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ORIGINAL ARTICLE
Year : 2018  |  Volume : 10  |  Issue : 1  |  Page : 8-13

Prevalence of refractive errors in Al Bahar Alahmar province in Sudan


1 Optometry Department, College of Health Sciences, University of Buraimi, Sultanate of Oman
2 Faculty of Optometry, El Neelain University, Khartoum, Sudan
3 Grand Optics, Muscat, Sultanate of Oman

Date of Web Publication4-Sep-2018

Correspondence Address:
Galal Mohamed Ismail
College of Health Sciences, University of Buraimi, POB 890, PC 512, Al Buraimi
Sultanate of Oman
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DOI: 10.4103/sjopthal.sjopthal_26_17

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  Abstract 


Purpose: The study was carried out to investigate the prevalence of refractive errors in al Bahar Alahmar province in Sudan. The aim was to identify the prevalence in the province and to help in improving the health strategic plans in the area as well as reviewing the eye care services provided in the region. Materials and Methods: Eye testing had been executed on 790 patients with ages ranged between 10 and 59 years and means of 41.7 standard deviation ± 10.1. All patients tested for distance vision using (tumbling E chart) and near vision using (tumbling E chart). The battery kept simple at the beginning of the test; however, noncycloplegic objective refraction followed using a streak retinoscope to refract and prescribe the required optical correction. Results: Decreased in vision was more common in the age group of (40–49) years old, right eye (RE); 38% and left eye (LE); 34% (χ2 = 20.83/df = 20/P = 0.04). Spectacles could improve the vision to 6/6 from 45.8% (unaided) in RE to 91.5% aided and from 44.4% to 90.6% for LE. The prevalence of refractive error was 37.1% for the total; of which 19.6% hypermetropia, 6.6%, myopia and 10.9% astigmatism, respectively. The prevalence of hypermetropia increased in those age (40–49) RE; 38% and LE; 39.4% with highly association with age (χ2 = 58.41/df = 12/probability P = 0.001). Myopia found in the age group (50–59) years old RE; 40.4% and LE; 37.8%, but without any significant association between myopia and age (χ2 = 46.28/df = 12/P = 0.74). In examination site, 66.8% of the ametropes were not wearing correction, but 12.4% wearing distance correction, 15.1% using near correction, and 5.7% wearing distance and near correction. Conclusion: Hypermetropia was the most common type of refractive errors. Refractive errors affect a sizable portion of these three towns, a substantial number of uncorrected refractive errors individuals were waiting for help. Thus, awareness and services must be dramatically improved to meet the needs.

Keywords: Astigmatism, hypermetropia, myopia, prevalence, spectacles


How to cite this article:
Ismail GM, Mohamed Ali AB, Hassan Dalil AB. Prevalence of refractive errors in Al Bahar Alahmar province in Sudan. Sudanese J Ophthalmol 2018;10:8-13

How to cite this URL:
Ismail GM, Mohamed Ali AB, Hassan Dalil AB. Prevalence of refractive errors in Al Bahar Alahmar province in Sudan. Sudanese J Ophthalmol [serial online] 2018 [cited 2018 Nov 16];10:8-13. Available from: http://www.sjopthal.net/text.asp?2018/10/1/8/240544




  Introduction Top


Refractive error is one of the most common causes of visual impairment worldwide and is the second leading cause of treatable blindness. It is a remediable cause of visual impairment, with correction of significant refractive error being a priority of VISION 2020: The Right to Sight, the joint global initiative of the World Health Organization's (WHO) and the International Agency for the prevention of blindness (Pascolini, 2012).[1] In the past few years, considerable attention has been drawn to the contribution of refractive errors to the global cause of visual impairment and blindness. This resulted from the realization that previous global estimates of blindness and visual impairment had underestimated the contribution of refractive errors.[2],[3] Refractive errors affect a large proportion of the population worldwide, irrespective of age, sex, or ethnic group.[4] Detection of refractive errors is achieved through screening programs. They are cheap to run and quick. Then filtering and diagnosis before the optimal treatment would be the remedy to reduce impaired vision or even blindness.[5] The shortages of refraction and spectacle provision in eye care services in underserved communities had negative consequences regarding lost educational and employment opportunities, as well as the economic cost to the family and government. This study was undertaken to estimate the prevalence and pattern of refractive errors among three towns (Port Sudan, Sinkat, and Sawaken) at Albahar Alahmar state community, Sudan, in Africa.

