Global uncorrected refractive error and presbyopia: the size of the problem.

Uncorrected refractive error is often ignored in the realm of global health priorities, yet its substantial impact on the economic and personal wellbeing of individuals and societies worldwide is undeniable. Myopia (shortsightedness), hyperopia (farsightedness), and astigmatism, grouped together under the term ‘refractive error’, cause blurred distance and/ or near vision, and presbyopia (age-related loss of accommodation) causes blurred near vision. Although presbyopia has a different mechanism to the other refractive errors, all these conditions can be corrected using spectacles or contact lenses. For the purposes of this article, therefore, we will use the term refractive error to refer to refractive error and presbyopia. Unless refractive errors are corrected (using spectacles, contact lenses, or otherwise), the children and adults affected will experience difficulties in tasks that are crucial for daily living, education, and employment. In this article, we summarise the estimated prevalence, the populations affected, and the implications if refractive error and optical services are not extended to everyone who needs them. We aim to equip policy makers and refractive error care providers alike to advocate for the resources required to tackle this global issue.