Help with poorly pear tree please!

My 10-year-old-ish pear tree has gone wonky again. A month ago it looked beautiful with fresh green leaves but suddenly the leaves develop rust-coloured patches all over them and fall off.  The patches are smooth on both sides so I don't think its scab, and theres no sign of insects.  There is actually new growth on the ends of some of the branches. Last year I wondered if it was too dry but that can't be the case this year.

All help gratefully received!

It might be pear rust, where the swellings on the back of the leaf develop over time. Have a look at this link to see if it's likely.

I agree with Alina, could be pear rust. IMO this could also be caused by the Pear Leaf Blister Mite so I think that a photo could enlighten us all, if that 's possible.