The appearance of a visible white strip beneath the colored part of the eye is known medically as scleral show. This condition occurs when the margin of the lower eyelid rests lower than its typical position, exposing more of the globe’s white exterior. While this look can cause cosmetic concern, it can represent a normal anatomical variation or signal an underlying medical issue requiring attention.
How the Eye Structure Creates the White Appearance
The white part of the eye is called the sclera, a dense, opaque layer of connective tissue that makes up the protective outer shell of the eyeball. The sclera extends from the clear cornea at the front to the optic nerve sheath at the back, maintaining the eye’s spherical shape. The colored central region is the iris, and the border where the sclera meets the cornea is called the limbus.
In a typical eye, the lower eyelid margin rests at or slightly above the limbus, covering the very bottom edge of the iris. Scleral show develops when the lower eyelid is pulled down or otherwise retracted, causing the visible white space between the lower edge of the iris and the eyelid.
Benign Causes of Lower Scleral Show
Many instances of scleral show are purely constitutional, meaning they are a result of inherited facial structure and pose no health risk. Some individuals are simply born with a slightly larger eye opening, relatively flat cheekbones, or a naturally low-set lower eyelid position.
Aging is another common, non-pathological factor that causes the lower lid to droop over time. As a person ages, the skin naturally loses elasticity and the underlying muscles, particularly the orbicularis oculi, lose tone and become lax. The supporting ligaments of the lower eyelid also weaken, allowing the lid to sag downward.
Temporary factors can also contribute to a mild scleral show, often related to shifts in facial volume. Significant or rapid weight loss can decrease the soft tissue and fat in the cheeks, which normally provides structural support to the lower eyelid. Severe fatigue or dehydration may temporarily reduce muscle tone and volume, making the lower eyelid appear slightly retracted until rest and hydration are restored.
Serious Medical Conditions Linked to Scleral Show
When scleral show is sudden, progressively worsening, or accompanied by other symptoms like pain or double vision, it often points to a pathological cause. The most common systemic illness linked to this finding is Thyroid Eye Disease (TED), also known as Graves’ Ophthalmopathy, an autoimmune condition.
In TED, autoantibodies target tissues within the eye socket, leading to inflammation and expansion of the orbital contents. This tissue expansion pushes the eyeball forward, a condition called proptosis or exophthalmos, which mechanically retracts the eyelids.
Scleral show can also be a complication following certain surgical procedures, particularly lower eyelid surgery (blepharoplasty) if too much skin or muscle is removed. This iatrogenic cause results from scarring and contracture that pulls the eyelid margin downward. Other less common causes include facial nerve paralysis, such as Bell’s palsy, which weakens the lower eyelid muscle and causes it to sag. Trauma that affects the bony orbit or the soft tissues of the eyelid can also result in scarring and subsequent eyelid retraction.
Options for Management and Treatment
Management for scleral show depends entirely on the underlying cause and the severity of any associated symptoms. For cases caused by genetics or mild aging where discomfort is not an issue, treatment may focus on cosmetic concerns. Non-surgical options, such as hyaluronic acid dermal fillers, can be injected into the cheek or tear trough area to provide structural support and subtly elevate the lower eyelid position.
If the scleral show is related to a pathological condition like Thyroid Eye Disease, the initial focus must be on treating the systemic illness with medications to manage the autoimmune activity. Once the disease is in a stable, inactive phase, surgical procedures may be required to reposition the eyelid. Eyelid-tightening procedures, such as canthopexy or canthoplasty, are performed to strengthen and raise the lower lid margin.
In severe cases involving significant proptosis, orbital decompression surgery may be performed to create more space for the expanded tissue and allow the eyeball to move back into its proper position. For all degrees of scleral show, managing associated symptoms like dry eyes is important. This is often accomplished through the consistent use of lubricating eye drops or ointments to protect the exposed ocular surface.