Cis-gender females undergo brow bone reduction much less frequently than men as it would be unusual for them to have a significant brow bone protrusion. These smaller protrusions do not usually require a bone flap setback technique as the amount of reduction needed can be done by bone burring alone. If the reduction needed is less than 4mm between the pupils (vertical line draw up superiorly) where the frontal sinus lies, bone burring can create an effective reduction. A preoperative x-ray can clearly show how thick the anterior sinus table is which will allow one to determine how much bone can be removed before entering the frontal sinus. Females also have the advantage of not only is the anterior frontal sinus expansion less than in males, the lateral extent of the paired frontal sinuses are also less. This means there is more solid bone on which to reduce out laterally.
Burring reduction (also known as shaving) of the brow bones also has a role in secondary or revisional brow bone reduction surgery. To gain a few extra millimeters or to smooth out irregularities and asymmetries, high speed burring offers an effective reshaping technique. This can apply to either a prior bone flap setback or a primary burring procedure in the properly selected patient.
Burring brow bone reduction can be done in some cases through less of an incisional scalp access than the setback bone flap method. But the concept of attempting doing it through an endoscopic approach, while appealing, has not been an effective method in my hands.
One dimension of the brow bone or supraorbital rims that is rarely discussed is that of its lower edge. This dimension of the tail of the brow bone has an influence on eye shape affecting the position of the eyebrow and the fullness of the supratarsal fold. Eye asymmetry can result from differences in the position of the lateral brow bone edge. Low bony rims can also close down the eye and may contribute to upper eyelid heaviness/fullness.
The anatomy of the lateral brow bone is very simple. In this area of the brow bone there is no frontal sinus and the bone is very thick before entering the intracranial space. The only piece of relevant anatomy is that of the lacrimal gland. It is just under the tail of the brow bone in the lacrimal fossa. The lower edge of the outer brow bone can be contoured/vertically reduced to create a more open eye or correct eye asymmetry. It is safe, causes no orbicularis muscle motion problems and can be done through the well known upper blepharoplasty incision.
Beyond the female who has an isolated tail of the brow bone protrusion, this technique has proven useful in secondary transgender brow bone reductions where this part of the brow has been overlooked and even in some traditional periorbital rejuvenation patients.
Dr. Barry Eppley