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Cornea Jul 2000The purpose of this article is to review available information regarding development, structure, and function of Bowman's layer in the cornea. Disease-related... (Review)
Review
PURPOSE
The purpose of this article is to review available information regarding development, structure, and function of Bowman's layer in the cornea. Disease-related abnormalities of Bowman's layer are described. A hypothesis is advanced to explain the development and maintenance of Bowman's layer.
METHODS
Literature review and hypothesis formulation based on previous studies.
RESULTS
Information is presented that supports the hypothesis that Bowman's layer forms as a result of cytokine-mediated interactions occurring between corneal epithelial cells and keratocytes that include chemotactic and apoptotic effects on the keratocytes. This hypothesis suggests that Bowman's layer results from such interactions beginning in early development and continuing into adulthood in humans and other animals, such as chickens.
CONCLUSIONS
Bowman's layer may be a visible indicator of ongoing stromal-epithelial interactions in the human and have no critical function in corneal physiology. Bowman's layer is commonly destroyed in diseases such as advanced bullous keratopathy where stromal-epithelial interactions may be interrupted. Bowman's-like layers often form in response to epithelium, for example when epithelial plugs extend into the stroma in corneas with radial keratotomy incisions.
Topics: Animals; Apoptosis; Basement Membrane; Cornea; Humans
PubMed: 10928749
DOI: 10.1097/00003226-200007000-00001 -
Cornea Mar 2017
Topics: Bowman Membrane; Corneal Transplantation; Humans; Keratoconus
PubMed: 28079692
DOI: 10.1097/ICO.0000000000001142 -
Transactions of the American... 1931
PubMed: 16692915
DOI: No ID Found -
Journal of Cataract and Refractive... Mar 2019We describe a variation of the original manual Bowman layer transplantation technique. After the isolation of the graft, a stromal pocket is created using a femtosecond...
We describe a variation of the original manual Bowman layer transplantation technique. After the isolation of the graft, a stromal pocket is created using a femtosecond laser. With the use of this technology, which entails preservation of the conjunctiva and the non-use of sutures, we avoid the scleral approach. The femtosecond laser proved to be a feasible surgical support of this technique.
Topics: Bowman Membrane; Corneal Stroma; Corneal Transplantation; Humans; Keratoconus; Laser Therapy; Visual Acuity
PubMed: 30851803
DOI: 10.1016/j.jcrs.2018.10.034 -
Cornea Oct 2007To review corneal wound healing with special reference to the function of the Bowman layer and Descemet membrane.
PURPOSE
To review corneal wound healing with special reference to the function of the Bowman layer and Descemet membrane.
METHODS
Corneal specimens were obtained from keratoplasties, including regrafted cases. Recipient corneal buttons were evaluated histopathologically with attention to 5 layers of corneal structure: 3 cellular layers consisting of epithelial cells, keratocytes, and endothelial cells and 2 acellular layers consisting of the Bowman layer and Descemet membrane.
RESULTS
Subepithelial fibrosis was found in advanced bullous keratopathy. The possible source of subepithelial fibrosis was either conjunctival stroma or corneal stroma through disruption of the Bowman layer. Subepithelial fibrosis was observed in the area of the Bowman layer disruption at the host-graft junction in regrafted cases. The Bowman layer was disrupted in eyes with not only keratoconus but also corneal dystrophy such as macular dystrophy and gelatinous drop-like dystrophy. Newly formed, thin Descemet membrane was found in keratoconic eyes of patients with acute hydrops. Retrocorneal membranes were observed in eyes with advanced bullous keratopathy and graft failure. Abnormal wound healing of Descemet membrane such as override and separation was found in the host-graft interface of regrafted eyes, causing stromal overgrowth.
CONCLUSIONS
The Bowman layer and Descemet membrane seem to serve as barriers to separate 3 cellular layers of epithelium, stroma, and endothelium. Disruption of the Bowman layer forms a new epithelial-stromal interaction and may cause cellular proliferative response. Separation of Descemet membrane can provide the trigger for emanating stromal tissue from the wound edge.
Topics: Bowman Membrane; Cell Proliferation; Corneal Diseases; Corneal Transplantation; Descemet Membrane; Follow-Up Studies; Fuchs' Endothelial Dystrophy; Humans; Postoperative Complications; Prognosis; Retrospective Studies; Wound Healing
PubMed: 17881922
DOI: 10.1097/ICO.0b013e31812f6f1b -
Survey of Ophthalmology 2015Corneal dystrophies are a rare group of hereditary disorders, that are bilateral, non-inflammatory, and progressive. Clinically, they can be classified based on the... (Review)
Review
Corneal dystrophies are a rare group of hereditary disorders, that are bilateral, non-inflammatory, and progressive. Clinically, they can be classified based on the anatomic layer of the cornea affected. Refractive surgery and phototherapeutic keratectomy (PTK) can be performed with caution in patients with certain corneal dystrophies, but should be avoided in others. For epithelial basement membrane dystrophy, photorefractive keratectomy (PRK) is the procedure of choice for treatment of refractive error, and PTK may be performed for the treatment of recurrent erosions or irregular astigmatism. PRK and laser-assisted in situ keratomileusis (LASIK) have been associated with exacerbation of combined granular-lattice corneal dystrophy. LASIK and PRK appear to be safe in mild forms of posterior polymorphous corneal dystrophy, whereas LASIK should be avoided in Fuchs dystrophy. The safety of refractive surgery and PTK in the remainder of epithelial, Bowman layer, and stromal dystrophies has yet to be established.
