) 21.9 (19.8 - 24.0)

Mahbubnagar 18.6 (16.8 - 20.5) 6.5 (5.4 - 7.8) 25.1 (23.0 - 27.3)


On applying binary logistic regression analysis, VI increased with increasing age. Compared

to those aged 40 – 49 years, the odds of VI increased to 8.3 (95%CI: 5.7 – 11.9) in 50 – 59

years age group, 32.3 (95% CI: 22.7 – 46.0) in 60 – 69 year age group and 96.4 (95% CI:

66.0 – 140.6) in those aged 70 years and older. The odds of having VI was higher among

women (OR:1.2; 95% CI: 1.0 – 1.4) compared to men though it was of borderline

significance. Having any education (OR: 0.4; 95% CI: 0.3 – 0.6) and current use of glasses

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(OR: 0.19; 95% CI: 0.1 – 0.2) were protective.VI was also higher in Mahbubnagar (OR: 1.0 –

1.5) compared to Adilabad district (Table 3).

Table 3: Effect of socio-demographic variables on prevalence of visual impairment

using binary logistic regression analysis

Adjusted Odds

Ratio 95% CI P value

Age group (years)

40 - 49 1.0

50 - 59 8.3 5.8–12.0 <0.01

60 - 69 32.3 22.7– 46.0 <0.01

70 & above 96.4 66.1 - 140.6 <0.01

Gender

Male 1.0

Female 1.2 1.0 - 1.4 0.06

Education

No Education 1.0

Any Education 0.4 0.3 - 0.6 <0.01

Spectacles use for distance

No 1.0

Yes 0.2 0.1 - 0.2 <0.01

Area

Adilabad district 1.0

Mahbubnagar district 1.2 1.0 - 1.5 0.02

Table 4 shows the causes of VI stratified by districts. Overall, cataract (54.7%) was the

leading cause of VI followed by uncorrected refractive errors (38.6%). The causes of VI

differed significantly in both the districts. The VI caused due to cataract was 59.2% in

Adilabad district compared to 51.4% in Mahbubnagar (p=0.04). Similarly, VI due to

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refractive errors was 32.7% in Adilabad against 42.8% in Mahbubnagar (p=0.01). Other

causes of VI were similar in both the regions.

Table 4: Causes of visual impairment stratified by district

Adilabad

(n=309)

Mahbubnagar

(n=432)

Both areas

combined

(n=741)

p values

% % %

Cataract 59.2 51.4 54.7 0.04

Refractive Error 32.7 42.8 38.6 0.01

Posterior segment disorders 5.2 3.2 4.0 0.19

Corneal opacity 1.9 0.9 1.3 0.23

Cataract Surgical

complications 0.3 1.2 0.8 0.21

Phthisis or absent globe 0.6 0.5 0.5 0.74

Total 100.0 100.0 100.0

Discussion

We reported the prevalence and causes of VI from two large districts in the newly formed

state of Telangana in India. Telangana has witnessed few population based studies in the last

decade and half, some of which were conducted using rapid assessment survey methods. The

prevalence of MVI and blindness across various rapid assessment studies carried out in the

state of Telangana are shown in Table 5.

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Table 5: Prevalence of visual impairment in various rapid assessment studies in

Telangana

Study / Area Year Sample

size

Moderate

Visual

Impairment

Blindness All visual

impairment

RACSS, Adilabad[2] 2007 2160 13.6% 8.0% 21.6%

RAVI (Warangal)[10] 2011 - 12 1357 12.5% 9.7% 22.2%

RAVI (Khammam)[10] 2011 - 12 1191 17.1% 9.2% 26.3%

Present study - Adilabad 2014 1550 16.6% 5.3% 21.9%

Present study -

Mahbubnagar 2014 1660 18.6% 6.5% 25.1%

The overall prevalence of VI found in the present study were comparable with the earlier

studies in Warangal and Khammam districts; however the proportion of MVI and blindness,

which by definition sum up to the given VI, differed.[10] In the present study, the prevalence

of MVI and blindness were 11.3% and 3.7% respectively whereas the corresponding

prevalence of MVI and blindness in the previous study was 8.5% and 5.1% respectively.[10]

While the prevalence of MVI was higher, the prevalence of blindness was lower.

