Cataract Prevalence and Its Associated Factors among Adult People Aged 40 Years and above in South Ari District, Southern Ethiopia

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Background
In the 10 th revision of the WHO International Statistical Classifcation of Diseases, Injuries, and Causes of Death, "Blindness" is defned as visual acuity of less than 3/60, or a corresponding visual feld loss to less than 10 °, in the better eye with the best possible correction.In view of the proportion of treatable eye diseases or treatable causes of blindness, such as cataract, trachoma, onchocerciasis, and some eye conditions in children, it was estimated that 75% of all blindness in the world could have been avoided [1].
Worldwide, 285 million people are estimated to be visually impaired: 39 million are blind, and 246 have low vision.Cataract is responsible for almost half of the global blindness.About 90% of the world's visually impaired lives in low-income countries.Of those people living with blindness, 82% are aged 50 and above; this group of people represents 19% of the world's population.Te problem is too critical in developing countries, where one blind individual takes two individuals out of the work force, if the blind person requires the care of an able adult [1,2].
In developing countries, cataract accounts for 50% of blindness, while in developed countries, it accounts for only 5% of blindness.In a study done in rural China, the prevalence of posterior subcapsular cataract was found to be 4.4% [3].In Indonesia, the prevalence of blindness due to cataract was 0.78% [4].In India, cataract was responsible for causing blindness in 0.73% of the population [5].In Pakistan, cataract is causing bilateral blindness in 1.75% of the population [6].
In many African countries, cataract is the leading cause of blindness [7].In a study done in Nigeria, cataract is responsible for causing 44.2% of the total blindness [8].By the same way, in Kenya, cataract is the leading causes of blindness and causes 42.9% of the blindness's [9].In Sudan, cataract by far causes 60% of the blindness, and it is among the highest in Africa [10].In a study done in Cape Town of South Africa, cataract is responsible for causing 27% of the total blindness [11].In Ethiopia, cataract is responsible for causing 49.9% of the blindness among the total 1.6% blind people [12][13][14].
Te WHO in its Vision 2020 "the right to sight" aims to eliminate blindness due to cataract by creating demand for the service, developing and mobilizing local man power and resources to provide cataract services, promoting services at a cost that all patients can aford, promoting services that are close to the community, and by creating good partnership between government and nongovernmental organizations.Even though there are lots to be done, Ethiopia launched Vision 2020 initiative in September 2002 [1,12].

Study Area and Period.
Te study was conducted from September to October 2021 in South Ari district of South Omo Zone, Southern Ethiopia.South Omo Zone is one of the 15 zones found in the SNNPR, with 8 rural districts and 1 town administration.According to the census projection for 2017, there are 783,264 residents living in the zone with diverse ethnic groups.South Ari district is one of the 8 districts found in the South Omo Zone having 255,361 residences in 2017.Te zone is 750 km and 525 km far from Ethiopian capital Addis Ababa and regional capital Hawassa in southwest direction.Te Secondary Eye Care Unit of Jinka General Hospital is the only cataract-related servicedelivering institution in the zone.

Study Design.
A community-based cross-sectional study design was used.

Population
Source population: all adult population aged 40 years and above found in South Ari district of South Omo Zone Study population: all adult population aged 40 years and above found in the selected kebeles of South Ari district of South Omo Zone Inclusion criteria: all adults aged 40 years and above found in the selected kebeles of South Ari district and who reside in the area for a minimum of six months before the study period Exclusion criteria: individuals who were seriously ill during the study period and do not hear 2.4.Sample Size Determination and Sampling Procedure 2.4.1.Sample Size Determination.Te sample size was determined using the double population formula by using Epi.info version 7, 1 : 1 ratio, and 80% power.Te sample size is determined by assuming cataract prevalence of 3.64% taken from a study done on low vision and blindness on adults above 40 years of age in Gurage zone, central Ethiopia, giving any particular outcome to be within 2% marginal error to increase sample size and 95% confdence interval of certainty [14] (see Table 1).
Te sample size was obtained from one objective in which prevalence of cataract was 333.It was multiplied by 10% for nonresponse rate.Te total sample size was 366, which is greater than the second objective sample size.So, 366 was the sample size of the study.

Sampling Procedure.
A simple random sample selection procedure was applied.From the 50 kebeles found in South Ari district, 6 kebeles were randomly selected using the lottery method.After the number of adults aged 40 years and above was identifed in each kebele, the sample was proportionally divided among each kebele.Te samples were then selected using the simple random sampling technique (see Figure 1).

