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ORIGINAL ARTICLE
Year : 2010  |  Volume : 4  |  Issue : 2  |  Page : 55-58

Profile of refractive errors and presbyopia in a university community: A clinical study


1 Department of Ophthalmology, Ahmadu Bello University Teaching Hospital, Shika-Zaria, Nigeria
2 Research and Training Unit, School of Nursing, ABU Teaching Hospital, Zaria, Nigeria

Date of Web Publication24-Mar-2011

Correspondence Address:
E R Abah
Department of Ophthalmology, Ahmadu Bello University Teaching Hospital, Shika-Zaria
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0331-3131.78273

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   Abstract 

Aim : To determine the prevalence and distribution of refractive errors and presbyopia in the university community.
Materials and Methods : A prospective study of all consecutive patients who visited A.B.U. Sick Bay between March 2009 and May 2010 was conducted. The ophthalmic nurse booked all patients whose visual acuity improved with the use of pinhole for further examination and refraction by one of two ophthalmologists who visited the facility twice a week. Those who did not turn up for refraction were excluded.
Results : A total of 1448 patients with mean age of 24.6 SD± 4.9 years, distributed along gender and occupational lines, were seen within the study period. The prevalence of refractive errors and presbyopia was 15.8%. The prevalence of refractive error alone in the sample population was 9.5%, that of presbyopia only was 4.2% and that of those who had both refractive error and presbyopia was 2.1% (i.e. total prevalence of refractive errors = 11.6%). However, the total prevalence of presbyopia among those above 40 years was 49.7%. The predominant errors were astigmatism and simple myopia.
Conclusion : Presbyopia and refractive errors, especially astigmatism and simple myopia, are common eye conditions in the university environment. Many patients would not turn up for their refraction appointments. It is recommended that mass enlightenment and screening for refractive errors be commenced, while routine assessment of new students and staff will also help to curb the negative impact on academic performance.

Keywords: Causes of blindness, presbyopia, prevalence, refractive errors, university community, visual impairment


How to cite this article:
Abah E R, Chinda D, Samaila E, Anyebe E E. Profile of refractive errors and presbyopia in a university community: A clinical study. Ann Nigerian Med 2010;4:55-8

How to cite this URL:
Abah E R, Chinda D, Samaila E, Anyebe E E. Profile of refractive errors and presbyopia in a university community: A clinical study. Ann Nigerian Med [serial online] 2010 [cited 2021 Jan 23];4:55-8. Available from: https://www.anmjournal.com/text.asp?2010/4/2/55/78273


   Introduction Top


Uncorrected refractive errors are a common cause of visual impairment and blindness worldwide. Although most errors can be corrected by optical or surgical methods, these treatments have some drawbacks and pose a large economic burden. [1] In 2008, there were 145 million people with visual impairment (VA < 6/18-3/60) and 8 million people were blind (VA < 3/60) from uncorrected refractive errors (i.e. 18% world's population). [2] There is compelling evidence for both genetic and environmental influence on refractive development. [3],[4],[5] The specific genetic polymorphisms or environmental risk factors responsible remain largely unknown, although earlier studies found near work, particularly reading, to be a significant environmental factor that may lead to myopia. [6],[7],[8] A susceptibility locus of myopia in the normal population is linked to the PAX 6 gene region on chromosome 11 [9] .Presbyopia is the loss of accommodation or recession of near point with age. Earlier studies in eastern Nigeria found the average age of onset to be about 40 years. [10] Similar study on refractive errors was conducted in Kaduna, [11] northern Nigeria, but this is the first in the university setting to the best of the knowledge of the authors. This study was conducted to determine the prevalence and distribution of refractive errors and presbyopia in the university environment, where performance is largely dependent on constant reading which is a remarkable visual task. It is expected to contribute to the need assessment for the correction of refractive errors and presbyopia in the university eye clinic and a gate-opener to the provision of low-cost but good quality spectacles to the university community. This is in view of the fact that Nigeria is a resource-limited country and 60% of its population lives below the poverty line, i.e. earning less than US$ 1 per day. [12]

