Preheat oven to 425°F. Roll half of pastry into 12-inch circle and use to line a 9-inch pie plate.
Combine sugar and corn starch in a large bowl. Add blueberries and lemon juice; toss to coat. Spoon mixture into pie crust.
Roll remaining half of pastry into 12-inch circle; fit loosely over filling. Trim overhang to 1 inch. Fold edges under; flute edge. Cut several 1/4-inch wide vents in top crust for steam to escape. If desired sprinkle top of crust with 1-2 tablespoons sugar.
Bake 45 to 50 minutes or until fruit is tender and juices that bubble up in center are clear and shiny. If edge begins to overbrown, cover with strips of foil. Cool on wire rack.