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Year : 2018  |  Volume : 7  |  Issue : 1  |  Page : 31-36

Prevalence of visual impairment in adults aged 18 years and above in a rural area of coastal Karnataka

1 Department of Community Medicine, Kasturba Medical College, Manipal, India
2 Department of Community Medicine, SRM University, Chennai, Tamil Nadu, India
3 Department of Community Medicine, K.S. Hegde Medical Academy, Nitte University, Mangalore, Karnataka, India

Date of Web Publication1-Mar-2018

Correspondence Address:
Dr. Chythra R Rao
Department of Community Medicine, Kasturba Medical College, Manipal Academy of Higher Education, Manipal - 576 104, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijhas.IJHAS_102_17

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BACKGROUND: Vision loss and age-related eye diseases are major global public health problems. The burden of visual impairment worldwide varies depending on the methods of assessment. The need for local data on the prevalence of visual impairment in adults coupled with limited resources necessitated the conduct of the study in a limited geographical area.
METHODS: A cross-sectional study was conducted in the field practice area of Department of Community Medicine of a Medical College. Study patients included adults aged ≥18 years, identified through purposive sampling. A semi-structured questionnaire was used to collect sociodemographic data. Snellen's chart for distant vision; reduced Snellen's chart for near vision and Ishihara chart for color vision was used. Data were analyzed using SPSS software version 15.
RESULTS: The study included 411 patients. Nearly 40% of the patients were ≥50 years. Among the patients, 195 (47.4%) had H/o refractive error, 78 (19%) had H/o hypertension, 56 (13.6%) had H/o diabetes, and 43 (10.5%) had H/o cataract. The most common ocular morbidity was arcus senilis 113 (27.5%) and cataract 28 (6.8%). Using Snellen's distant vision chart low vision (<6/18) was present among 91 (22.1%) and 15 (3.6%) had <3/60. Forty percent had low near vision (<N9) and 12 (2.9%) were blind (<N36) by Snellen's near vision chart. Abnormal color vision by Ishihara chart was seen among 3%. The prevalence of distant and near visual impairment was more among unemployed/retired (51.3%; 62.5%), aged ≥60 years (54.7%; 74.2%) and those with H/O chronic diseases (Diabetes –44.6%; 69.6% and hypertension – 48.1%; 65.4%).
CONCLUSIONS: Farsightedness was detected among a quarter of the population, while impaired near vision was detected among two.fifths of the study group. Nearly 7% of patients had cataract and were referred for further evaluation. Advancing age and the presence of comorbidities were significant determinants of visual impairment.

Keywords: Adults, blindness, cataract, rural, visual impairment

How to cite this article:
Rao CR, Shetty RS, Narayanan S S, Kini S, Kamath V, Kamath A. Prevalence of visual impairment in adults aged 18 years and above in a rural area of coastal Karnataka. Int J Health Allied Sci 2018;7:31-6

How to cite this URL:
Rao CR, Shetty RS, Narayanan S S, Kini S, Kamath V, Kamath A. Prevalence of visual impairment in adults aged 18 years and above in a rural area of coastal Karnataka. Int J Health Allied Sci [serial online] 2018 [cited 2022 Jun 28];7:31-6. Available from: https://www.ijhas.in/text.asp?2018/7/1/31/226251

  Introduction Top

The World Health Organization estimates that worldwide there are 45 million people who are blind with an additional 135 million individuals who are visually impaired.[1] Globally, it is known that cataract is the leading cause of blindness, with 16–20 million people suffering from blinding cataract.[2],[3] In country-specific terms, India is the country with the highest number of blind people with an estimate over 9 million individuals, with the most prevalent cause of blindness and low vision being a un-operated cataract, as indicated by several population-based studies over the past two decades.[4],[5],[6],[7] Nationwide blindness prevalence surveys conducted in neighboring countries such as Nepal and Pakistan yielded an all age blindness prevalence rate of 0.8% and 1%, respectively.[8],[9] A subsequent survey in two administrative regions of Nepal identified a blindness prevalence rate of 3% in people 45 years and older.[10]