In addition, the National Health Insurance Scheme, which is expected to cater for the poor, does not take care of cost of spectacles; rather, it covers for the cost of refraction alone. It is believed that this study and its effects would support the total global effort at reducing the burden of visual impairment and blindness caused by refractive error. [13]


   Materials and Methods Top


A prospective study of 1448 patients was conducted at the Ahmadu Bello University Sick Bay, Samaru, between March 2009 and May 2010. The Sick Bay provides health care for students, academic and non-academic staff of the university and their relations. Consecutive new and old patients who visited the clinic were first seen by one of two ophthalmic nurses. They booked all patients whose unaided visual acuities were worse than 6/6 in one or both eyes but improved with the use of pinhole for refraction. They also booked those whose unaided near VA was worse than N5 at 33 cm. Those who complained of eye strain during near work or for distance were refracted, irrespective of their unaided VA. Those who were spectacle users had their refraction reviewed. The anterior and posterior segments of these patients were examined and retinoscopy was done manually. Subjective refraction was performed for each of them by one of the two ophthalmologists who visited the clinic twice a week. A total of 27 glaucoma suspects and those who needed additional ancillary aids and further management were referred to the nearby Ahmadu Bello University Teaching Hospital, Shika-Zaria. Those who could not keep their appointment for refraction were excluded from the study.


   Results Top


[Table 1] shows the socio-demographic characteristics of the 1448 patients. Most of them were aged between 21 and 30 years (41.9%) and 11 and 20 years (22.5%), and they were predominantly students (63.5%) and males (59.1%). Out of the 1448 patients seen within the study period, 229 (15.8%) had one form of refractive error, presbyopia or both. Refractive error is defined as an error of 0.5 diopters or more in either eye, while presbyopia is difficulty seeing near in those aged 40 years and above and is correctable with convex lenses of 1.0 diopter or more. [14] One hundred and sixteen of them (50.7%) were males and 113 (49.3%) were females with mean age of 24.6 SD± 4.9 years. The prevalence of refractive errors alone in the study population was 9.5%.For those who had presbyopia only (without error for distance) it was 4.2% in the sample population and 33% in those above 40 years. However in those who had presbyopia along with other errors for distance it was 2.1% across the sample population and 16.7% in those above 40 years of age. This means that the actual prevalence of presbyopia in those above 40 years was 49.7%. Similarly, the actual prevalence of refractive error across the sample population was 11.6%. Twelve (7.1%) of those with refractive error were corrected and 7 (7.6%) of those with presbyopia were corrected, indicating that most of them were uncorrected. The prevalence of spectacle use in this sample was 7.3%. Their age and sex distributions are shown in [Figure 1] and [Table 2] and [Table 3]. The relationships between age and gender distribution and the disorders found (refractive errors and presbyopia) were not statistically significant (P > 0.5). The range of refractive errors found in this sample was −3.25 to +2.50.
Table 1: The socio-demographic characteristics of the patients

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Table 2: Age and sex distribution of patients with presbyopia only

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Table 3: Age and sex distribution of patients with refractive error and presbyopia

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Figure 1: Age and Sex Distribution of Patients with Refractive Error only

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Out of 137 patients who had refractive errors, students constituted 78.1%, and those affected were predominantly between 11 and 30 years old [Figure 1] Among those who had presbyopia only, students constituted 46%, while among those with both refractive errors and presbyopia, students formed 9.7%. Refractive error was more common than presbyopia among students with reference to the total sample population. Specific values for the students show that 11.6% of the students had refractive error alone, 3.0% of them had presbyopia alone, while 0.3% had presbyopia along with error for distance (3.3% of the students had presbyopia and 11.9% had refractive error). The various categories of the errors of refraction show that myopia is the commonest [Figure 2].
Figure 2: Bar chart showing the classifi cation of errors of refraction (MYP, myopia; HYP, hypermetropia; SMA, simple myopic astigmatism; SHA, simple hypermetropic astigmatism; CMA, compound myopic astigmatism; CHA, compound hypermetropic astigmatism; MA, mixed astigmatism)

