The Anatomy of the Eye

By Mrs Sabrina Shah-Desai / 01 Mar 2015

London-based consultant oculoplastic surgeon Mrs Sabrina Shah-Desai discusses the importance of a thorough knowledge of the periorbital anatomy

The periorbital area (Figure 1) is the aesthetic epicentre of the face; its delicate critical structures and intricate anatomic relations pose a unique challenge for even the most experienced aesthetic practitioner. The thin fragile eyelid skin and mobile orbicularis oculi lend themselves to the possibility of overfilling and Tyndall effect,1 whilst the complex vascularity can result in visible bruising and swelling,2 having a negative impact on the patient experience. Vascular compromise and visual loss2 are devastating complications that must be avoided at all costs. Mid-facial ageing is a combination of the ‘gravitational theory’ (vertical descent of soft tissues due to ligamentous attenuation)3 and the ‘volumetric theory’ (relative volume loss and gain of neighbouring fat compartments oftheface).4 In2007,RohrichandPessa published their seminal study on the facial fat compartments.5 This not only serves

as a road map to understanding facial ageing, but has also revolutionised how we rejuvenate the ageing face. To successfully navigate the hollows and troughs of the periorbital zone, it is vital to understand how ageing in one sub-zone affects the other, rather than non-specific targeting of the tear trough or cheek.
Using an anatomical guide to the deep and superficial facial fat compartments for volume restoration, in multiple key areas, results in a naturally harmonious rejuvenation to lift and fill the central face (eyelid, eyebrow, temple, cheek and mid-face). 

The lid-brow junction

Eyebrows form the lower boundary of the upper third of the face. They are often most aesthetically pleasing when they are positioned at the superior orbital rim, with a gentle arc which peaks at the middle and lateral third (this arch being flatter in men). The ideal ‘club-shaped’ female brow is positioned 3-5mm above, whilst the ‘T-shaped’ male brow should lie at the level of the supra orbital rim.6 The lid-brow junction is convex in youth, due to the retro orbicularis oculi fat pad (ROOF), the temporal fossa fat pad and superficial lateral orbital fat pad, which contributes to eyebrow and upper-lid volume.7 When people reach their mid 40’s, there is bony recession of the superior orbital rim8 and the upper lid orbital sulcus looses soft tissue volume. This is typically in the middle third and the entire brow extending onto the temple and the lateral orbital area, possibly due to deflation of the superior and lateral orbital superficial fat compartments and the ROOF.9,10
The resultant brow ptosis occurs laterally more than medially, mainly due to the weight of unsupported tissue mass over the temporal fossa in association with lateral orbicularis oculi and corrugator muscle activity (brow depressors), lack of frontalis contraction in the lateral brow (brow elevator), and also from gravitational pull of the heavy cheek and lateral facial tissues. Lambros11 has shown the deflator effects of volume loss can cause an illusion of facial soft tissue descent, thus brow descent is often overestimated. Recent studies suggest that eyebrows can actually remain level or may even elevate with age.12

Treatment tips

1. Consider restoration of volume in the temple, brow and upper lid sulcus at three to four points, with the lateral canthal area as an optional extra (Figure 4).
2. Use a soft filler, which can be moulded.
3. The superior sulcus area needs very small aliquots injected supra periosteally along the supraorbital rim, above the orbital septum, staying lateral to the supraorbital notch.
4. The temple hollows need larger volumes, placed into the superficial fascia of each temple behind the frontozygomatic process, to soften the bony contour of the lateral orbital rim.


Differentiating descent from deflation

Volumetric deflation of the upper-lid and lid- brow junction causes a ‘flatness’ replacing the ‘convex’ fullness of this zone accompanied by an alteration in the drape of upper-lid skin. Landmarks for brow position are based upon underlying bony anatomy; the superior orbital rim is easily palpable and serves as a fixed landmark for the medial head of the brow. Deflation due to soft tissue volume loss can present as temple hollows, with skeletonisation of the lateral orbital rim and clipping of the eyebrow tail (Figures 2a pre- and 2b post-rejuvenation). Upper eyelid deflation can present as ‘medial A-shaped hollow’ or localised central and lateral hollowing of the upper lid sulcus, with the development of an extra fold of skin above the natural eyelid skin crease (Figures 3a and 3b). 

