There are 285 million people worldwide who have visual impairment because of eye disease or uncorrected refractive error (nearsightedness, farsightedness, or astigmatism). Of these, 246 million have low vision and 39 million are blind (uncertainties, 10 to 20%). Uncorrected refractive errors are the leading cause of visual impairment (43%), followed by cataracts (33%), glaucoma (2%), age-related macular degeneration, diabetic retinopathy, trachoma, and corneal opacities, all approximately 1%.1 The distribution of blindness worldwide does not follow a consistent pattern, with 90% of the blind in low-income countries.2 In developed areas, cataract accounts for only 5% of blindness versus 50% in underdeveloped regions of the world.3
Burkina Faso (West Africa) is one of the poorest countries of the world, with a Human Development Index of 0.389, which gives the country the position 177 of the 182 countries listed. Per million inhabitants, there is only one ophthalmologist providing a surgery rate lower than 500 surgeries per year and million people.4 Health organization global initiatives have called for increased surgical volume worldwide while maintaining good visual results.5
The high prevalence of cataract has led to the implementation of multiple projects throughout the world to eradicate blindness caused by this treatable disease.6–10 These initiatives involve the performance of a large number of surgical procedures in mass campaigns. Our participation is in one of these mass cataract surgery campaigns in the context of international cooperation.
Despite the overwhelming evidence for the need of action to combat blindness caused by cataracts in developing countries, there are few publications that evaluate the visual outcomes in terms of efficacy and safety. The practice of cataract surgery during mass campaigns in these areas is usually limited by access to medical supplies and the surgical complexity of the cases. The purpose of this article is to present an analysis of the visual and refractive results of a mass campaign for people of very low income by applying the standard methodological approach normally used for evaluating refractive outcomes. This campaign has been promoted by nongovernmental organizations in eye care and is the first study conducted in Burkina Faso for this purpose.
A consecutive, prospective, case-series study that included the 315 eyes of 305 patients who underwent cataract surgery during the campaign that the nongovernmental organizations Stop Blindness and Vision Without Borders conducted. Surgeries were performed between November 28 and December 14, 2008, in a district hospital in Bobo-Dioulasso (Burkina Faso).
Cases eligible for inclusion had corrected distance visual acuity (CDVA) less than 20/80 (0.6 logMAR) in the best eye because of cataract and low incomes (check by local counter partner). They were excluded if they had any other ophthalmic disease thought to be the main cause of blindness. There was no limitation of age. Cases were recruited by qualified local staff (nurses specialized in ophthalmology) in the Bobo-Dioulasso area before the arrival of the surgical team. The tenets of Declaration of Helsinki were followed, and informed consent about the surgical procedures and the participation in the study was obtained from each patient before surgery. There is no ethics committee for approving research studies in Burkina Faso. The local institution in charge of approving the sanitary actions and health studies (Le Direction Générale de la Santé du Burkina Faso) authorized the campaign, including the clinical research. Postoperative VAs were classified as good outcomes (VA, ≥20/60), borderline outcomes (VA between 20/80 and 20/200), or poor outcomes (VA, <20/200) according to the World Health Organization’s Prevention of Blindness Program guidelines.11
Previous to the preoperative examination performed by our team, patients had been selected by local assistants in a screening examination that included uncorrected distance VA (UDVA) measurement, in daylight, using a Snellen Tumbling-E chart at 6 m and anterior segment examination with torchlight before surgery. As the great majority of cases were hypermature white cataracts in which refractions could not be done, the same mean values were considered for CDVA.
Preoperative examinations such as detailed slit lamp examination (91102242 by Bobes, Spain), rebound tonometry ICare (Tiolat Oy, Helsinki, Finland), keratometry (Helmholtz by Bobes, Spain), A-scan biometry (A-scan by OTITM, Spain), and all routine preoperative examinations were performed by our team at the hospital on the same day as the surgery. Topical anesthesia and peribulbar anesthesia were provided.