Accordingly, National Program for control of blindness control in India has focused primarily on Cataract.[11],[12] Although such programs have improved the coverage of cataract surgery, results of the surgery have always not resulted in good postoperative vision outcomes.[12],[13],[14] Undercorrected refractive error is the most common cause of reversible blindness in India.[15] Studies from urban India show that about 49.3 million of those aged 15 years and above may have refractive errors.[16] As refractive errors are a major cause of mild to moderate visual impairment in the population, knowledge of the prevalence of refractive errors would be helpful in planning public health strategy. The rural Indian population differs from the urban in many aspects. There are limited data available on the prevalence of refractive errors in the adult Indian population and few population-based data from the rural population. Data pertaining to blindness and causes of visual impairment is sparse in this part of coastal Karnataka. In this study, we report the prevalence of visual impairment and the effects of various factors affecting visual acuity among adults aged >18 years and above in a rural area of coastal Karnataka.

  Materials and Methods Top

This was a cross-sectional study conducted in a village under the field practice area of Department of Community Medicine, of a Medical College hospital. Situated along the coastal area of Udupi district of Karnataka state, the field practice area under the Department of Community Medicine covers a population of 42,000 living in 8600 families spread out in 12 villages. These villages have a homogenous population in terms of occupation, socioeconomic status, and food habits. Department of Community Medicine provides healthcare services to this population through a network of four Rural Maternity and Child Welfare Centers (RMCW) and one Urban Health Center. These centers are manned by ANM (Auxiliary Nurse Midwives) and run outpatient clinics. The detailed information of the population in the field practice area is documented and updated periodically with the help of field ANM'S in the family folders maintained at the respective RMCW homes.

Institutional Ethical Committee clearance was obtained before initiation of the study. (IEC: 81/2014) Study participants included adults in the age group of ≥18 years and residents, who have been residing for more than 1 year in the survey area. Severely ill and noncooperative patients were excluded from the study. The sample size was calculated based on a study done by Raju et al.[17] with the prevalence of visual impairment being 49.4%. By applying the formula Prevalence = 4pq/d 2, for 10% relative precision a sample size of 410 patients was obtained. Convenient sampling was used to identify the houses in the village. After selection of the houses, house visits were made and individuals satisfying the inclusion criteria and providing written informed consent were included in the study. A team comprising medical students, postgraduates, medico-social workers, and faculty from the Department of Community Medicine were involved in data collection. Teams involved in the survey were trained in survey methods, data collection through interviews, visual inspection, and testing for visual acuity. A semi-structured pre-designed, pretested questionnaire was administered to the patients. The pretesting was done among the subjects visiting the rural health centers for routine care, to check for the ease of administering and nature of questions. The questionnaire comprised of details on sociodemographic variables, awareness about visual impairment and cataract, history of eye problems and history of any surgery to the eye. The vision was tested for each eye. For distant vision simple Snellen's chart [18] was used and for near vision, reduced Snellen's chart was used. People using spectacles were tested both with and without using spectacles. The patient was asked to read the Snellen's chart from a distance of six meters. When the patient was able to read up to the 6 m line, visual acuity was recorded as 6/6 which was considered normal. Similarly, depending on the smallest line which the subject was able to read from a distance of 6 m, his/her vision was recorded as 6/9, 6/12, 6/18, 6/24, 6/36 or 6/60. If he/she was not able to see the top line from a distance of 6 meters, he/she was asked to slowly walk toward the chart till he/she could read the top line. Depending on the distance at which he/she could read the top line, his/her vision was recorded as 5/60, 4/60, 3/60, 2/60 or 1/60. If the subject was unable to read the top line even from a distance of one meter, he/she was asked to count fingers (CF) of the interviewer. His/her vision was recorded as CF-1, CF-2, CF-3, or CF-Close to face. If the patientwas not able to CF, the patientwas asked if he/she can appreciate hand movements. If he can appreciate hand movements (HM), visual acuity was recorded as HM+. When the patient was not able to distinguish hand movements, it was noted whether he/she can perceive light (PL) or not. If the subject was able to PL, the vision was recorded as PL + and if not the vision was recorded as PL−. Categories of visual impairment were graded as shown in [Table 1].
Table 1: Categories of visual impairment according to Snellen's distant vision chart

