Preheat oven to 350°F.
For TOPPING: Mix oats, flour, brown sugar, butter, vanilla and cinnamon in a small bowl until crumbly. Stir in walnuts, if desired; set aside.
For FILLING: Combine brown sugar, corn starch and cinnamon in a medium saucepan. Gradually stir in orange juice and corn syrup until smooth. Add cranberries.
Bring to boil over medium-high heat, stirring constantly; boil 1 minute. Remove from heat. Stir in pears. Spoon into pie crust.
Sprinkle TOPPING evenly over pie.
Bake 40 minutes or until center of pie is firm. Cool completely on wire rack before cutting.