All operations were performed by seven Spanish surgeons in the operating room of the District 22 Hospital of Bobo-Dioulasso. Extracapsular cataract extractions (ECCEs) with intraocular lens (IOL) implantation were undertaken. The IOLs were donated by ophthalmic lens companies for the purpose of the campaign. These were mainly rigid PMMA (poly[methyl methacrylate]) IOLs.
During the operation, the surgeon performed a limbal incision of 8 to 9 mm at the 12 o’clock position and tried to make a circular continuous capsulotomy (CCC), in many cases under trypan blue staining of the anterior capsule. Trypan blue staining was used for performing a CCC in 185 white hypermature cataracts. If capsular calcifications or other anterior segment anomalies prevented this maneuver, a discontinuous anterior capsulotomy was performed using a cystitome or scissors. After the extraction of the nucleus and the cleaning of the cortical remnants, an IOL was implanted in the posterior chamber. In-the-bag implantation was performed in all cases, in which a complete CCC was done (225 surgeries). Different A constants were applied to biometric calculation depending on the implanted model of IOL, following the instructions of the manufacturer. The dioptric power of the IOL was selected for emmetropia in the operated eye. If an exact power was not available for a case, we chose the immediate greater value for leaving the eye in a slightly residual myopic status. Continuous sutures were performed using 10/00 black monofilament after injecting a solution of 0.1 mL (1 mg) of cefuroxime in the anterior chamber.
All cases were performed under a day-case routine, with the patients leaving the clinic after compressive occlusion of the operated eye and with a postoperative appointment for the following day. TobraDex (Alcon, Cusi, El Masnou, Spain) was given to the patients, and they were instructed about how to take care of their eyes.
Sutures, corneas, IOLs, and pupils were assessed in the first postoperative visit by handheld slit lamp examination 1 month after surgery. Rebound tonometry was used to measure intraocular pressure, with hypotensive treatment being provided if necessary.
The 3 months’ postoperative examination included the evaluation of the UDVA and CDVA slit lamp examination, rebound tonometry, keratometry, retinoscopy, and refraction. Objective refraction was done with a retinoscope (Welch Allyn 3.5v Halogen HPX Streak Retinoscope, Model 18200), followed by a subjective refraction using trial frames and lenses. All examinations and refractions were performed by two Spanish optometrists and one local ophthalmic nurse. The incidence and nature of intraoperative and postoperative complications were also recorded.
Arithmetical means, medians, SDs, and SEs were calculated for UDVA and CDVA (after converting the values into logMAR); sphere, cylinder, spherical equivalent, and defocus equivalent were recorded for each eye at every visit.
According to these data, refractive efficacy and safety indexes (efficacy: UDVA 3 months after surgery/CDVA before surgery; safety: CDVA 3 months after surgery/CDVA before surgery) were calculated, and the results were plotted following the recommended standards.12
Data Management and Analysis
Data were tabulated using a spreadsheet (Microsoft Excel, Windows XP Professional, Microsoft). This was also used to perform the calculations for parameters defined as the spherical equivalent and the equivalent defocus for each case.
Statistical analysis was performed using the Sigma Plot 11.0 for Windows (SYSTAT Software Inc):
Descriptive statistics of continuous variables for the description of the samples: mean, SD, median, minimum, maximum, and range.
Descriptive statistics for categorical variables, obtaining frequencies and percentages of the categories.
Comparison tests of means or medians (t test or Mann-Whitney U test) after applying Kolmogorov-Smirnov test on the samples to determine if the data conformed to a normal distribution.
The values of VA were recorded on a decimal scale, later being transformed into logMAR for mathematical and statistical analysis. As efficacy and safety indexes are calculated using a mean value expressed usually on a decimal scale, such data were calculated after the conversion of the arithmetical means of spontaneous and uncorrected long-distance VAs (UDVA and CDVA, respectively) expressed with the logMAR scale.
