The impact of presbyopia on the quality of life in a semi-urban community in Southwest Nigeria

In lowand 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 spectacles.1 The effects of uncorrected presbyopia include loss of employment opportunities, impaired quality of life for the individual and loss of economic gain for the family and society at large. Near visual impairment from uncorrected presbyopia is therefore of public health concern in many parts of the world. Its presence signifies inadequate eye care services because its treatment with corrective spectacles is most likely the simplest and most cost-effective eye care intervention.


Introduction
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 spectacles. 1 The effects of uncorrected presbyopia include loss of employment opportunities, impaired quality of life for the individual and loss of economic gain for the family and society at large. Near visual impairment from uncorrected presbyopia is therefore of public health concern in many parts of the world. Its presence signifies inadequate eye care services because its treatment with corrective spectacles is most likely the simplest and most cost-effective eye care intervention.
Globally, few studies have been carried out to assess the impact of presbyopia on the quality of life of affected persons. The paucity of research on the prevalence of presbyopia and its impact on the quality of life in low-and middle-income countries is because of the perception that presbyopia is unimportant in locations where reading is uncommon. However, there is no evidence basis for this, and the few impact on the quality-of-life studies carried out so far had shown that presbyopia impacts greatly on the quality of life of people living in the rural areas of the developing countries as well. 2,3 In addition, available studies used different lower age limits and definition for presbyopia, making comparison of findings difficult.
The Andhra Pradesh study 4 in India found that subjects who are presbyopic and not using spectacles were more likely to report difficulty with near work than subjects who were using glasses. About 76.3% of the subjects stated they had moderate to severe difficulty in recognising small objects and performing near work such as threading a needle. 4 http://www.avehjournal.org Open Access In a study conducted amongst 1709 Tanzanian subjects found that compared with non-presbyopes, being presbyopic increased the odds of reporting some difficulty with nearvision tasks by twofolds, moderate difficulty by fivefolds and high difficulty by greater than eightfolds. Similarly, in a study conducted in the United States, it was discovered that presbyopia was associated with worse vision-targeted health-related quality of life compared to younger patients with emmetropia. 5 Furthermore, in the Zanzibar study, 6 it was found that 99.4% of participants required help for near activities at baseline, whilst at follow up 6 months after being provided presbyopic spectacles, 85.8% of participants no longer required help for near tasks. Also the mean visual score increased from 64.4% at baseline to 91.5%. A study conducted in China by Lu et al. 7 showed that persons with presbyopia have worse overall self-rated vision and high difficulty with activities of daily living such as threading a needle and sorting grains compared with non-presbyopes, whilst Luo et al. 8 found that presbyopia is associated with a decrease in the quality of life similar to that seen in hypertension.
In Nigeria, Bekibele 9 found that near-vision impairment had a significant impact on all domains of the quality of life, whilst Chiroma 10 also found that presbyopia was associated with reduced quality of life. Similarly, in a more recent Calabar study, 11 South-south Nigeria, presbyopic subjects in a community-based local council survey were significantly associated with reduced quality of life.
This study was designed to be part of a broad communitybased one for the determination of presbyopia and refractive errors in Sagamu Local Government Area (LGA) of Ogun State, Nigeria, towards planning a comprehensive optical services for the area and the environs. There was no previous data for the LGA. Part of this study had been reported in an earlier article. 12

Aim
To determine the impact of uncorrected presbyopia on the quality of life of adults aged 30 years and above in Sagamu LGA of Ogun State, Nigeria.

Research methods and design
The study was carried out in Sagamu LGA of Ogun State in Nigeria amongst adults aged 30 years and above between 17 September 2012 and 25 November 2012.
Ogun State is one of the 36 States in Nigeria and situated between latitude 6.2°N and 7.8°N and longitude 3.0°E and 5.0°E 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
Study population 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 (VA) worse than 6/60, debilitated or severely ill persons and those whose VA could not be tested.

Study design
The study was a population-based descriptive and crosssectional study. It was conducted using a multi-stage 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. The sampling details are contained in an earlier article on prevalence of presbyopia and spectacle coverage which was obtained at the same community-based dissertation research. 12 The minimum sample size was calculated using the Leslie Kish formula. 4 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, examinations and refractions 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 semi-structured questionnaire which contained age, occupation, level of education, domiciliation, near-vision task difficulties, etc., was administered by the trained research assistants who were fluent in English and the local dialect. The questionnaire was translated from English to Yoruba and back-translated from Yoruba to English to ensure consistency. It was serially numbered to avoid duplication.
The data were entered and analysed using Statistical Package for Social Sciences V 16 statistical software. Near-vision tasks were then compared between those with uncorrected presbyopes and non-presbyopes. Also, their perception of quality of life for near tasks were compared.

Prevalence of presbyopia
The overall prevalence of presbyopia ( . 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 = 0.0001) 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. Table 2 shows that the prevalence of presbyopia is significantly associated with age, level of education and occupation. However, there is no significant association between prevalence of presbyopia and place of domicile or gender.
There is a sharp increase in the prevalence of presbyopia from 26% in the 30-39 years age group to 93.8% in the 40-49 age group. This is followed by a steady increase in 50-59 age group before a decline in the 60-69 and 70-79 age groups.
The prevalence of presbyopia is lowest in those with postsecondary school education (66.1%), whilst it is highest in those without any formal education (90.7%). With respect to occupation, the prevalence of presbyopia is highest amongst the unskilled labourers (95.2%), whilst it is lowest amongst the professionals (64.7%).

