The male brow is a different shape to the female brow. This is because the frontal sinus tends to be larger in the male. The sinus expands in adolescence and causes bossing above the nose which extends above the eye sockets. The bone is heavier in the male and the rim of the eye socket lower, the combined effect is to make the brow lower and the eyes appear deeper and relatively stern compared to the female. The forehead in the female is more convex and not as high.

Large frontal sinus seen on a lateral X-ray of the facial skeleton which has expanded to create prominent bossing of the brow.

Illustration of the surgical procedure to recontour the brow by removing the anterior plate of the frontal sinus, remodelling it and fixing further back in order to reduce brow bossing. 

An incision is made through the scalp or through the skin just in front of the hairline to expose the bone. The brow can be re-contoured with a bur and any residual concavity of the brow reshaped using bone cement. If the bossing is particularly severe and the anterior plate of the frontal sinus thin then it may be necessary to remove the anterior bony plate of the sinus, reshape it and fix it further back. The bone fragments are fixed in place using wire or small titanium plates and screws.