Study site

A retrospective cohort study conducted in three towns of eastern of Sudan (Al Bahr Al Ahmar state) in May 2012, Port Sudan, Sinkat and Sawakin [Figure 1]. Al Bahr Al Ahmar state is one of the 16th states of Sudan. It has an area of 212,800 km2 and an estimated population of 1,396,000. Port Sudan is the principal city of the state and the seaport of Sudan. It has an area of 212,800 km and an estimated population of 1,396,000 (2010). The population, mainly Arab or Nubian Sudanese, includes the indigenous Beja, West Africans, and small minorities of Asians and Europeans (http://www.britannica.com and www.mapsoftworld.com).[6] Two main eye hospitals are in the state, one in Port Sudan and the second is in Sawaken. The numbers of optometrists in the three towns are around 13 in Portsudan only. The numbers of private optics places are seven, and it concentrated in Port Sudan city.
Figure 1: Al Bahr Al Ahmar www.mapsoftworld.com 17/11/2017

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The target population

The patients participated in the study reflected the natural status of the community in the three towns of Al Bahr Al Ahmar state.


  Materials and Methods Top


The ophthalmic survey contained a battery of tests carried out by level four students from optometry faculty, al Neelain University. The team supervised by optometry clinical instructors and locally qualified optometrists. The clinical equipment used was portable and all standard testing criteria were considered. Eye examinations have been done in approximately 10 min, for samples who had been referred to refraction clinic mainly complained symptoms related to blurred vision, contained name: ABCs, old glasses, symptoms, and medical history (general, ocular, and family). The following examinations were carried out: uncorrected visual acuity was performed monocularly and binocularly, using Snellen E chart at a 6 m distance with comfortable indoor illumination to maintain the standard visual assessment. Patient instructed to identify the direction of the E letter on monitor verbally. The smallest line that patients named the directions correctly reported. A pinhole used when visual acuity does not reach (6/6). Because this study is just for screening, noncycloplegic was not used initially, a streak retinoscope was used and handheld trial lenses, then subjective refraction performed for all patients to estimate the refractive state of the eye (AI Rowaily, 2010).[7] Near visual acuity had been tested using the Reduced E Snellen chart test at a distance of 35 cm, with standard illumination. Each eye was tested separately. The near vision was recorded as the smallest type which can be identified comfortably by the patient.[8] Volunteers who were amblyopic, strabismus or having corneal or lens opacities were excluded from the study. The consent of all volunteers was taken verbally.


  Results Top


The quantification of refractive error is not straightforward because refraction comprises three components, namely sphere, cylinder, and cylinder axis, all of which contribute to the visual outcome.[9] Refractive error was quantified as the spherical equivalent refractive error (SE) for both eyes, which is the algebraic sum of the sphere power plus, half the cylinder power, the unit being diopter (D).[10] Refractive error cut-off point was defined according to their SE for both eyes as follows, Emmetropia between +0.50 and −0.50 D sphere. The cut-off points for hypermetropia degree by age in both eyes are defined as low: +0.50 to +2.00 D, moderate +2.25 D to +5.00 D, high >+5.00 D.[11] Low myopia −0.5 to <−3.00 D, moderate myopia -3.00 to <−6.00D, high myopia >−6.00D.[12] Astigmatism was defined as cylinder power ≥0.50 (no compound spherical error) in one or both eyes.[13]

The data sheets were reviewed for accuracy and completeness of information on the collection. The subjective refractive data obtained were analyzed using the statistical package for social sciences IBM SPSS version-16 software program (SPSS Inc., Chicago, Illinois, USA). All tests were two-sided, and the results were quoted in proportion with confidence interval (CI) at 95% level. Therefore, a P < 0.05 was considered statistically significant for all analyses. t-test or Chi-square used to identify differences in proportions and Spearman correlation (r) was used to identify an association between variables.[14]

A total of 791 patients were screened, 250 patients with significant corneal or lens opacity that could affect the visual function were excluded from the analysis, 541 patients had been referred to refraction test according to visual complaining were represented the sample of this study. However, 293 patients out of 541 only found to have significant refractive errors. Patients ages ranged from 10 to 59 years old with mean (+SD) 41.7 + 10.1, thus 52.5% (n = 284) of the subject's sample (541) were males and 47.5% (n = 257) were females [Figure 2].
Figure 2: Prevalence of refractive errors