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For testing near vision, the subject was asked to read the Snellen's near vision chart from a distance of 35 cm from the eyes. Accordingly, the near vision was recorded as N5, N8, N10, N12 or N18. Colour vision was recorded using Ishihara chart. Eyes were also examined to look for Redness, watering, strabismus, arcus senilis, ocular mobility, ptosis and pupillary reaction. Standard case definitions for these common conditions were uniformly used. People who were found to have visual impairment were referred to the Medical College Teaching Hospital for detailed evaluation and further management. Data were analyzed using Statistical Package for the Social Sciences 15.0 (Chicago, SPSS Inc). Prevalence was reported as percentages. Categorical data were summarized as proportions with a percentage. Univariate analysis of the factors associated with visual impairment was done using Chi-Square Test. A value of P < 0.05 was considered to be statistically significant.

  Results Top

A total of 411 patient were surveyed during the study. The sociodemographic details of the study population are depicted in [Table 2]. There were a higher proportion of females as compared to males, due to their availability in the homes during the time of the survey. Their distribution of the study patient across age groups was similar. Three-fourths of them belonged to middle Socioeconomic status, as per the assessment using modified Udai– Pareek scale.
Table 2: Sociodemographic details of the study population (n=411)

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Among the surveyed population, as per the history provided by the subjects 195 (47.4%) had H/o refractive error, 78 (19%) had H/o hypertension, 56 (13.6%) had H/o diabetes, 43 (10.5%) had H/o cataract and 18 (4.4%) H/o eye injury. On visual examination, the most common ocular morbidity found was arcus senilis 113 (27.5%) followed by cataract 28 (6.8%). Pseudophakia (intraocular lens) in either of the eyes was found in 29 (7.1%) of the study population.

Examination for visual impairment revealed that 91 (22.1%) of the study population had low vision (<6/18) and 15 (3.6%) of the study population were blind (<3/60) by using Snellen's distant vision chart. Majority of the study participants 166 (40.4%) had a low near vision ([Table 3] shows the prevalence of visual impairment among the study population.
Table 3: Prevalence of visual impairment among the study population

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As distant and near vision abnormality were the most common visual impairments detected, its association between various patient characteristics were analyzed using Chi-Square test [Table 4]. The prevalence of low distant and near vision was high among illiterates/primary school level education subjects compared to higher level education which was statistically significant (P < 0.0001). The study participants who were unemployed/retired and aged ≥ 60 years had a higher prevalence of low vision (distant and near) compared to others (P < 0.0001). Study participants with H/O chronic diseases like diabetes and hypertension had a higher prevalence of visual impairment compared to normal subjects (P < 0.0001).
Table 4: Association between subject characteristics and visual impairment by Univariate analysis

