To start off, here’s a tip to keep your lenses clean and free of scratches for as long as possible:

Don’t let anything other than dedicated optical cloths touch your lenses!

That means never clean your glasses with anything other than a clean microfiber cloth or a disposable cleaning tissue.

If you don’t have any at your disposal and you absolutely have to clean your glasses, use hand soap in running water and air-dry your glasses. Don’t dry them with toiler paper or paper towels: they’re a lot more abrasive than they appear and they will leave microscopic scratches on your lenses. Especially since most lenses are made of soft plastic nowadays.

I know it’s hard to resist the temptation of blowing gently on your dirty lenses and cleaning them with your shirt, because you really want to remove that smudge of that piece of dirt that’s been bugging you. But you absolutely need to resist the temptation: wait until you can clean your glasses properly. If you don’t, the dirt that’s already on the lenses will act as an abrasive and scratch them.

Me, I usually carry a disposable, pre-moistened wipe in my wallet in case of an emergency. But those things are expensive and I’m usually never far from a public bathroom with soap and water, so I never use it. But I have one if I need it.

The rest of the time, I buy lens cleaning fluid and microfiber cloths in bulk. I usually keep a bottle of fluid and a pack of microfiber cloths at work, and another at home. They last me and my family a very long time and ultimately bring the cost of always cleaning our glasses safely down to almost nothing.

My favorite brand is this one:

But really you can use any fluid to clean lenses or optical equipment. They’re available in all supermarkets and opticians.