Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) is a potentially blinding disease in which there is a breakdown at the limbus (the junction of the clear corneal tissue and the white conjunctival tissue) and the corneal surface becomes replaced by hazy conjunctival tissue.

The limbus is located at the peripheral edge of the cornea and acts as a physical barrier separating the clear cornea from the surrounding conjunctiva and its blood vessels that cover the sclera, or white part of the eye.1 In normal, healthy eyes, superficial corneal epithelial cells shed naturally and are replaced by stem cells located at the limbus.2 In people who have LSCD, this renewal does not occur as it should and tissue is instead replaced by conjunctival epithelial cells, which lack the transparency needed for clear vision.3

This growing problem is made worse by the fact that it is easily overlooked in the early stages when vision-saving treatment can be most effectively applied. Such delay can lead to epithelial defects, corneal ulcers and scars, conjunctivalization of the cornea, vision loss and pain.

What Causes Limbal Stem Cell Deficiency?

The corneal epithelium completely regenerates every three to ten days.4 This repair process requires constant cell renewal from peripheral limbal stem cells.5 However, individuals who have LSCD lack these vital cells, which compromises corneal epithelium renewal and leads to injury and vision loss.

There are many possible reasons why limbal stem cells might be in short supply. Causes fall into one of two categories: congenital or acquired. Congenital causes for LSCD include aniridia, keratitis associated with multiple endocrine deficiency, dyskeratosis congenita, and epidermal dysplasia. 6,7,8,9,10,11,12,13 Acquired causes include burns, ocular surgery, contact lens misuse and ocular surface inflammatory diseases.14,15,16,17,18,19

How Is LSCD Diagnosed?

In some cases, LSCD develops slowly and your doctor can detect it before it starts to interfere with your vision or cause significant discomfort. However, unfortunately patients often present with both pain and blurry or decreased vision. Other symptoms can include contact lens intolerance, photophobia, tearing, and blepharospasm.20

In addition to patient-reported symptoms, your doctor can determine whether you have limbal stem cell deficiency based on your history and clinical signs, such as a hazy epithelium and/or epithelial staining, indicating breakdown of the epithelial cells. If any of these signs and symptoms point toward LSCD, laboratory tests will likely be used to confirm a diagnosis.

When LSCD is treated early, cell loss can usually be halted or reversed. On the other hand, if LSCD progresses to total limbal deficiency, surgery may be the only option.

Medical and Surgical Treatments for LSCD

If left untreated, limbal stem cell deficiency can cause recurrent epithelial erosions and infection, as well as pain and loss of vision.

LSCD is often medically treated when it’s caught early on. Artificial tears, punctual occlusion, Vitamin A ointment, autologous serum, cyclosporine and topical cortical steroids might be recommended in such cases. Other options include debridement and amniotic membrane transplantation.

If total limbal stem cell deficiency occurs or if the above measures fail, more aggressive surgical management will likely be needed.21 Furthermore, even after transplant surgery, the cornea may not remain clear and a repeat procedure may be necessary.22 There is also a risk of rejection from allogeneic transplants. 23

Scleral Lenses for LSCD

Scleral lenses are common for the management of ocular surface diseases, including LSCD.2425 In patients who have not yet progressed to total limbal stem cell deficiency, scleral lenses can act as a bandage, optimizing the health of the ocular surface and helping to stabilize it.

Scleral lenses feature a large-diameter that allows the lens to vault (not touch) the cornea and limbus, resting instead on the white part of the eye, known as the sclera. Beneath the lens, a fluid-filled reservoir hydrates the corneal epithelium, offering an environment conducive to cell regeneration. The lens also protects the cornea from the mechanical shearing effect of the eyelids that occurs during blinking.

Scleral lenses provide excellent surface protection and continuous lubrication, potentially reducing the risk of damage to the surviving corneal epithelial cells.26 Indeed, scleral lenses might allow some patients with LSCD to delay or avoid more aggressive surgical intervention.27

If you have LSCD, visit your eye doctor to determine the most appropriate management strategy for you.

 


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