A total of 305 patients (56.1% male) underwent cataract extraction in at least one eye, 10 of them with bilateral surgery. Mean age was 61.97 ± 14.39 years. The right eye was operated on in 47.30% of cases.
The average ocular axial length was 23.17 ± 1.21 mm, and keratometric values ranged from 50 to 37.64 diopters (D) (43.39 ± 1.79 D for K1 and 43.21 ± 1.64 D for K2). The mean keratometric astigmatism was 0.87 ± 0.84 D.
The mean intraocular pressure (IOP) varied from 16.71 ± 6.49 mm Hg (range, 2 to 55 mm Hg) before surgery to 11.99 ± 4.69 mm Hg (range, 6 to 44 mm Hg).
Visual and Refractive Outcomes
Table 1 shows the number of cases, mean values, SDs, and SEs calculated before and 3 months after surgery for UDVA and CDVA and refractive values at 3 months.
Category of visual loss in the operated eye after surgery with and without correction is shown in Table 2. Most eyes had poor VA (CDVA, <20/200; logMAR, 1.0) preoperatively (88.70%), with a mean VA of logMAR 2.17 ± 0.70 (20/2000 Snellen).
Good outcomes (VA, ≥20/60) were achieved in 38.35% of eyes without correction and 68.7% with correction. Poor outcomes (VA, <20/200) were found in 9.16% of the cases with correction.
The Refractive Efficacy and Safety Indices were calculated. The Refractive Efficacy Index expresses the ability of the procedure to provide a good uncorrected long-distance VA and is calculated by applying the equation UDVA 3 months after surgery/CDVA before surgery. The Safety Index indicates the capability of the surgery to preserve or improve the best spectacle corrected distance VA and is calculated as follows: CDVA 3 months after surgery/CDVA before surgery. The mean Refractive Efficacy and Safety Indices calculated for the operated eyes 3 months after surgery were 9.6 and 15.81, respectively.
The diopric power of the IOLs implanted was slightly different from those calculated as ideal (21.65 ± 3.68 D vs. 22.02 ± 3.43 D, respectively). The mean spherical equivalent calculated for the operated eyes 3 months after surgery were −0.87 ± 1.90 D.
The refractive result ranged between ±0.5 D in 22.1% of the cases. Increasing the range to ±1.00 D accounts for 40.5% of the cases. Fig. 1 illustrates the predictive ability of the operations showing the percentage of eyes that could be included in one of the seven intervals of calculated residual spherical equivalent after operations.
The most common intraoperative complication was the rupture of the posterior capsule (9 of 315, 2.9%), and the worst was expulsive hemorrhage in one eye (1 of 315, 0.31 %). Other adverse outcomes were retrobulbar hemorrhage after anesthesia (1 of 315, 0.31 %) and in toto extraction of the lens (1 of 315, 0.31%) experienced in one eye that had zonular weakness before surgery.
The most common postoperative complication at 24 hours was high IOP (≥30 mm Hg) in 13.01% (41 of 315), followed by decentration of the IOL, 0.31% (1 of 315), and pupillary capture of the IOL optic, 0.31% (1 of 315). There were no cases of acute postoperative endophthalmitis.
Three months after surgery, the following were diagnosed: pupillary capture of the IOL optic (0.62%, 2 of 315), bacterial conjunctivitis (0.95%, 3 of 315), ocular surface irritation caused by loosening of the continuous limbal suture (1.9%, 6 of 315), IOP 30 mm Hg or higher (0.95%, 3 of 315), chronic corneal edema (0.31%, 1 of 315), retinal detachment (0.95%, 3 of 315), posterior capsular opacity (2.9%, 9 of 315), subclinical decentering of the IOL (0.31%, 1 of 315), and ptosis of the upper lid (0.62%, 2 of 315). Posterior capsule opacity was considered when Elschnig pearls or a progressive significant fibrosis was thought to affect the sight of the operated eye.
