Presbyopia in African tropical environment: sociodemographic and clinical aspects about 500 cases in the ophthalmology department of the teaching Hospital of Cocody (Abidjan, Ivory Coast)
Presbyopia is defined as the loss of power of lens accommodation related to age. It causes an inability of the eye to focus on near objects and images clinically reflected by a gradual decline of near vision. Its prevalence in countries with low and middle income is uncertain because most studies of refractive errors in these countries have been limited to distance vision . In the absence of data on the study of presbyopia in the general population, African studies in hospitals have shown that presbyopia began earlier and was more severe than in Europe and North America [2-5]. Furthermore, other authors found that it affected women earlier than men . These data from the literature lead us to make the following assumptions:- Presbyopia in the African tropical environment has epidemiological and clinical characteristics, especially in mélanoderma person
– The use of computer programs on refractors which determine the value of addition according to the age, based on temperate countries data involves risks of poor correction of presbyopia in the African tropical environment.
– Presbyopia occurs earlier in women than in men and is less severe in man than in woman.
The objectives of this study were to:
• Describe the socio-demographic and clinical characteristics of presbyopia in African tropical environment, in order to improve the clinical management.
• Analyze, firstly, the correlation between gender and the age of onset of presbyopia and secondly, the correlation between gender and the value of the addition for near vision.
Materials and Methods
It was a Cross-sectional study of ten week (04 January to 12 March 2010) performed in the outpatient unit of the ophthalmology department of the teaching hospital of Cocody (Abidjan, Ivory Coast). We recruited systematically (non-probabilistic) and for ten weeks, five hundred (500) presbyopic patients who agreed to participate in the survey during the term thereof, under the following criteria:
Inclusion Criteria [1, 7]
• The melanoderma patients, phakic, unable to read at 33 centimeters and without optical correction, optotypes sizes corresponding to paragraph 2 on the Parinaud scale(P2), or R1 / 2 on that of Rossano.
• Patients with near visual acuity improved with opportunity to read the above optotypes at 33 centimeters after the addition of convex spherical lenses of at least one (01) diopter. The addition for near vision was made after the correction of distance vision by the subjective method.
• Patients were already or not holders of optical correction for both distance vision and for near vision.
• The pseudophakic or aphakic patients.
• Patients that near visual loss was due to an organic cause (cataract, maculopathy etc.) and / or was not improvable despite the addition of convex spherical lenses over a diopter.
• Patients that anisometropia exceeded one diopter (spherical equivalent, to avoid disruptive effects might have had a large anisometropia on the quality of vision).
The variables studied were:
• Socio-demographic characteristics: age, gender, occupation and educational level. These data were collected in the questioning but age was determined using the patient’s identity document. Age in years was noted.
• The reason for the consultation.
• The previous use or not of corrective glasses to determine the prevalence of uncorrected refractive disorders due to lack of data in general populations.
• The previous correction of presbyopia in patients already carrying correcting glasses was checked in order to estimate the prevalence of uncorrected presbyopia given the lack of data in general populations.
• The physiological age of first presbyopia correction among holders of corrective lenses.
• The nature of the ametropia for far vision, “as revealed by the study of refraction during the consultation of the patient”.
• The duration of wearing corrective lenses for patients that already had optical correction.
• The value of addition for near vision.
Data were recorded on individual survey forms, anonymous and numbered. They were then entered on an input mask and processed using Epi Data version 3.1.
Demographic data were analyzed by calculating averages or proportions. As for the correlation studies, they have been the subject of statistical tests involving comparison of means and variances.
During an oral interview, patients were informed of the interest of the study and reassured of his confidential marked by the anonymity of the survey forms. After being informed of their right to accept or refuse to participate, we got from them a verbal agreement before the start of the investigation; we have not recorded any audio consent. The reason is that sociologically these records sometimes give rise to reluctance and refusal of participation in surveys.