These differences in the contribution of MVI and blindness towards VI can be attributed to

differences in demographic profiles, availability and accessibility of services across the

districts. We also found differences in the prevalence of VI in Adilabad and Mahbubnagar

districts, again suggesting a difference in availability and uptake of services. Other socio-

demographic factors may also be influencing this. For example, high levels of migration were

found in Mahbubnagar compared to Adilabad district.[14] And also the proportion of rural

population is higher in Mahbubnagar compared to Adilabad district. A higher prevalence of

MVI and lower prevalence of blindness may also reflect an early trend where people with

more severe levels of VI (blindness) are utilizing the services more than that in the past. This

trend may also be attributed to the availability of good quality services in the form of

secondary centres and vision centres in the vicinity as these are the largest service providers

in the region.[6]

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The nation-wide survey conducted in 2008 in India found the prevalence of blindness and

moderate VI as 8% and 16.8% respectively.[3] Another study from two districts in Telangana

found 9.5% blindness and 14.7% moderate visual impairment.[10] Both those studies

included only those who were aged 50 years and older. In the same age group (≥50 years), we

found blindness and moderate VI as 5.8% and 17.2% respectively. There seem to be a large

variation in prevalence of VI across the country and also within the districts in the state of

Telangana as noted in the preceding discussion.[10]

It is well known that the prevalence of VI is higher in older age groups and we had similar

findings in our study.[15] The association between gender and VI varied across the studies in

India. In our study, the association between gender and VI were of borderline significance.

Earlier studies found a significantly higher proportion of VI among women.[3 15 16] Another

recent study from the same state reported a similar prevalence of VI in both the genders.[10]

The varied association can be attributed to issues related to access and uptake of services

among women in the state of Telangana. There is some evidence for this from other studies

where utilization of eye care services is reported. The studies on barriers have shown a

decline in the proportion of people who reported accessibility as a barrier for the uptake of

eye care services in Andhra Pradesh.[17] Studies have also reported a higher prevalence of

spectacles among rural women compared to men, suggestive of higher uptake of services.[18]

In many community settings, literacy can be considered as a surrogate measure for the socio-

economic status of an individual. We found that those who were educated had lower odds of

having VI. It is possible that those who were educated had better awareness, affordability and

access to eye care services compared to their uneducated counterparts.[17] This can also

partly be attributed to higher visual demands among those who were educated. It also may be

due to varying levels of perception of ‘felt need’ among those with and without any

education. We found that those who were using spectacles at the time of examination were

less likely to have VI which was an expected finding.

A majority of the VI in Telangana is avoidable. Cataract and refractive errors continue to

remain the leading causes of visual impairment in the region though there are regional

variations in the proportion of VI caused due to these two conditions.[10]. Together, cataract

and refractive errors contribute to over 90% of the total VI. From the planning of eye care

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services perspective, nine out of every ten people with VI may benefit from either cataract

surgery and/or spectacles in rural Telangana, both of which can be addressed through primary

and secondary eye care. If these two levels of care are integrated and provide services of high

quality, most of blindness and visual impairment can be eliminated in rural Telangana. A

recent report by the World Bank has identified cataract surgery as one of the essential

surgeries which is cost-effective and feasible for implementation with a significant impact on

an individual.[19]

Among the various rapid assessment study methods used, Rapid Assessment of Avoidable

Blindness (RAAB) is most commonly used method. However, RAAB examination mandates

ophthalmologist to conducted fundus examination with a direct ophthalmoscope in cases of

visual impairment, availability of ophthalmologist in the field can be hurdle in certain

situations. Morever, RAAB provides very limited information on spectacle use, spectacle

provider and spectacle coverage which are important indicators for primary eye care models

such as vision centres. We used RAVI methodology as it can provide vital indicators on

primary eye care programmes, it is faster and less expensive than RAAB. Sampling

methodology is both RAAB and RAVI are similar.