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Prevalence of refractive errors from those who had refractive errors (293) 52.9% (n = 155) hypermetropia, 17.75% (n = 52) myopia and 29.35% (n = 86) astigmatism. Spectacles could improve the vision to 6/6 from 45.8% (unaided) in RE to 91.5% aided and from 44.4% to 90.6% for LE. Majority of patients with reduced vision were within the age group (40–49) years old (RE: 38.2%, LE: 34%). Hypermetropia was more common in (40–49) years old (RE: 38% and LE: 39.4%, χ2 = 58.41/df = 12/P < 0.001). Low hypermetropia was the most common degree RE 90.3% and LE: 87.3%. The most common type of myopia degrees was low 90.4% for RE and 88.9% for LE eye and it was higher among age group (50–59) years old for both eyes. Hypermetropia was to be significantly higher in female (RE: 52.8% and LE: 58.1% than in males RE: 43.9% and LE: 42%). In examination site, 66.8% of patients were not wearing glasses although they had defective vision while 12.4% wearing distance correction, 15.1% using near correction and 5.7% wearing distance and near correction [Table 1].
Table 1: Results of unaided vision and aided vision

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[Table 2] demonstrates significantly decreased in vision with advancing age (χ2 = 20.83/df = 20/P = 0.04), this agrees with[15] who reported that vision at a distance deteriorated with age, sometimes even with the proper correction number of people unable to secure 6/6 (1.0).
Table 2: Results of Vision and age

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With[11] who observed the significant occurrence of myopia in age (10–19) assumed: Over the next 10–15 years of life, there is further decrease in hypermetropia and increase in the frequency of myopia [Table 3].
Table 3: Spherical equivalent for hypermetropia (degree) by age in RE

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Same tables showed low myopia was the most common degree in both eyes depends on[12] categorization. This finding was higher than[16] at the same degree, low myopia was 28.60%, moderate myopia 13.47% and high myopia 1.20% [Table 4].
Table 4: Spherical equivalent for myopia (degree) by age for RE

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From [Table 5], hypermetropia was common in females rather than in males, this relationship between hypermetropia and gender was significantly high at (χ2 = 55.97/df = 12/P = 0.03), this finding attributed to differences between biometric ocular parameters between men and women. This is in agreement with study of[17],[18] who stated this may be because women's eyes have a shorter axial length and shallower anterior chamber depth than those of men and hence a higher probability of being hyperopic, also similar with[19] who demonstrated that women had a significantly higher prevalence of hypermetropia 55.6% versus 44.7% of males.
Table 5: Hypermetropia and gender

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It was not agreed with[20] who supposed there is no known gender difference in the prevalence of hyperopia, but there is evidence of the influence of ethnicity on the prevalence of hyperopia. Native Americans, African–Americans, and Pacific Islanders are among the groups with the highest reported prevalence of hyperopia.

Only a few studies have investigated spectacle wearing rates within the screening programs.[21] [Table 6] shows the majority of patients with defective vision were not wearing spectacles when they came to examination site; although, they had refractive errors. It could result from the lack of awareness of refractive error, low level of education, discomfort, negative parental attitudes, concerns over appearance, beliefs that glasses will harm the eyes, low-income level, lack of eye services, and health insurance. This finding is consistent with.[22]
Table 6: Distribution of spectacle wears in subjects

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  Discussion Top


Various studies have documented the prevalence of refractive errors in different population groups; the results vary considerably on the type of sampling method used, size of the population screened, distribution of refractive errors, and the variation geographical location in these studies. Prevalence of refractive errors in this study is 37.1% higher than a local study among North Kordofan population 31%.[23] Although it is difficult to specify the prevalence of hypermetropia due to variations in its definition by researchers (for example, with or without cycloplegia, spherical equivalent, and least hyperopic meridian)[20] [Figure 1].

Hypermetropia in the current study was the most common type of refractive errors (52.9% n = 155) because the majority of patients fall into group (40–50) years old, this attributed to presbyopic age at which acquired hypermetropia occurs. It is similar to[24] and[23] who suggested an apparent increase due to progressive failure of accommodation occurs with advancing age. It was also agreed with[17] assumed the increase in hyperopia with age might be due to a loss of residual accommodation or decrease in the power of the aging lens. Also agreed with[25] they suggested that the increase in hyperopia with age may be due to a loss of residual accommodation or decreasing lens power with aging or an increasing optical density of the lens cortex making the lens more uniformity refractive.

