Aesthetic surgery of the periorbital area ranks among the most challenging of surgical procedures. The complex and fragile anatomy, the proximity of vital structures, and the tremendous psychological and social import attached to the eyes require precise judgment when performing surgical rejuvenation of this area. Although incisional CO2 laser and laser resurfacing have been practised for many years, it is necessary to review the benefits of the laser as a surgical tool. Furthermore, it is paramount to recall the unique importance of this technique in skin tightening. Appropriate patient selection is essential for successful results and unwanted complications, so this article aims to re‑evaluate these standards.
Facial ageing reflects the dynamic, cumulative effects of time on the skin, soft tissues, and deep structural components of the face, and is a complex synergy of textural changes to the skin and loss of facial volume. Many of the facial manifestations of ageing reflect the combined effects of gravity, progressive bone resorption, decreased tissue elasticity, and redistribution of subcutaneous fullness1. As in all other organ systems, the skin and its appendages undergo characteristic changes with advanced ageing. Many of the changes to the face secondary to ageing are the result of time acting on skin that is becoming progressively thinner, drier, and less elastic.
At the periorbital area, as well as changes to the skin, there are also additional changes of facial expression. The superior-medial orbital components of the orbicularis oculi muscle function as depressors of the medial eyebrow, while the superior lateral orbital orbicularis partly acts as a depressor of the lateral eyebrow. Forceful contraction of the orbital component induces concentric folds emanating from the lateral canthus, resulting in lateral canthal lines or ‘crow’s feet’.
Facial ageing is associated with a loss of soft tissue fullness in certain areas (periorbital, forehead, malar, temporal, mandibular, mental, glabellar, and perioral sites) and persistence or hypertrophy of fat in others (submental, lateral nasolabial fold and labiomental crease, infraorbital fat pouches, and malar fat pad)2, 3.
One anti-ageing breakthrough that has come with the advance of technology, according to many, is skin resurfacing treatments with CO2 laser therapy. This article discusses the use of this technology for facial rejuvenation, focusing particularly on the rejuvenation of the eyes.
Anatomy of the eyes
The eyelids protect the anterior surface of the globe. Additionally, they aid in the regulation of light reaching the eye; in tear film maintenance, by distributing a protective and optically important tear film over the cornea during blinking; and in tear flow by their pumping action on the conjunctival and lacrimal sacs4.
The structures that must be considered in eyelid anatomy are the skin, subcutaneous tissue, the orbicularis oculi muscle, the submuscular areolar tissue, the fibrous layer consisting of both the upper and lower tarsus and the orbital septum; the lid retractors of the upper and lower lids; and the retroseptal fat pads and the conjunctiva.
The orbital septum represents the anatomic boundary between the tissue of the lid and the orbital tissue. The upper and lower lids can be considered similar structures with differences mainly in the lid retractor arrangement.
The upper eyelid extends superiorly to the eyebrow, which separates it from the forehead. The upper eyelid skin crease (superior palpebral sulcus) is approximately 8–11 mm superior the eyelid margin and is formed by the attachments of the superficial insertion of levator aponeurotic fibres (8–9 mm in men, 9–11 mm in women). The inferior eyelid fold (inferior palpebral sulcus), which is seen more frequently in children, runs from 3 mm inferior to the medial lower lid margin to 5 mm inferior to the lateral lid margin.
The nasojugal fold runs inferiorly and laterally from the inner canthal region along the depression of separation of the orbicularis oculi, forming the tear trough. The malar fold runs inferiorly and medially from the outer canthus toward the inferior aspect of the nasojugal fold.
[pull_quote align=”right” ]The orbicularis oculi muscle can be divided into the orbital and palpebral parts, with the latter being divided further into the pre-septal and pre‑tarsal portions.[/pull_quote] The open eye represents the palpebral fissure between the lid margins, which is 28–30 mm in length and approximately 9 mm in maximum height. The distance between the medial canthus to the mid-line of the nose is approximately 15 mm.
The skin of the eyelids is the thinnest of the body (≤ 1 mm). The nasal portion of the eyelid skin has fine hairs and more sebaceous glands than the temporal aspect. The transition from this thin eyelid skin to the thicker skin of the eye brow and the cheek skin is evident.