A large randomly selected representative sample and a high response rate are the strengths of

this study which provides decent external validity to the findings of this study. Extrapolating

the data from this study to the 6.8 million people in the two districts of Mahbubnagar and

Adilabad, there could be at least 300,000 people with VI among those aged 40 years and

older, of whom 270,000 can be helped either by providing cataract surgery or spectacles.

Massive efforts are required to address this huge burden of avoidable VI.

The study protocol and the definitions used to assign causes in this study have a tendency to

over-estimate the prevalence of cataract and refractive errors and underestimate the

prevalence of posterior segment diseases such as glaucoma and diabetic retinopathy. This

holds true for all rapid assessment methods. Though the causes of VI may be prone for

misclassification of causes due to the use of these definitions, the prevalence of VI in itself

may not be influenced by this methodology. Despite this limitation, the data from this study

can be used for planning eye care services in the region. The low cost of the surveys and the

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use of local resources make such studies repeatable at regular intervals to access the changing

trends in burden of VI over time.

In conclusion, VI continues to remain a challenge in Adilabad and Mahbubnagar districts in

the newly formed state of Telangana, most of which can be addressed by cataract surgery and

spectacles. A multi-pronged approach that can provide quality eye care in rural Telangana

and also remain affordable and accessible is needed to comprehensively address this

challenge of VI in the state of Telangana.

Acknowledgements:

The authors thank the volunteers for their participation in the study. The authors acknowledge

the assistance for Rajesh Challa (vision technician) in data collection, and thank Mr. D.

Sandeep Rao and Mr. Devichander Chowdry for their logistic support for the study. Prof. Jill

Keeffe is acknowledged for her scientific inputs on the earlier versions of the manuscript.

The authors also thank Dr. Sreedevi Yadavalli for her language inputs on earlier versions of

the manuscript.

Competing interests:

“We have read and understood BMJ policy on declaration of interests and declare that we

have no competing interests.”

Funding Support: This work was supported by Hyderabad Eye Research Foundation, India

and Christoffel Blindenmission (CBM), Germany.

Contributorship Statement: The financial support for this study was provided by

Hyderabad Eye Research Foundation, India. SM conceived the idea, designed and conducted

the study, analysed the data and wrote the manuscript. EK assisted in data collection and

supervised the field activities. RCK and GNR reviewed the earlier version of the manuscripts

and provide the intellectual inputs.

Data sharing statement

It is a small study. No additional data available.

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REFERENCES

1. Stevens GA, White RA, Flaxman SR, et al. Global prevalence of vision impairment and

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trends in the prevalence of blindness and visual impairment in a rural district of India:

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3. Neena J, Rachel J, Praveen V, Murthy GVS. Rapid Assessment of Avoidable Blindness in

India. PLoS ONE 2008;3(8).

4. WHO. Universal Eye Health: A global action plan 2014-2019, 2013:28.

5. Dandona L. Blindness control in India: beyond anachronism. Lancet 2000;356 Suppl:s25

6. Census. Registrar General and Census Commissioner, Census of India 2011. In: Ministry

of Home Affairs, Government of India, eds. New Delhi, 2011.

7. Thomas R, Paul P, Rao GN, Muliyil JP, Mathai A. Present status of eye care in India. Surv

Ophthalmol 2005;50(1):85-101.

8. Rao GN, Khanna RC, Athota SM, Rajshekar V, Rani PK. Integrated model of primary and

secondary eye care for underserved rural areas: the L V Prasad Eye Institute

experience. Indian J Ophthalmol 2012;60(5):396-400.

9. Rao GN. The Barrie Jones Lecture-Eye care for the neglected population: challenges and

solutions. Eye (Lond) 2015;29(1):30-45.

