Refractive errors can also be called ametropia. This is a situation whereby the eye refractive system fails to bring images or focus images clearly on the retina. This usually results in blur vision in an otherwise normal eye. Refractive error is the second leading cause of blindness and according to Serge et al. (2008), it accounts for 18% if visual impairment. Refractive errors remain the leading cause of low vision. The three main types of refractive errors include myopia, hyperopia and astigmatism.

Myopia is a clinical condition whereby parallel rays of light are brought to focus before the retina when the eye accommodation system is at rest, resulting in blur vision. Hyperopia is an error of refraction in which parallel rays of light from infinity come to focus behind the retina, when accommodation is at rest. The etiology includes axial hypermetropia, curvature hypermetropia and index hypermetropia. On the other hand, astigmatism is a type of refractive error where the refraction varies in different meridians. Consequently, the rays of light entering the eye cannot converge on a focus point but form a focal line. The etiology consists of corneal astigmatism, lenticular astigmatism and retinal astigmatism.

According to the World Health Organization’s estimate in the global magnitude of visual impairment caused by uncorrected refractive errors in 2004, 153 million people over 5 years of age are visually impaired from uncorrected refractive errors. Out of this number, eight million are blind.

PROBLEM STATEMENT

Refractive errors remain one of the leading causes of visual impairment in Cameroon. It is the leading cause of low vision. The prevalence of refractive errors varies from nation to nation and even among low-income countries like Cameroon. Globally, 18% of visual impairment is due to refractive errors yet no published study has been done in the North West Region of Cameroon (Bamenda) to this effect. Otulana et al. (2021) in a related work, observed that available data on refractive error in Africa, generally are limited. The case of Bamenda, in the North West region of Cameroon is even worse

RATIONAL

There has been no such study in this area. It is necessary to determine the prevalence of refractive errors in this region and compare with other studies in nearby region as well as compare with the global trend.

• RESEARCH GENERAL OBJECTIVE

Determine the prevalence and main types of refractive errors in patients of 6years old and above at the Nkwen Baptist Health Center.

• SPECIFIC OBJECTIVES

1. i) Describe the demographic profile of patients with refractive errors.
2. ii) To determine the prevalence of refractive errors amongst patients of 6 years old and above attending the clinic.

iii) Identify the main types of refractive errors diagnosed at the Nkwen Baptist Health Center.

• RESEARCH HYPOTHESIS

Refractive errors are common in Nkwen Baptist Health Center.

In the United States, the prevalence of myopia has been estimated at 3% among children aged 5-7 years, 8% among those aged 8-10 years, 14% among those aged 11-12 years and 25% among adolescents aged 12-17 years. In particular ethnic groups, a similar trend has been demonstrated although the percentages in each age group may differ. Ethnic Chinese children have much higher rates of myopia at all ages. A national study in Taiwan found that the prevalence was 12% among 6 years old and 84% among adolescents aged 16-18 years. Similar rates have been found in Singapore and Japan.  American Academy of Ophthalmology (2017).

According to Zhang et al. (2022), there was a high proportion of myopia among school students in the city of Weifang, which gradually increased with age, and with the highest prevalence in the Changyi areas. They also reported a higher myopia prevalence for girls than that in boys.

The prevalence of refractive errors including the sociodemographic distribution vary from place to place. According to Zahra et al. (2020), in a study done on the prevalence of refractive errors and visual impairment among school age children aged 6-15, of Hargesia, Somaliland, Somalia, refractive errors prevalence was recorded at 15.7%. A similar hospital-based study in the Gynaeco-Obstretric and pediatric hospital in Yaounde by Eballe et al. (2009) revealed a 43.1% prevalence rate within the age group of 6-15 years.

A study in India by Dandona et al. (2002) revealed that reduced vision due to uncorrected refractive errors was a major health problem among school children. In the study it was also found that, the prevalence of uncorrected vision in Andra Pradesh was 2.7%. Refractive errors were found to be the cause in 61% of the eyes with visual impairment. Myopia was seen in 4.1% of the cases. There was a gradual shift towards myopia with increasing age in both boys and girls. Myopia risk was associated with female gender, and a father with a high level of schooling. Hypermetropia was seen in 0.8% of children with no significant predictors and the prevalence of astigmatism was 2.8%.  

