The image you sent looks like Fabraea leaf spot which is a fungal infection brought on by wet weather and poor air circulation.  Good clean up in fall of fallen leaves and keeping the area around the tree open and clear of litter will help to stop reinfection but to save the foliage this year you will need to spray a fungicide following instructions on the label. Your pear will need treatment twice a  year in fall and spring. Sometimes there is not much else to do when the spring is cold and wet and fungi bodies multiply rapidly. Good luck and Keep growing, Marianne Binetti