According to the World Health Organization, a follow-up of the results of cataract surgery campaigns should be undertaken to improve the quality of successive campaigns because the benefit of these types of studies performed with scientific rigor has been demonstrated to improve the humanitarian activities in the field of vision. Limberg and colleagues13 found that, when monitoring the surgical results, the surgeons were more sensitive to quality control, and this resulted in a lower complications rate and better visual outcomes. Yorston and colleagues,14 after applying the conclusions of a comprehensive follow-up of the cataracts operated on in an eye hospital of Kenya for 1 year, demonstrated an improvement in the visual outcomes when comparing the results obtained in the first and fourth quarters of the follow-up period. It seemed that this improvement was also related to a change in the attitude of the surgeons and a better attention to the selection of patients that led to a lower complications rate and better visual results.14 This is the first study to assess the outcome of cataract surgery in the context of an international cooperation campaign developed by a flying team in Burkina Faso. There are no previous studies on cataract surgery in Burkina Faso, and there are only a few published in the region. This study has the potential to provide quality control to our outcomes and for those in similar settings.
In our study, we report the results of a campaign developed by flying in a foreign surgical team. We recognize that, although this model is effective, it is expensive and limited in the volume of care it can deliver. Equipping a local hospital and training a local team is less expensive, has far greater capacity, and can produce excellent results, as it has been proved in many places where this has been established as a preferred model. Therefore, we have recently started the surgical training of local staff to drive self-sustainability of this service.
The Refractive Efficacy Index calculated for our series was 9.6; 88.75% of our patients had a UDVA of less than 0.05 before surgery, whereas at 3 months after surgery, 38.3% of them achieved UDVAs 20/60 or better and 76.7% achieved 20/200 or better. These numbers are similar to those published by Cook15 in Sierra Leona, with 41.7% of the patients seeing 20/60 or better but worse than the data provided by Yorston and Foster16 after evaluating the results of 461 ECCE performed in a Kenyan eye hospital (78.2%). However, the Kenyan series were not in the context of a charity or cooperation program. So, the socioeconomic status of the patients and the concurrent ocular diseases could have an important impact on the results of the two studies.
The Refractive Safety Index calculated for our operated eyes was 15.81, with 68.7% of the eyes achieving a CDVA of 20/60 or better 3 months after procedures. Yorston and Foster16 reported a CDVA of 20/60 or better in 94.3% of their patients. Welsh,17 in a study of more than 3000 cataract operations in South Africa, reported that 98% of the patients achieved a CDVA better than 20/80 in the postoperative control. It is important to consider that neither series was in the context of mass campaigns with a charitable aim. Egbert and Buchanan,18 in Ghana, found 75% of patients with VA 20/100 or better.
Safety and efficacy indices have been used in our article in the same way as in refractive surgery reports, even considering that the visual outcomes are far from the ones reached during trials conducted in developed countries. It is important to consider the potential reasons. The results in our series are more similar to those published with the same technique (ECCE with IOL insertion) in the same region. Isawumi and colleagues19 reported that, for the eyes operated on in three hospitals in Nigeria, visual outcomes (CDVA) were good in only 47.5% of the patients, moderate in 37.6%, and poor in 15%. These authors emphasize in their conclusions that poor visual outcomes had been significantly associated with comorbidity, which could not be visualized before surgery.
The high illiteracy rate, the low preoperative values of VA (97.9% of the eyes presenting VA ≤20/200), the poor conditions of eye health before surgery, and the required complex surgical technique are all factors associated with poor outcome.
