Prevalence and causes of ocular morbidity seen among rural adult population of Osun State, southwest Nigeria


Context: World Glaucoma and Kidney Days were planned for community eye/health screening. Aims: To assess the prevalence and causes of common eye disorders and visual impairment (VI) in two rural communities of Osun State. Settings and Design: Descriptive cross-sectional. Materials and Methods: Ethical clearance was obtained. Serial recruitment of all consenting adults presenting at Alajue and Ibokun communities over 2 days was done. Sociodemographic data were obtained. Visual acuity and anterior and posterior segment examinations were done. Refraction was done as necessary. Intraocular pressures (IOPs) were checked for cup:disc ratio >0.6 and perimetry done at base hospital for glaucoma suspects. VI was classified according to the World Health Organization ICD.10. Descriptive analysis was carried out. Chi-square with P-values and 95% confidence intervals (CIs) were used to test for significance. Results: In all, 259 subjects-100 males (38.6%) and 159 females (61.4%)-participated. Mean age was 39.73 years (standard deviation [SD] 16.6). The commonest eye disorders were cataract 67 (25.9% CI: 20.5-31.2), refractive error 66 (25.5% CI: 20.2-30.8), glaucoma 17 (6.6% CI: 3.5-9.6), pterygium 14 (5.4%), conjunctivitis 11 (4.2%), hypertensive retinopathies 10 (3.9%, 95% CI 1.5-6.2), cornea opacities 3 (1.2%), and di glaucoma was abetic retinopathy 2 (0.8%). Glaucoma and IOPs were significantly correlated (P = 0.039). CVF changes and glaucoma was significantly associated (P < 0.001). Prevalence of moderate VI was 73 (28.2%, CI: 22.7-33.7), severe VI 9 (3.5%, CI: 1.2-5.7), and blindness 5 (1.9%, CI: 0.2-3.6). Conclusions: There is need to establish community eye-outreach centres to identify cases for cost-effective cataract, refractive error, and glaucoma services. This could reduce the occurrence of these vision and life-threatening disorders.

Keywords: Adults, ocular morbidity, prevention, rural, screening Key Messages: This cross-sectional rural population survey done showed commonest ocular morbidities such as cataracts, refractive errors, glaucoma, and pterygium. Hypertensive and diabetic retinopathies were also detected. Incorporating eye outreach into community health-centers or primary health care could prevent and ultimately reduce the occurrence of these ocular and life-threatening diseases

How to cite this article:
Isawumi MA, Hassan MB, Asekun-Olarinmoye EO, Akinwusi PO, Adebimpe WO, Alebiosu CO. Prevalence and causes of ocular morbidity seen among rural adult population of Osun State, southwest Nigeria. Ann Trop Med Public Health 2013;6:465-71
How to cite this URL:
Isawumi MA, Hassan MB, Asekun-Olarinmoye EO, Akinwusi PO, Adebimpe WO, Alebiosu CO. Prevalence and causes of ocular morbidity seen among rural adult population of Osun State, southwest Nigeria. Ann Trop Med Public Health [serial online] 2013 [cited 2020 Dec 5];6:465-71. Available from:

A survey reported that over 1,000,000 adults are blind, 3,000,000 are visually impaired, and 42 out of every 1000 adults 40 years of age and above are blind. [1] Overall, two out of three Nigerians are blind from causes which could be avoided, such as cataract, which is the single most common cause of blindness, closely followed by glaucoma. [2] In screening camps, various eye conditions causing ocular morbidity could be seen. These can arise either from anterior segment diseases, e.g., cataracts and corneal opacities, or posterior segment diseases, e.g., optic atrophy, age-related macular degeneration. Refractive errors have also been documented by several authors across the world. [3],[4],[5]

The World Glaucoma Week and the World Kidney Week of 2011 presented an opportunity for members of the College of Health Sciences, Osun State University, to increase people’s awareness on noncommunicable diseases such as kidney problems and glaucoma. This was part of a larger study on assessment of health risks in these communities which led to raising awareness and screening for the commonest noncommunicable diseases such as hypertension, diabetes, kidney diseases, and glaucoma.

The study intended to screen for and identify common eye disorders that could cause visual impairment (VI) or blindness. Strategies could then be advised for their prevention from the primary/community level of care.

This is hoped to help achieve part of the Millennium Development Goals of VISION 2020.

The aims and objectives are to assess the prevalence and causes of ocular morbidity and VI among Alajue and Ibokun communities of Osun State and advice strategies for their prevention.

Materials and Methods

Study area: The screening exercise was carried out at Alajue, a rural community in Ede South Local Government Area of Osun State, and Ibokun, a suburban community in Obokun Local Government Area of Osun State. It is located in the tropical rain forest belt of southwestern Nigeria. The people are mostly farmers.