Only a few studies have investigated spectacle wearing rates within the screening programs.[26] [Table 6] shows the majority of patients with defective vision were not wearing spectacles when they came to examination site although they had refractive errors. It could result from lack of awareness of refractive error, low level of education, discomfort, negative parental attitudes, concerns over appearance, beliefs that glasses will harm the eyes, low-income level, lack of eye services, and health insurance. This finding is consistent with. They attributed that, people are lacking the knowledge and awareness of refractive error, there is lack of a regular visit to the eye care professionals because there are not enough ophthalmologist and refractionist. Physically challenged, old age and frail, living alone, dependence on others for activities of daily life and travel inconvenience may result in the consequence that these individuals are not exposed to the ophthalmic service. There is a different requirement of life quality and cultures, some people have a relatively low demand for life quality and lower need of spectacles.[27]


  Conclusion Top


Hypermetropia was the most common type of refractive errors. Refractive errors affect a sizable portion of these three towns, a substantial number of uncorrected refractive errors individuals were waiting for help. The results could be one of the elements used for planning self-sustaining refractive error services in the state and awareness program about refractive errors. Optometric service must be accessible and affordable for people to reduce the growing occurrence of visual impairment resulted from refractive errors, this can be obtained by create new optical centers and employ the freshly graduated optometrist in Sawaken and Sinkat because most of optical centers and optometrists are concentrated in Portsudan. The primary eye care is a core aim of the health providers. Future researchers should include screening for Sudanese eyeball parameters related to gender, also the factors and barriers that led to the emergence of a large proportion of people who do not wear correction in spite the presence of a refractive error. Thus awareness and services must be dramatically improved to meet the needs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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2.
Sight Test and Glasses could Dramatically Improve the Lives of 150 Million People with Poor Vision. WHO news Release, 11 October 2006. Geneva: WHO; 2006. Available from: http://www.who.int/mediacentre/contacts/en/. [Last accessed on 2018 May 29].  Back to cited text no. 2
    
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Krishnaiah S, Srinivas M, Khanna RC, Rao GN. Prevalence and risk factors for refractive errors in the South Indian adult population: The Andhra Pradesh eye disease study. Clin Ophthalmol 2009;3:17-27.  Back to cited text no. 18
    
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Ezelum C, Razavi H, Sivasubramaniam S, Gilbert CE, Murthy GV, Entekume G, et al. Nigeria National Blindness and Visual Impairment Study Group. Refractive error in Nigerian adults: Prevalence, type and spectacle coverage. Invest Ophthalmol Vis Sci 2011;52:5449-56.  Back to cited text no. 19
    
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Moore BD. Optometric clinical practice guidelines care of the patient with hyperopia. Reference Guide for Clinicians. The U.S.A: American Optometric Association; 1997.  Back to cited text no. 20
    
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Castanon Holguin AM, Congdon N, Patel N, Ratcliffe A, Esteso P, Toledo Flores S, et al. Factors associated with spectacle-wear compliance in school-aged Mexican children. Invest Ophthalmol Vis Sci 2006;47:925-8.  Back to cited text no. 21
    
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Ezelum C, Razavi H, Sivasubramaniam S, Gilbert CE, Murthy GV, Entekume G, et al. Refractive error in Nigerian adults: Prevalence, type, and spectacle coverage. Invest Ophthalmol Vis Sci 2011;52:5449-56.  Back to cited text no. 22
    
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Elhage MM. Some Aspects of Ametropia in North Kordofan State. Thesis for Master Degree in Optometry; 2008. p. 70-1.  Back to cited text no. 23
    
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Shimizu N, Nomura H, Ando F, Niino N, Miyake Y, Shimokata H, et al. Refractive errors and factors associated with myopia in an adult Japanese population. Jpn J Ophthalmol 2003;47:6-12.  Back to cited text no. 25
    
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Rauschnabel PA, Brem A, Ivens BS. Who will buy smart glasses? Empirical results of two pre-market-entry studies. Int J Technol Mark 2015;11:123-48.  Back to cited text no. 27
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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