The mean spherical equivalent 3 months after surgery was −0.87 ± 1.90 D. In Fig. 1, results on predictability showed a high percentage of eyes with mildly to moderately overcorrected myopia. The ideal IOL was not always available to achieve the goal of emmetropia, and in these cases, we chose the closest most powerful IOL. This decision was intentional because it has the advantage of providing better near vision (reading glasses independence). A hyperopic outcome is not desirable in pseudophakia because it would require the use of optical compensation for both far and near. The refractive outcomes were limited by the accuracy of biometry in very dense cataracts because the measurement of axial length is often nonaxial. Moreover, the use of many different types of IOL complicated the IOL calculation. The dropout rate of 30% has to be recognized in interpreting the results. This rate is difficult to avoid, taking into account the socioeconomic condition of the operated patients.
In a developing country like Burkina Faso, where cataract backlog is still a socioeconomic problem, procedures like phacoemulsification are an expensive treatment option. Extracapsular cataract extraction with posterior chamber IOL implantation surgery is a viable cost-effective alternative. Extracapsular cataract extraction was chosen because of the mature cataracts, the technological independence, and the surgical skills of the surgeons.
Some authors suggest that MSICS (manual small-incision cataract surgery) is an alternative that induces less astigmatism, resulting in better uncorrected VA20,21 and lower cost.22 Extracapsular cataract extraction has been taught in Europe for almost two decades as the technique of choice for cataract surgery and later as the technique for “rescue” when complications during phacoemulsification happen. However, our surgeons started to practice ECCE as they were more comfortable with this technique at the beginning.
For this reason, most published articles about surgical campaigns in the region deal about ECCE and not about MSICS. Today, many are moving to MSICS technique because there is evidence that the results are more favorable in terms of speed of the procedures, visual recovery, and complications.
Last year, our group funded travel for a specialized nurse to Gambia to be trained in ECCE cataract surgery (which is the method of choice in the area). Today, she routinely performs cataract surgery in the hospital, and we provide her technical support and supplies for developing her actuation.
The most common intraoperative complication in our series was the rupture of the posterior capsule, which occurred in nine eyes (2.9% of the patients). This rate is low if compared with that reported in other studies in the neighboring regions Ghana, 10%,18 and Sierra Leone, 11.4%,15 and even acceptable when managing difficult cases in the theaters of developed countries. These data reflect the skill and experience of the ophthalmologists participating in the campaign.
The most common immediate postoperative complication was high IOP (≥30 mm Hg) in 13.01% of the patients, which was usually temporary and related to residual viscoelastic in the anterior chamber.
The most common 3-month complication was capsular opacification. Ruit et al.23 documented 21% capsular opacification in a 2-year follow-up in Nepal, Lindfield and colleagues24 reported a 9.7% incidence in Bangladesh, and Isawumi and colleagues19 reported a 6.28% incidence in Nigeria, whereas in our study, we found only a 4.4% incidence. Although this complication is easily manageable in a developed country, the lack of a neodymium YAG laser in Burkina Faso makes the impact of this condition important. Furthermore, the incidence will increase during the period of follow-up.
Postoperative refractive correction results in almost doubling the “good” visual outcomes (38.35 to 68.7%). This shows the importance of refractive correction for the best possible vision, in accordance with other studies.13,25 Monitoring of outcomes seems to be associated with better management of complications and improved visual outcomes.14 Visual health care professionals should ensure that every patient has access to refractive correction postoperatively, and they should continue to refine their surgical technique, including the possibility of moving from ECCE to MSICS, and routine use of biometry. If refractive error is not corrected postoperatively, many individuals may continue to experience suboptimal vision after surgery.
The cataract surgery performed by trained surgeons in mass campaigns in developing areas is effective and safe, improving the visual function of the patients when the proper technique and standardized protocols are followed. Cataract surgical campaigns must ensure that they provide refractive correction and appropriate preoperative assessment and counseling. An effective surgical audit process plays an essential role for achieving this goal.
Calle Corbeta no. 6
Calpe 03710 (Alicante)
The authors have no proprietary or commercial interest in the medical devices that are involved in this article.
Received May 23, 2012; accepted September 26, 2012.
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