Fat is sparse in pre-septal and pre-orbital skin, and is entirely absent from pre-tarsal skin. Subcutaneous tissue is absent over the medial and lateral palpebral ligaments, where the skin is adherent to the underlying fibrous tissue.
The orbicularis oculi muscle
The orbicularis oculi muscle is one of the superficial muscles of facial expression. Invested by the superficial muscle-aponeurotic system (SMAS), muscle contracture is translated to movement of the overlying tissues by the fibrous septa extending from the SMAS into the dermis. The orbicularis oculi muscle can be divided into the orbital and palpebral parts, with the latter being divided further into the pre-septal and pre‑tarsal portions. The palpebral portion is used in blinking and voluntary winking, while the orbital portion is used in forced closure. Facial nerve innervation arises from the temporal branches and zygomatic branches of the facial nerves.
The orbital portion extends in a wide, circular fashion around the orbit. It has a curved origin from the medial orbital margin, being attached to the superior orbital margin, maxillary process of the frontal bone, and medial palpebral ligament. The fibres from the upper and lower lid join laterally to form the lateral palpebral raphe, which is attached to the overlying skin. The pre-tarsal portion lies anterior to the tarsus; submuscular areolar tissue consists of variable loose connective tissue. Superior continuance in this submuscular plane arrives at the retro-orbicularis oculi fat (ROOF), which is best developed in the eyebrow region. Additionally, the suborbicularis oculi fat (SOOF) is found in the lower lid in a continuance of this plane. The tarsal plates are composed of dense fibrous tissue and are responsible for the structural integrity of the lids. Their posterior surfaces adhere to the conjunctiva.
The medial canthal tendon, which is also called the medial palpebral ligament, is linked with the orbicularis oculi muscle and lacrimal system. The lateral canthal tendon (lateral palpebral ligament) is formed by dense fibrous tissue arising from the tarsi and passes laterally deep to the orbital septum to insert into the lateral orbital tubercle. The orbital septum is a connective tissue structure that attaches peripherally at the periosteum of the orbital margin (the arcus marginalis); it centrally fuses with the lid retractor structures near the lid margins, thus acting as a diaphragm. Although usually depicted diagrammatically as a discrete layer immediately posterior to the orbicularis oculi muscle, the orbital septum is a multilaminated structure that is part of the anterior orbital connective tissue framework. The septum has a laxity consistent with the mobility of the eyelids.
Ligaments, levators and retractors
The orbicularis retaining ligament attaches the orbicularis oculi to the inferior orbital rim; it is broader and stronger inferolaterally than centrally. The expanded lateral end of the orbicularis retaining ligament is continuous with the orbital thickening. The orbital thickening is a fibrous fusion between the orbicularis fascia covering the peripheral part of the orbicularis oculi, and the underlying deep fascia (i.e. to the periosteum and the deep temporalis fascia). The orbital thickening extends across the entire width of the frontal process of zygomatic bone and onto the deep temporal fascia for a variable distance. With age, the retaining ligament becomes distended and thinned, with the changes being greater centrally than laterally. During surgery, the detachment of the orbital thickening and the lateral part of the retaining ligament will completely release the superficial fascia from the orbital rim.
The levator palpebrae superioris (LPS), which is the main retractor of the upper eyelid, arises at the orbital apex from the undersurface of the lesser wing of the sphenoid bone. The levator muscle and superior rectus muscle share a developmental origin and are connected by fibrous attachments. The LPS proceeds anteriorly for 40 mm and ends in an aponeurosis approximately 10 mm behind the orbital septum. The levator complex changes direction from a horizontal to a more vertical direction at the superior transverse ligament (Whitnall’s ligament). The levator aponeurosis spreads laterally and medially to form lateral and medial horns. The medial horn attaches to the posterior lacrimal crest. The lateral horn divides the lacrimal gland into orbital and palpebral lobes before attaching to the lateral orbital tubercle. The aponeurosis fuses with the orbital septum prior to reaching the level of the superior tarsal plate border. At the inferior edge of this fusion, some aponeurotic fibres descend to insert into the lower third of the anterior surface of the tarsal plate. An anterior extension from this fusion inserts into the pre-tarsal orbicularis oculi muscle and overlying skin, forming the upper-lid skin crease.