Variables. Te dependent variable is the occurrence of cataract (yes/no).
Independent variables are as follows: (i) Sociodemographic factors: sex, age, educational level, occupation (ii) Systemic illnesses: hypertension, diabetes mellitus, arthritis (iii) Current eye condition: visible cloudiness, previous eye surgery (iv) Previous history: trauma to the eye, positive family history

Operational Defnitions
Blindness: visual acuity of less than 3/60, or a corresponding visual feld loss to less than 10 °, in the better eye with the best possible correction [1] Social blindness: visual acuity result of less than 3/60 in the best eye with the best possible correction [1] Economic blindness: visual acuity result of less than 6/ 60 but greater than or equal to 3/60 in the better eye with the best possible correction [1] Low vision: visual acuity of less than 6/18 but equal to or better than 3/60, or a corresponding visual feld loss to less than 20 °, in the better eye with the best possible correction [1] 2 Advances in Public Health Bilateral blindness: a presenting visual acuity of less than 3/60 in the better eye [5] Cataract blindness: a presenting visual acuity of less than 3/60 in the better eye, caused by lens opacity [1] Cataract: visual acuity of less than 3/60 in the better eye that can be explained by clear visual cloudiness [1] Barrier: factors that prevent a patient from accessing care [3] 2.7.Data Collection Tools and Procedures.Te data were collected by using a pretested structured data collection instrument developed from diferent literature studies.Te data were collected in three stages.Te frst stage involved registration of eligible people which incorporated registration of sociodemographic data like age, sex, ethnicity, educational level, religion, and occupation.Te second stage had visual acuity testing of each eye.Te visual acuity was measured using a modifed Snellen's "E" Tumbling chart.All individuals with vision less than 3/60 in one or both eyes proceeded to the third stage, while those with vision of 3/60 or better were not examined further.Te frst and second stages were piloted by two ophthalmic nurses.Te third stage of data collection was conducted by a cataract surgeon.Using a pen torch and direct ophthalmoscope, the eyes were examined for the presence of cataract and their maturity level was graded.Te people with cataract in one or both eyes were asked why they had not had cataract surgery.At the end of the examination, all people with cataract and  Advances in Public Health other treatable blindness were referred for treatment to the nearby Jinka General Hospital Secondary Eye Care Unit.

Data Quality Assurance.
Training was given for both data collectors and supervisor for two days before the pretest and for a day after the pretest on the objective of the study, procedures, and techniques of data collection, review of key terminologies, and ethical issues of the study by the principal investigator.Te data collection checklist was pretested on eighteen adults aged 40 years and above in two rural kebeles found in Jinka town administration having similar geographic and demographic nature with the study setting before the actual data collection to make sure that the questions were clear, consistent, and could easily be understood by the data collectors.Te overall activity of data collection was supervised and coordinated by the principal investigator and trained supervisor.During data collection period, the collected data were checked for completeness and for its consistencies by the principal investigator and supervisor everyday.After data collection, each data collection checklist was checked for completeness and consistency.
2.9.Data Analysis and Presentation.Collected data were entered to Statistical Package for Social Science (SPSS) version 20 for analysis.Descriptive statics was applied to describe variables of the study.In descriptive statistics, tables, graphs, and frequencies were used to present the information.Association of the independent variables with the dependent variables (presence or absence of cataract) was computed using the binary logistic regression model.Bivariate and multivariable analyses were done to identify factors which were statistically signifcant with the development of cataract, and results were presented using COR and AOR with their 95% confdence intervals.Bivariate analysis at signifcance level of 0.25 was included for the multivariate analysis.Te Hosmer and Lemeshow goodnessof-ft test having a P value >0.05 was selected as a candidate for multivariate analysis.Finally, the association of independent variables with the outcome variable was presented using AOR with their 95% confdence interval.