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  Discussion Top

Visual impairment is a major health problem that greatly limits the mobility as well as the quality of life of individuals. In this community-based study, to assess visual impairment among adults in rural households 22% of the study population had low vision (<6/18) and 3.6% were blind (<3/60) as per Snellen's distant vision chart. Nearly 40% had near vision impairment. In a study conducted by Chandrashekhar et al.[19] in a population similar to the present study, the prevalence of blindness among aged 50 years and above was 6.6%. In the present study, it was observed that the overall prevalence of blindness was 3.6% and 9.3% for distant and near vision, respectively, among participants aged 60 years and above. Vijaya et al.[20] among patients aged ≥40 years documented a prevalence of 15.7%. Differences in the age group of the study could have contributed to the varying prevalence between populations within rural areas of South India. In the present study, 28 (6.8%) participants had cataract, and refractive error (distant or near vision) was found among 200 (48.7%) of the subjects. In a study by Purty et al.[21] cataract was found in 103 (32.1%), and refractive error was identified among 79 (24.6%) individuals aged 60 years and above. Raju et al.[17] reported an unadjusted prevalence of 26.9% myopia and 18.7% hyperopia among the rural population in Tamil Nadu. In this study, low near vision was found in 43% and low distant vision in about 25.7%. Refractive error was the major cause of visual impairment (71.4%), whereas, cataract was the major cause of severe visual impairment and blindness (70.3%), as per the study findings from three tribal areas of Andhra Pradesh.[22] Differences in reported visual impairment are due to the varied methodology employed for data collection. Some authors have documented results as per history obtained from the subjects, whereas some have detailed evaluation by an expert ophthalmology team. Cataract was the leading cause of low vision even in the United States.[23] similar to findings of the RAAB India Study Group [24] The Yazd Eye Study from Iran too, reported the main causes of visual impairment to be cataracts (41.5%), diabetic retinopathy (17%) and age-related macular degeneration (13.8%).[25] In contrast, a community-based survey among participants aged 60 years or older in a rural community in China, reported only 5.4% visual impairment.[26] Cataract is the most leading cause of treatable blindness worldwide followed by age-related diseases and complications secondary to chronic diseases, which has been reflected by the present study similar to other published literature.

In the present study, H/o injury to the eye, refractive error and age were significant predictors of low distant vision. Literacy status, refractive error, and age were identified as significant predictors of low near vision. Study subjects with a history of chronic diseases such as diabetes and hypertension had a higher prevalence of visual impairment compared to normal subjects. Age and female gender have been similarly identified to be associated with visual impairment from, Iran,[25] China,[26] and Poland.[27] Similarly, literacy status was identified to be a significant predictor in studies from Andhra Pradesh [22] and China.[26] Old age coupled with the lack of knowledge on self-care could have contributed to the higher prevalence. Similarly, the need for self-care among patients with chronic diseases is higher, coupled with an inherent predisposition to ophthalmic complications with diabetes and hypertension may have possibly led to the significant association with visual impairment.

Unequal gender representation was a limitation of the study. Three-fourths of the study population were females, due to unavailability of males as the survey timings coincided with the working hours. An obvious limitation of the study design is that; reverse causality cannot be ruled out in cross-sectional studies. Detailed ophthalmic evaluation including an evaluation of intraocular pressure and direct ophthalmoscopy could not be accomplished in the field, and only referral to the tertiary care hospital could be provided. However, an eye camp was held subsequently with the help of local donors and the individuals who were detected to have visual impairment during the survey were evaluated by an optometrist, ophthalmologist team. Spectacles were provided for refractory errors while subjects with cataract were recommended surgery at low cost at the referral hospital.

Visual impairment might affect the daily functioning, especially among elderly individuals with other co-existing comorbidities. In spite of the availability of services, the turnout for referrals made for cataract surgery was poor, indicating the underlying fear, anxiety associated with surgical procedures. Hence, future studies need to identify perceived barriers, underlying cultural factors and attitudes towards availing treatment for visual impairment.

  Conclusions Top

Distant vision was impaired among one-fourth of the study population, while 43% had impaired near vision. Cataract was present among 6.8% of the patients. Higher age, low literacy levels and the presence of comorbidities such as diabetes and hypertension were significantly associated with the presence of visual impairment. This exemplifies the need for early detection and adequate management of avoidable causes of blindness through community ophthalmology services.


We would like to acknowledge the help of the Ophthalmology, Optometry team and local bodies for the conduct of the camp for the visually impaired.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4]

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