To prepare crust, weigh or lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, oats, brown sugar, salt, baking soda and cinnamon in a medium bowl, stirring well to combine. Drizzle butter and juice over flour mixture, stirring until moistened (mixture will be crumbly).
Reserve 1/2 cup oat mixture. Press remaining oat mixture into the bottom of an 11 x 7 baking pan coated with cooking spray.
Prepare filling by combining blueberries, sour cream, granulated sugar, flour, vanilla, lemon zest and egg white in a medium bowl, stirring well. Spread blueberry mixture over prepared crust; sprinkle reserved oat mixture evenly over filling.
Bake for 40 minutes or until edges are golden. Cool completely in pan on a wire rack.