Study design: A descriptive cross section was utilized.

Study population: Adults resident in these communities.

Sampling technique: The communities for the study sites were chosen purposively, while the participants were selected by serial recruitment of all consenting adults presenting on the day of the screening.

Prescreening Activities

Proper community entry was done through prior visits and discussions with the community leaders, the chiefs, women leaders, and youth leaders. The purpose and the advantages of the free health and eye screening to be carried out were explained to them. Permission to come into the community was thereafter sought and granted. Details of screening procedure and average duration of time for screening test per person were explained. Assurance that participant will not be exposed to any harm was given. A date was agreed upon after the community members were duly informed.

Inclusion criteria: All consenting adults 18 years of age and above who were residents of the communities were eligible for the survey.

Exclusion criteria: All persons less than 18 years of age and not residents of the communities were excluded.

Study instruments: A semistructured questionnaire and data collection form were used to obtain data. Others included Snellen’s visual acuity chart, trial lens box, penlight, batteries, tonometers, macular grid test papers, and ophthalmoscopes

Data collection/survey: Two trained research assistants administered the questionnaire and obtained demographic data such as age, sex, and occupation. Other vital statistics such as height, weight, and blood pressure were also measured. The ophthalmic nurses carried out the measurement of visual acuity (unaided and aided with either glasses or pinhole) in an open and well-illuminated area. This was done from a distance of 6 m, one eye at a time. VI was classified according to the World Health Organization ICD.10.

Any eye that did not see up to 6/9 but improved with pinhole was assessed to be a case of refractive error. Any participant who complained of difficulty in reading or seeing small prints was also sent for refraction. Refraction was carried out by one of the Ophthalmologist using Heine retinoscope after which glasses were prescribed accordingly. Those that could not be attended to were referred to the hospital. The consultant ophthalmologists carried out the examination of the anterior and posterior segments of the eye. Loupes were used to examine the anterior segment. In the posterior segment examination, dilated fundoscopy using 1% Mydriacyl eye drops made by Alcon was carried out where cataract or other pathology prevented a good view of fundus or medium. Heine Beta 200 Binocular Indirect Ophthalmoscope with a 20D lens was used for visualization of vitreous for opacities, bands or traction, and the discs. The optic disc was assessed as normal (if pink), pale, or cupped. The retinal vessels were assessed for copper wiring, silver wiring, tortuosity, engorgement, beading, narrowing, microaneurysms, and dot and blot hemorrhages while the macula was examined for hard exudates, hyperpigmentation, scars, cottonwool spots, and retinal hemorrhages, in cases of hypertensive and diabetic retinopathies. Intraocular pressures (IOPs) were checked using the Perkins handheld applanation tonometer. Where IOP > 22 mmHg and cup:disc ratio >0.6, participants were diagnosed glaucoma suspects. Furthermore, with signs of field defects on perimetry done using the confrontation method, glaucoma suspect was diagnosed. These participants were given antiglaucoma eye drops and referred to the base hospital in Osogbo, where central visual field was done to confirm, determine characteristic glaucomatous changes and for follow-up management.

Any participant who complained of difficulty in reading or seeing small prints was also sent for refraction. Refraction was carried out by one of the ophthalmolgist using Heine retinoscope after which glasses were prescribed accordingly.

Data management: Data was entered into a computer after manual sorting. The Soft Package for Social Sciences version 16 was used to analyze data. Descriptive analysis was used to generate frequency tables, means, and standard deviation. Bivariate analysis of categorical variables was done. The level of significance was derived with chi-square test, confidence interval set at 95% and P value <0.05.

Ethical consideration: Ethical clearance was obtained from the Ethics and Research Committee of the College of Health Sciences, Osun State University, Osogbo.

Written informed consent was also obtained from all participants after thorough explanation of the purpose, procedures, and content of the research.


A total of 259 subjects-100 males (38.6%) and 159 females (61.4%) were seen and screened. Age ranged from 18 to 90 years with a mean of 39.73 years and standard deviation (SD) 16.6 years.

[Table 1] shows the sociodemographic characteristics of the participants.

Table 1: Sociodemographic characteristics of participants

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Visual acuity distribution showed 172 (66.4%) with normal vision, 73 (28.2%) with mild VI, 9 (3.5%) with moderate-to-severe VI, and 5 (1.5%) with unilateral blindness.