10. Marmamula S, Narsaiah S, Shekhar K, Khanna RC, Rao GN. Visual Impairment in the

South Indian State of Andhra Pradesh: Andhra Pradesh - Rapid Assessment of Visual

Impairment (AP-RAVI) Project. PLoS One 2013;8(7):e70120.

11. Bhaduri G. National Programme for Control of Blindness--a review. Indian journal of

public health 1997;41(1):25-30, 32

12. Marmamula S, Madala SR, Rao GN. Rapid assessment of visual impairment (RAVI) in

marine fishing communities in South India--study protocol and main findings. BMC

Ophthalmol 2011;11:26.

13. StataCorp. Stata Statistical Software: Release 12. College Station, TX: StataCorp LP.,

2011.

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mortality in a rural cohort in India: the Andhra Pradesh Eye Disease Study. PLoS One

2013;8(10):e78002 .

15. Dandona L, Dandona R, Srinivas M, et al. Blindness in the Indian state of Andhra

Pradesh. Invest Ophthalmol Vis Sci 2001;42(5):908-16

16. Dandona R, Dandona L, Srinivas M, et al. Moderate visual impairment in India: the

Andhra Pradesh Eye Disease Study. Br J Ophthalmol 2002;86(4):373-7

17. Marmamula S, Khanna RC, Shekhar K, Rao GN. A population-based cross-sectional

study of barriers to uptake of eye care services in South India: the Rapid Assessment

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Fig. 1: Map showing the study areas in Adilabad and Mahbubnagar districts in the state

of Telangana

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354x140mm (300 x 300 DPI)

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STROBE 2007 (v4) Statement—Checklist of items that should be included in reports of cross-sectional studies

Section/Topic Item

# Recommendation Reported on page #

Title and abstract 1 (a) Indicate the study’s design with a commonly used term in the title or the abstract 1

(b) Provide in the abstract an informative and balanced summary of what was done and what was found 1

Introduction

Background/rationale 2 Explain the scientific background and rationale for the investigation being reported 2

Objectives 3 State specific objectives, including any prespecified hypotheses 3

Methods

Study design 4 Present key elements of study design early in the paper 3

Setting 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data

collection

3,4

Participants

6

(a) Give the eligibility criteria, and the sources and methods of selection of participants 3,4

Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if

applicable

3,4

Data sources/

measurement

8* For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe

comparability of assessment methods if there is more than one group

4

Bias 9 Describe any efforts to address potential sources of bias 4

Study size 10 Explain how the study size was arrived at 4

Quantitative variables 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and

why

4

Statistical methods 12 (a) Describe all statistical methods, including those used to control for confounding 6

(b) Describe any methods used to examine subgroups and interactions 6

(c) Explain how missing data were addressed 6

(d) If applicable, describe analytical methods taking account of sampling strategy 6

(e) Describe any sensitivity analyses NA

Results

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Participants 13* (a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility,

confirmed eligible, included in the study, completing follow-up, and analysed

NA

(b) Give reasons for non-participation at each stage 7

(c) Consider use of a flow diagram

Descriptive data 14* (a) Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential

confounders

(b) Indicate number of participants with missing data for each variable of interest

Outcome data 15* Report numbers of outcome events or summary measures 7

Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence

interval). Make clear which confounders were adjusted for and why they were included

7

(b) Report category boundaries when continuous variables were categorized 7

(c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period 7

Other analyses 17 Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses 7,8,9

Discussion

Key results 18 Summarise key results with reference to study objectives 10

Limitations 19 Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and

magnitude of any potential bias

12

Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from

similar studies, and other relevant evidence

12

Generalisability 21 Discuss the generalisability (external validity) of the study results 12

Other information

Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on

which the present article is based

14

*Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.

Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE

checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at

http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org.

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BMJ Open€¦ · The world Health Organization’s recent report on ‘Universal Eye Health: A global action plan 2014-2019’ highlights the need for regional surveys to generate