Sociodemographic Characteristics.
A total of 366 adults aged 40 years and above participated in the study with the response rate of 98.1%.Seven (1.9%) individuals were not willing to take the eye examination.Half of the study participants (173 (48.2%)) were in the age range of 40-49 years, followed by those in the age group of 50-59 years who were 94 (26.2%).Sex wise, 197 (54.9%) of participants were male and 162 (45.1%) were females (Table 2).
With respect to ethnicity composition, a vast majority of 344 (95.8%) were Ari followed by Amhara (13 (3.6%)).In terms of educational level 1, 83.8% of the study participants were illiterate.Farming was the leading type of occupation constituting 218 (60.7%) of participates followed by being housewife, 34.8%.Pertaining to religion, 55.2% were protestant and 33.1% were orthodox (Table 2).
Men and women were found to have diferent prevalences of cataract.Accordingly, the prevalence of cataract was found to be 4.57% among men and 11.75% among women.Only 10 (35.7%) of those having cataract have had a surgery prior to the study, while the vast majority did not have.Of those who had a previous eye surgery, 63.6% experienced a cataract surgery and 36.4% experienced a trachomatous trichiasis surgery.
Regarding already known status of systemic illness, a vast majority of 292 (81.3%) reported as having no known history of the commonly recognized systemic illnesses.From those who reported as having a known history of systemic illness, 37 (55.2%) reported as having a known history of Advances in Public Health hypertension and 13 (19.4%)reported as having a known history of diabetes mellitus.A history of trauma to the eye was reported by 33 (9.2%) participants, and 9 (2.5%) reported as having a positive family history of cataract.
From those who were found to have cataract, 10 (35.7%) thought that they had cataract due to age followed by 6 (21.5%) participants who thought cataract is their problem correctly.Te remaining 17.9% considered other diseases as a cause and 7.1% considered natural as the cause of their blindness.Surgery was considered by 8 (28.5%) participants as a remedy followed by 7 (25%) who thought cataract had no treatment (Table 4).

Reason for Failure to Utilize Cataract Surgical Service.
Only 25% (95% CI 10.7-42.9) of those who had cataract had ever tried a surgery for their problem.Te vast majority (75%) failed to try the surgery due to many reasons.Cost was reported repeatedly by 71.4% of participants as a leading cause for failure to try surgery followed by no one to accompany, which was a concern of 52.4% participants.Not knowing where to get the service, too far distance, and no trust on surgery were among the reasons for failure to access surgery, being a disquiet of 23.8%, 19%, and 19% of participants, respectively (Figure 4).

Bivariate Analysis
Result.Accordingly, in the bivariate analysis, the following variables with a p value less than 0.25 were candidates to multivariable analysis: adults aged 80 years and above, female sex, history of hypertension, and trauma to the eye (see Table 5).

Multivariable Analysis Result. Te logistic regression
technique was used to assess the relative efect of the explanatory variable on the outcome variable.To avoid an excessive number of variables and unstable estimates in the subsequent model, only variables with a P value less than 0.25 were kept in the subsequent analyses.Te multivariable analysis result showed that from the total fve variables, four variables were found to have signifcant independent association with cataract.
According the sex of the respondents, females were 3.5 (AOR 3.52; 95% CI: 1.39-8.83)times more likely to develop cataract than males.Individuals with a known history of hypertension were 4.5 (AOR 4.5; 95% CI 1.56-13.21)times more likely to develop cataract than those with no known history of systemic illnesses.Adults in the age group of 70-79 were 5 times (AOR 5.07; 95% CI: 1.09-23.62)and those aged 80 years and above were 6 (AOR 6.01; 95% CI: 1.29-27.92)times more likely to develop cataract than individuals in the age group of 40 to 49 years (see Table 5).