Wolfram et al. (2014) found the prevalence of refractive errors in the European adult population aged 35 to 37. It revealed that myopia was represented in 35.1% of the study population, hyperopia in 31.8%, astigmatism in 32.3% and anisometropia in 13.5%. It was also noted in this study that the prevalence of myopia decreased, while the prevalence of hyperopia, astigmatism and anisometropia increased with age.

 A similar study done by Schellini et al. (2009) in Brazil showed that myopia was most prevalent among those aged 30-39 years (29.7%) and least prevalent among children under 10 years (3.8%). Hypermetropia was most prevalent in the age group under the age of 10 years (86.9%) and least prevalent in the fourth decade (32.5%). At the age of 70 years or older astigmatism and anisometropia had a respective prevalence of 71.7% and 55.0%. Myopia and hypermetropia were significantly associated with age, whereas anisometropia and astigmatism increased in line with age. This work also confirmed the age-related risk factors for refractive error and revealed several gender, occupation and ethnic-related risk factors.

According to Syaratul et al. (2008) in a study carried out in Malaysia, it was found that, the main cause of uncorrected visual impairment among school children between the ages of 6-12 years old was refractive errors, which was responsible for 90.7% of the cases. Myopia was found to be the most common refractive error with a prevalence of 5.4%, followed by hypermetropia with 1.0% and finally astigmatism with 0.6%. A significant correlation was noted between myopia development with increasing age, more hours spend on reading books and background history of siblings with glasses and whose parents are of higher educational level.

Research done in Ghana by Ovenseri et al. (2010) in the Cape coast municipality of central region to determine the prevalence of refractive errors among school children had a prevalence of 25.6%. Astigmatism was more common with a prevalence of 14.1%, followed by myopia with 6.9%; and lastly hypermetropia with 4.6%.

A systematic review by the American Medical Association (2004) on the prevalence of refractive errors in Western Europe, United states and Australia among children showed a prevalence of myopia of 24% in USA, about 27% in Western Europe, and about 16% in Australia. For hypermetropia, the prevalence was 10% in USA, 12% in Western Europe and 6% in Australia.

Research by Vitale et al. (2008) to describe the prevalence of refractive error in the United States found that the age-standardized prevalence of hyperopia, myopia, and astigmatism were 3.6%, 33.1%, 36.2% respectively. Myopia was more prevalent in females (40%) than in males (33%); among 20–39-year-olds. Persons aged ≥60 years were less likely to have myopia and more likely to have hyperopia and/or astigmatism than younger persons. Myopia was more common in non-Hispanic whites (35.2%) than in non-Hispanic blacks or Mexican Americans (25.1%).

A retrospective study among children attending a tertiary eye facility in Ibadan, Nigeria by Olusanya et al. (2019) showed a prevalence of myopia to be at 23.2%, simple myopic astigmatism at 21.9% and compound myopic astigmatism at 20.8%.

According to Tayo et al. (2017) astigmatism was the commonest cause of refractive error 64.80%, followed by hyperopia 21.50% and myopia 13.70% at a community eye hospital in Ogun State, Southwest of Nigeria.

Ezegwui et al. (2017) in Enugu state South-East Nigeria found that among school children the prevalence of refractive error was about 2.1% within the age of 7 to 13 years old with myopia having a higher 1.9% prevalence and hyperopia, 0.1%.

According to a study done by Otulana et al. (2021) on the prevalence and patterns of refractive errors in a tertiary health facility in South West Nigeria, they found the prevalence of refractive error to be 10.6%. The magnitude of refractive error stood at 33.8% for astigmatism, 32.2% for hyperopia and 23.3% for myopia.

According to Hashemi et al. (2017), the prevalence of refractive errors in children was found to be 11.7% myopia, 4.6% hyperopia, and 14.9% astigmatism. In adults, myopia, hyperopia, and astigmatism were found at 26.5%, 30.9%, and 40.4% respectively.

