Abstract
Background
The use of population-based method to assess the prevalence of presbyopia and spectacle use is few even though it is more reliable compared to the commoner hospital based studies. This study was carried out to determine the need for spectacle services in our coverage area.
Aim
To determine the prevalence of presbyopia among adults of 30 years old and above in Sagamu local government area of Ogun state, South-West, Nigeria.
Design
The study was a population based descriptive and cross-sectional design.
Setting
The study was carried out using a multistage cluster random sampling with probability proportional to size of regular adult residents of Sagamu Local Government area, Sagamu, Ogun state, Nigeria.
Materials and Methods
Examination of respondents included administration of semi-structured interviewer assisted questionnaire and distance visual acuity measurement with or without pinhole at 6 meters using the Snellen’s charts. Automated refraction with subjective refraction was carried out in all participants with presenting visual acuity (PVA) worse than 6/9 but with an improvement with pinhole. Near assessment was done at 40cm with the distance correction in place if required. Ocular examination was also carried out in all participants that had refraction including pupillary dilatation when indicated.
Results
The prevalence of presbyopia was 80.9%. There was an increasing prevalence with age (p<0.001) with a 100% prevalence in the ≥80 years age group. The mean add requirement was +2.24DS. The met presbyopic need was 22.9% and the unmet need 58%. The presbyopic spectacle coverage was 28.4% which was positively associated with younger age (p=0.034), attaining at least secondary school education (p<0.001), and living in an urban area (p<0.001).
Conclusion
The prevalence of presbyopia is high in this community and found in persons younger than 40 years and the spectacle coverage for the population is low with a high unmet spectacle need. There is a need to provide near vision spectacles to a large proportion of residents in the community.
Keywords: Community-based, Prevalence, Presbyopia
Introduction
Presbyopia, the loss of the ability to see clearly at a normal near working distance, while fully corrected for distance vision, affects 100% of the population by the fifth decade of life1.
Presbyopia has now been recognized as an aspect of refractive error that needs to be addressed hence its inclusion in the World Health Organization (WHO) 2006-2011 strategy of vision 2020 for refractive errors and low vision2. The overall aim of this strategy is to eliminate avoidable visual impairment and blindness due to uncorrected refractive error and to reduce the magnitude of uncorrected presbyopia.
In low and middle income countries, studies have shown that more than half of adults over the age of 30 years have presbyopia and the majority of these do not have corrective spectacles3. In these countries also, only few presbyopia studies have used a population-based approach, making it difficult to draw conclusions about the prevalence of presbyopia in the general population.
This study aims to determine the prevalence of presbyopia, the unmet presbyopia need and the presbyopia correction coverage using a community based approach in an urban/rural South-western Nigerian community in Sagamu LGA.
The LGA covers 641km2 with a population of 255,885, comprising 126,855 males (49.6%) and 129,030 females(50.4%) by 2006 Nigerian census4. Those 30 years and older were 29.3% by national average. Thus, estimated total population of 30 years and older in the LGA was 74,974.
MATERIALS AND METHODS
The study was carried out in Sagamu Local Government Area (LGA) of Ogun State in Nigeria among adult population aged 30 years and above between 17th September and 25th November, 2012.
Ogun State is one of the 36 States in Nigeria and situated between latitude 6.20N and 7.80N and longitude 3.00E and 5.00E in the south-west zone of the country. Eye care services are available at the eye clinic of the Olabisi Onabanjo University Teaching Hospital (OOUTH) in the area, some private hospitals and optical clinics. The eye clinic of OOUTH is the only public institution providing eye care service to the people of the local government.
Study population
This consisted of the permanent residents of the town and village settlements within the local government.
Inclusion and Exclusion criteria
All individuals aged 30 years and above who had been resident in the study area for at least 6 months were enumerated and invited to participate in the study. The exclusion criteria were those with corrected visual acuity (V.A.) worse than 6/60, debilitated or severely ill persons and those who’s V.A. could not be tested.
Ethics and consent
Ethical approval was obtained from the ethical committee of Olabisi Onabanjo University Teaching Hospital, Sagamu and consent from the Medical Officer of Health of Sagamu Local Government Council. Written/oral informed consent was obtained from the participants prior to the interview and examination. The tenet of the declaration of Helsinki was strictly adhered to.
