Vision-related Quality of Life After Cataract Surgery in West Africa

<jats:title>Abstract</jats:title>         <jats:p><jats:bold>AIMS</jats:bold>To study the vision related quality of life (VRQoL) before and after a mass cataract surgery campaign in a low-income country and to describe the impact of cataract surgery on quality of life (QOL). <jats:bold>METHODS</jats:bold>All the patients who had cataract surgery in Bobo-Dioulasso (Burkina Faso) during a campaign for the prevention blindness were examined. VRQoL was assessed using a modified version of the WHO/PBD VF20. The questionnaire was carried out before and three months after the surgery. A QOL related to vision index (QOL-RVI) was calculated from the scores obtained.<jats:bold>RESULTS</jats:bold>A total of 305 patients (56.1% male) underwent cataract extraction. Mean age was 61.97 ± 14.39 years. The majority of eyes (88.70%) had preoperatively poor visual acuity (CDVA&lt;20/200). Three months after surgeries, good visual outcomes (VA ≥20/60) were achieved in 38.35% of eyes without correction and 68.7% with correction. At this time, QOL-RVI had improved postoperatively in 90.2% of patients, had not changed in 3.1% and was worse in 6.7%.  Significant differences were detected (Wilcoxon test p &lt;0.05) for all items tested before and after surgeries. Correlations for the patients after operations showed that there was a significant relation between a global estimated QOL-RVI and the UCVA previous to the surgery (ρ -0.196 p=0.014), regarding the same index and the BCVA after the procedures (ρ -0.35 p=0.00018). <jats:bold>CONCLUSIONS</jats:bold>Cataract surgery increases the quality of life of patients living in low-income countries such as Burkina Faso and the improvement correlates with the recovery of the visual acuity.</jats:p>

section_content: It is estimated that 237. 1 million people (80% uncertainty interval 101. 5 million to 399. 0 million) worldwide suffer from moderate or severe visual impairment due to eye disease or uncorrected refractive error. [1] Of these, 38. 5 million (13. 2 million to 70. 9 million) are blind (visual acuity worse than 3/60). Uncorrected refractive errors are the leading cause of visual impairment (53. 9%) followed by cataracts (24. 1%), age related macular degeneration (3,7%), glaucoma (1. 9%), diabetic retinopathy (1. 3%). The growth and ageing of the world's population are the main factors for the increase in the number of blind and visually impaired. [2] The modern concept of health suggests that the effectiveness of eye care and initiatives for the prevention of blindness should go beyond traditional clinical data collection and assessment. Clinical measures such as VA (visual acuity) give us an assessment of vision loss, but they do not fully characterize visual de cits faced by a disabled person in their daily activities. Therefore, the WHO recommends the use of methods to characterize visual function and vision-related quality of life (QOL) as a supplement to clinical evaluation. 

As a result, the study of the assessment of visual function and QOL related to vision has been grown in interest, which has led to the development of instruments in the form of questionnaires, aiming to measure patients' perception of the impact of a disease and its treatment. [3] The assessment of the impact on QOL generated by visual de cits caused by cataract is only possible if certain objective parameters for evaluating its progress, the indication for surgery and improvement are recorded. 

Visual Health is a major factor in the QOL and is closely related to the individual's independence and their interaction with the environment. The questionnaires on QOL and visual function have proved to be a valid tool to fully characterize the visual di culties faced by a visually impaired person in their daily activities. [4] [5] [6] Visual impairment has negative effects on QOL and a signi cant impact on daily life including social activities and emotional condition. Studies in different populations have shown that visual impairment is signi cantly associated with a decrease in QOL measured by the different questionnaires. [7, 8] The purpose of cataract surgery is to improve visual acuity and visual function and it is assumed that this implies an improvement in the QOL. [9] The World Health Organization (WHO) developed in 1994 a generic measure of QOL called World Health Organization QOL (WHO / QOL). [10] This article reports ndings on visual acuity and QOL outcomes in an African population of a low-income country, Burkina Faso. We report the results in terms of impact on QOL caused by cataracts and cataract surgery, obtained when using a vision-speci c QOL questionnaire based on the WHO / QOL and adapted to consider local culture and environment. There are no studies regarding QOL after cataract surgery in Burkina Faso in the literature.
section_name: Introduction

section_name: Material And Methods

section_content: The present study is an analytic prospective study including a single cohort (before-after study) which involved a sample of population of all ages operated for cataract in one or both eyes in the context of a mass cataract surgery campaign for the prevention of blindness.
section_name: Study design

section_content: 305 patients were included. All of them underwent extracapsular cataract extraction with intraocular lens implantation during the campaign that the nongovernmental organizations, Stop Blindness and Vision Without Borders, conducted. Surgeries were performed in a district Hospital in Bobo-Dioulasso (Burkina Faso). 

