|Year : 2014 | Volume
| Issue : 2 | Page : 153-157
Blindness and cataract surgical services in Atsinanana region, Madagascar
Jean-Baptiste Randrianaivo1, R Michele Anholt2, Diarimirindra Lazaharivony Tendrisoa1, Nestor Jean Margiano1, Paul Courtright3, Susan Lewallen3
1 Eye Department, University Hospital, Tamatave, Madagascar
2 Department of Ecosystem and Public Health, University of Calgary, Canada
3 Kilimanjaro Centre for Community Ophthalmology Tanzania, Moshi, Tanzania; Kilimanjaro Centre for Community Ophthalmology International, University of Cape Town, Cape Town, South Africa
|Date of Web Publication||1-Apr-2014|
Kilimanjaro Centre for Community Ophthalmology International, H53 OMB, Groote Schuur Hospital, Observatory 7925, Cape Town, South Africa
Source of Support: This study was funded by Seva Canada, Conflict of Interest: None
| Abstract|| |
Purpose: To assess the prevalence and causes of avoidable blindness in Atsinanana Region, Madagascar, with the Rapid Assessment of Avoidable Blindness (RAAB) survey. We analyzed the hospital records to supplement the findings for public health care planning.
Materials and Methods: Only villages within a two-hour walk from a road, about half of the population of Atsinanana was included. Seventy-two villages were selected by population-proportional-to-size sampling. In each village, compact segment sampling was used to select 50 people over age 50 for eye examination using standard RAAB methods. Records at the two hospitals providing cataract surgery in the region were analyzed for information on patients who underwent cataract surgery in 2010. Cataract incidence rate and target cataract surgery rate (CSR) was modeled from age-specific prevalence of cataract.
Results: The participation rate was 87% and the sample prevalence of blindness was 1.96%. Cataract was responsible for 64% and 85.7% of blindness and severe visual impairment, respectively. Visual impairment was due to cataract (69.4%) and refractive error (14.1%). There was a strong positive correlation between cataract surgical rate by district and the proportion of people living within 2 hours of a road. There were marked differences in the profiles of the cataract patients at the two facilities. The estimated incidence of cataract at the 6/18 level was 2.4 eyes per 100 people over age 50 per year.
Conclusions: Although the survey included only people with reasonable access, the main cause of visual impairment was still cataract. The incidence of cataract is such that it ought to be possible to eliminate it as a cause of visual impairment, but changes in service delivery at hospitals and strategies to improve access will be necessary for this change.
Keywords: Blindness, Cataract, Incidence, Madagascar
|How to cite this article:|
Randrianaivo JB, Anholt R M, Tendrisoa DL, Margiano NJ, Courtright P, Lewallen S. Blindness and cataract surgical services in Atsinanana region, Madagascar. Middle East Afr J Ophthalmol 2014;21:153-7
|How to cite this URL:|
Randrianaivo JB, Anholt R M, Tendrisoa DL, Margiano NJ, Courtright P, Lewallen S. Blindness and cataract surgical services in Atsinanana region, Madagascar. Middle East Afr J Ophthalmol [serial online] 2014 [cited 2022 Jul 1];21:153-7. Available from: http://www.meajo.org/text.asp?2014/21/2/153/129767
| Background|| |
Recent WHO estimates place the number of people visually impaired globally at 285 million, of whom 39 million are blind.  Ninety percent of the world's affected adults and children live in low to middle income countries and 80% are affected by diseases that are treatable or preventable including cataract, corneal disease, trachoma and refractive error.  Vision 2020: The Right to Sight initiative was designed to address the issue of avoidable vision loss and recommends planning eye care services for populations of around 1-2 million. The RAAB methodology was designed to provide basic information for this purpose.  A number of RAAB surveys have been conducted in Africa. These surveys have reported varying prevalences of blindness (visual acuity <3/60) among those 50 years and older from 7.5% in Eritrea,  3.3% in Malawi,  2.4% in Tanzania  , 2.0% in Kenya  , 1.8% in Rwanda  and 1.1% in Burundi.  The low prevalence in the latter two surveys may represent the effects of civil unrest, where mortality could be disproportionately higher in people with disabilities such as vision loss. However, it is apparent that there is variation in blindness in eastern Africa. Madagascar, technically part of the World Health Organization (WHO) sub-Saharan Africa region, is an island nation in the Indian Ocean with a population of approximately 20 million. To the best of our knowledge there have been no previous population-based surveys of eye disease or visual impairment in Madagascar.