According to research done in Ethiopia by Kedir and Girma (2014), the prevalence of refractive error was found to be 3.5% among rural school-age children (aged 7 to 15 years) of Goro District, Gurage Zone, with myopia being 2.6% and hyperopia 0.9%.

Besufikad et al. (2018) discovered that myopia constituted the highest refractive defects followed by astigmatism and lastly, hyperopia among patients visiting the Boru Meda Hospital’s secondary eye Unit.

The prevalence of refractive errors among the school-going children in East Sikkim, India in research carried out by Bhutia et al. (2018) had a higher prevalence of myopia (31.1%) followed by astigmatism (2.6%) and hyperopia (2.6%). Refractive errors were more common between the age group of 14 to 17 years with females having a slightly higher refractive error than males.

In the Middle East research done by Khoshhal et al. (2019), it was discovered that the respective prevalence of myopia, hyperopia, and astigmatism was 4.0%, 8.0%, and 15.0% in people less than or equal to 15 years old and 30%, 21%, and 24% in subjects over 15 years old. The research also came out to show that myopia, hyperopia, and astigmatism was 3.5%, 12.4%, and 9.0% in male and 4.2%, 13.1%, and 9.9% in female subjects aged less than or equal to 15 years old, respectively. In subjects above 15 years, the prevalence was 31.7%, 14.5%, and 31.5% in males and 31.9%, 11.2%, and 31.0% in females, respectively.

Galvis et al. (2018) in Colombia found out that in children and adolescents, the hyperopia prevalence decreased while myopia prevalence increased with age. The estimated prevalence of refractive errors in hyperopia was 32.3%, myopia 12.9%, mixed astigmatism 2.8% and anisometropia 1.9%. In the adult group, a contrary trend was observed. Myopia prevalence reached 15.7% in urban and 9.2% in rural areas, and for hyperopia, the rates were 29.4% in urban and 36.1% in rural areas. 

The prevalence of refractive errors in the INK Area of Durban South Africa done by Mashige et al. (2016) discovered that myopia and astigmatism were significantly more prevalent in men within the age group of 35 to 90 years while hyperopia was significantly associated with education. The prevalence of refractive error within this age bracket was 57.3%, with percentage distribution of myopia 11.4%, hyperopia 37.7%, and astigmatism 25.7%.

According to Duru (2017), the prevalence of refractive errors amongst children aged 5 – 15 years old in Port Harcourt, Nigeria was astigmatism 11.5%, hyperopia 7.4% and myopia 3.8%.

Abah et al. (2010) in their study on the prevalence of refractive errors in the Ahmadou Bello University Teaching Hospital, Nigeria found the prevalence of refractive errors to be 9.5%.

The results of Kumah et al. (2016) in the study on refractive errors amongst administrative staff of senior High schools in the Kumasi metropolis, Ghana revealed the overall prevalence of refractive errors to be 30.8%. In this study, hyperopia was the leading type of refractive error with 17.5%. Myopia was the second with 10.8% and the least was astigmatism that recorded 2.5%.

STUDY DESIGN AND PERIOD

This was a cross-sectional, descriptive and retrospective study. This study was carried out within a period of 12 months from January 1^st to December 31^st 2021. All the cards or files of the patients within the study period were retrieved. The cards that met the inclusion criteria were sorted and the ones with refractive error noted. Files with incomplete records were eliminated. Particular attention was paid to the types of refractive errors diagnosed and other variables like sex and age.

STUDY SITE

This study was carried out at NKWEN BAPTIST HEALTH CENTER – Bamenda at the ophthalmologic unit. It is found at Finance Junction Nkwen, Bamenda III, Mezam Division, North-West Region of Cameroon. The modern infrastructure has 114 bed capacity, and over 350 staff who attend to over 600 patients daily. The ophthalmologic department receives about 13000-15000 patients per year. The unit registered a total of 13592 patients in the year 2020. (Statistics from hospital registers, both new and review cases).

