Since economic reforms beginning in 1986, Vietnam has experienced rapid economic growth and made great progress towards the Millennium Development Goals. The government has also implemented a nationwide social health insurance scheme known as Vietnam Social Security (VSS). However, not all members of the population have benefitted from these structural transformations. These inequities are reflected in eye health. As is the case around the world, untreated cataracts are the largest cause of blindness and low vision in Vietnam [1]. Despite being included in the VSS scheme, cataract surgery is not universally accessible. Economic and geographic barriers disadvantage poor and vulnerable groups, including women [2,3].

Vision loss robs people of their productivity, health and happiness. Poverty and blindness are tightly linked through a cycle in which poverty increases the risk of visual impairment and visual impairment causes poverty [4]. Moreover, there is a link between vision loss and co-morbidities (e.g. injuries sustained from falls) [5]. People with vision loss are also more susceptible to mental illness [6]. Caregivers (usually women and girls) are also economically disadvantaged as the time they spend caring comes at the expense of being otherwise productive [7].

International studies confirm that successful cataract surgeries lead to important economic and quality of life improvements for patients and that these benefits can accrue quickly [8]. However, such studies have tended to focus on improved labour market outcomes [9,10]. As such, when caregivers are factored into the analysis it is often to highlight foregone earning opportunities [11]. However, the large literature on surgical interventions and well-being suggests that the benefits of restoring sight should extend beyond the additional earning capacity of individuals and include a raft of other benefits to both patients and caregivers [11].

This study makes a number of contributions to understanding the broader benefits of cataract surgery. It looks at changes in measures of well-being by studying patients both before and after surgical interventions. It incorporates a wider variety of well-being measures than existing studies that focus on either economic or psychological measures, but not both. It also focuses on patients and caregivers in poor communities in a developing country where formal support networks are relatively limited and, as such, people are more reliant on family for support. Hence the role the caregiver plays is potentially large.

Written consent was obtained from all participants. Visually impaired participants were read a participant information statement in the presence of their caregiver and were asked to sign the consent form in the presence of the surveyor and caregiver. Written forms with the signatures of all participants are safely stored at in the Ho-Chi-Minh City University of Social Sciences. Ethics approval was obtained from the Human Research Ethics Committee of RMIT University and the Ho-Chi-Minh City Ophthalmologic Hospital Ethics Committee. Both ethics committees reviewed and approved the consent forms.

Sample size was based on the following calculations. Using demographic data available from the Vietnam census and Household Living Standards Surveys, coupled with a 99% confidence level and a 5% 2-sided significance level, the minimum sample size was estimated to be 65 patients and caregivers, respectively. To err on the side of caution we targeted a sample size equal to 20% above the required minimum. The overall sample is comprised of 82 patients and 83 caregivers, surveyed both before and three months after cataract surgery.

The initial period of data collection began in late-August to mid-October 2016. The Ho-Chi-Minh City Ophthalmologic Hospital was approached to assist with the recruitment of participants. Potential participants were asked whether they needed help with their daily tasks due to their visual impairment. To be eligible for the research project the person needed to respond ‘yes’. The sample therefore captures patients who were either blind or visually impaired.

Separate surveys for patients and caregivers were prepared. The questionnaires were based on a similar survey used in Vietnam [10] while the sampling techniques outlined in Grosh and Glewwe [12] were used. The patient survey captures the severity of visual impairment with questions that measure the extent of functional vision using a 4-point Likert scale, identifying whether they have difficulties with activities such as reading newspapers, recognising faces, reading text on the TV, or, more generally, in any way in their daily life.

Both patient and carer questionnaires collected information on the economic activities of patients and caregivers with questions about their monthly incomes and how much time they spend on various activities. These questionnaires are augmented with measures of physical and mental health using international survey instruments developed by the World Health Organization (WHO) for use in the World Mental Health Survey Initiative. Mental health questions from the Rand Corporation’s Rand 36-item Health Survey were also included to capture whether individuals feel (i) nervous, (ii) calm and peaceful, (iii) happy, or (iv) depressed. The survey also examines levels of hope using an index created by Snyder et al. [13]. It is based on the responses to six questions and can take values between 0 and 36. Self-efficacy is measured using Schwarzer and Jerusalem’s self-efficacy scale [14]. It is based on the response to 10 questions and can take values between 10 and 40.

This study focuses on Vietnam, a middle-income country with comparatively good healthcare, but with large unmet demand for cataract surgeries. Cataract surgery is already considered to be among the most cost-effective interventions in health care [16,17]. It is also known to deliver large economic benefits and improve the quality of life of patients. Studies of the impacts of cataract surgery have tended to focus on the financial improvements–increased income, wealth and employment–and/or have centred on the patient themselves.

This study confirms previous work that the benefits of restoring sight are substantial. It extends the existing evidence base to show that cataract surgery has broader non-monetary impacts on patients as well as their caregivers. These include improved physical and mental health as well as a number of psychosocial measures of well-being. We find statistically significant improvements in all measures of well-being for both patients and, importantly, their caregivers. Indeed, caregivers are often subject to low levels of income and psychological well-being akin to the visually impaired.

Our findings are naturally subject to a number of important limitations. First, survey findings emanate from a small sample of just 82 cataract patients and 83 caregivers. Secondly, the sample is not nationally representative, with most participants being poorer members of Vietnam’s population since they were eligible for subsidised treatment from the charity campus of the Ho-Chi-Minh City Ophthalmologic Hospital. The sample was also restricted to willing participants living in and around Ho-Chi-Minh City. Third, the study examines impacts on a number of measures of well-being. However, for the survey these were selected on an ad hoc basis rather than being drawn from an established underlying conceptual framework or theory of change. Further, all outcomes but particularly psychosocial measures such as hope and self-efficacy are prone to large measurement error. Finally, the study assesses outcomes at just one point of time: three months after surgery.

Future work could attribute shadow prices to these effects in order to include them in a measure such as a Social Return on Investment Analysis. Doubtless, if appropriately valued, these true benefits would permit benefit-to-cost ratios to dwarf current estimates. Indeed, it is rare in international development to identify such large social impacts from a proven intervention. This is particularly true when cataract surgery is fully or partly subsidised for the poor in developing countries. Further studies should also be based on larger samples of participants which would allow for sub-group analysis to detect differences in benefits for different groups within the population. For example, the impacts of restoring sight might differ between the poor and the non-poor, men and women, the young versus the old, the rural versus the urban, and the employed versus unemployed. Outcomes could also be compared across sufferers of different eye diseases, for example cataract versus glaucoma patients.

Other research in the region may also highlight implications of cataract interventions in ways that are more pertinent to other developing nations. Indeed, Vietnam enjoys a comparatively strong public health sector, which is not necessarily the case in some of its neighbouring countries. Replicating this work in nations with more significant health-resource constraints is likely to highlight how economic development interacts with both the benefits and costs of eye disease.

This study finds that cataract surgery considerably improves the well-being of patients and their caregivers. Improvements are observed in monetary dimensions of well-being, including employment, work and income, and non-monetary dimensions such as autonomy, self-assessed health, mental health, life satisfaction, hope, and self-efficacy. With untreated cataract remaining the world’s largest source of avoidable blindness these impacts show that money spent on expanding cataract surgical capacity is a sound, and much-needed, social investment. Future research should examine whether outcomes over a longer post-surgery period (such as six months or a year) persist or increase.