Vision impairment (VI) significantly impacts individuals, families, and economies globally. Achieving the Sustainable Development Goals requires understanding and mitigating this impact. While the global cost of VI is substantial (estimated at US$3 trillion in 2010, projected to rise by 20% by 2020, and with annual global productivity losses estimated at $410.7 billion in 2018), population-based research to estimate the economic impact in different countries, especially in the Caribbean, is limited. This study addresses this gap by using data from the 2014 National Eye Survey of Trinidad and Tobago (NESTT), the most comprehensive population-based eye survey in the Caribbean in over two decades. The study takes a societal perspective, encompassing direct (medical and non-medical) and indirect (productivity loss) costs, as well as intangible losses (loss of wellbeing). The methodology adheres to the Cost of Vision Loss Consensus Guidelines (2010), providing a comprehensive cost-of-illness analysis that aims to accurately capture the 'true cost to society'. By itemizing and valuing associated costs, the study aims to provide valuable insights for policymakers and inform resource allocation decisions for eye health.

Existing literature highlights the significant global economic burden of vision impairment (VI) and blindness. Previous studies have estimated the worldwide economic and health burden of VI and projected increases in costs. However, systematic reviews reveal a lack of population-based observational research with detailed estimation of VI’s economic impact in diverse countries. The heterogeneity in methodologies across previous cost-of-vision loss studies has hindered meta-analyses. Furthermore, the absence of data on the economic impact of VI in the Caribbean underscores the need for this study. The existing literature stresses the importance of considering not only direct healthcare costs but also indirect costs (productivity losses) and intangible losses (wellbeing impacts). The Disability Adjusted Life Year (DALY) is frequently used to capture such intangible effects. The review also notes the lack of standardization in cost tools, often leading researchers to create their own costing approaches. This highlights the need for a standardized approach, particularly given the varying healthcare systems and socioeconomic factors across different countries.

This study utilized data from the 2014 National Eye Survey of Trinidad and Tobago (NESTT), a comprehensive population-based eye survey employing multi-stage, random cluster sampling. A total of 4263 adults aged 40 years and above were included. The study collected data on visual acuity, demographics, socioeconomic factors (using an adapted socioeconomic questionnaire), eye care service utilization, and costs associated with VI. A contemporaneous national eyecare system survey provided additional data on healthcare costs. The study employed a societal perspective, encompassing direct medical costs (eye care services, treatments, medication), direct non-medical costs (refractive correction, low vision aids, transportation), indirect costs (productivity loss due to VI, sick leave, informal care), and intangible costs (loss of wellbeing, estimated using DALYs). Statistical analyses, including multi-level mixed effects logistic regression models and post-stratification adjustments, were used to analyze the data. Sensitivity analyses were conducted to assess the impact of parameter uncertainty on the total cost estimates. The study carefully defined and estimated each cost category, using a variety of data sources (e.g., provider surveys, price lists, participant questionnaires) and applying appropriate unit costs and inflation adjustments. Specific methods for estimating each cost category are meticulously described (e.g. estimating productivity loss using human capital approach, valuing informal care using the opportunity cost method). The study also discusses the challenges in assigning monetary value to intangible effects, utilizing DALYs and sensitivity analyses to explore the impact of varying disability weights. Transfer payments and dead weight losses were excluded from the final cost estimates, consistent with many other cost studies.

The study estimated the total societal cost of VI in adults aged 40 and above in Trinidad and Tobago in 2014 to be TT$3,842,324,655 (UK£365,650,241), equivalent to £675 per capita. Loss of wellbeing constituted 73.3% of the total cost. Excluding this, the economic cost was TT$1,025,045,399, with indirect costs accounting for 70.5%, followed by direct medical costs (17.9%) and direct non-medical costs (11.6%). The study estimated 64,431 cases of distance VI and 120,842 cases of near VI, with a significant proportion (86.1% of distance VI cases) being potentially avoidable. Sensitivity analyses revealed that the choice of disability weights significantly influenced the cost estimates associated with lost wellbeing. There was a strong association between greater levels of presenting VI and lower household income, employment rates, and educational attainment. Individuals with VI were more likely to be employed in service and elementary occupations and had significantly lower educational attainment than those with normal vision. Eye care service utilization varied by vision level, with lower utilization among those with severe VI. Analysis of occupational categories revealed that the majority of participants fell into professions, elementary occupations, and service/market sales positions, whether VI or normally sighted. The study also identified a significant contribution of topical ophthalmic medication costs to direct costs, and suggested potential cost reduction interventions.

This study's findings demonstrate the significant societal economic impact of VI in Trinidad and Tobago. The substantial contribution of intangible costs (loss of wellbeing) highlights the need to consider the broader impact of VI beyond direct healthcare costs. The high proportion of indirect costs (productivity losses and informal care) underscores the influence of VI on economic productivity and family dynamics. The study's findings suggest that policy decisions based solely on direct health sector costs would underestimate the true societal burden of VI. The findings also suggest potential areas for intervention and investment, such as reducing acquisition costs of topical ophthalmic medications, improving access to low vision services and aids, strengthening workplace-based enablement policies, and implementing cost-effective preventive programs. The study’s comparison with findings from high-income countries reinforces the significance of intangible effects and productivity losses in the overall cost of VI. The differences in cost components across countries underscore the need for further research to understand the specific determinants of the economic burden of VI in different contexts.

This study provides the first comprehensive estimate of the societal economic impact of VI in Trinidad and Tobago, revealing a substantial burden borne largely by individuals and families. The findings highlight the need to incorporate intangible costs and indirect costs when assessing the overall burden of VI and planning interventions. Future research should focus on developing cost-effective strategies to prevent and manage VI, exploring the cost-effectiveness of various interventions, and improving the standardization of cost-of-VI study methodologies for better cross-country comparisons. The identified areas for potential investment, including improving access to sight-saving interventions in the public sector and addressing market failures, suggest crucial areas for policy intervention.

The study was limited to adults aged 40 years and above, excluding the institutionalized population and those under 40. Non-response bias and recall bias may have influenced the results. The study excluded transfer payments and dead-weight losses, and did not explicitly measure certain indirect costs (falls, fractures, and other complications associated with VI). The assumptions made, such as using market prices of labor to estimate opportunity costs, may affect the accuracy of cost estimates. Variations in disability weights can also influence the estimates of lost wellbeing, highlighting the need for further investigation and standardization. Finally, the lack of data on individual participant income might limit the precision of the productivity loss estimates.