Scleral show is an anatomical condition where the lower white part of the eye, the sclera, is visible beneath the iris. This occurs because the lower eyelid margin rests lower than its normal position. While it can be present naturally, scleral show frequently signals that the lower eyelid has lost tension or structural support. The appearance often suggests a permanently tired, sad, or startled look, leading people to seek consultation. This altered eyelid position can also lead to functional problems affecting the health and comfort of the eye.
Defining Scleral Show Anatomically
The human eye is composed of the colored iris surrounded by the white sclera. In a typical, well-supported eye, the margin of the lower eyelid should rest precisely at the lower border of the iris, or just slightly below it. The limbus is the anatomical ring that marks the boundary between the clear cornea and the white sclera.
Scleral show is defined by a visible crescent of white sclera appearing between the lower edge of the iris and the eyelid’s margin when the lower eyelid drops. The extent of the condition is measured by the vertical distance the eyelid has descended from its ideal position. Even a small descent of one or two millimeters can significantly change the eye’s appearance and function.
The lower eyelid is supported by the tarsoligamentous sling, which includes the tarsal plate and the canthal tendons. The lateral canthal tendon, located at the outer corner of the eye, acts as an anchor that keeps the lower lid taut and properly positioned against the eyeball. Scleral show indicates a failure or weakening of this support system, allowing the eyelid to sag.
Underlying Factors Contributing to Scleral Show
The most frequent reason for scleral show is the natural process of aging. Over time, supportive ligaments, particularly the lateral canthal tendon, lose elasticity and become lax. This weakening, combined with the loss of volume in the midface, causes the lower eyelid to descend and pull away from the globe.
Scleral show is also a recognized complication following lower eyelid blepharoplasty, a surgery to remove excess skin, muscle, or fat. If too much tissue is removed, or if deeper tissues scar and contract during healing, the eyelid is pulled downward, resulting in lower eyelid retraction. The scarring shortens the anterior lamella, which is the outer layer of the eyelid, causing vertical tension that pulls the lid margin down.
Other causes include congenital factors, such as a naturally prominent eyeball or mid-face hypoplasia, where underdeveloped cheekbones provide less support to the lower lid. Facial nerve damage or paralysis, such as from Bell’s palsy, can lead to the weakening of the orbicularis oculi muscle, which is essential for maintaining proper eyelid tone and position. Trauma or previous surgeries that cause significant scar tissue formation can also exert a downward pull on the eyelid, forcing the sclera to become visible.
Functional and Aesthetic Consequences
Scleral show extends beyond cosmetic concerns, often leading to uncomfortable functional issues. When the lower eyelid pulls away from the eye, it exposes a greater surface area of the ocular globe to the air. This increased exposure causes chronic irritation and dry eye syndrome.
The eye may feel gritty, burning, or sensitive to light because the tear film is no longer spread effectively across the cornea. This poor distribution of tears can result in excessive tearing (epiphora) as the eye attempts to compensate for dryness. In severe cases, the inability to close the eye completely, known as lagophthalmos, can occur during sleep, risking damage to the cornea.
Aesthetically, the exposed sclera creates a noticeable round-eye appearance, making the eyes look overly wide, startled, or hollowed out. This change contributes to the perception of being constantly fatigued or sad, which is often the primary motivation for seeking correction. The functional discomfort combined with the aesthetic change significantly impacts a person’s quality of life.
Treatment and Management Options
The management of scleral show is determined by its underlying cause and severity, often beginning with non-surgical supportive care. For mild cases or temporary irritation, non-surgical methods focus on protecting the eye’s surface, typically involving frequent use of lubricating eye drops or ointment, especially at night. Dermal fillers or structural fat grafting can also be placed in the cheek or under-eye area to restore lost volume and provide subtle upward support to the lower eyelid.
Surgical correction is often necessary for persistent or functionally significant scleral show, involving procedures to tighten and elevate the lower eyelid. The most common surgical approach is a canthopexy or canthoplasty, which aims to tighten the lateral canthal tendon and re-anchor the outer corner of the eyelid to the orbital bone. Canthopexy uses sutures to reinforce the tendon, while canthoplasty involves cutting and reconstructing the tendon for more significant repositioning.
For more severe cases, particularly those complicated by significant scarring or tissue deficiency, additional structural support may be required. This involves the use of a spacer graft, where material like hard palate mucosa or cartilage from the ear or nose is inserted into the inner lining of the eyelid to provide permanent vertical support.