Can anyone recommend a suitable pair of safety glasses which don't steam up - thank you.

Frank

it would help if you gave a reason/activity for the safety glasses, there are occassions where other eye protection is more appropriate to the task OR other factors impact fogging e.g. wearing a medical style mask

As an ex-motorcyclist, I battled with glasses/visors steaming up for years. Anti-fogging sprays I found expensive and of little use. There were some anti-mist wipes that weren't too bad. The old remedy of washing up liquid applied dry and then polished worked as well as anything else and cost next to nothing.

I agree that the style of face covering has an effect. Standard face masks are notorious for causing glasses to steam up, unless you put a small tissue folded up under the top of them to absorb moisture. Agree with Brian that a larger face covering you can perch your glasses on top of works reasonably well.