Study design
The study was a population based descriptive and cross-sectional study. It was conducted using a multi-staged stratified cluster random sampling technique with probability proportional to size. The sampling unit was the household which was taken to consist of all individuals who live under the same roof. To arrive at a chosen household a 4-staged cluster sampling as follows was used: Sagamu LGA has 15 wards with 3 classified as rural. So, the wards to be enumerated were randomly chosen at ratio 4 to 1 by balloting after number the wards alphabetically(Stage 1). The urban wards has 66 settlements whilst the rural has 33 with an Oba or Baale heading each settlement. Eleven(11) were chosen from urban but 3 from rural using systematic random sampling after calculating the sampling interval of 6 for urban and 12 for rural until the required number is reached. The first settlement is chosen among the first 1 to 6 for urban or 1 to 12 for rural and then the 6th and 12th thereafter consecutively (Stage 2). At the chosen settlement on the day of survey a bottle is spinned until it stops, and the house the bottle faces becomes the first one to be enumerated (Stage 3). Then, the consecutive households with eligible consented individuals were thereafter screened until the required number of 50 is reached. In small settlements, if less than 50 is obtained the adjacent settlement is screened to reach the required number (Stage 4).
The minimum sample size was calculated using the Leslie-Kish formula5. The minimum sample size calculated was 441, but was adjusted to 662 after using 1.5 for design effects.
Each eligible individual was given an identification slip to bring to the examination centre where interviews, examination and refraction were performed.
For the study, we used the N8 optotype (1M or 20/50 Snellen acuity) as the end point of near vision testing. We measured near vision by placing the near chart 40 cm away from the subject. We defined people as presbyopic if both of the following were true: they were unable to read the N8 optotype with distance correction in place, or they were able to read at least one more line with the addition of a plus lens. The distance correction was determined with the aid of an autorefractor and subjective refraction using trial lenses. The degree of presbyopia was determined as the minimum amount of plus lens needed to achieve the maximum improvement in lines read to the end point (N8).
The data was entered and analysed using Statistical Package for Social Sciences V 16 statistical software.
Results
Out of the 662 enumerated participants, 607 completed the face to face interview and examination, giving a response rate of 91.7%. Thirty six (5.4%) participants were not available on the examination day, while 19(2.9%) were not eligible based on the exclusion criteria. The age of the participants ranged between 30 and 86 years with a mean of 49.7 +/- 11.4 years. Three hundred and sixty nine (369, 60.8%) participants were females, giving a male to female ratio of 1:1.6. This is in similar to higher female ratio in the population structure of the LGA(50.4%).
Examination Findings
Presenting distance vision in 66.5%(404) of participants was normal (≥6/9), 19.0%(115) had mild visual impairment (<6/9-6/18), 13.0%(79) with moderate visual impairment (<6/18-6/60); none had severe visual impairment (<6/60-3/60) and 1.5%(9) were blind (<3/60 in the better eye). After correction, 83.7%(508) participants had normal vision, 10.7%(65) mild visual impairment and 5.6%(34) with moderate visual impairment.
The presenting and corrected near visual acuities of participants were as presented in Table 1.The Table also showed that the majority of the participants 477 (78.6%) had a presenting near visual acuity of between N10 and N24 (20/63-20/100) while after correction, 529 (87.1%) had a corrected near visual acuity of N5 (20/20).
Table 1. Presenting and corrected near visual acuities of the participants.
| Near Vision | Presenting near VisualAccuity (%) at 40cm | Corrected near V A (%) at 40cm |
| N5- N8N10-N14N16-N24N36 | 117(19.3)254(41.9)223(36.7)13(2.1) | 604(99.5)3(0.5)00 |
| Total | 607(100) | 607(100) |
Prevalence of Presbyopia
The overall prevalence of presbyopia among the study participants was 80.7% (95% CI 77.4-83.7) as shown in Table 2.
