Step 1: Create two new layers in the Layers palette by clicking on the New Layer icon at the bottom of the Layers palette.
Step 2: Right-click on the Lasso Tool in the toolbar and select the Polygonal Lasso Tool.
Step 3: Click once with the Polygonal Lasso Tool in the center of the eye, click again on the edge of the image, and double-click a little bit further from your last point to complete the selection.
Step 4: Fill the selected area with white. (Edit menu- Fill)
Step 5: Deselect (Ctrl D) and click on the other new layer to create the white beam with the other eye by doing step 3 and 4 again for that eye.
Step 6: Double-click on one of the eye layers to bring up the Layer Style box. Click on "Outer Glow", change the color to an appropriate laser glow color (red and green are traditional, right?). Move the Spread and Size sliders to control the amount of glow. Repeat for the other eye layer.