Orbital septum: the barrier of the fat pads
Quick facts
- Definition
- Fibrous sheet that closes the opening of the orbit and separates the eyelid from the orbital contents.
- Peripheral attachment
- To the periosteum of the orbital margin, along the arcus marginalis.
- Attachment in the eyelid
- Upper: aponeurosis of the levator palpebrae. Lower: edge of the tarsus and the lid retractor tissues.
- Function
- Keeps the orbital fat in place and acts as a barrier against the spread of infection.
- Relevance in facial harmonization
- Its weakening explains eyelid bags, which are not treated with filler.
The orbital septum is a thin fibrous sheet that closes the opening of the orbit, like a curtain between the eyelid and the contents inside the eye socket. It arises from the periosteum of the orbital margin and attaches, in the upper eyelid, to the aponeurosis of the levator palpebrae muscle and, in the lower eyelid, to the edge of the tarsus and the retractor tissues. Its function is to keep the orbital fat in place. When it loses firmness with age, that fat moves forward and forms the eyelid fat pads.
Where is the orbital septum?
| Eyelid layer (from outside to inside) | What it is |
|---|---|
| Skin | The thinnest in the body |
| Orbicularis oculi muscle | Closes the eye |
| Orbital septum | The fibrous barrier |
| Orbital fat (postseptal) | The pads: in the lower lid, medial, central and lateral compartments; in the upper lid, medial and central |
| Retractors and tarsus | Structures that move and support the eyelid |
At the orbital margin, the septum fuses with the periosteum in a thick band called the arcus marginalis. Just below, in the lower eyelid, lies the orbicularis retaining ligament, which anchors the muscle to the bone. The relationship between the two explains the shape of the tear trough and the palpebromalar groove.
Why does it matter in facial harmonization?
- Bag or tear trough: a lax septum lets fat move forward, creating volume below the eye. A tear trough hollow, by contrast, is a lack of volume in the trough. The two can coexist, and the assessment is covered in under-eye circles: types and assessment.
- Limit of filler: true bags usually have a surgical indication (blepharoplasty). Filling around them may camouflage the transition in selected cases, but it can also increase volume and swelling in the area.
- Barrier against infection: the septum separates preseptal cellulitis, which is more superficial, from orbital cellulitis, which is more serious. Redness and swelling of the eyelid with pain on moving the eye, a visual change or fever call for urgent medical care.
- Upper eyelid: the fat behind the upper septum helps give the eyelid volume. Losing it contributes to a hollowed upper eyelid crease.
How does it show up in the assessment?
- Looking up: the lower bags usually become more evident when the person looks up.
- Light pressure on the closed eye: the bag projects more in the lower eyelid, which helps tell it apart from swelling.
- Variation through the day: swelling that changes a lot in the morning suggests a fluid retention component.
- Standardized photo from the front and in profile: documents the bag before any procedure.
Also called: orbital septum, septum orbitale, palpebral septum.
Frequently asked questions
What happens when the orbital septum becomes lax?
The sheet loses firmness with age and the fat behind it moves forward, forming eyelid bags. This is different from a tear trough hollow, and treatment is usually surgical, with assessment by a plastic surgeon or ophthalmologist.
Does filler fix an eyelid fat bag?
Generally not. Filling the tear trough may smooth the transition between the bag and the cheek in selected cases, but it does not remove the bag and, in some patients, may leave the area fuller and more swollen.