Describe uncorrected refractive error as a public health problem.

The Scale of the Problem

• Uncorrected refractive error is the single largest cause of visual impairment in the world, and the second largest cause of blindness after cataract. It affects well over a billion people
• It was invisible until the definitions changed. While impairment was measured by best-corrected acuity, a person who needed spectacles but did not have them counted as normal. Measuring presenting acuity revealed the burden, and it is a striking example of a definition determining what a health system sees
• Its consequences are educational, occupational and social — children underachieve and are labelled slow or inattentive; adults cannot work at the distance their trade requires; and the elderly with uncorrected presbyopia lose the ability to read, sew, count money and take medication correctly

Delivering Refractive Services

• The barriers are predictable and each has a practical answer: lack of awareness that the problem is correctable; cost of both the examination and the spectacles; access, since refraction services are urban; the belief that spectacles weaken the eyes, which is widespread and must be contradicted explicitly; and cosmetic and social concerns, especially for girls and young women
• What works — school screening with free spectacles; vision centres providing refraction and dispensing on the spot, since a prescription requiring a second journey is often never filled; ready-made spectacles for presbyopia and simple refractive error, which are cheap and can be dispensed by trained non-specialists; task-shifting refraction to optometrists and refractionists; and workplace programmes
• The evidence for productivity gain is strong: providing reading glasses to presbyopic tea-pickers and weavers has been shown to increase output measurably, which converts an eye care intervention into an economic development argument and unlocks funding that health budgets alone would not provide
• Quality matters — an incorrect prescription, a poorly fitted frame or a lens of poor optical quality discredits the whole service and the patient will not return
• The WHO 2030 target is a 40 percentage-point increase in effective coverage of refractive error — "effective" meaning that the person received the spectacles and achieved good vision and is wearing them
• Do not forget the second pair — a child who breaks or loses spectacles and cannot replace them is back where they started, so free replacement is part of the programme, not a luxury