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   Discussion Top


The results of this study show that 92.9 and 92.4% of those with refractive error and presbyopia, respectively, in the sample population were uncorrected. In the late 1990s, two papers from different parts of the world, Australia and India, highlighted the fact that uncorrected refractive error was a significant cause of blindness and the major cause of impaired vision. [15],[16] Myopia was found to be responsible for much of the uncorrected refractive errors in the world. [17] Since then, hospital based studies on refractive errors have been carried out in different geographical locations in Nigeria. Bagaiya and Pam [11] found uncorrected refractive errors to be a common cause of visual impairment in Kaduna. In addition, they also found low-grade hyperopia to be the commonest spherical error. Adegbehingbe [18] found myopia to be the commonest spherical error in Ile-Ife. Koroye-Egbe [19] found uncorrected astigmatism to be the commonest refractive error in Bayelsa.

In Lagos, Adefule-Ositelu [20] found myopia to be more common among ophthalmic patients in Lagos University Teaching Hospital. Adeoti [21] also found uncorrected myopia to be the commonest in Oshogbo. In addition, Nwora and Ezepue [22] discovered a little excess of uncorrected myopia in eastern Nigeria. Similar to the findings in Kaduna, uncorrected refractive errors are found to be a common cause of visual impairment in the university community of Zaria. The prevalence in both the settings was 12.7 and 15.8%, respectively, although the commonest spherical error among patients attending the university health facility was myopia (simple type of not more than −3.25D/S). Details about refractive error are presented in [Figure 2].

Students constituted 78.1% of the patients with uncorrected refractive errors, and since they are from different parts of the country, this could explain the difference in the predominant error of refraction. This finding is in line with that of Adefule-Ositelu [19] in Lagos, and Adegbehingbe [17] in Ile-Ife. The fact that not all patients were refracted means that some uncorrected hyperopes who had 6/6 vision (after accommodation) and did not complain of eye strain must have been missed out. The total prevalence of patients with uncorrected presbyopia alone or with other uncorrected refractive errors was 6.3%. This is very low compared with 31.8% reported for southwest Nigeria [17] and 56% for northern Nigeria [11] which has the same geographic setting. This may be because the study was based within the university and most of the patients were students who were below the presbyopic age.

This study provides a preliminary report on the prevalence of uncorrected refractive error and presbyopia within the university community. Since most of the patients with uncorrected refractive errors are students (78.1%) and the National Health Insurance Scheme caters only for the cost of refraction even for the university staff, it is only rational to make available affordable and good quality spectacles for them, if it cannot be provided free of charge. Refraction services should be targeted at individuals in the peri-adolescent and middle age range. [23] This can only be achieved if cost is not overlooked as a stumbling block within a resource-limited economy like ours.


   Acknowledgments Top


The authors thank the ABU Management through the Medical Director of the ABU Sick Bay for giving approval for this study. We also thank the nurse, Hadiza Lawal, of the Nursing Services, ABUTH Shika-Zaria, for her assistance in the data collection, and the staff and the nurses at the Sick Bay, particularly, CNO A. L. Shittu and ACNO I. Junaid, for their cooperation.

