Bowman's layer

The Bowman's 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 of the eye. It is composed of strong, randomly oriented collagen fibrils 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.[1]

Bowman's layer
Vertical section of human cornea from near the margin. Magnified.
  1. Oblique fibers in the anterior layer of the substantia propria
  2. Lamellae, the fibers of which are cut across, producing a dotted appearance
  3. Corneal corpuscles appearing fusiform in section
  4. Lamellae, the fibers of which are cut longitudinally
  5. Transition to the sclera, with more distinct fibrillation, and surmounted by a thicker epithelium
  6. Small bloodvessels cut across near the margin of the cornea
Details
Identifiers
Latinlamina limitans anterior corneae
MeSHD050541
TA98A15.2.02.019
FMA58273
Anatomical terminology

In adult humans, Bowman's layer is 8-12 μm thick.[2] With ageing, this layer becomes thinner.

The function of the Bowman's layer remains unclear and it appears to have no critical function in corneal physiology.[3] 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.[4]

Part of the Bowman's layer is ablated by the photorefractive keratectomy 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's layer is named after Sir William Bowman (1816–1892), an English physician, anatomist and ophthalmologist, who discovered this structure. Bowman's layer is not a true basement membrane, despite being originally referred to as such.[5][6]

See also

References
  1. Kenyon, KR. Morphology and pathologic responses of the cornea to disease. In: Smolin G, Thoft RA, eds. The Cornea. Scientific Foundations and Clinical Practice. Boston: Little, Brown & Co.; 1983:45.
  2. Hogan MJ, Alvarado JA, Weddell E: Histology of the Human Eye. Philadelphia: WB Saunders, 1971
  3. Wilson, SE; Hong, JW (Jul 2000). "Bowman's layer structure and function: critical or dispensable to corneal function? A hypothesis". Cornea. 19 (4): 417–20. doi:10.1097/00003226-200007000-00001. PMID 10928749. S2CID 10793246.
  4. Lagali, N; Germundsson, J; Fagerholm, P (Sep 2009). "The role of Bowman layer in corneal regeneration after phototherapeutic keratectomy: a prospective study using in vivo confocal microscopy". Invest Ophthalmol Vis Sci. 50 (9): 4192–8. doi:10.1167/iovs.09-3781. PMID 19407024.
  5. Mills, Stacey, ed. (2020). Histology for Pathologists (5th ed.). Wolters Kluwer. p. 337. ISBN 978-1496398949.
  6. Wilson, S. E. (2020). "Bowman's layer in the cornea– structure and function and regeneration". Experimental Eye Research. 195: 108033. doi:10.1016/j.exer.2020.108033. PMC 7283008. PMID 32339517.
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