What would you recommend for those ?
If you go into a pharmacy and ask for 99% alcohol, they should have it for you. Often they don't put that stuff out on the shelves. It may or may not be isopropanol.
Sure is, managed to get some 99% Isopropanol from a friend here in town. Needed stuff without poison for my use...Ethanol is denatured. Most likely much of the 5% is the poisons added to it.
Rebel!99% Isopropyl alcohol with medical grade cotton swabs if you want to do it properly. I find regular old Q-tip brand cottons swabs work just fine for cheaper optics though.
Fairly detailed information on cleaning procedures/tools/solvents available here: https://www.repairfaq.org/sam/laseratr.htm#atrcln