Brow ptosis is a common condition in the later part of life. It should be considered in the evaluation of all patients who are interested in a blepharoplasty. Often, the pseudoptosis observed in patients with dermatochalasis can be partially or completely corrected with a brow lift; therefore, consideration of a brow lift as a primary or adjunctive procedure should always be kept in mind.
Most patients do not appreciate the extent to which brow malposition contributes to the overall appearance of the aging periorbital area. This needs to be pointed out specifically to help the patient understand why a blepharoplasty alone often does not fully correct the problem. If a manual lift of the brow to the desired position significantly improves the patient's appearance, a browplasty, either alone or combined with blepharoplasty, should be considered. If a blepharoplasty is performed without recognizing any associated brow ptosis, the lateral eyebrow can appear pulled down, which produces an undesirable sad appearance. When both surgical procedures are performed together, eyelid surgery should follow brow correction in order to avoid removing too much skin.
See the image below.
Brow ptosis may be asymmetric, the brows being unequal or uneven. Sexual variations in brow appearance and configuration should be considered. Females generally have brows that are more arched and above the level of the supraorbital rim. Brow fat pads may be more prominent in men and in both sexes may become diffusely or segmentally ptotic.
Brow ptosis is very common in the general population, increasing steadily in prevalence for those older than 50 years. It is even more common in the population of patients interested in blepharoplasty or having dermatochalasis.
Gravity and age, as well as genetic inclination and physiognomy, all play a part in the etiology of brow ptosis. Aging changes in the eyelids and face are related to loss of tone in the various layers underlying the skin. Changes that occur in the upper eyelid skin are usually due to passive stretching, loss of support, or redundancy of skin secondary to lowering of the brows. The adhesion of the fascial planes decreases with age, and with the effect of gravity, the soft tissue of the forehead slips down the frontal bone.
Usually, brow ptosis is noted when the patient becomes concerned about cosmesis with increasing age. It may also be discussed with patients with symptoms of ocular fatigue secondary to the continuous action of the frontalis muscle or with symptoms of limitation in superior visual field due to overhanging skin. 
Indications include (1) cosmesis, (2) relief of ocular fatigue secondary to the continuous action of the frontalis muscle, and (3) improving restricted superior visual field due to overhanging skin.
A thorough understanding of forehead anatomy is essential to evaluate brow ptosis. The layers in the mid forehead are skin, dermis, superficial galea, frontalis muscle, deep galea, and periosteum. The forehead skin is much thicker than the eyelid skin. The dermis and subcutaneous fat are connected to the underlying frontalis muscle by multiple fibrous septae. The paired frontalis muscles originate just anterior to the coronal suture line. A smooth fibrous sheath, the galeal aponeurotica, envelops the frontalis to form both superficial and deep galeal layers. The periosteum lies beneath the deep galeal layer.
Laterally, the frontalis muscle ends or becomes markedly attenuated along the temporal fusion line of the skull. Here, the superficial galea, the superficial temporalis fascia, and the periosteum of the frontal bone fuse. The confluence of these tissue planes is called the zone of fixation. Near the junction between the temporal fusion line of the skull and the orbital rim, a fibrous band called the orbital ligament connects the superficial temporal fascia to the orbital rim. This structure effectively tethers the lateral brow to the orbital rim.
The eyebrow fat pad (ie, subgaleal fad pad) is a transverse band of fibroadipose tissue 2-2.5 cm above the orbital rim. It lies within the subgaleal space between the deep galeal layer and the periosteum and is firmly attached to the frontal bone at the superior orbital rim. It allows movement of the frontalis muscle in the lower forehead. The eyebrow fat pad is continuous inferiorly with the suborbicularis space in the eyelid.
Two additional muscles in the forehead can cause furrows in the glabellar region. The procerus muscle is continuous with the medial portion of the frontalis muscle and inserts into the nasal bone glabellar subcutaneous tissue. It causes horizontal wrinkles of the glabella. The corrugator supercilii muscle is obliquely oriented, passing from the subcutaneous brow to the frontal bone medially. It causes vertical glabellar furrows.
Several important neurovascular structures occur in the forehead. The frontal branch of the facial nerve lies within the superficial temporal fascia before entering the frontalis muscle. The deep division of the supraorbital nerve that innervates the frontoparietal scalp passes from the orbital rim between the deep galeal layer and the periosteum toward the superior temporal line of the skull. The superficial division of the supraorbital nerve passes from the orbital rim beneath and within the frontalis muscle to terminate in the anterior scalp. The supratrochlear nerve pierces the corrugator.
Several factors contribute to the appearance of the aging forehead and brow. These include changes in the quality of the skin, loss of tissue support, and forehead and glabellar furrows related to action of the underlying facial muscles. The lateral eyebrow segment usually becomes ptotic before the medial segment does because less structural support exists in this area. The absence of the frontalis muscle lateral to the temporal fusion line allows the brow and preseptal fat pads to slide over the temporalis fascial plane and push the lateral eyebrow segment downward. With an increasingly medial temporal line, less lateral eyebrow support is available from the frontalis muscle. The final brow position depends on the dynamics between the frontalis muscle pulling the brow up and the descending temporal soft tissue dragging it down.
See Surgical therapy.