STUDY POPULATION AND SELECTION OF STUDY PARTICIPANTS

All patients, 6 years old and above who attended the clinic from January 1^st to December 31^st 2021.

INCLUSION CRITERIA   

All files of patients 6 years old and above were included in the study.

EXCLUSION CRITERIA

All files with incomplete records or patients less than 6 years old were excluded from the study.             

All patients seen out of station on outreach basis were not included              

SAMPLE SIZE CALCULATION AND SAMPLING 

The sample size was calculated using Cochran’s formula⁷:

Where:

• n= required sample size
• p=% of occurrence of state or condition. In this case, we shall use 43.1% which was obtained in a study by Eballe et al. (2009).
• E= the desired level of precision (i.e., the margin of error)
• Z=the value corresponding to the number of confidence required. In this case 1.96
•  

Z=1.96 (i.e. for a 95% CI), E= 5%

n = 43.1 (100-43.1) (1.96)² /5² = 373

SAMPLING METHODS

A consecutive sampling method was used, with every file that met the inclusion criteria over the study period included in the study. 

STUDY VARIABLES

The variables analyzed were: age, sex, presenting visual acuity, corrected visual acuity, diagnoses, residence, family history, etc. 

DATA COLLECTION INSTRUMENTS

To facilitate this study, the following materials were used:

1. 1. 1. Structured questionnaire 
      2. A-4 papers
      3. Cases files and delivery registry.
      4. Pen, pencil and eraser.
      5. Investigator observation: 1 diary.
      6. Write-up: laptop computer and USB drive.
      7. Bag to gather the above materials. 

On completion of data collection per patient, the data collection sheets were checked and edited for completeness and legibility of the data collected.

The procedure was a simple retrospective records or files review.

DATA ANALYSIS

In this study, Stata 9.1 software was used for statistical analysis. Continuous variables were expressed as median with the interquartile range or mean with standard deviation according to their distribution. Categorical variables were presented as proportions, percentages or frequencies. We used Fischer test or Chi square test to compare proportions between groups.

ETHICAL CONSIDERATIONS

Ethical clearance was obtained from the institutional Review Boards (IRB) of SAERA and the Cameroon Baptist convention IRB, (CBCIRB). Administrative authorization was obtained from the administrator of the Nkwen Baptist Health center.

Privacy and confidentiality

1. 1. The required information was extracted from the patients’ file and filled into a structured questionnaire, without the identity of the clients revealed.
   2.  
   3. All questionnaires were coded to conceal patients’ true identity.
   4.  
   5. The materials were kept under lock and key in my office in the eye department of the said health center.
   6.  
   7. Use of personal computer with a password to restrict access.
   8.  
   9. Worked on the files only in the Medical Record.
   10.  
   11. Room and replaced to shelf as soon as possible.
   12.  
   13. The questionnaires were destroyed by burning after compiling and analyzing the data

Out of the 5645 files sorted, 5636 files were eligible during the study period. It is important to note that nine files were rejected for incomplete records. From the 5636 files, 2114 were males giving 37.5% while female constituted 3522 giving 62.5%. The male-to-female ratio stood at 1:2. The data revealed that, 926 children within the age group of 6 – 15 years old were consulted. A total of 1543 patients within the age group of 16 – 30 years old were also seen within the study period and 3167 patients that consulted were adults (more than 30 years old) (see Table 1).

Table 1. Demographic prevalence of refractive errors and patterns.

From the results obtained, 612 patients out of the 5636, were diagnosed with refractive errors, giving a prevalence of refractive errors of 11%. The research excluded children less than 6 years old.

Of the 612 patients diagnosed with refractive errors, 104 (17%) were children 6 – 15 years old, 217 (35.5%) were in the age group of 16 – 30 years old and 291 (47.5%) were adults (more than 30 years old). The results also indicated that 445 females were diagnosed with refractive errors against 167 for their male counterpart, representing 72.7% and 27.3% respectively. The male-to-female ratio was 1:3.