The lower lids and infraorbital junction

As the infraorbital area is really a continuum of the mid face, treatment of this zone must include assessment and treatment of the related subzones in the mid-face.
On the deep surface of the orbicularis muscle, at the superior border of the malar region, lays the medial compartment of sub orbicularis oculi fat (SOOF) and further laterally its lateral compartment. The deep medial cheek fat overlies the infraorbital foramen (Figure 5). At the medial infraorbital rim, the tear trough ligament (TTL), attaches to the skin, forming a gentle tear trough groove. Laterally this continues as the orbitomalar ligament (OML). Descent and atrophy of these bony attachments of the superficial musculo aponeurotic system (SMAS) and SOOF contribute to unmasking of the inferior orbital rim and the tear trough. Prolapse of the deep orbital fat, through a naturally weak area of the medial orbital septum, creates eye bags.13 Ageing changes can cause the inferolateral > inferomedial orbital rim to recede, and loss of the maxillary projection (bone) below the orbit14 is a major contributor to laxity and descent of the medial cheek soft tissue. Ageing of the mid-face is a mix of atrophy and descent of soft tissue, which is visible as a worsening tear trough deformity with a loss of the smooth blend between the SOOF and malar fat pad, leading to an abrupt transition between the lid-cheek junction, cheek flattening and mid-face ptosis. Superficial filler injections in the mid-face can weigh tissues down further, whilst deep injections with rigid fillers can “lift and fill” the mid- face, so it is important to target appropriate areas in the infraorbital and mid-face zones (Figure 5). 

Infraorbital zone:

As the superficial inferior fat pad overlies the infraorbital rim and it tends to deflate early, it should be assessed and treated in three zones from the medial canthus to the medial corneal limbus.
Zone 1: The tear trough extends inferolaterally 
Zone 2: The middle infraorbital groove extends from the medial to lateral corneal limbus.
Zone 3: The lateral infraorbital groove extends from the lateral corneal limbus to the lateral canthus.

Mid-face sub zones:

Zone 4: The infraorbital hollow lies directly under zone 2 and over the infraorbital foramen, which corresponds to the deep medial fat compartment.
Zone 5: The infrazygomatic or sub malar hollow corresponds to the medial SOOF.
Zone 6: The malar mound corresponds to the lateral SOOF. Lateral Canthal area: Where ROOF continues caudally as SOOF.

Tear trough treatment tips:

  1. Treat mid-face zones 4, 5 and 6 first, placing a rigid filler pre periosteal.1 This can decrease the need for treatment in the medial tear trough.
  2. Use small aliquots of soft filler in zone 1, place filler pre periosteal but deep to the muscle.
  3. Avoid over volumisation in zones 1 and 2 as this causes a sausage- like bulge in what is naturally a gentle depression.
  4. Palpate the infraorbital bone and place filler below septum (not behind or above it), as this will only worsen any eye bag.

Periorbital vascular anatomy

Branches of the external carotid artery (ECA) provide the blood supply to the face with the exception of a mask-like area of the central forehead, upper eyelids and the upper part of nose, which are supplied though the internal carotid system (ICA) by the ophthalmic artery. Vascular anastomoses between ECA and ICA are danger zones for the aesthetic practitioner as inadvertent intravascular injection can lead to vascular compromise and permanent blindness.14

Vascular watershed areas (Figure 6) 

The infraorbital foramen: Infraorbital vessels arise from maxillary branch of external carotid which anastomose with branches of the ophthalmic artery. The supraorbital notch and glabella: Supraorbital and supratrochlear, infratrochlear and external nasal branches of ophthalmic artery anastomose with branches of the external carotid artery. The temple area: Superficial temporal artery crosses the zygomatic arch and 2cm above the arch divides into anterior and posterior branches. The anterior branch anastomoses with branches of the ophthalmic artery. 

Tips to avoid intravascular injection16,17

  1. Mark the vascular watershed and inject ‘on the bone’ in that area.
  2. Avoid fast anterograde injections and large volumes.
  3. Always aspirate prior to injection.
  4. Consider cannulas vs needles, unless using a smaller gauge needle. 
  5. Choose HA filler as hyaluronidase can be used to remove the product, if there is inadvertent intravascular injection.