Cases eligible for inclusion had corrected distance visual acuity (CDVA) < 20/80 (0. 6 Log MAR) in the best eye due to cataract. They were excluded if they had any other ophthalmic disease thought to be the main cause of blindness. There was no limitation in age. Cases were recruited by quali ed local staff in the Bobo-Dioulasso area before the arrival of the surgical team. All patients had to be able to understand and respond to the questionnaire.
section_name: Studied population

section_content: 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 the rst interview and the surgery. The local institution in charge of approving sanitary actions and health studies (Le Direction Générale de la Santé du Burkina Faso) authorized the campaign and the clinical research.
section_name: Research Ethics Approval.

section_content: The questionnaire was based on the "Quality of Life and Vision Function Questionnaire (WHO/PBD-VFQ-20)" (Table1) which is a quantitative structured questionnaire including twenty closed questions. 

Quali ed local people collaborated in the adaptation of the questionnaire. It was translated into French, the o cial language of Burkina Faso, and in an unwritten form into various local dialects. The method used was the standard procedure recommended by the WHO: initially, making a rst translation, including forward and backward translation, then a discussion group was formed to address the differences and nally, the chosen response factors were evaluated via visual analog scales after selecting 20 patients for testing. 

These patients performed the test on the day of visual inspection and again the following day. The validity and reliability of this method were evaluated by standard psychometric methods, including the acceptability of the questions, internal consistency, reliability of the test, internal analysis and analysis against external criteria as well as the use of speci c thresholds. [11] The modi ed WHO/PBD-VFQ-20 -adapted to Burkinabe population-that was used for the present study is shown in Table 1. The excluded items were question 3 (there are not many stairs in Bobo-Dioulasso), question 6 (not many patients have shelves), 9 and 13 (as it was di cult to explain), 17 (duplicated in question 7), 18-20 (social di culties in expression of feelings). We included 4 new questions, 13 (role limitation), 14 and 15 (far vision), and 16 (dependence).
section_name: Questionnaire: variables for the study and methodology of the interviews

section_content: Patients were interviewed individually by local investigators and the questionnaire was carried out before and three months after surgeries, asking about the patient's perception of their vision and well-being. The quality of life and how it changes with cataract surgery was assessed using a questionnaire with closed questions with three possible answers ("good-bad-average" or "yes-no-a little bit"). The reason for giving only three responses was to simplify the options and facilitate the completion of the questionnaire. Rating scales with fewer response categories are likely to be more functional. [12] The assessment was done in this way: if the question was not applicable it was not taken into account for the scoring but it was registered as "not applicable", value 1 for a negative value (No or bad), value 2 for an intermediate value (average or a little bit) and 3 for a positive (yes or good).
section_name: Excluded

section_content: A quality of life related to vision index (QOL-RVI) was calculated from the scores obtained. For each item this index was de ned as the number of patients who responded "3" -good-divided by the total amount of patients and multiplied by 100. 

For each patient the QOL-RVI was the sum of the results in all questions divided by the number of responses. On receipt of this index for each patient and at each time (preoperative and at 3 months) a bivariate analysis was done correlating this index with different variables involved throughout the study so any "risk factors" could be detected to get higher or lower QOL depending on the outcome of such correlations. 

The QOL-RVI for each patient was later correlated with age, sex, UCVA and BCVA and the values of visual acuity were recorded on a decimal scale, later being transformed into log MAR for mathematical and statistical analysis. 

Finally, a global QOL-RVI was estimated for the procedure (cataract surgery) as the arithmetical mean of the QOL-RVI for each item (expressed as a percentage) and the same for each patient (expressed as a numerical value). 

Data were tabulated using a spreadsheet (Microsoft Excel, Windows XP Professional, Microsoft ™). 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, descriptive statistics for categorical variables, comparison tests of means or medians (t-test or Mann-Whitney test) after applying Kolmogorov-Smirnov test on the samples and Wilcoxon test. Statistical signi cance was considered for comparisons when p values were under 0. 05 (p < 0. 05). Bivariate analysis for studying the correlation between pairs of variables the Spearman coe cient was used.
section_name: Variables for the study

