For those of you who, like me, wear glasses treated for sun glare and night driving, my optician gave me an important tip about cleaning them: never dry wipe them - for example, with a tissue. They should Always be cleaned under running water and then a drop of mild soap. Then dried with loo paper. If you wipe them with anything while they are dry, the microscopic grains of dust on them will eventually cause scratches. As these glasses are pretty expensive, it is Worth bearing in mind.