In the anterior segment, 14 (5.4%) subjects had pterygia and relative afferent pupillary defect (RAPD) each, while 3 (1.2%) had secclusio papillae. There were three opaque cornea, one with uniform cloudiness and two with central opacities. Conjunctivitis and pterygia were commoner among females. Bilateral cataracts were seen in 6, unilateral in 54 participants, and complicated cataract in 1 participant. A total of three eyes had pseudophakia; 1 unilateral and 1 bilateral. There was only one eye with aphakia. Nobody presented with couching. [Table 2] shows further findings and the prevalence of anterior segment pathologies. Prevalence of moderate VI was 73 (28.2% CI: 22.7-33.7), severe VI 9 (3.5% CI: 1.2-5.7), and the blinds 5 (1.9% CI: 0.2-3.6).

Table 2: Anatomical distribution of anterior segment abnormalities by age group and gender among the participants

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Prevalence of posterior segment pathologies included newly diagnosed glaucoma 17 (6.6% CI: 3.5-9.6), diabetic retinopathy 2 (0.8% 95% CI -0.3 to -1.8), and hypertensive retinopathy 10 (3.9% 95% CI: 1.5-6.2). [Table 3] shows further findings in the posterior segment.

Table 3: Anatomical distribution of posterior segment abnormalities among the participants

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[Table 4] shows the frequency distribution of the IOPs and the significant correlation between the recently diagnosed glaucoma subjects and IOP (χ2 = 0.555, P = 0.039). The mean IOP was 18.64 mmHg (SD 6.81).

Table 4: Frequency distribution of IOPs among the participants and correlation between glaucoma subjects and their IOPs

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[Table 5] shows the significant relationship between the recently diagnosed glaucoma patients and the visual field changes (χ2 = 193.927, P ≤ 0.001).

Table 5: Newly diagnosed glaucoma versus central visual field results

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Often times, people living in the rural areas have difficulties in accessing health care and facilities. Even if the basic primary health care facilities are available, it will take the people in the community some distance to travel out to the tertiary or specialist centre to get eye care. A number of factors have been found to be responsible for utilization/patronage of eye care services among which are accessibility, affordability, and acceptability. [6] The result found in this community screening showed that the females were almost double the males. Could it be that they are more health conscious or that the males had gone to the farm leaving behind the females? This corroborates the report of Fotouhi [7] who in a study on eye care utilization in Tehran population in 2006 reported that more women sought eye care than men. Hassan et al. also corroborated the same thing in a similar environment in the same region although a hospital-based study, [8] while Clendenin [9] in 1997 reported that no significant difference between genders was found in terms of eye services utilization. [9] The age group below 45 years was more than the others probably because they are more active. The age group over 65 years was next. Most people in this group usually have one type of eye problems or the other because of age, particularly cataracts and glaucoma. An increasing frequency of cataract with age was noticed. This is not unexpected as its occurrence increases with age. A study found that increasing age was associated with increasing prevalence of all major blinding conditions. [3] This was actually found in this study as cataract was the most prevalent anterior segment disorder in these communities with 25.9%, thus confirming already established findings from other prevalence studies in the country. [3] And this is about twice the National average, a result that is not unexpected for a rural community as in Nakamura et al., [10] in prevalence and causes low vision and blindness in a rural Southwest Island of Japan: The Kumejima study found out that the prevalence of low vision and blindness in the adult residents of an island in southwest Japan was 1.5-3 times higher than the prevalence reported in an urban city on the Japanese mainland as well as higher prevalence of VI resulting from cataract and corneal opacity than that on the mainland. [10] A total of three eyes had pseudophakia. There was only one eye with aphakia. This shows that only a few had cataract surgery done, leaving a backlog of cataract patients. This readily translates to the fact that there is inadequate cataract surgical service in these communities. Similarly, in the nine province rural survey, to determine the prevalence and outcomes of cataract surgery in China, it was found out that two thirds of those with bilateral VI or blindness remained in need of sight-restoring surgery, while others with posterior capsule opacification after cataract surgery needed treatment, and refractive errors needing corrections were common. [11]

In this study, we noticed that nobody presented with couching. This was rather surprising. It could have been by chance that either nobody with couching turned up or that couchers are not patronized in this community. Almost 50% of cataracts were found to be couched from the Nigerian national survey results. [12] Further community survey is required to ascertain this.

Refractive errors were the next common disorder. About 77% of them were females and 42% of these were seen in the <45 years age group (P = 0.002). Those who were refracted were given prescription for correction.