 
   References Top

1.Javitt JC, Chiang YP. Socio economic aspects of laser refractive surgery. Arch Ophthalmol 1994;112:1526-30.  Back to cited text no. 1
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2.Allen F, Clare G, Gordon J. Changing Patterns in Global Blindness: 1988 - 2008. Commun Eye Health J 2008;21:37-9.  Back to cited text no. 2
    
3.Stambolian D, Ciner EB, Raider LC, Moy C, Dana D, Owens R, et al. Genome-wide scan for myopia in the old order Amish. Am J Ophthalmol 2005;:5469-76.  Back to cited text no. 3
    
4.Wojcie-Chowski R, Moy C, Ciner E, Ibay G, Reider L, Bailey-Wilson JE, et al. Genomewide Scan in Ashkenazi Jewish families demonstrates evidence of linkage of ocular refraction to a QTL on Chromosome Ip36. Hum-Genet 2006;119:389-99.   Back to cited text no. 4
    
5.Hammond CJ, Sneider H, Gilbert CE, Spector TD. Genes and environment in refractive error: The Twin Eye Study. Invest Ophthalmol Vis Sci 2001;42:1232-6.  Back to cited text no. 5
    
6.Angle J, Wissmann DA. The epidemiology of Myopia. AMJ Epidemiol 1980;11:220-8.  Back to cited text no. 6
    
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9.Hammond CJ, Andrew T, Mak YT Spector TD. A susceptibility locus for myopia in normal population is linked to the PAX6 gene region on Chromosome 11: A genome scan of dizygotic twins. Am J Hum Genet 2004;75:294-304.  Back to cited text no. 9
    
10.Ezepue UF. The distribution of Presbyopia in the Eye Clinic of the Eastern Nigeria Medical Centre Enugu. Orient J Med 2003;15:32-5.  Back to cited text no. 10
    
11.Bagaiya T, Pam V. Refractive errors in Kaduna Nigeria. Niger J Surg Res 2003;5:106-9.  Back to cited text no. 11
    
12.United Nations Development Programme (UNDP) Human Development Report; 2007. p. 229-300.  Back to cited text no. 12
    
13.Naidoo K Govender P. Case finding in the clinic: Refractive errors. CommunEye Health J 2002;15:39-40.  Back to cited text no. 13
    
14.Thiagalingam S, Cumining RG, Mitchell P. Factors associated with under corrected refractive errors in an older population: The Blue Mountain Study. Br J Ophthamol 2002;86:1041-5.  Back to cited text no. 14
    
15.Dandona L, Dandona R, Naduvilath TJ, McCarty CA, Srinivas M, Mandal P, et al. Burden of moderate visual impairment in an urban population in Southern India. Ophthalmology 1999;106:487-504.  Back to cited text no. 15
    
16.Taylor HR, Livingston PM, Stanislavsky YL, McCarty CA. Visual impairment in Australia, distance visual acuity, near vision and visual field findings of the Melbourne visual impairment project. Am J Ophthalmol 1997;123:328-37.  Back to cited text no. 16
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17.McCarty CA. Editorial: Refractive error. Br J Ophthalmol 2006;90:521-2.  Back to cited text no. 17
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18.Adegbehingbe BO, Majekodunmi AA, Akinsola FB, Soetan EO. Pattern of refractive errors at Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria. Niger J Ophthalmol 2003;11:76-9.  Back to cited text no. 18
    
19.Koroye-Egbe A, Overensi-Ogbomo GO, Adio AO. Refractive error status in Bayelsa State, Nigeria. Journal of Nigerian Optometric Associations2010;16:11-6.  Back to cited text no. 19
    
20.Adefule-Ositelu AO. Refractive errors in Lagos, Nigeria. Niger Med J 1995;29:101-3.   Back to cited text no. 20
    
21.Adeoti CO, Egbewale BE. Refractive errors in Mercyland Specialist Hospital, Osogbo, Western Nigeria. Niger Postgrad Med J 2008;15:116-9.   Back to cited text no. 21
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22.Nworah PB, Ezepue UF. Prevalence of errors of refraction in a Nigerian Eye Clinic. Niger J Med 1991;1:57-9.  Back to cited text no. 22
    
23.Ayanniyi AA, Folorunsho FN, Adepoju FG. Refractive ocular conditions and reasons for spectacles renewal in a resource limited economy. BMC Ophthalmol 2010;10:1471-2415.  Back to cited text no. 23
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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