Infraorbitaldarkcircle refers to a serious cosmetic problem in which the infraorbital eyelid area appears relatively dark. Infraorbital dark circles are seen in all ages, genders, and races, and they increase with aging (skin laxity, changes in subcutaneous fat distribution). As a cosmetic problem, infraorbital dark circles are not harmful to physical health and are not associated with serious disease, but there is growing concern about their emotional health effects. Dark orbital circles are a serious cosmetic problem for women and, from a medical perspective, have a considerable impact on one’s quality of life – they look tired, sad, and depressed, often exacerbated by lack of sleep. There are many products on the market today for masking dark circles under the eyes. Despite the popularity of infraorbital dark circles, research on their causes and treatment is currently scarce. Causes and Mechanisms Possible causes of dark circles include: 1. Hyperpigmentation (pigmented): Hyperpigmentation of the under-eye area is a common cause of dark circles. The types of hyperpigmentation include: dermal melanocytosis, post-inflammatory hyperpigmentation (secondary to atopic or allergic contact dermatitis). Hyperpigmented dark circles usually appear as a light brown band (slightly curved in shape) on the skin in the immediate area below the infraorbital rim. The dark circles appear darker when there is a lower lid bulge due to a pseudo-herniation of the orbital fat (the lower lid bulge creates a shadow effect and exacerbates the dark circles). When the lower lid skin is extended by hand, there is no whitening or significant pigmentation of the pigmented areas. Causes of dermal melanocytosis include congenital and environmental factors (excessive sun exposure, medication). Clinically, dermal melanocytosis presents as a gray or blue-gray color (melanin color formed through the dermis). The reason why suborbital dark circles are common in patients with atopic dermatitis or allergic contact dermatitis is because of post-inflammatory hyperpigmentation caused by the patient’s scratching. Other factors that can lead to hyperpigmentation around the orbit include: persistent abnormal pigmentation erythema, fixed drug rash, and heredity. 2. Thin, translucent (vascular) lower lid skin overlying the orbicularis oculi: The thin, translucent lower lid skin overlying the orbicularis oculi is another common factor contributing to infraorbital dark circles. The orbicularis oris muscle lies directly under the skin with no (or very little) subcutaneous fat between it and the skin. If the skin is too thin and translucent, the subcutaneous vascular plexus or intraocular choroidal veins may become prominent, resulting in dark circles. This type of dark circle usually appears throughout the lower lid area, with a pale blue appearance as the prominent blood vessels pass through the thin skin. This pale blue appearance is more pronounced on the inner part of the lower lid and usually worsens during menstruation. If the lower lid skin is stretched by hand, there is no whitening of the dark area, but the light blue color deepens (because the stretching makes the skin thinner) – a useful test to determine the distribution of blood vessels. Our experience with autologous fat grafting has shown that this part of the skin is so thin and the amount of subcutaneous fat is so sparse that it is impossible to separate the skin from the subcutaneous vessels using an injection cannula; instead, excellent long-term results are obtained using a blunt cannula to inject a thin layer of autologous fat between the skin and the muscle (as a barrier to mask the vessels), so that the vessels causing the translucency may be located within the muscle . 3. Shadows due to skin laxity and tear troughs (senescence): Skin laxity and periorbital wrinkles are common manifestations of aging. As we age, UV-induced and aging-related degeneration of collagen and elastin within the eyelid and periorbital skin tissues will occur. In addition, collagen degradation is further promoted by the release of collagenases from the damaged epidermis. This type of photoaging-induced skin laxity forms a shadow on the lower lid, resulting in infraorbital dark circles. The tear trough, a depression centered on the medial aspect of the infraorbital rim, is also associated with aging: loss of subcutaneous fat, thinning of the skin along the orbital rim tract, and therefore a hollowing of the orbital rim area, combined with a pseudo-herniation of the infraorbital fat, results in a shadow of the tear trough that is accentuated by light. With the help of Wood’s lamp and polarized light imaging, the pigmentary and vascular causes of suborbital dark circles can be effectively evaluated and differentiated. Treatment 1. Topical application Topical depigmentation agents usually require several months of continuous use to be effective. The mechanism of action of depigmentation agents is: inhibition of tyrosinase activity, inhibition of DNA synthesis in overactive melanocytes, reduction of epidermal melanin, and thickening of the epidermis (granular layer). (1) Hydroquinone Hydroquinone is currently the most widely used depigmenting agent