In terms of age and sex disaggregation, refractive errors were more common in females in the age group of 6 – 15 years old recording 77 cases (74%) against 27 cases (26%) for their male counterparts. The results also showed that refractive errors were more common in females in the age group of 16 – 30 years old with 164 cases (76%) as against 53 cases (24%) for the male folk of this same age group. The results in adult group (more than 30 years) were similar. The female recorded 204 cases (70%) against 87 cases (30%) for the male.

In terms of diagnosis, the most common type of refractive error diagnosed was astigmatism with 446 cases making 73% of the total cases diagnosed. The second leading type of refractive error from the results is myopia with 114 diagnosed cases giving 19% and the least common type of refractive errors diagnosed in the study period was hyperopia with 52 cases (8%).

Eight children (6 – 15 years old) presented with high myopia (values more than -6.00DS), nine patients in the age group of 16 – 30 years old also presented with high myopia and four adults (more than 30 years old) had high myopia. Summarily, of the 114 myopic cases, 21 (18%) presented with high myopia (see Figure 3).

From the results obtained, all the types of refractive errors were more common in females than in males. Out of the 446 cases of astigmatisms, 329 (74%) were females and only 117 cases were males representing 26%. Hyperopia with 52 cases diagnosed had 33 females (63%) against 19 (37%) for males. Myopia had 114 cases and females represented 73% (83 cases) against their male counterparts with 27% (31 cases) (see Table 1).

In terms of age category, the results showed that the highest prevalence of refractive error was registered in adolescence (16 – 30 years old). In this group, 1543 patients were consulted and 217 were diagnosed with refractive errors, giving a prevalence rate of 14%. From this study, children (6 – 15 years old), registered the second highest prevalence rate. In this group, 926 patients were consulted and 104 were diagnosed with refractive errors making a prevalence rate of 11%. The adult group (more than 30 years old), registered the least prevalence rate. 3167 patients consulted in this age group and only 291 diagnosed with refractive errors. The prevalence of refractive error in this age group was 9%. It was also noted that quantitatively, the adults recorded the highest number of refractive errors, with 291 cases, followed by the age group of 16 – 30 years old with 217 cases and the least was children (6 – 15 years old) with 104 cases.

The prevalence of refractive errors in terms of age and sex disaggregation registered interesting results. In the male folk within the age group of 6 – 15 years old, 375 patients consulted and 27 diagnosed with refractive errors and this gave a prevalence rate of 7% while in female folk of the same age group, 551 patients consulted and 77 diagnosed with refractive errors, giving a prevalence rate of 14%. The number of males who consulted in the 16 – 30 years age group (adolescence) were 561 and 53 of them had refractive errors making prevalence rate of 9% while in their female counterparts, 982 were consulted and 164 were diagnosed with refractive errors, giving a prevalence rate of 17%. In those above 30 years old, the male consultations stood at 1178 and only 87 cases diagnosed with refractive errors giving a prevalence rate of 7%. In the same vein, 1989 consultations registered in the female population of this age group and 204 diagnosed with refractive errors making a prevalence rate of 10% (see Table 2).

Table 2. Prevalence of refractive errors according to age and sex.

From the overall results, 2114 males consulted and 167 had refractive errors making a prevalence rate of 7.8% while 3522 females consulted and 445 diagnosed with refractive errors making a prevalence rate of 12.6%.

However, in summary, 5636 patients consulted during the study period and 5024 had no refractive error. Six hundred and twelve (612) patients diagnosed with refractive errors making the overall prevalence rate of refractive errors in this area to be 11%.

The prevalence of refractive errors by types showed that astigmatism, which registered 446 diagnosed cases from 5636 consultations, had a prevalence rate of 8%. Myopia had 2% with 114 cases diagnosed and hyperopia had a prevalence rate of 1% with 52 cases diagnosed. Therefore, it was observed that more people were diagnosed with astigmatism and the least prevalence of refractive error type in the population was hyperopia (see Figure 1).

Figure 1. Prevalence of refractive error by type.

