How to clean your spectacles properly

Modern spectacle lenses are plastic with several very thin coatings on top: anti glare, scratch resistance, sometimes blue cut. The coatings are what you are actually cleaning, and they are far softer than glass. Dust and grit are harder than they are.

So a dry wipe, however soft the cloth, drags grit across the coating and leaves the fine haze of micro-scratches that makes an old pair look tired. Heat lifts coatings; a pair left on a dashboard in the sun can craze in an afternoon. Household sprays, alcohol and ammonia strip them chemically. None of this is the lens wearing out. It is the lens being cleaned wrong.

Once a day is plenty. Between washes, a lens spray from the shop and a clean microfibre cloth will handle fingerprints. Wash the cloth itself every couple of weeks, without fabric softener, because a dirty cloth just spreads grit.

The frame collects skin oil, sweat and sunscreen, and it is why a pair starts to slide. The same soapy rinse cleans it. Nose pads go yellow and hard over a year or two; swapping them for new ones is a few minutes at the counter and makes an old pair feel new. Temple tips crack and can be replaced the same way.

If the frame loosens, do not tighten the screws yourself with a kitchen knife. Bring it in; an adjustment is a few minutes at the counter.

Anti glare, blue cut and photochromic lenses all use exactly the same routine. The coatings are why the routine matters; a plain uncoated lens forgives more. Photochromic lenses are not damaged by sunlight, that is their job, but they too dislike heat, so the dashboard rule applies doubly.