Visual function and quality of life
The study showed that presbyopes are significantly more likely to require help from others because of near-vision problems. This is highlighted in Table 3. Table 3 shows that presbyopes are more likely to depend on other people than non-presbyopes. Table 4 shows the proportion of study sample engaging in the near-vision activities and those having difficulty in carrying out the activity. The most difficult presbyopic activities were reading, threading needle and recognising small objects. Table 5 shows that presbyopes were more likely to report moderate and severe difficulty in almost all the near-vision-    Table 1 shows that the overall prevalence in men is higher than that in women although this is not statistically significant amongst the 608 (out of 662 enumerated participants) who completed the face-to-face assessment before the end of the survey in each locality. Male age group: N = 239; Female age group: N = 369.  (4) in column 3(4) in column 1(2) 100. = ×  Table 6 shows that presbyopes are significantly more likely to complain about not being satisfied with near vision compared to non-presbyopes. Presbyopes are also more likely to report requiring help from others because of near-vision problems. However, there is no statistical difference between presbyopes and non-presbyopes in reporting problems with family, feeling looked down upon and being satisfied with general health.

Discussion
This study was carried out to determine a population-based impact of uncorrected presbyopia on the quality of life of adults aged 30 years and above in Sagamu LGA of Ogun state. This is important because although some populationbased studies on presbyopia have been carried out in Nigeria, 10,11,12,13,14,15 many are not linked to quality of life, and there is none from this local government.
The overall prevalence of presbyopia (Table 1) amongst the study participants was 80.8% (95% CI 77.4-83.7), with increasing prevalence with age (p = 0.0001) up to a 100% prevalence in the ≥80 years age group. This is similar to the findings documented by other researchers in Nigeria and other parts of the world. 5,7,8,10,16 There was no statistical difference between the prevalence of presbyopia between urban and rural dwellers (81.8% [urban] vs. 78.9% [rural]). This is similar to the findings of Laviers 6 in Zanzibar. However, Nirmalan et al. 5 found a higher prevalence amongst rural dwellers, whilst Burke et al. 16 found a higher prevalence amongst the town dwellers.
Multivariate analysis of the risk factors for presbyopia showed that older age (odds ratio [OR] = 0.08, p = 0.0001) and lower level of education (OR = 2.45, p = 0.004) were associated with higher risk of presbyopia. However, there was no significant association between gender, occupation or place of domicile and a higher risk of presbyopia.
More details on prevalence of presbyopia is already published. 12 The study showed that presbyopes are significantly more likely to require help from others because of near-vision problems as shown in Table 3.

Impact on the quality of life
With respect to the impact on the quality of life, this study found that 78.1%, 77.8% and 40.4% of presbyopes reported moderate to severe difficulty with reading, threading needles and writing, respectively. This is consistent with the findings of Chiroma 10 in Abuja where 95.8% of presbyopes reported moderate to severe difficulty with reading and 75.6% reported moderate to severe difficulty with recognising small objects.
It is also similar to the findings of the Andhra Pradesh 4 study where about 76.3% of subjects reported moderate to severe difficulty in recognising small objects and performing near work such as threading a needles.
There was an almost three-times dependency because of near-vision impairment in presbyopes compared to nonpresbyopes similar to findings previously documented by other researchers. 5,6,7,8 Presbyopes significantly reported not being satisfied with near vision (p = 0.0001) and requiring help because of a nearvision problem (p = 0.0004) more than non-presbyopes. This is consistent with the findings previously documented in Tanzania 3 and Abuja. 10 It is also similar to that found in Ibadan 9 where it was documented that near-vision impairment had a significant impact on all domains of the quality of life.
Comparing difficulty in near-vision tasks between presbyopes and non-presbyopes as illustrated in Table 5, presbyopes had higher levels of difficulty for reading, writing, cooking, sorting grains, threading needle, cutting fingernails, dressing children, identifying working tools, recognising small objects, harvesting, lighting and adjusting lamp and winnowing grains. These differences were statistically significant in all except harvesting, lighting and adjusting lamp and winnowing grains. This is similar to findings in many studies around the world. 8,9,10,11,16 Also, comparing satisfaction with near vision between presbyopes and non-presbyopes (Table 6), about 20% of presbyopes were not satisfied, whilst less than 5% of nonpresbyopes felt so. This difference was statistically significant. Presbyopes are also more likely to report requiring help from others because of near-vision problems. However, there is no statistical difference between presbyopes and non-presbyopes In conclusion, the impact of reduced near vision on the quality of life in Sagamu, Ogun State, Nigeria (consisting of urban, semi-urban and rural communities) seems obvious and similar to findings in urban, 4,5 semi-urban 4,10 and rural 3,4,7 populations around the world. The study indicates a clear need for optical services to include presbyobic corrections in this community.
However, some limitations can be identified in this community-based study including the apparent dissimilarity between the presbyopes and non-presbyopes. The two groups are not age and sex-matched to reduce co-founders. The samples obtained from the community were just compared. This is common in all studies performed on this subject. So, a study to compare age and sex-matched groups is recommended for the future.