Our sample consisted of 258 men (51.6%) against 242 women (48.4%) thus a slight male majority with a sex ratio of 1.06. The average age for all patients was 48.18 years (range 35 to 77 years) with a standard deviation of 6.8. In male patients, the mean age was 48.33 years (range 36 to 65 years with a standard deviation of 6.436). In female patients, the mean age was 47.98years (range 35 to 77years with a standard deviation of7.326 and a median of 47years).The level of education is characterized by a majority of patients at university level (41%), followed by patients of high school level (33.2%). A small proportion of low-educated patients were noted: 17.4% primary level, 7.2% un-schooled and 1.2% that had only a Koranic instruction in Arabic. Socio professionally, most patients were in the education sector (15.8%), followed by those in the informal sector who consists of artisans and small shopkeepers (18.8%). The least represented category was the agricultural sector (2.6%). Moreover, agents of financial services accounted for 5.8% while the executives of the public and private administration and businessmen all represented 6.2% of the workforce.
Refractive history and clinical aspects
A slight majority of patients were in their first prescription for corrective lenses (265 patients, 53%). Those who already wore glasses (235 people, or 47%) were doing it since 9.91 years on average (1-35 years with an ecard type of 7.337). Among these former holders of glasses, 197 patients (83.82%), including 103 women and 94 men already benefiting from a correction of presbyopia. Among them, the average age of the first correction of presbyopia was 51.52 years. Clinically, the main reason for consultation was the decreased visual acuity (93.4%).This complaint was followed by the loss of far vision (28.2%), headache (17.8%) and oculalgia (7.2%). Other motives such as eye pruritus (6.4%), control of glaucoma, or photophobia (2%) had been raised by some patients.
The average age of the first correction of presbyopia is not depending on gender, according to the Student t testTable I: Comparison of means age of the first correction of presbyopia according to genre.
The average age of the first correction of presbyopia in all male patients (258 patients) was 45.21 years (standard deviation of 5.263 with extremes of 36 and 59 years) while among female patients (242 patients) it was 44.88 years (range of 35 and 77 years) [Table I] and the value of the addition was 1.968 diopters for men (range of 1.00 and 3.25 diopters with a standard deviation of 0.520) and 1.923 diopters for women (range of 1.00 and 3.50 diopters with a standard deviation of 0.565). In all patients (N = 500), the average value of the addition for near vision was 1.946 diopters (range of 1.00 and 3.50 diopters with a 0.542 standard deviation) for an average age of 48, 18 [Table II].
According to the Student t test, P = 0.95: for a given average age, the average value of the addition is not dependent on gender.
Table II: Comparison the average values of the addition for near vision in terms of the average age of patients according to gender.
In total, in 229 cases (45.8%), presbyopia was isolated. presbyopia was associated with myopia in 57 patients (11.4%), associated with hyperopia in 109 patients (21.8%), combined with a simple astigmatism in 68 patients (13.6%) and associated with astigmatism compound or mixed in 37 patients (7.4%). Furthermore, the average age of the first correction of presbyopia is statistically related to the type of ametropia associated with presbyopia [TableIII].
The analysis of this table shows, from the degree of significance of the tests that the average age of first presbyopia correction depends on the type of ametropia which it is associated and also on gender.
Table III: Comparison of average ages of first correction of presbyopia according to the type of ametropia associated.
The majority of our patients were between 40 and 59 years (87%), corresponding to the age group of the working population  and the age of onset of presbyopia according to many authors [7, 9-11]. We can deduce that, given the prevalence of uncorrected presbyopia in low-income countries, it could be a cause of sensory disabilities and of low productivity in these countries. Consequently, routine screening strategies for presbyopia and other insidious eye diseases occurring after the fourth decade such as chronic open-angle glaucoma should be in place in these countries.
The gender breakdown indicates almost equal proportions with a sex ratio of 0.97. This slight male predominance might be explained by the non-random method of recruitment of our patients but also by the difference in purchasing power between man and woman in Favor of man, in the African context.
For, beyond the fourth decade, women are more vulnerable to presbyopia, for hormonal reasons [7, 12].
