Screens, smartphones and modern LED lighting emit an increased proportion of blue light. A blue-light filter is either applied as a special anti-reflective coating on the lens or lightly tinted into the lens material. It mainly reduces the high-energy short-wave blue portion (HEV light) while largely preserving the rest of the colour spectrum. The aim is a calmer, higher-contrast image with less glare – not blocking blue completely, which would be neither possible nor sensible.
The main beneficiaries are people who spend many hours at a monitor and complain of tired, burning eyes or sensitivity to glare. The lenses are available with a prescription (including progressive) or as pure comfort glasses without correction. Note: the scientific evidence for a medical benefit (such as better sleep or retinal protection) is limited; larger reviews found no clear proof. A subjective gain in comfort is nonetheless possible for sensitive individuals.
At least as important for relaxed screen viewing are good working conditions: sufficient distance, correct lighting, regular breaks (e.g. the 20-20-20 rule) and, if needed, a correctly fitted screen or workplace lens. Anyone with persistent symptoms despite new glasses should have their prescription and eye health checked.
In Switzerland the blue-light filter usually comes as a surcharge on top of the anti-reflective coating – a guide value of about CHF 50–120 per lens or pair, depending on provider and lens type (no guarantee). Pure comfort glasses without prescription are sometimes cheaper. Basic insurance does not cover such glasses for adults.