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What is limbal stem cell deficiency?

What is limbal stem cell deficiency?

Limbal stem cell deficiency (LSCD) is characterized by a loss or deficiency of the stem cells in the limbus that are vital for re-population of the corneal epithelium and to the barrier function of the limbus. When these stem cells are lost, the corneal epithelium is unable to repair and renew itself.

Which heritable ophthalmic disorder is associated with limbal stem cell deficiency?

Aniridia-related keratopathy, as it is most commonly known, occurs as a result of peripheral and progressive conjunctivalization of the corneal surface, that is, a form of limbal stem cell deficiency (Fig. 1).

What are limbal stem cells?

Limbal stem cells are the adult stem cells located in the basal epithelial layer of the corneal limbus that aid in the renewal of the corneal epithelium.

What are palisades of Vogt?

The palisades of Vogt are distinctive normal features of the human corneoscleral limbus. Our clinical studies indicate that they are more discrete in younger and in more heavily pigmented individuals, and that they appear more regular and prominent at the lower limbus than at the upper limbus.

Why are limbal stem cells important?

The microenvironment of the limbus is considered to be important in maintaining the stemness of stem cells. Limbal stem cells also act as a “barrier” to conjunctival epithelial cells and normally prevent them from migrating on to the corneal surface.

What happens when the limbus is damaged?

If the stem cells at the limbus are damaged, the renewal process is interrupted. The complete or partial loss of these stem cells — limbal stem-cell deficiency (LSCD) — allows the opaque conjunctiva to grow over the cornea. This can lead to intense pain and, in the most-severe cases, blindness.

What is the corneal limbus?

Abstract. The limbus forms the border between the transparent cornea and opaque sclera, contains the pathways of aqueous humour outflow, and is the site of surgical incisions for cataract and glaucoma.

Where are limbal stem cells?

Limbal stem cells are located on the basal epithelium in the limbal crypts of the Vogt’s palisades located in the narrow zone between the cornea and the bulbar conjunctiva (arrow). The loss of limbal stem cells results in cornea conjunctivalization (a) and pannus (b) with impairment of visual function.

What produces conjunctiva?

Function. The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland. It also contributes to immune surveillance and helps to prevent the entrance of microbes into the eye.

What is limbal girdle of Vogt?

White limbal girdle of Vogt is a very common, bilateral, innocuous, age-related condition characterized by chalky-white, crescentic deposits (elastotic degeneration) along the nasal and temporal perilimbal cornea. It may or may not be separated from the limbus by a clear zone (Figure 6-1B).

What impact does the limbus have when damaged?

The corneal epithelium is a stratified squamous epithelium from which superficial terminal cells are naturally shed. Limbal stem cell deficiency (LSCD) is characterized by a loss or deficiency of the stem cells in the limbus that are vital for re-population of the corneal epithelium and to the barrier function of the limbus.

Can We expand limbal stem cells in culture?

Vigorous attempts are being made to expand limbal stem cells in culture to preserve or even enrich the stem cell population. Ex vivoexpanded limbal stem cell treatment in limbal stem cell deficiency was first reported in 1997. In the 20 years since, various protocols have been developed for the cultivation of limbal epithelial cells.

Which imaging techniques are used in the diagnosis of limbal stem cell deficiency?

In vivo confocal microscopy and optical coherence tomography as innovative tools for the diagnosis of limbal stem cell deficiency. J Fr Ophtalmol 2018 Nov;41 (9):e395-e406.

What is the pathophysiology of stem cell deficiency?

Pathophysiology. Limbal stem cell deficiency (LSCD) is characterized by a loss or deficiency of stem cells which are vital for re-population of the corneal epithelium. Corneal transparency is essential for vision, and thus the outer protective stratified corneal epithelium is under constant, rapid renewal with vigorous repair mechanisms.

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