The Bowman layer (Bowman's membrane, anterior limiting lamina, anterior elastic lamina) is a smooth, acellular, nonregenerating layer, located between the superficial
epithelium and the
stroma in 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 ...
of the
eye. It is composed of strong, randomly oriented
collagen fibril
Fibrils (from the Latin ''fibra'') are structural biological materials found in nearly all living organisms. Not to be confused with fibers or filaments, fibrils tend to have diameters ranging from 10-100 nanometers (whereas fibers are micro ...
s in which the smooth anterior surface faces the epithelial
basement membrane and the posterior surface merges with the collagen lamellae of the corneal stroma proper.
In adult humans, Bowman layer is 8-12
μm thick. With ageing, this layer becomes thinner.
The function of the Bowman layer remains unclear and appears to have no critical function in corneal physiology. Recently, it is postulated that the layer may act as a physical barrier to protect the subepithelial nerve plexus and thereby hastens epithelial innervation and sensory recovery. Moreover, it may also serve as a barrier that prevents direct traumatic contact with the corneal stroma and hence it is highly involved in stromal wound healing and the associated restoration of anterior corneal transparency at the morphological level.
Part of the Bowman layer is ablated by the
photorefractive keratectomy
Photorefractive keratectomy (PRK) and laser-assisted sub-epithelial keratectomy (or laser epithelial keratomileusis) (LASEK) are laser eye surgery procedures intended to correct a person's vision, reducing dependency on glasses or contact lense ...
refractive surgery (commonly known as PRK). As the layer is non-generative, the section of the layer ablated in the procedure is lost forever.
History
The Bowman layer is named after Sir
William Bowman (1816–1892), an English
physician
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
,
anatomist
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...
and
ophthalmologist, who discovered this structure. Bowman layer is not a true basement membrane.
[ Mills, Stacey (ed). Histology for Pathologists. 5th ed., pp.337. Wolters Kluwer, 2020. ]
See also
*
Refractive surgery
*
Descemet's membrane
Descemet's membrane ( or the Descemet membrane) is the basement membrane that lies between the corneal proper substance, also called stroma, and the endothelial layer of the cornea. It is composed of different kinds of collagen (Type IV and VIII) ...
References
External links
*
Diagram at sheinman.comDiagram at cornea_crosssection_en.jpg
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Human eye anatomy
de:Hornhaut#Bowman-Membran