The region of Atsinanana in eastern Madagascar has a population of 1,244,897 people and an established ophthalmic service in government hospitals in two coastal towns, Toamasina (Tamatave) and Vatomandry. Both facilities have one ophthalmologist and have been providing surgical eye care services for at least five years, at fairly low levels. With the establishment of a regional VISION 2020 plan in 2009, service delivery doubled in 2010 and continues to increase. In view of the lack of survey information from Madagascar, we planned a RAAB for Atsinanana as part of an analysis of available services. We also wanted to estimate the incidence of cataract using a recently developed model and to examine hospital data to understand the use of services. Early in the planning phase, we recognized that about half of the population lived in areas too remote to reach in less than one day of travel by foot from the nearest road or motorcycle path; many required 3-4 days walk. Therefore, a decision was made for the RAAB to sample only villages within a two-hour walk from the nearest road, recognizing that the results would represent the prevalence and causes of visual impairment in populations with relatively better access to services. For modeling the incidence of operable cataract and the cataract surgical rate (CSR) required to deal with these, the sample from this special population with access should be representative of the whole population since the model does not depend on service delivery.  The CSR is defined as the number of surgeries per million population per year.
From hospital data we sought to determine if districts where large segments of the population lived more than 2 hours from a road would also have lower cataract surgical rates.
| Materials and Methods|| |
Ethics approval for this study was granted by the Ministry of Health, Madagascar. This study followed the tenets of the Declaration of Helsinki. The 2010 census showed that there were 1081 villages in Atsinanana with a total population of 1,244,174 of which 425 villages (population 578,888) were within a two-hour walk from the nearest passable road. From the sample frame of 425 villages, 72 villages were selected by a probability proportional to size method.
Four teams were trained, each including a consultant ophthalmologist and a health assistant. A test of interobserver variability was performed with 40 patients and repeated until the kappa score was 0.6 or better for each team compared to the team with the most experienced examiner. Compact segment sampling was used to select households within each village. This sampling involved sketching maps of the village, dividing them into segments of approximately 500 people including 50 people aged ≥50 years in each segment, then selecting one segment randomly. Households were visited door to door until 50 people ≥50 years had been enrolled. If the segment did not yield 50 people then another segment was randomly chosen and the sampling continued. If an enrolled subject was not available, attempts were made to examine him on return visits.
After obtaining oral consent from the subject, an eye examination was performed according to the RAAB survey methods, using the standard examination forms. Briefly, visual acuity was tested outside using available correction with a tumbling E chart; pinhole vision (assumed to be the best corrected vision) was tested on all eyes with presenting VA < 6/18. The lens was examined inside in a dark room with a direct ophthalmoscope; further examination was conducted with torch and ophthalmoscope to determine the principal cause of visual acuity in any eye less than 6/18. All findings were recorded on the standard RAAB survey record. The principal cause of blindness or visual impairment was assigned for each eye and the cause for the person was the disorder that was easiest to treat. The WHO definitions for visual impairment and blindness with presenting correction are: (i) visual impairment (VI), visual acuity (VA) <6/18 to 6/60, (ii) severe visual impairment (SVI), VA < 6/60 to 3/60, and (iii) blind, VA < 3/60. Participants presenting with cataract in either eye were questioned as to why cataract surgery had not been done. Patients that had cataract surgery were asked for details about their surgery and their satisfaction with the outcome. People identified with operable cataract were informed where surgery is performed and a schedule for outreach visits was developed to reach the most remote areas.