Conclusions

A sound anatomic approach to surgery with thorough pre-operative planning remains the basis for achieving successful cosmetic and reconstructive outcomes. This should be no different for non-surgical rejuvenation of the eyelids and adjacent areas, where the injector is well trained with a firm understanding of the facial vascular anatomy, safe injection planes, varied injection techniques and types of filler for achieving pleasing aesthetic results in different anatomical areas. The hyper dynamic periorbital area should ideally be treated with low molecular weight, high viscosity materials which are easier to inject and mould. This area should be assessed with non-flash photography, whilst the patient is seated, to assist with patient education by identification of areas of deflation. Treating the patient whilst seated upright, after marking areas of deflation and key anatomic landmarks, allows for injection in the correct plane, using conservative volumes and avoiding adverse events due to incorrect placement and overcorrection.
Using different injection techniques like retrograde linear threading for the cheek, lateral brow and lateral tear trough region (with a cannula or needle), serial puncture technique (with a needle) at targeted sites like the medial superior sulcus and fanning technique (with a cannula) for the lateral cheek and temple area, helps reduce adjacent tissue trauma and minimizes the risk of intravascular injection.1 The primary goal of ‘eye-zone’ rejuvenation is restoration of youthful 3-dimensional periorbital topography, so that the eyelids are not harshly demarcated from, but naturally blend into the brow and cheek. 

References

  1. Jaishree Sharad. ‘Dermal Fillers for the Treatment of Tear Trough Deformity: A Review of Anatomy, Treatment Techniques, and their Outcomes’. J Cutan Aesthet Surg. 2012 Oct-Dec; 5(4): 229–238.
  2. Lafaille P, Benedetto A. ‘Fillers: Contraindications, side effects and precautions’. J Cutan Aesthet Surg. 2010;3:16–9.
  3. Wulc AE, Sharma P, Czyz CN. ‘The anatomic basis of midfacial aging’, Hartstein ME, Wulc AE, Holck DEE, eds. Midfacial Rejuvenation, (New York: Springer Science+Business Media, 2012) p.15-28.
  4. Donofrio LM. ‘Fat distribution: a morphologic study of the aging face’, Dermatol Surg, 26 (2000), p.1107-1112.
  5. Rohrich RJ, Pessa JE. ‘The fat compartments of the face: anatomy and clinical implications for cosmetic surgery’, Plast Reconstr Surg, 119(2007), p.2219-2231.
  6. Freund RM, Nolan III WB. ‘Correlation between brow lift outcomes and aesthetic ideals for eyebrow height and shape in females’, Plast Reconstr Surg, 97 (1996) p.1343-8.
  7. Rohrich R, Arbique GM, Wong C, Brown S, Pessa JE.‘The anatomy of suborbicularis fat: implications for periorbital rejuvenation’, Plast Reconstr Surg 124 (2009) p.946-951.
  8. Kahn DM, Shaw RB Jr. ‘Aging of the bony orbit: a three-dimensional computed tomographic study’, Aesthet Surg J, 28 (2008) p.258-64.
  9. Kikkawa DO, Lemke BN, et al. ‘Relations of the SMAS to the orbit characterization of the orbitomalar ligament’, Ophthal Plast Reconstr Surg, 12 (1996) p.77-8.
  10. Lucarelli MJ, Khwarg SI, et al. ‘The anatomy of midfacial ptosis’, Ophthal Plast Reconstr Surg, 16 (2000) p.7-22. 
  11. Lambros V. ‘Observations on periorbital and midface aging’, Plast Reconstr Surg, 120 (2007) p.1367–1376, discussion 1377.
  12. Matros E, Garcia JA, Yaremchuk MJ. ‘Changes in eyebrow position and shape with aging’, Plast Reconstr Surg, 124 (2009) p.1296-301.
  13. Kakizaki H, Jinsong Z, etal. ‘Microscopic anatomy of the Asian lower eyelids’, Ophthal Plast Reconstr Surg, 22 (2006) p.430-3.
  14. Mendelson & Wong.‘ Changes in the Facial Skeleton With Aging: Implications and Clinical Applications in Facial Rejuvenation’, Aesthetic Plast Surg, 36 (2012) p.753-760.
  15. McCleve D, Goldstein JC. ‘Blindness secondary to injections in the nose, mouth, and face: cause and prevention’, Ear Nose Throat J, 74 (1995) p.182-188.
  16. David Funt, Tatjana Pavicic. ‘Dermal fillers in aesthetics: an overview of adverse events and treatment a proaches’. Clin Cosmet Investig Dermatol. 2013; 6: 295–316.
  17. Katie Beleznay, Shannon Humphrey, Jean D.A. Carruthers, Alastair Carruthers. ‘Vascular Compromise from Soft Tissue Augmentation Experience with 12 Cases and Recommendations for Optimal Outcomes’. J Clin Aesthet Dermatol, 2014 Sep; 7(9): 37–43. 

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