The corneal limbus (''Latin'': corneal border) is the border between the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

and the sclera (the white of the eye). It contains

stem cells In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of ...

in its palisades of Vogt. It may be affected by

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

or by aniridia (a developmental problem), among other issues.

Structure

The corneal limbus is the border between the

and the sclera. It is highly vascularised. Its stratified squamous epithelium is continuous with the epithelium covering the cornea. The corneal limbus contains radially-oriented fibrovascular ridges known as the palisades of Vogt that contain

. The palisades of Vogt are more common in the superior and inferior quadrants around the eye.

Clinical significance

Cancer

The corneal limbus is a common site for the occurrence of corneal epithelial

neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

Aniridia

Aniridia, a developmental anomaly of the

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

, disrupts the normal barrier of the cornea to the conjunctival epithelial cells at the limbus.

Glaucoma

The corneal limbus may be cut to allow for

aqueous humour The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the poster ...

to drain from the

anterior chamber The anterior chamber ( AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. In hyphema, blood f ...

of the eye into the subconjunctival space. This can be used in

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

treatment. The hole created only needs to be small, although slightly bigger than needed to account for gradual healing. This procedure sometimes fails, particularly if the hole is large. It can lead to eye irritation from blebbing.

Trabeculectomy Trabeculectomy is a surgical procedure used in the treatment of glaucoma to relieve intraocular pressure by removing part of the eye's trabecular meshwork and adjacent structures. It is the most common glaucoma surgery performed and allows draina ...

, a surgery used to treat glaucoma, is best performed with an incision through the superior part of the corneal limbus. Mattress suturing may be used to close this incision.

History

The word "limbus" comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

meaning "border".

References

External links

* - "Sagittal Section Through the Eyeball" * https://web.archive.org/web/20060510060508/http://www.vetmed.ucdavis.edu/courses/vet_eyes/images/s_4021_2.jpg {{Authority control Human eye anatomy Ophthalmology drugs