In terms of prevalence of refractive error types by sex, it showed that myopia was more prevalent in female with 73% against their male folk with 27%. Hyperopia was common in female with 63% against the male with 37% and astigmatism was more prevalent in female with 74% against the male with 26%.

 The distribution of refractive errors types in the study population was 73%, 19% and 8% for astigmatism, myopia and hyperopia respectively (see Figure 2).

Figure 2. Distribution of refractive errors.

Figure 3. High myopic values by age disaggregates.

Figure 4. Refractive Errors types by age disaggregates.

Discussion       

From the results of this study, the prevalence of refractive errors in Bamenda, case study of Nkwen Baptist Health Center, was 11%. It therefore follows that refractive errors account for up to 11% of the total clinic attendance. The rest of the eye diseases put together contributed barely 89% of the total clinic attendance. This result is similar to the 10% results obtained by Otulana et al. (2021) in their study, Prevalence and pattern of refractive errors in a tertiary health facility in southwest Nigeria. It is also similar to the 9.5% results obtained by Abah et al. (2010) in their study in the university community in Nigeria. Ovenseri et al. (2010) found a higher rate of 25.6% in their research work in Ghana. Their research was limited to school children, who need vision most and will consult at the slightest of blur vision. This can be the reason for such variation. Zahra et al. (2020) in their study in Somalia, in 2020 found a prevalence rate of 15.7%. This can be explained by the variation in the prevalence of refractive errors from region to region.

The distribution of refractive errors according to age in this study revealed that children constituted 17% (104 cases), adolescents 35.5% (217 cases) and adults 47.5% (291 cases). The high percentage in adults could be due to the high number consulted (3167) during the study period. In summary, it was realized that refractive errors were present in all age groups. Otulana et al (2021) reported similar findings in the health facility study in Nigeria. In their research as well as this study, children were less than one-fifth of the study population. The reason for the low presentation of children is beyond this study but it could be because children depend on their parents for health care including eye consultation. Moreover, some parents in the developing countries have a wrong perception about wearing eyeglasses and may not encourage their children to seek eye care in hospitals. Another glaring reason is that some eye conditions like cataract, age-related macular degeneration (ARMD), diabetic retinopathy, presbyopia, etc. come with advanced age and hence more adults tend to consult in the eye clinic for these conditions.  

Quantitatively, more females (445 cases) were diagnosed with refractive errors than males (167 cases). This represented 72.7% for females against 27.3% for males, in terms of diagnosed cases. It can be partly explained by the variation in the male to female ratio in this study, which stood at 1:2. The reasons for more females consulting than males cannot be ascertained from this study. However, it can be attributed to the fact that more women access health and eye care facilities than men do as purported by Otulana et al (2021) in their research work in Nigeria. Men maybe too busy with other unrelated health matters.

Within the various age groups, the distribution of refractive errors was grossly unequal. Amongst the children (6 – 15 years old), the females had 74% and the males had 26%. In the adolescents (16 – 30 years old), the females represented 76% against 24% for their male counterparts. In the adult population, the females and males had 70 and 30% respectively. This may be explained by the fact that more females, in all the age groups, consulted within the study period.

The study revealed that refractive errors are present in all sexes as well as all age groups. The difference can only be with the percentages in the age groups and sexes. This result is consistent with many authors like Olusanya et al. (2019) who found that refractive errors had age and sex distribution in their retrospective study in Nigeria.

All the main types of refractive errors were diagnosed amongst the patients who presented during the study period. The results found that the patterns of refractive errors presented in different rates among the study population. Among the diagnosed refractive errors, astigmatism was the commonest type with 73%, followed by myopia with 19% and lastly hyperopia with 8% (see Figure 2). This is consistent with results obtained by Ovenseri et al. (2010) in Ghana. Tayo et al. (2017) also found astigmatism as the commonest refractive errors with 64.80%. However, there was lack of agreement between above authors and this study on myopia and hyperopia rates. These authors found more hyperopia than myopia in their respective results. Moreover, in sharp contrast to this result, Ezegwui et al. (2017), Syaratul et al (2008), Bhutia et al (2018) and Besufikad et al. (2018) in their respective studies found myopia to be the highest type of refractive error. On the other hand, Kumah et al. (2016) in the study on refractive errors amongst administrative staff of senior High schools in the Kumasi metropolis, Ghana recorded that hyperopia was the leading type of refractive error with 17.5%. All of these differences could be due to the regional variation and/or the targeted population.