Table 2. Distribution of presbyopia by gender and age group.
| Male | Female | Both Sexes | Both Sexes | |||
| Age Group (No) | Frequency (%) | Number (No) | Frequency (%) | Number (No) | Frequency (%) | |
| 30-39 (38) | 8 (21.1) | 89 | 25(28.1) | 127 | 33(26) | |
| 40-49 (77) | 72 (93.5) | 115 | 108 (93.9) | 192 | 180(93.8) | |
| 50-59 (63) | 62 (98.4) | 86 | 85 (98.8) | 149 | 147(98.7) | |
| 60-69 (46) | 42 (91.3) | 65 | 62 (95.4) | 111 | 104(93.7) | |
| 70-79 (12) | 11 (91.7) | 12 | 11 (91.7) | 24 | 22(91.7) | |
| ≥80years(2) | 2 (100) | 2 | 2(100) | 4 | 4(100) | |
| Total (238) | 197 (82.8) | 369 | 293 (79.4) | 607 | 490(80.7) | |
| ≥ = greater than or equal to. | ||||||
The youngest presbyope was 31 years old and 33 (6.7%) of those with presbyopia were less than 40 years of age. There was an increasing prevalence with age (p<0.001) with a 100% prevalence in the ≥80 years age group. However, there was a decline in prevalence in the 60-69 and 70-79 age groups compared to that of the 50-59 age group.
The prevalence of presbyopia was found to be significantly associated with age (p <0.001), level of education (p <0.001) and occupation (p <0.001). However, there was no significant association between prevalence of presbyopia and place of domicile (p=0.385) or gender (p =0.293). There was a sharp increase in the prevalence of presbyopia from 26% in the 30-39yrs to 93.8% in the 40-49 age groups. This is followed by a steady increase in 50-59 age group (98.7%) before a decline in the 60-69(93.7%) and 70-79(91.7%) age groups. The prevalence of presbyopia was lowest in those with post- secondary school education (66.1%) while it is highest in those without any formal education (90.7%).
Using multivariate analysis for risk factors, those who were50 years of age and above were more likely to have presbyopia (p<0.001) and attaining at least a secondary school education (p =0.004). Having myopia (p<0.001) were negatively associated with presbyopia while hypermetropia (p<0.001) and having cataract (p <0.001) were positively associated with presbyopia. There is no significant association between gender(p=0.293), occupation(p=0.293), place of domicile(p=0.385) and presbyopia.
Presbyopia correction coverage, ‘met’ and ‘unmet’ needs
Prior to the study, one hundred and thirty nine (139) participants out of the 607 had spectacle corrected near vision of at least N8 giving a met presbyopic need of 22.9%. Three hundred and fifty two (351) participants could not read N8 at 40cm because of uncorrected presbyopia. Therefore, the unmet need was 57.8%. This is therefore a need of about 43,335 (57.8% of 74,974 persons) spectacles in the local government area. This is inclusive of the 19 study participants who had spectacles but could not read N8 at presentation.
The presbyopic correction coverage for the study sample is 28.4% (95% CI 24.5-32.5) as shown in Table 3.
Table 3. Presbyopic correction coverage, ‘met’ and ‘unmet’ needs.
| Characteristics | SampleN= 607 | No with Presbyopia (490) | Met need N (%) | Unmet need N (%) | Presbyopia correction coverage (%) | P value |
| Gender | A | B | C | D | C/B X 100 | |
| Male | 239 | 197 | 54 (22.6) | 143 (59.8) | 27.4 | 0.830 |
| Female | 369 | 293 | 84 (22.8) | 209 (56.6) | 28.7 | |
| Age | ||||||
| 30-39 | 127 | 33 | 8 (6.3) | 25 (19.7) | 24.2 | |
| 40-49 | 192 | 180 | 56 (29.2) | 124 (64.6) | 31.1 | |
| 50-59 | 149 | 147 | 52 (34.9) | 95 (63.8) | 35.3 | 0.034* |
| 60-69 | 110 | 103 | 17 (15.4) | 86 (77.5) | 16.5 | |
| 70-79 | 24 | 22 | 4 (16.7) | 18 (75.0) | 18.2 | |
| Above 80 | 5 | 5 | 1 (20.0) | 4 (80.0) | 20.0 | |
| Level of Education | ||||||
| No formal | 107 | 97 | 6(5.6) | 91 (85.2) | 6.2 | |
| Primary school | 178 | 153 | 26 (14.6) | 127 (71.3) | 17.0 | <0.001* |
| Secondary school | 145 | 123 | 39 (26.9) | 84 (57.9) | 31.7 | |
| Post-secondary school | 177 | 117 | 68 (38.4) | 49 (27.7) | 58.1 | |
| Domiciliation | ||||||
| Urban | 390 | 319 | 106 (27.2) | 213 (54.6) | 33.2 | |
| Rural | 218 | 171 | 33 (15.1) | 138 (63.3) | 19.2 | |
| Total | 607 | 490 | 139(22.9%) | 351(57.8%) | 28.0% | |
| *Significant p values | ||||||
It is significantly higher in the 50-59 years age group and those with post-secondary school qualifications. The presbyopic correction coverage is also significantly higher in urban areas than rural area. However, there was no significant difference in the presbyopic correction coverage between males and females.