The level of education and socio-professional category The majority of patients had completed secondary and superior education. So they can read and write and they feel more clearly and can be as early visual impairment caused by presbyopia. Regarding the socio professional category, we noted the predominance of professionals in the field of education. They are followed, in terms of proportion, by informal sector workers who are generally craftsmen and considerably solicit near vision. This justifies the distinction between physiological presbyopia and functional presbyopia as proposed by Nirmalan PK et al . Indeed, applied to our study, this distinction would allow to define the functional presbyopia as a decrease in near vision, hindering enough the professional activity to require optical correction for near vision. Presbyopia seen in this angle, agents of financial services, executives of public or private administration and business men should be much represented in our sample being given that their business activities are based on the near vision and intermediate vision, either to read or to write . these data contradict the definition of the proposed functional presbyopia. This contradiction could simply be due to the method of recruitment of our patients which was not random. Furthermore, the study was conducted in a public hospital whose services costs are relatively low to allow wider access to the most disadvantaged populations; another recruitment bias could have been possible. In fact, senior managers who have a lot more money and are usually covered by private health insurance would tend to attend private hospitals. Moreover, we found a high proportion of household (11.6%) which, a priori, do not do high-precision tasks requiring very good near vision, but are forced to solicit near vision to read on cell phone screens widespread in our context, even among those without a high level of education.
Refractive error history and clinical data
Refractive error history
Just over half of the patients were at their first prescription of corrective lenses. This is consistent with the hypothesis of a high prevalence of disorders of refraction and uncorrected accommodation in low-income countries, like ours and African countries in south of the Sahara. For those who already wore corrective lenses since 9.91 years on average, the majority had a correction of presbyopia. Presbyopia is an acquired disorder, it could easily motivate a consultation than with a refraction disorder in which the patient may not be aware. In our study we did not assess when the last correction for used glasses was, this period seems very long in general in low-income countries. Because in these countries where the lack of resources makes access to eye health services difficult , regular checks of refraction could be a luxury that could not afford the majority of populations. Furthermore, the name “corrective lenses” given to the glasses would think that wearing these glasses would correct in the long term, the refractive disorder for which they were prescribed and could be a justification for the non-renewal of the optical correction. We noted that 53% patients were in their first optical corrections, while 45.8% of the entire sample had an isolated presbyopia. The difference of 36 patients, although small, confirms our idea that some refractive errors in adults are diagnosed when presbyopia necessitates the use of glasses for near vision.
The clinical characteristics of presbyopia
1. The reason for consultation
The most frequent reason for consultation was a decrease near vision. The consultation would be motivated by the perceived need for a correction for near vision, for the fulfillment of certain recreational or professional tasks such as reading. The decrease of distance vision evoked by a high proportion of patients is always associated with a decrease near vision. This is explained by the fact that low static refractive errors are fairly well supported as long as they do not interfere with work. As against the inability to read or perform high-precision professional actions in near vision that reveals the pre-existing visual disturbance, namely poor distance vision. In other cases, the presbyopic “will ignore himself” and is detected at the time of consultation for the renewal of his glasses for distance vision. Headache and oculalgia reported within the scope of the conventional functional symptoms of presbyopia, especially in early stage [15, 16].
2. The age of the first correction of presbyopia
Among the former holders of glasses, the average age was 51.52 years, while for all patients, it was 45, 21 years for men and 44, 88 years for women. The big difference of this data among former holders of glasses and all patients (including newly diagnosed with presbyopia) may be explained, firstly, by a difficult estimation of the age of the first correction of presbyopia among former glass holders and partly by a real reduction in the age of the first correction because of the large current socio-economic changes. Indeed, for a no particularly important event in the life of the patient such as the screening of presbyopia, recall the precise date, using the single memory may be difficult or impossible. However, we note that among all patients, the first correction of presbyopia occurs mid-forties, with no significant difference between men and women (Table I). These indicate particularly in Africa, Central America and India, an earlier onset of presbyopia in the fourth decade than in the fifth [8-11]. Geographical factors such as the latitude would influence the onset of presbyopia. Indeed, it was found that subjects living near the equator become presbyopic earlier than those who were far away [17-20]. Indeed, Ivory Coast is pretty close to the equator. But the decisive factor would be climate, i.e. the average annual temperatures, more they are high, more presbyopia comes early [21, 22]. We believe that our study underestimated the earliness of onset of presbyopia and it would occur earlier in our conditions. This bias is due to a late consultation despite the decreased visual acuity, because of the difficult access to services and ophthalmic corrective lenses, as reported by Nirmala and all in India . A study of presbyopia in private hospitals frequented by people with greater financial resources and benefiting most of the time of diseases covers (private insurance, mutual etc.) could confirm this. Furthermore, one might question the impact of certain negative social representations related to wearing prescription glasses on the late detection of presbyopia despite the early onset of decrease near vision.
