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.

Study population consisted of the permanent residents of the town and village settlements within the local government.

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.

The study was a population-based descriptive and cross-sectional 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.

Ethical approval was obtained from the Ethical Committee of Olabisi Onabanjo University Teaching Hospital Research (Ethical Clearance Number: OOUTH/DA:326/795) on 14 September 2012. Consent was obtained from the Medical Officer of Health of Sagamu Local Government Council. Written and/or oral informed consent was obtained from the participants prior to the interview and examination. The tenets of the Declaration of Helsinki were strictly adhered to throughout the study.

The overall prevalence of presbyopia (Table 1) amongst the study participants was 80.8% (95% confidence interval [CI] 77.4–83.7). 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.

X² = 122.6, p = 0.0001, degree of freedom (df) = 5; X² = 189.7, p = 0.0001, df = 5.

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 post-secondary 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%).

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-related task except for activities like harvesting, lighting/adjusting lamp and winnowing grains.

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.

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 Chiroma¹⁰ 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 Pradesh⁴ 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 non-presbyopes 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 near-vision problem (p = 0.0004) more than non-presbyopes. This is consistent with the findings previously documented in Tanzania³ and Abuja.¹⁰ It is also similar to that found in Ibadan⁹ 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 non-presbyopes 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 reporting problems with family, feeling looked down upon and being satisfied with general health.

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.