‘Near Add’ required
The ‘near add’ requirement of the 490 participants classified as being presbyopic is as shown in Table 4.
Table 4. ‘Near add’ required to read N8 at 40cm.
| AGE GROUPIN YEARS | ||||||
| Power (diopters) | 30-39 N (%) | 40-49 N (%) | 50-59 N (%) | 60—69 N (%) | 70-79 N (%) | 80 And Above N (%) |
| +1.00 - +1.75 | 33 | 129 | 1 | 0 | 0 | 1 |
| +2.00 - +2.75 | 0 | 48 | 105 | 10 | 1 | 0 |
| +3.00 | 0 | 3 | 41 | 86 | 14 | 2 |
| +3.50 | 0 | 0 | 0 | 8 | 7 | 2 |
As the age of the participants increased, the near add required to read N8 at 40cm increased
Discussion
The proportion of those with normal vision was similar to the 79.5% obtained in the Southwest geopolitical zone by the Nigerian National Blindness and Visual Impairment study group, even though the national survey involved participants of 40 years of age and above6.
The prevalence of presbyopia(80.7%) in this study is higher than 62% obtained by Burke et al1 in Tanzania and 69.9% in South India7; but lower than 84.5% obtained by Sherwin8 in Kenya, and the 89.2% obtained by Laviers9 in Zanzibar. The lower prevalence obtained in Tanzania1 may be due to the pinhole effect of outdoor testing, but that in India7 is probably from racial and environmental differences. For example, Asians are known to have higher incidence of myopia which will lower the prevalence of presbyopia10. The higher values obtained in Kenya8 and Zanzibar9 may be due to the fact that older age groups (50 years and above), where presbyopia is more prevalent, were studied.
The youngest presbyope was 31 years old and the prevalence of presbyopia was 26% among the 30-39 year old age group. Similar findings have been documented in Nigeria by other researchers11,12. This is possibly because there may be more hyperopic participants in these studies thereby resulting in earlier onset of presbyopia. However, earlier onset of presbyopia in the 30s in hot climates as against the 40s in cooler environments due to earlier occurrence of accommodation failure has been previously highlighted by Weale13.
This study found the prevalence of presbyopia to be positively associated with increasing age. This is similar to findings documented by other researchers in Nigeria and other parts of the world1,9,12,13,14.
There was a statistically significant decline in the prevalence of presbyopia from 98.7% in the 50-59 year age group to 93.7% in the 60-69 year age group and 91.7% in the 70-79 year age group. This may be due to the fact that subjects in these age groups may have had lenticular nuclear sclerosis thus negating the need for near spectacles. Also, the senile miosis usually found in these age groups may have introduced some pinhole effect of between 0.5 -1.0D of focus therefore making some participants to read N8 unaided. Similar findings have been reported in Nicaragua15 and by Mingguang et al16 in their multiethnic study.
The prevalence of presbyopia was found to be higher in males (82.8%) than in females (79.4%) though this is not statistically significant. This is similar to findings previously documented by Naidoo et al in South Africa17.
There was a negative association between presbyopia and attaining secondary and tertiary education similar to findings in Tanzania1. This may be due to the higher prevalence of myopia which has been found to be associated with those with higher levels of education delaying the development of presbyopia in some of the participants18,19. However, some investigators16,20 have documented no association between presbyopia and education. Further study of the relation between type and frequency of activity and near vision use is needed to help explain the association of higher education and presbyopia.