3. The value of the addition for near vision
The average value of the addition for near vision did not show any significant difference between men and women. However, it is estimated that for an average age of 48 years, the average value of the addition is 2.00 δ (seen the steps of progression of 0.25 diopters of most of the convex spherical lenses used to correct presbyopia). The value of the addition for near vision, correlated with age exceeds the values as proposed by some authors, for example an addition of 1.50 to 49 δ and δ 2.00 to 54  . These data confirm that in Africa (in our conditions), presbyopia is more severe than in Europe and North America [1-5], although our study did not prove the earlier appearance. And unlike some authors, we found no significant difference between men and women regarding the age of onset of presbyopia and its severity [17, 23, 24]. 4. The type of ametropia associated with presbyopia and average age of the first correction, depending on the type. In the majority of cases (54.2%), presbyopia was associated with myopia (21%), hyperopia (40.2%) and astigmatism simple, compound or mixed (38.8%). Even though these values do not match the distribution of ametropia in the general population, they are consistent with the literature data. Indeed, the amplitude of accommodation is higher in myopic than in the hyperopic, presbyopia would manifest later in the myopic according Mc Brien and al, after a study on the accommodative amplitude among students 18-22 years . By cons, Schaeffer and al showed that refractive errors did not affect the dynamics of natural accommodation , LM Abraham and allhave studied the phenomenon in subjects of 35 to 50 years that they have called subjects in “peri-presbyopia age”. This study confirmed that the amplitude of accommodation of myopia was greater than that of emmetropic and hyperopic but before age 45 years. At that age and beyond, they found no significant differences between the accommodations amplitudes of these different groups . Furthermore, we must consider the index myopia caused by the debutant nuclear cataracts that improve near vision of presbyopic. These come earlier in the tropics and can therefore underestimate the prevalence of presbyopia . The age of the first presbyopia correction varies depending on if it is isolated or associated with ametropia. When associated with ametropia, age also varies by type of ametropia (Table III). These data are consistent with the fact that firstly the nearsighted has greater accommodative amplitude that emmetropic before age 45 and on the other hand, the formation of a nuclear cataract after that age transforms presbyopic to nearsighted and improves their near visions . The age of the first correction in simple astigmatism which is the lowest of all is also consistent with the principles stated above, since the functional symptoms associated with astigmatism may increase the need of optical correction in case of beginning presbyopia. By cons, on the same Table III, we found an average age of first correction of presbyopia higher among hyperopic and mixed or compound astigmatism, not in accordance with these principles. This discrepancy leads to search for other factors not involved in determining the age of onset of presbyopia (physiological presbyopia), but in the age determination from which its clinical manifestation restrict the activity of the subject, to render necessary the optical correction for near vision (presbyopia functional). These would be professional factors, environmental factors and even cultural factors.
Presbyopia is the earliest manifestation and probably the most obvious eye senescence. It occurs in midlife; it is supposed to occur earlier in the tropics than in temperate zone and results in a decrease in near visual acuity. Its precocity could not been highlighted by our study. But the value of the addition for near vision is significantly higher for the same age, in our conditions than values usually accepted in temperate countries. Consequently, clinicians must consider this difference to adapt the correction of presbyopia, when using automated refractors. We found no difference between man and woman about presbyopia.
The earliness of the onset of presbyopia in our terms, not found in our study, does not call into question the accepted data but would pose the problem of early detection of it. Indeed, the motivation of the consultation for a decrease of near visual acuity depends much more on professional factors and may be cultural than physiological decrease in amplitude of accommodation. A better understanding of presbyopia in our environmentrequires specific studies on the amplitude of accommodation. Moreover a good knowledge of sociocultural factors which influence the refractive care demand for both distance vision and near vision would reduce the prevalence of ametropia not corrected in our low-income countries. Finally, the correction of presbyopia patients of African origin in temperate countries where the value of the addition is predetermined according to age and using certain software, should consider our data.
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