Data from the RAAB examination forms were entered daily by double entry into the RAAB software program (RAAB version 4.02, International Centre for Eye Health, London, UK) which generated automatic reports.
For estimating the incidence of cataract and the CSR required to deal with cataract in Atsinanana Region, we used a previously described model.  Briefly, the model classifies eyes as having cataract if there is a lens opacity responsible for VA of <6/18 or if the lens has been surgically removed. The model uses a compartment system to classify people as having no cataract, unilateral cataract, or bilateral cataract. People may move through the compartments or expire at one of three transition rates; the transition rates are determined mathematically assuming an exponential rate of change; these rates describe the incidence of unilateral and bilateral cataract. Once incidence is determined, the corresponding CSR is determined by considering the percentage of the population over the age of 50 (those presumably at risk for cataract). The model is based on the assumptions that: (1) the population is relatively closed, i.e. there is no significant movement of people over aged 50 or over in or out; (2) that people with cataract are "biologically older" and have a mortality rate 1.5 times that of those without cataract, (3) that non age-related risk factors in a population are relatively stable over time and (4) that the majority of cataract operations are performed in eyes with visual acuity <6/18.
Data from surgical records kept at both hospitals for the calendar year 2010 were examined and the following information was collected: age, sex, district of residence, presenting visual acuity in the operative eye, and whether the surgery was first eye or second eye. This information was used to calculate the actual CSR for each district and for the region overall, assuming that residents of Atsinanana did not travel outside the region to get surgery. People who traveled in to the region for surgery were not counted in the CSR. We used the 'regress" command in Stata (StataCorp. 2009. Stata Statistical Software: Release 11. College Station, TX: StataCorp LP.) to test for correlation between CSR and the percent of the population with access to services.
| Results|| |
Of 3600 people enrolled, 3157 (87.7%) were examined. The sample was a good representation of the population "with access" [Table 1].
|Table 1: Age and gender of people examined compared to population with access to services and to entire region|
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The entire urban district of Toamasina I was included in the sample and approximately 30% of Manapotsy and Marolambo districts were included in the sample [Table 2].
|Table 2: Population, survey coverage, and cataract surgical rate (2010) by district|
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The prevalence of bilateral blindness (VA < 3/60), severe visual impairment (SVI, defined as VA < 6/60 and ≥3/60) and visual impairment (VI, defined as VA < 6/18 and ≥6/60) with presenting correction in the sample was 1.96% (95% confidence intervals (CI): 1.95-1.97), 0.89% (95% CI: 0.88-0.90), and 6.37% (95% CI: 6.36-6.38), respectively [Table 3]. The age and sex adjusted prevalence of blindness, SVI, and VI were 1.62% (95% CI: 1.1-2.1), 0.79% (0.5-1.1), and 5.67% (4.83-6.5), respectively.
|Table 3: Prevalence of blindness, severe visual impairment and visual impairment|
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The leading causes of blindness were cataract (64.5%) and posterior segment causes (27.4%). Severe visual impairment was due to cataract (85.7%) and posterior segment disease (7.1%) and VI was due mainly to refractive error (52.5%) and cataract (41.3). The number of people with these and other causes is presented in [Table 4], [Table 5].
|Table 4: Main causes of blindness and visual impairment in people with available correction|
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|Table 5: presents the results of adjusting the sample prevalence and causes for the age and sex of the population over age 50 with access to services in Atsinanana region|
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The cataract surgical coverage (CSC) by eye and by person are presented in [Table 6].