Discussion
Te fnding of this study revealed the prevalence and associated factors of cataract.Te overall prevalence of cataract in this study was 7.8% (95% CI: 5.0-10.6).Te associated factors of cataract in this study were adults aged 80 years and above, female sex, history of hypertension, and trauma to the eye, which were signifcantly associated with cataract.
Te prevalence of cataract in the study area was 7.8% which is relatively higher than the reported prevalence of 6.28% in Kenya and 3.64% in Gurage zone and lower than 13.27% in Sudan and 15% in central Ethiopia [9,10,14,16].Worldwide, the prevalence of cataract among adults aged 40 years and above has been reported to vary between 1.6% and 35.1% by diferent researchers [3,6,15,[17][18][19]. Tere are several factors infuencing the diference in the prevalence between countries and researchers, such as variations in reporting methods and standards.Tere may also be measurement bias and errors in the ascertainment of cataract.
In this study, the prevalence of cataract rises with age from 5.2% in the age group of 40-49 to 21.1% among those aged 80 years and above.Tis fnding is consistent with studies conducted in rural India zone and Gurage [5,14].Women were found to have a higher prevalence of cataract than men.Te result of this study revealed that 11.73% women and 4.57% men had cataract.Tis fnding is consistent with studies done in Pakistan, India, and diferent parts of Ethiopia [5,6,12].
In this study, 67.9% of the reported cataract was bilateral, which is consistent with the reported prevalence of bilateral cataract in Pakistan, which is 61.9% [6].Te majority 71.3% (95% CI: 66.7-75.9) of participants had a visual acuity of ≥6/ 18; and one fourth of the study participants 25.6% had visible cloudiness in their either eye which is consistent with studies done in Sudan and India [10,18].
Surgery was considered as a treatment for cataract by 28.6% of participants of this study; this fnding is relatively higher than similar study fnding in rural India which reported that 13.3% considered surgery as a treatment for their problem [20].Tis may be explained by the time of the study conducted which resulted in the advancement of information communication and expansion of health facilities.
One fourth of the study participants, 25% (95% CI 10.7-42.9),had visited medical care for cataract-related service.Tis fnding is higher than the reported trend of seeking for care among individuals with cataract in Gurage zone (3.5%) and rural India (13%) [14,18].Tis may be Cost related to surgery was reported by 71.4% of the study participants as the main barrier for accessing medical care.Te fndings are comparable with results of many studies conducted in diferent parts of Ethiopia, 67.3% in Gurage and 78.1% in Central Ethiopia [21].Te fnding is also comparable with results of many developing countries: Kenya 46%, Sudan 45.8%, Nigeria 61%, and Pakistan 76.1% [6,10,17].
After adjusting for possible confounders, age is one of the factors associated with the occurrence of cataract.In this study, adults aged 70 years and older were more likely to develop cataract as compared to those aged 40-49 years of age.Te association of age with development of cataract was also noted in several other studies conducted in diferent parts of the world [5,20,22].Tis may be explained by the natural process of protein clump, which is the core component of lens in addition to water, through time.As a person gets older, the protein component of the lens which was arranged in a precise way to keep the lens clear and let light pass through it may clump together and start to cloud the lens which may grow larger with time making it harder to see, leading to faster development of cataract.
Sex has been signifcantly associated with cataract.Being female has signifcant association with the chance of developing cataract.Tis fnding is consistent with the studies done in Gurage, in eight regions of Ethiopia, India, and Pakistan [6,12,14,16,20].Tis may be explained by the poor access and poor health facility utilization trend females had in the area.

Advances in Public Health
In this study, having a known history of hypertension has a statistical signifcant association with the development of cataract.Adults with a known history of hypertension are more likely to develop cataract than those with no known history of hypertension.Tis result is consistent with fnding in Korea [15].Tis may be explained by the vasospasm and ischemic change nature of hypertension on diferent organs of the body.Te eye is one of the sensitive organs to be afected by this change, and development of cataract is the manifestation.

Strengths of the Study.
Te analytic approach and community-based study help to detect the true magnitude and factors and helps to generalize the fnding.

Limitation of the Study.
Factors like the use of steroid, long time exposure to X-ray and UV rays, hepatitis B infection, myopia, and other ocular comorbidities that might contribute to poor vision along with cataract were not assessed during data collection, and thus, their association with cataract was not drawn.

Conclusion and Recommendations
6.1.Conclusion.Generally, the prevalence of cataract among adults aged 40 years and above was high.Te prevalence increased with age.Cataract-related cost was found to be the main barrier to service utilization among patients with cataract.
In this study, respondents' age, sex, result, and known history of hypertension were found to have statistically signifcant association with cataract.Accordingly, older age, female sex, and individuals with a known history of hypertension had a higher chance of developing cataract.6.2.Recommendations 6.2.1.To Woreda District.It is better to improve services like examination room in each health institution and to give information to community.

To Community.
It is better to come to health institutions as early as possible to examine eye problems even if it is cataract or not.

Figure 1 :
Figure 1: Schematic presentation of sampling procedure on prevalence of cataract and associated factors in South Ari district, Southern Ethiopia, in December 2021.

FACTORSFigure 4 :
Figure 4: Factors infuencing individuals with cataract from seeking medication in South Ari, Southern Ethiopia, in December 2021.

Table 1 :
Sample size determination for associated risk factors of cataract among adult people aged 40 years and above in South Ari district, Southern Ethiopia, 2021.

Table 3 :
Visual acuity result of left and right eye of participants in South Ari district, Southern Ethiopia, in December 2021.
Figure 3: Prevalence of cataract with age in South Ari district, Southern Ethiopia, in December 2021.

Table 4 :
Patients view on cause and treatment of cataract in South Ari, Southern Ethiopia, in December 2021 (n � 28).

Table 5 :
Bivariate and multivariable logistic regression analysis of cataract prevalence and factors associated with it in South Ari district, Southern Ethiopia, in December 2017.