Various forms of conjunctivitis were found among females only and in the age group 45-54 years. The authors think that it was so reflected because women are more cosmetically sensitive. Pterygia also showed a similar trend where about 64% of them were females, with majority of them also in the 45-54 years age group. In contrast to a community-based study in rural Beijing, more males than females (5.13% vs 3.17%) significantly had pterygia, which were significantly seen among the people living in the low latitude and low precipitation areas (P ≤ 0.001). This corroborated the theory of ultraviolet exposure and pterygia formation. [13]

Corneal opacity was seen among three people, two of which were post-traumatic corneal ulcers. These commonly arise from farm injuries. The third case was due to measles keratopathy, which occurred during childhood. Similar results were previously documented, [4] where the common eye problems encountered were cataract (48.0%), glaucoma (21.1%), allergic conjunctivitis (16.4%), refractive errors (12.4%), age-related macular degeneration (0.7%), and corneal opacities (0.7%). No case of uveitis was seen in this study. This is in contrast to what Rathinam et al[14] found in a rural population-based study of prevalence of uveitis in southern India. The results suggested that nearly 1 in 200 persons had been affected by ocular inflammation in at least one eye by mid- to late adulthood, and therefore would be an important cause of ocular morbidity and vision loss in that population. Males and older persons tended to have higher prevalence in the study. [14]

In the posterior segment, however, glaucoma ranked highest with 6.6%, where females made up 64.7% with the majority occurring in the 65 years and above age group. This makes glaucoma rank the third commonest ocular disorder in these communities. In a previous study, age was seen as a risk factor for developing cataracts and glaucoma. [3]

There was a significant correlation between the newly diagnosed glaucoma patients and increased IOP (P = 0.039). It is a known fact that IOP, when high or normal, could be a high-risk factor for development of glaucoma. It is not surprising that not all of them were diagnosed glaucoma since a condition like myopia could mimic it. There was also significant central visual field changes found among the newly diagnosed glaucoma patients (P < 0.001), where more than 80% of them had characteristic glaucomatous visual field changes. Glaucoma was found to be the commonest cause of functional low vision in Nigeria. [15]

There was a case of retinal detachment as seen with traction bands within the vitreo-retina. Further retinal changes showed signs of diabetic retinopathy such as cottonwool spots, chronic cystoid macular edema, hard exudates, and tortous/engorged/beaded vessels. During screening at a community pharmacy in Puerto Rico, 22% of previously undiagnosed people had diabetic retinopathy and 19% were newly diagnosed as having glaucoma. [16]

It is worth noting that hypertension and diabetes, followed by kidney diseases, have become the commonest noncommunicable diseases in the world today. [17]

Hypertensive retinopathies with copper and silver wiring of arterioles, and cotton wool spots were seen. An added advantage of this general screening was the ability to identify diabetics and hypertensives for the first time. This would help to prevent sudden death as hypertension has been identified as the commonest killer of adults in Nigeria. [18] Age-related maculopathy was also seen. This is known to lead to low vision and blindness among adults. [15] The prevalence appears low in our environment as compared to findings in the Caucasians where it has been documented to be the first cause of blindness among people 50 years and above. [19] Results from WHO Global estimates 2010 have shown that the ability of glaucoma, diabetic retinopathy, and age-related macular degeneration, causing VI, is presently becoming more than those from infective causes such as trachoma and corneal opacities. [19] More than 50% of people having diabetes are unaware of their condition and would therefore not be receiving treatment. Also, about 40% of this same group would develop chronic kidney disease (CKD) which increases the risk of cardiovascular diseases and other complications of diabetes. [20] A general health status screening would be very effective in preventing ocular complications which could lead to blindness.

Recently, tele-ophthalmology and tele-screening have been used to screen for and detect cases of diabetic retinopathy and age-related macular degeneration in rural communities. These are efforts geared toward prevention of blindness among the elderly in remote areas. Necessary treatments are also given to the needy during these screenings. [21],[22] These methods also look very attractive as means of overcoming some sociocultural barriers during medical screening of a community. [23] We look forward to such medical practice in the Nigerian underserved rural populations in future. These we hope would help in the prevention and reduction of avoidable blindness and deaths.

This study also showed that cases of trachoma were not seen while those of corneal opacities were few.


The causes of ocular morbidity found were mostly preventable or treatable. Commonest anterior segment disorders were cataract and corneal opacity, while glaucoma accounted for the most prevalent of posterior segment pathologies in these communities. Hence, health education at primary level of care is required for early identification. Prompt referral is also necessary as these cases cannot be managed at primary care level.

There is a need for establishing a community eye-outreach center to identify and refer blinding cases as well as life-threatening conditions such as hypertension and diabetes.

Limitation of the Study

The inability to carry out refraction for all the cases of refractive error would have limited the extent of the services (glasses prescription) rendered to the participants. This was due to the shortage of manpower.


The authors thank all the laboratory staff of the College of Health Sciences, Osun State University, Ophthalmic Nurses and Ophthalmology residents who participated in the field work.

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Source of Support: Self, Conflict of Interest: None


DOI: 10.4103/1755-6783.127802


[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]

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