Spectacle coverage
The presbyopic correction coverage for the study was 28.0% while the met need was 22.7% and unmet need 57.8%. In comparison to other studies, the presbyopic correction coverage is similar to that obtained in Abuja (21%)12 and Fiji (24.6%)21 while it is higher than that obtained in Kenya(6.3%)8 and Zanzibar (17.6%)9. However it is lower than the presbyopic correction coverage of 51.5% obtained in China19 and 55% obtained in Brazil22. These coverage differences may be related to socioeconomic factors in the different populations.
Higher presbyopic correction coverage was associated with younger age group (30-59 years), attaining at least secondary school education and urban dwelling. This is consistent with findings obtained in Zanziba9 and Timor-Leste21 while the study carried out in China19 showed no association between presbyopic correction coverage and age, gender or education.
Conclusions
In conclusion, the prevalence of presbyopia is high in this community and found in persons younger than 40 years and the spectacle coverage for the population is low with a high unmet spectacle need. There is a need to provide near vision spectacles to a large proportion of residents of this LGA.
Acknowledgment
The contribution of Drs Musibau RO and Abikoye PO, as well as that of Mrs Ogundipe MC during the data collection is hereby appreciated. This work was originally part of the data obtained by one of the authors for the preparation and submission of her dissertation to the National Postgraduate Medical College of Nigeria for the award of a Fellowship in 2014.
References
- 1.Burke AG, Patel I, Munoz B, Kayongoya A, Mchiwa W, Schwarzwalder AW, West SK. Population-Based Study of Presbyopia in Rural Tanzania. Ophthalmology. 2006;113(5):723–727. doi: 10.1016/j.ophtha.2006.01.030. [DOI] [PubMed] [Google Scholar]
- 2.World Health. Action plan 2006-2011. Geneva, Switzerland: WHO; 2007. Vision 2020, The Right to Sight: Global initiative for the Elimination of Avoidable Blindness. [Google Scholar]
- 3.Patel I, West SK. Presbyopia: Prevalence, Impact and Intervention. J. Comm. Eye Health . 2007;20(63):40-41(63):40–41. [PMC free article] [PubMed] [Google Scholar]
- 4.Nigeria Data Portal. [2016 Jan 25]. http://nigeria.opendataforafrica.org/xspplpb/nigeria-census http://nigeria.opendataforafrica.org/xspplpb/nigeria-census
- 5.Araoye M. Research Methodology with statistics for health and social sciences. Nathadex; Ilorin, Nigeria.: 2003. pp. 117 - 118–128. [Google Scholar]
- 6.Kyari F, Gudlavalleti MV, Sivasubramaniam S, Gilbert CE, Abdull MM, Entekume G, Foster A. Nigerian National Blindness and Visual Impairment study. Invest Ophthalmol Vis Sci. 2009;50(5):2033–2039. doi: 10.1167/iovs.08-3133. [DOI] [PubMed] [Google Scholar]
- 7.Nirmalan PK, Krishnaian S, Shamanna BR, Rao GN, Thomas R. A population based assessment of presbyopia in the state of Andhra Pradesh, South India: The Andhra Pradesh Eye Disease Study. Invest Ophthalmol Vis Sci. 2006;47(6):2324–2328. doi: 10.1167/iovs.05-1192. [DOI] [PubMed] [Google Scholar]
- 8.Sherwin JC, Keeffe JE, Kuper H, Islam A, Muller A, Mathenge W. Functional presbyopia in a rural Kenya population: the unmet presbyopic need. Clin. Experiment. Ophthalmol. 2008;36(3):245–251. doi: 10.1111/j.1442-9071.2008.01711.x. [DOI] [PubMed] [Google Scholar]