Topics: Corneal Dystrophies, Hereditary; Humans; Keratomileusis, Laser In Situ; Lasers, Excimer
PubMed: 25307289
DOI: 10.1016/j.survophthal.2014.08.003 -
Experimental Eye Research Apr 2002Analysis of corneal tissue from normal and keratoconic donors has revealed differences which may represent early signs in the pathogenesis of keratoconus. Peripheral...
Analysis of corneal tissue from normal and keratoconic donors has revealed differences which may represent early signs in the pathogenesis of keratoconus. Peripheral areas of keratoconic tissue obtained from transplant surgery were targeted to ascertain cellular disposition and morphological changes which may be masked within the extensive damage of the central keratoconic cone. Peripheral keratoconic corneae exhibited discrete incursion of fine cellular processes into Bowman's membrane. These processes originated from keratocytes and were often observed in conjunction with a defined indentation from the basal epithelium. Comparison of the lysosomal enzymes cathepsin B and G with constitutively expressed cytoplasmic esterase determined that both cathepsins were elevated within keratocytes of keratoconic tissue compared with normal tissue. Some clusters of keratoconic keratocytes had elevated levels of cathepsin exceeding all others. Cathepsin-rich keratocytes localized with morphologically compromised regions of Bowman's membrane. The presence of cell nests deeper within the stroma indicated that the catabolic changes, which are visible within the acellular Bowman's membrane, are probably also occurring deeper within the stroma, but are masked and not readily detectable.
Topics: Cathepsin B; Cathepsin G; Cathepsins; Cornea; Epithelium, Corneal; Humans; Image Processing, Computer-Assisted; Keratoconus; Microscopy, Confocal; Serine Endopeptidases
PubMed: 12076091
DOI: 10.1006/exer.2001.1157 -
Cell and Tissue Research Jul 1988The basement membrane of Bowman's capsule (BCBM) of the rat was studied by means of a modified tissue-preservation technique for transmission electron microscopy, which...
The basement membrane of Bowman's capsule (BCBM) of the rat was studied by means of a modified tissue-preservation technique for transmission electron microscopy, which avoids the usual thorough fixation in OsO4 and applies tannic acid and uranyl acetate for staining (Sakai et al. 1986). At most sites the BCBM is multilayered, consisting of one to seven dense layers separated by electron-lucent layers. The latter, which can be termed laminae rarae, contain fine filaments which connect the dense layers to each other and the innermost dense layer to the basal cell membrane of the parietal epithelium. The laminae densae are basically composed of fine filaments arranged in an anastomosing pattern. Individual filaments ranging from 5 to 15 nm in diameter, combine to form filament bundles up to 100 nm in thickness and 1 to 2 micron in length. Within a dense layer, filaments and filamentous bundles are oriented mainly in the same direction. Often the inner dense layers do not form a continuous sheet, and the filamentous bundles are arranged in anastomosing or spiral patterns to form a ribbon-like structure that we call a "microligament". These microligaments are often embedded in basal furrows of the parietal epithelium and are best developed around the vascular pole. Intracellular actin bundles of the parietal cells are regularly associated with these extracellular ribbon-like structures of the basement membrane. In conclusion, the BCBM has an unusual structure: the laminae densae are characterized by their filamentous nature and are arranged in different patterns, i.e. as a multilayered mat and as microligaments.
Topics: Animals; Basement Membrane; Cytoskeleton; Epithelium; Female; Kidney Glomerulus; Kidney Tubules; Rats; Rats, Inbred Strains
PubMed: 3416336
DOI: 10.1007/BF00221750 -
Journal Francais D'ophtalmologie 1985Keratoglobus is a bilateral corneal disease characterised by thinning and protrusion of the entire corneal surface. The cornea is of normal size and usually transparent....
Keratoglobus is a bilateral corneal disease characterised by thinning and protrusion of the entire corneal surface. The cornea is of normal size and usually transparent. Acute corneal edema due to rupture of Descemet's membrane and perforation even from minimal trauma are the most frequent complications. Keratoglobus may be associated with blue sclera, hyperextensibility of the joints or auditory problems. Most often it is a congenital disease with autosomal recessive transmission, but it may be secondarily acquired to an advanced keratopathy (keratoconus), to trauma or to exophthalmos. We report 5 cases of keratoglobus. 4 patients underwent penetrating keratoplasty. The anatomical abnormalities of congenital keratoglobus (3 cases) are constants : an absent Bowman's membrane, a disorganized stroma containing granular material, a thickened, striated Descemet's membrane with breaks, folds and verrucosities. On the other hand, acquired keratoglobus (1 case) shows localised breaks in Bowman's membrane resembling those of keratoconus. The anatomopathological differences are discussed.
Topics: Adult; Aged; Child; Cornea; Corneal Dystrophies, Hereditary; Corneal Stroma; Corneal Transplantation; Descemet Membrane; Female; Humans; Keratoconus; Male; Microscopy, Electron; Middle Aged; Sclera
PubMed: 3889124
DOI: No ID Found -
American Journal of Ophthalmology Nov 1960
Topics: Basement Membrane; Bowman Membrane; Cornea; Epithelium, Corneal; Humans
PubMed: 13752050
DOI: 10.1016/0002-9394(60)90354-8