One hundred and twenty-nine eyes underwent cataract surgery, of which 125 (97%) received an intraocular lens. Seventy-four (59.7%) of these eyes had a presenting visual acuity ≥6/18 while 22 (17.7%) were <6/18 but ≥6/60 and 28 (22.6%) were <6/60. The visual acuities improved with best correction to 91 (73.4%), 11 (8.9%), and 22 (17.7%), respectively. Reasons for presenting outcomes <6/18 were pre-existing conditions in 13 eyes, surgical problems in 9 eyes, refractive error in 13 eyes and long-term sequelae of surgery in 16 eyes.
Incidence modeling of cataract indicates an expected 2.38 new eyes with cataract (at the <6/18 level)/100 eyes in people aged ≥50 years each year. With 10% of the population of Madagascar ≥50 years, this translates into a CSR of 2380 needed to operate on all eyes with incident cataract at the <6/18 level. This is similar to the estimates for several other districts in eastern Africa. 
The 2010 cataract surgical rates in the districts are also presented in [Table 2] and varied greatly from only 35 per million population in the most remote district (Manapotsy) to 750 per million population for the urban area of Toamasina. The correlation between the percent of the population with access to services and the CSR was statistically significant (r = 0.89, P = 0.002). In districts with low CSRs, there was a tendency for more patients to have light perception (LP) vision at time of surgery while in districts with high CSR patients tended to have better preoperative vision. The two surgical facilities had different profiles of patients receiving surgery [Table 7].
|Table 7: Cataract surgical service delivery at the two surgical centers in Atsinanana region|
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| Discussion|| |
This is the first survey of visual impairment in Madagascar; it is important to recognize that the survey represents a population who live in villages within a two-hour walk of the nearest road. In spite of this, 72.6%, 92.9%, and 94% of blindness, severe visual impairment and visual impairment, respectively, were still due to avoidable causes, including cataract, refractive error and corneal scar. These findings are similar to those from other RAAB surveys in eastern Africa. ,, One can assume that, among populations in the remote areas who have to travel several days to access services, the prevalence of blindness and the proportion due to avoidable causes is at least this high. Interestingly, the modeling of cataract incidence in Madagascar produces very similar results to those from other eastern African sites.  This may be due to similarities in environment or genetics. The population of Madagascar is mixed, ethnically, and recent evidence indicates that most Malagasy have a genetic makeup blended of Austronesian and Bantu genes. 
Regarding the calculations of CSR for each district within Atsinanana Region, the strong correlation between the percent of the population with access to services and the CSR is entirely expected and demonstrates the importance of distance as a barrier to cataract surgery, as shown in a recent study in a nearby region in Madagascar.  Outreach services are now offered in Atsinanana but the challenge of getting to people in the most remote areas still exists.
The analysis of patients who underwent surgery at each of the hospitals shows that patients at one hospital are operated earlier, with better VA and this may be a factor in influencing more patients to come from outside Atsinanana Region to take advantage of this service. Waiting until patients are blind to operate is likely to discourage them from ever taking advantage of surgery. However, unless there is a very high probability of a good outcome it is difficult to advocate for earlier surgery. The high number of poor outcomes in this survey is similar to that reported in other regions of eastern Africa but it reflects the outcomes of past years and not necessarily the state of surgery at present.
In summary, although we only examined the population with access, this survey provides useful information for planning future health care services. With cataract surgical coverage (by eye at 6/18 and 6/60) of only 22% and 37%, respectively, there is clearly much room for improvement. Modeling the incidence of cataract at 6/18 indicates that a consistent CSR of around 2300 over time could address a significant proportion of cataract visual impairment, if the quality of surgery is adequate. Emphasis should be placed on quality of surgery being performed at each of the hospitals and this should be monitored carefully. Investigation into whether patients are being turned away (and why) from one of the hospitals may lead to changes that will improve the patients' view of services. Reaching those who live far from roads will continue to be a challenge and the survey preparations highlighted that this includes about half of the population. Annual monitoring of CSR by district will be useful to evaluate who is receiving services and to revise strategies to improve equity.
This study was funded by Seva Canada.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]