section_content: A total of 305 patients (56. 1% male) underwent cataract extraction in at least one eye, 10 of these with bilateral surgery. The mean age was 61. 97 ± 14. 39 years. The right eye was operated in 47. 30% of cases. Of the total number of patients, 196 (64%) came back 3 months after the surgery for the follow up and QOL evaluation. We recorded more than 22 different ethnic groups, with a majority of Mossi (32%) and Bobo (13%). 78% of the patients were illiterate and 61% of them had a monthly income less than 15,000 Fcfas (32$).
section_name: Results

section_content: Table 3 shows the number of cases, mean values, standard deviations and standard errors calculated before and three months after surgery for UDVA and CDVA. The majority of eyes had poor visual acuity (CDVA < 20/200, log MAR: 1. 0) preoperatively (88. 70%) with a mean VA of log MAR 2. 17 ± 0. 70 (20/2000). Three months after cataract surgery, best-corrected visual acuity increased to 0. 52 ± 0. 44 logMAR. 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. [13] Quality of life related to vision outcomes. 

Quality of life scores improved postoperatively in 90. 2% of patients, did not change in 3. 1% and were worse in 6. 7%. 

Regarding QOL-RVI for each item, signi cant differences were detected (Wilcoxon test p < 0. 05) for all tested when comparing the results before and after surgeries. In all cases, the result could be considered better at months with two exceptions: question 2, patients had more pain after surgery and question 4, they had brighter light glare after surgery. The questionnaire scores improved in all domains after surgery in 1. 42 times. 

Table 2 shows the QOL-RVI for each of the 16 items in the questionnaire before surgery and after surgery at 3 months. Figure 1 shows graphically the rates pre-surgery and post-surgery at 3 months for the 196 patients who completed the survey. The mean preoperative global QOL-RVI was 1. 73 (±0. 37) and at the 3rd month after surgery it was 2. 47(±0. 31). Expressed as a percentage these values were 36. 5% (±20. 9) and 73. 3% (±18. 8) respectively. Figure 2 shows the variation in the score of the QOL-RVI obtained for each patient (every patient is a blue dot) in two different controls (preoperatively and at the 3rd month postoperatively). In this graph, when the points are located in the upper half of the table the overall quality index for that patient had improved after surgery. 

Statistical correlations for the 196 patients before and after surgery at 3 months with the Spearman correlation coe cient (ρ) and P value for the statistic T Student before and after surgery showed that there was a moderate but signi cant relation between the estimated index before surgeries and: the UCVA log MAR before operations (-0. 196 p = 0. 014), the BCVA log MAR after cataract extractions (-0,35 p = 0,00018), and the age (-0,194 p = 0,007). There was no relation between the index pre or post and gender. The correlation between the QOL-RVI and the ve variables described is shown in Table 3.
section_name: Visual acuity outcomes

section_content: QOL questionnaires have proven many times to be a useful tool for evaluating the well-being of patients after cataract surgery in in developed countries. [14, 15] However, in developing countries there are substantial differences regarding the type and severity of the pathology, the chance of the people to have successful treatment and the impact of the disease on the patient's daily lives. In such context only a few number of papers report the real in uence of this disabling disease and its treatment in Africa. [6, 14] This aspect has greater signi cance when considering that most of the people who are blind due to cataracts live in developing regions. [2] Studies in different populations showed that visual impairment is associated signi cantly with a decrease in the QOL as measured by different questionnaires. [9, 16, 17] Visual symptoms caused by cataracts are highly associated with the decrease in QOL related to vision. 

[18] Cataract surgery aims at improving the VA and visual function as this implies an improvement in the QOL. [19, 14] There are no references about studies on this topic in Burkina Faso, one of the poorest countries in the world. 

The overall score of the questionnaire (QOL-RVI for the procedure) signi cantly improved 3 months after the operations. QOL scores improved postoperatively in 86. 2% of patients and 95. 3% of patients reported good or average at 3 months after surgery. These results are comparable to those obtained when QOL studies are conducted in developed countries. [20] Polack et al demonstrated the validity and reliability of this questionnaire for cataract patients in Kenya, the Philippines and Bangladesh, supporting the suitability of the questionnaire as a tool for evaluation in low-income settings. [21, 22] Given the special characteristics of our patients, this questionnaire was adapted to a 16-item questionnaire. 

A signi cant relationship between the estimated index before surgeries and both variables -UCVA before operations and also BCVA after cataract extractions-showed a direct relationship with the index and the VA. The worse the UCVA preoperatively, the worse the indexes before surgery and, in the same way, the indexes after procedures were better the better the BCVAs. 

The patients operated scored qualitatively their levels of sight as "su cient, average or bad" when the UCVAs ranged at ≥ 20/100, from 20/100 to 20/200 and < 20/200 respectively. These data should be interpreted in the context of a group of patients whose mean preoperative uncorrected VA was equal to 20/100. 