worldwide and remains the standard of care for hyperpigmentation. Its mechanism of action is to inhibit DNA and RNA synthesis, promote melanosome degradation, and destroy melanocytes. Hydroquinone needs to be used continuously for at least 3 months to 1 year, with effects usually appearing after 5-7 weeks (usually preceded by erythema and peeling). Hydroquinone can be used in combination with other ingredients, the best known combination formula being Kligmanformulation (5% hydroquinone, 0.1% retinoic acid, 0.1% dexamethasone), whose reported side effects include: erythema, peeling, gummy corn rash, irritant and allergic contact dermatitis, nail discoloration, and increased melanin after paradoxical inflammation. (2) Retinoic acid Topical retinoic acid (0.01%-1%) depigmentation mechanism lies in the inhibition of tyrosinase transcription, significant thickening of the skin granular layer and epidermis. After topical application of retinoic acid, the change of melanocyte number was not obvious, but the damage of melanocytes was obvious. The period of topical application of retinoic acid is longer than that of hydroquinone, and significant whitening begins to occur after 24 weeks. Common side effects of retinoic acid include: erythema, peeling, burning, and stinging. (3) Other depigmenting ingredients include azelaic acid, steroids, tretinoin, pidobenzone, etc. The principle of configuring different mixed preparations is to increase the efficacy while reducing side effects. Chemical peeling The principle of chemical peeling is to remove epidermal or upper dermal lesions by applying one or more chemical ingredients topically to the skin to cause controlled damage. (1) TCA (15%, 25%, 50%, 75%) is a superficial exfoliating agent, which can act on the epidermis and dermis at maximum concentration, and epithelial re-formation can occur from the epidermal appendages. (2) Fruit acids are a class of organic acids widely contained in fruits and vegetables. Among them, glycolic acid is the most commonly used. 50-80% of glycolic acid can cause epidermal relaxation and needs to be administered by a physician on an outpatient basis (topical application for a few minutes, followed by immediate rinsing with water or 1% sodium bicarbonate). 3.Laser For pigmented dark circles, a variety of pigmented lasers are available, including: (1) Q-switched ruby (694-nm) laser, Q-enabled emerald (755-nm) laser, Nd:YAG (1064-nm) laser, of which the Nd:YAG laser is effective for both pigmented and vascular dark circles. Since the retina and choroid are the tissues with the highest melanin content in the body, they may be damaged by the laser even when the eyelids are closed. Therefore, special attention should be paid to eye safety during laser treatment of the eye. Once the treatment area is close to the eye, larger metal eye shields should be used. For aging-related problems such as skin laxity and tear troughs, peel-off or non-peel-off laser lasers and surgical procedures can be used. (2) CO2 laser resurfacing is effective for periorbital skin laxity and wrinkles, with side effects including erythema and temporary hyperpigmentation. Studies have shown that dark circles due to skin laxity can be treated with exfoliative laser (Figure 4), but may result in longer-term skin discoloration side effects for skin types III and IV. (3) Non-exfoliative laser/light technologies used for the treatment of photoaging wrinkles include: pulsed dye laser, semiconductor laser, Nd:YAG (1064-nm) laser, erbium glass (1054-nm) laser and intense pulsed light. These systems cause selective thermal damage to the dermis by selectively acting on water-containing tissues and are mostly equipped with epidermal cooling devices. Non-exfoliative techniques are not as effective as exfoliative ones, but the side effects are more moderate and the recovery period is shorter. (4) In addition, the emerging fractional technology is also suitable for the treatment of infraorbital dark circles caused by skin laxity and hyperpigmentation. 4. Autologous fat grafting For suborbital dark circles due to thin and translucent eyelid skin covering the orbicularis oculi (subcutaneous vascular plexus and orbicularis oculi choroidalis plexus color through the skin), autologous fat or soft tissue filler injections can be used to supplement the suborbital volume. In those with thin skin at the eyelid and cheek lid junctions, soft tissue filler must not be injected too shallowly or visible or palpable nodules are likely to develop. However, if injected too deeply, the filler will not be effective in covering the blood vessels that cause dark circles. Therefore, autologous fat grafting is the most ideal filler material for the infraorbital region (although there is controversy regarding its long-term viability). 5. Surgery The use of transconjunctival blepharoplasty combined with phenol chemical peels has been reported to be effective with few side effects for dark circles due to hyperpigmentation and pseudo-herniation of orbital fat. Treatment of suborbital dark circles associated with tear troughs is more complex and may require invasive methods to lift the maxillary soft tissue, graft fat or remove fat, and excise the septum.