Of the 114 myopic cases diagnosed, 21 presented with high myopia (high myopia here was defined as myopic values more than -6.00DS). That is, 18% of the myopic cases have high myopia. This is far more than the 2.7% high myopia results obtained by Otulana et al. (2021), in their study on the prevalence and patterns of refractive errors in a tertiary health facility in South West Nigeria. It therefore follows that if the high myopic cases in the population are not screened and offered glasses early enough, they may develop amblyopia (lazy eye). Unfortunately, it was out of the scope of this study to evaluate how many of these cases had their refractive errors corrected. It is advisable to do a systematic follow up to ensure these cases have their correction.

The prevalence of refractive errors in terms of age showed variations. Prevalence of refractive errors in children (6 – 15 years old), showed 11%. This is similar to the 15.7% results obtained by Zahra et al. (2020) among school age children 6 – 15 years old, of Hargesia, Somaliland, Somalia. However, this result grossly differed with the result obtained by Eballe et al. (2009) in a similar hospital-based study in Yaounde, which revealed a 43.1% prevalence rate within the age group of 6 – 15 years old. Though the reasons for this marked difference between Eballe et al. (2009) and this study was not very clear in this research, sensitization and intentional screening might have played a role.

The prevalence of refractive errors in the 16 – 30 years old group stood at 14%. This is the age group with the highest prevalence rate in this study. This could be because patients in this age group can better cooperate for subjective refraction and may not have other eye disease that can compromise their vision. Duru et al. (2017) found the highest prevalence rate in the 9 – 12 years old group. However, their study was limited to schoolchildren aged 5 – 15 years in Port-Harcourt.

The adult group according to this study had the least prevalence of refractive errors rate of 9%. The simple explanation here is that this group usually presents in the clinic because of other eye conditions like age related cataract, glaucoma, ARMD, diabetic retinopathy, presbyopia, etc.

There was a difference in the prevalence of refractive errors among the various age groups of male and female gender. The prevalence of refractive errors in male children (6 – 15 years old) was 7% while the female of the same age group had prevalence rate of 14%. The prevalence of refractive errors in the male group of 16 – 30 years old was 9% against 17% for their female counterparts. In the adult group (above 30 years old), the male folk had 7% and the female folk had 10%. Generally, the prevalence of refractive errors was higher in females than males in all age groups. Tayo et al. (2017) reported similar trend in their study on refractive errors patterns at a community eye hospital in South West of Nigeria.

It was a health facility-based study. This may not reflect the realities of refractive errors in the general population. In addition, the non-computerized filling system made the work too cumbersome with the limited time. Also, some of the patients who presented with 6/6 vision did not benefit refraction. Maybe children who accommodated to compensate for their refractive errors were missed. Lastly, there was an armed conflict in this region during the study period and movement was limited as well as some people were internally and/or externally displaced from this area.

To conclude, the prevalence of refractive errors is as common as 11% in this study site. This means that for every one hundred eye conditions there are eleven refractive errors. Astigmatism was at the top with prevalence rate of 8%, followed by myopia with 2% and the least is hyperopia with 1%.  As a recommendation, it will be beneficial that affordable and effective strategies for vision screening of the population be incorporated into the health program of the ministry of health to prevent some devastating consequences of visual impairment on the population. Similar research should be done with a much wider and inclusive approach. This health facility should computerize the filling system for easy access. Health systems in Cameroon should collaborate with international non-governmental organizations like CBM, sight savers international in early diagnosis and corrections of refractive errors in underprivileged communities like Bamenda. These strategies should target all the age groups of both sexes. In addition, eye care staff should be intentional about refraction in children.

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