To compare our index of QOL related to vision with that obtained in other series has some complexity, because there are many different models of surveys. [12] Besides validated questionnaires, some authors adapt existing ones and others create their own questionnaires. [23] The way in which the results are expressed also often differs from one study to another. Some authors give a positive value to a higher number [24] while others give it to a low number. [21] Some focus on one aspect of the questionnaire, [25] while others speak exclusively about the general score. [26] Figures
section_name: Discussion

section_name: Funding

section_content: The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.
section_name: Funding

section_name: Statements And Declarations

section_content: Since we do not contemplate the VA in the contralateral eye, it could be thought that such aspect may imply a bias. However, it is important to remember that most of our patients were included for blindness due to hypermature bilateral cataract. 

In our series, no signi cant correlation was found between the results of the questionnaire obtained during the preoperative interview (overall index of QOL) and both, age or sex. These results are consistent with studies conducted in Kenya [21] and China. [27] The correlation between age and the overall rate at 3 months was equal to -0,194. In this case, there was a weak but statistically signi cant relationship, indicating that decreases in the index were more frequent in older patients. This result contrasts with those obtained in the previously mentioned studies, which found no statistical differences. [27, 21] A signi cant negative correlation was found between preoperative UCVA log MAR and quality of life (the lower the VAs, the greater the QOL-RVI) and a similar result for the correlation between postoperative BCVA log MAR and QOL-RVI. These results are consistent with those published by Gothwal for questionnaire TyPE-spec and its subscales of glare and near vision, which with minor modi cations was a good measure of visual function in patients with cataracts. [21] They are also consistent with the report published by Rosen et al. in a study on 233 patients where they found that the VF-14 was signi cantly correlated with the VA in the operated eye. [28] The strength of the correlation between the VA and the index of QOL related to the vision depends on the characteristics of the population studied, as reported by Chan et al. In this study, a questionnaire was adapted to the Chinese population and they found that improvements in QOL correlate only moderately with improvements in the AV and patient satisfaction. [27] This improvement in QOL related to the vision of our patients also coincides with the results published by Polack et al. They applied the WHO/PBD VF20 questionnaire a year after cataract surgery to low-income patients; and they found that QOL related to vision improved after surgery to similar levels to those of the population with normal vision. [21] QOL scores improved postoperatively in 90. 2% of patients, did not change in 3. 1% and were worse in 6. 7%. Chan et al found slightly lower values in Hong Kong four months after surgery, [27] as the questionnaire of QOL improved in 83. 6% of patients postoperatively, remained unchanged in 3. 6% and was worse in 12. 7%. In this same study, generally questionnaire scores improved in all domains after surgery by 0. 68 times, whereas the improvement in our study was 1. 42 times. Regarding the patients who reported a decrease in QOL after the surgery, it is important to point out that the evolutive degree of the cataract did not allow examination of the posterior segment of the eye in many cases. So, when a patient suffering some unnoticed comorbidity that could limit postoperative visual improvement was operated, it is reasonable to think that the procedure decreased his QOL. 

Finally, it is necessary to indicate that, considering that the majority of patients operated had very poor vision in both eyes, the population analyzed presented an ideal pro le to correlate an improvement in visual function with the perceived QOL. On the other hand, the low literacy rate of the patients (22%) was a challenge when it comes to responding to the questionnaire. 

It can be concluded from our study that cataract surgery increases the QOL of patients living in a developing country such as Burkina Faso and that the improvement correlates with the recovery of the visual acuity.

section_content: Acknowledgements: Rosalie Sanon and Blaise Ouédraogo Financial disclosure: The authors have no proprietary or commercial interest in the medical devices that are involved in this manuscript.
section_name: Statements And Declarations

section_content: The authors have no relevant nancial or non-nancial interests to disclose.
section_name: Competing Interests

section_content: All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Isabel Signes-Soler, Jaime Javaloy, Robert Montés-Micó, Gonzalo Muñoz, Raúl Montalbán Llamusí, Ana Maria Hernandez Baeza, César Albarrán-Diego. The rst draft of the manuscript was written by Isabel Signes-Soler and all authors commented on previous versions of the manuscript. All authors read and approved the nal manuscript.
section_name: Author Contributions

section_content: 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 the rst interview and the surgery. The local institution in charge of approving sanitary actions and health studies (Le Direction Générale de la Santé du Burkina Faso) authorized the campaign and the clinical research.
section_name: Research Ethics Approval

section_content: Informed consent was obtained from all individual participants included in the study.
section_name: Consent to participate