- 9.Laviers HR, Omar F, Jecha H, Kassim G, Gilbert C. Presbyopic spectacle coverage, willingness to pay for near correction and the impact of correcting uncorrected presbyopia in Zanzibar, East Africa. Invest Ophthalmol Vis Sci. 2010;51(2):1234–1241. doi: 10.1167/iovs.08-3154. [DOI] [PubMed] [Google Scholar]
- 10.Pan CW, Zheng YF, Anuar AR, Chew M, Gazzard G, Aung T, Cheng CY, Wong TY, Saw SM. Prevalence of refractive errors in a multiethnic Asian population: the Singapore epidemiology of eye disease study. Invest Ophthalmol Vis Sci. 2013;54(4):2590–2598. doi: 10.1167/iovs.13-11725. [DOI] [PubMed] [Google Scholar]
- 11.Muhammad RC, Jamda MA, Langnap L. Prevalence of presbyopia in rural Abuja, Nigeria. Ann Nigerian Med . 2015;9:56–60. [Google Scholar]
- 12.Adegbehingbe BO, Majekodunmi AA, Akinsola FB, Soetan EO. Pattern of refractive errors at Obafemi Awolowo University Teaching Hospital, Ile-Ife. Nigerian Journal of Ophthalmology. 2003;11(2):76–79. [Google Scholar]
- 13.Uche JN, Ezegwui IR, Uche E, Onwasigwe EN, Umeh RE, Onwasigwe CN. Prevalence of presbyopia in a rural African community. Rural and Remote Health. 2014 Aug;14 [PubMed] [Google Scholar]
- 14.Weale RA. Refractive errors and Presbyopia In: Johnson GJ, Minassian DC, Weale RA, West SK. Epidemiology of Eye Disease.2. London: Arnold Publishers; 2003. pp. 135–154. [Google Scholar]
- 15.Hookway LA, Frazier M, Rivera N, Ramson P, Caballo L, Naidoo K. Population-based study of presbyopia in Nicaragua. Clin Exp Optom. 2016 Jul 10; doi: 10.1111/cxo.12402. [DOI] [PubMed] [Google Scholar]
- 16.Mingguang H, Amza A, Leon BE, Naidoo KS, Sapkota YD, Thulasiraj RD, Varma R, Zhao J, Kocur I, NG Congdon. Age-related Prevalence and Met Need for Correctable and Uncorrectable Near Vision Impairment in a Multi-country Study. Ophthalmology. 2014;121:417–422. doi: 10.1016/j.ophtha.2013.06.051. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Naidoo KS, Jaggernath J, Martin C, Govender P, Chinanayi FS, Chan VF, Ramson P. Prevalence of presbyopia and spectacle coverage in an African population in Durban, South Africa. Optom Vis Sci. 2013 Dec;90(12):1424–1429. doi: 10.1097/OPX.0000000000000096. [DOI] [PubMed] [Google Scholar]
- 18.Tavezy-Hornock K, Ying Lai M, Varma R. The Los Angeles Latino Eye study group. Myopic refractive errors in adult Latinos: The Los Angeles Latino Eye study. Invest Ophthalmol Vis Sci. 2006;47(5):1945–1852. doi: 10.1167/iovs.05-1153. [DOI] [PubMed] [Google Scholar]
- 19.Xu L, Li J, Cui T, Hu A, Fan G, Zhang R, Yang H, Sun B, Jonas JB. Refractive errors in Urban and rural adult Chinese in Beijing. Ophthalmology. 2005;112(10):1676-83(10):1676–1683. doi: 10.1016/j.ophtha.2005.05.015. [DOI] [PubMed] [Google Scholar]
- 20.Lu Q, He W, Murthy GV, He X, Congdon N, Zhang L, Li L, Yang J. Presbyopia and near vision impairment in rural Northern China. nvest Ophthalmol Vis Sci. 2011;52(5):2300–2305. doi: 10.1167/iovs.10-6569. [DOI] [PubMed] [Google Scholar]
- 21.Ramke J, Toit du R, Palagyi A, Brain G, Naduvilath T. Correction of refractive error and presbyopia in Timor Leste. Br J Ophthalmol. 2007;91:860–866. doi: 10.1136/bjo.2006.110502. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Duarte WR, Barros AJD, Dias-da-costa JS, Caltan JM. Prevalence of near vision deficiency and related factors: a population based study in Brazil. Cad Saude Publica. 2003;19(2):551–559. doi: 10.1590/s0102-311x2003000200022. [DOI] [PubMed] [Google Scholar]