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Journal of Refractive Surgery... Feb 2022To evaluate the feasibility and report long-term outcomes with Bowman's membrane relaxation (BMR) for enhancing the residual refractive error following femtosecond...
PURPOSE
To evaluate the feasibility and report long-term outcomes with Bowman's membrane relaxation (BMR) for enhancing the residual refractive error following femtosecond intrastromal lenticule implantation (FILI).
METHODS
BMR was performed using a Hessburg-Barron trephine to create a circular incision into the Bowman's membrane and anterior corneal fibers up to the depth of approximately 120 to 130 µm. After enhancement, clinical outcomes were analyzed for a mean period of 36 months (range: 14 to 57 months).
RESULTS
Four eyes of 3 patients (mean age: 29 years) underwent enhancement with BMR for a significant residual refractive error of +2.25 diopters (D) spherical equivalent following FILI for high hyperopia (mean spherical equivalent: +7.00 D). After BMR, the residual refraction reduced to +0.31 D, resulting in improvement in uncorrected distance visual acuity from 0.55 to 0.33 logMAR. The mean front keratometry values increased from 46.20 to 49.30 D, and the mean back keratometry values increased from -5.90 to -6.30 D following BMR, the latter returning to the baseline (pre-FILI) value of -6.30 D. An increase in Q-value with a corresponding increase in higher order aberrations was observed. Corneal biomechanics indicated reduction of stiffness and other parameters after enhancement. No intraoperative or postoperative complications were noted.
CONCLUSIONS
BMR may be an effective technique for enhancement of residual hyperopia following tissue addition techniques such as FILI. BMR may reverse the posterior curvature changes, negating the steepening effect of the anterior cornea following tissue addition, potentially aiding in the enhancement. .
Topics: Adult; Bowman Membrane; Corneal Stroma; Corneal Surgery, Laser; Corneal Topography; Humans; Hyperopia; Refraction, Ocular
PubMed: 35156459
DOI: 10.3928/1081597X-20211215-01 -
Journal of Cataract and Refractive... May 2008
Topics: Bowman Membrane; History, 19th Century; Humans; Keratectomy, Subepithelial, Laser-Assisted; Keratomileusis, Laser In Situ; Lasers, Excimer; Ophthalmology; Surgical Flaps
PubMed: 18471609
DOI: 10.1016/j.jcrs.2008.03.006 -
Eye & Contact Lens Apr 2021Herein, we report the outcomes of intrastromal Descemet membrane (DM) transplantation in corneas with advanced keratoconus. Three eyes (three patients) showed advanced...
Herein, we report the outcomes of intrastromal Descemet membrane (DM) transplantation in corneas with advanced keratoconus. Three eyes (three patients) showed advanced keratoconus. No eye underwent prior UV-cross-linking or any other ocular surgery. In all eyes, A donor DM was implanted into a mid-stromal pocket and clinical outcomes were evaluated up to 24 months after surgery. All procedures were uneventful. Up to 24 months postoperatively, the DM graft was well-positioned and barely visible within the recipient stroma; all corneas were clear. No eye showed signs of keratoconus progression throughout the follow-up. No changes were observed in uncorrected and best contact lens corrected visual acuity, central endothelial cell density, corneal thinnest point pachymetry, and maximum keratometry values. No early or late postoperative complications were observed. Intrastromal DM transplantation may be an alternative to intrastromal Bowman layer transplantation in advanced keratoconus, to postpone deep anterior lamellar or penetrating keratoplasty.
Topics: Corneal Topography; Corneal Transplantation; Descemet Membrane; Follow-Up Studies; Humans; Keratoconus; Refraction, Ocular; Visual Acuity
PubMed: 33044374
DOI: 10.1097/ICL.0000000000000749 -
Archives of Ophthalmology (Chicago,... Dec 1966
Topics: Cornea; Electrocoagulation; Eye Diseases; Humans
PubMed: 5924934
DOI: 10.1001/archopht.1966.03850010770002 -
American Journal of Ophthalmology Apr 1974
Topics: Collagen; Connective Tissue; Cornea; Electrocoagulation; Endoplasmic Reticulum; Epithelium; Eye Diseases; Fibroblasts; Humans; Microscopy, Electron; Postoperative Complications
PubMed: 4819457
DOI: 10.1016/0002-9394(74)90470-x -
The Tohoku Journal of Experimental... Sep 2023X-linked Alport syndrome is a hereditary progressive renal disease resulting from the disruption of collagen α3α4α5 (IV) heterotrimerization caused by pathogenic...
X-linked Alport Syndrome with Type IV Collagen α5 Chain Staining Revealing Normal Expression in the Glomerular Basement Membrane and Negative on Bowman's Capsule and Distal Tubular Basement Membrane: A Case Report.
X-linked Alport syndrome is a hereditary progressive renal disease resulting from the disruption of collagen α3α4α5 (IV) heterotrimerization caused by pathogenic variants in the COL4A5 gene. This study aimed to report a male case of X-linked Alport syndrome with a mild phenotype accompanied by an atypical expression pattern of type IV collagen α5 [α5 (IV)] chain in glomerulus. A 38-year-old male presented with proteinuria (2.3 g/day) and hematuria. He has been detected urinary protein and occult blood since childhood. A renal biopsy was performed at the age of 29 years; however, a diagnosis of Alport syndrome was not considered. A renal biopsy 9 years later revealed diffuse thinning and lamellation of the glomerular basement membrane. Α staining for α5 (IV) revealed a normal expression pattern in the glomerular basement membrane and a complete negative expression in Bowman's capsule and distal tubular basement membrane. Using next-generation sequencing, we detected a COL4A5 missense variant within exon 35 (NM_000495.5: c.3088G>A, p. G1030S). The possibility of X-linked Alport syndrome should be considered when negative expression of α5 (IV) staining on Bowman's capsule was observed.
Topics: Male; Humans; Child; Adult; Nephritis, Hereditary; Collagen Type IV; Bowman Capsule; Glomerular Basement Membrane; Exons
PubMed: 37495524
DOI: 10.1620/tjem.2023.J060 -
Journal of Cataract and Refractive... Jul 2021To compare the elastic modulus of thin corneal lamellas using 2D stress-strain extensometry in healthy ex vivo human corneal lamellas with or without the presence of...
PURPOSE
To compare the elastic modulus of thin corneal lamellas using 2D stress-strain extensometry in healthy ex vivo human corneal lamellas with or without the presence of Bowman layer.
SETTING
Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Switzerland; ELZA Institute, Dietikon, Switzerland; Department of Ophthalmology, Philipps University of Marburg, Germany.
DESIGN
Prospective experimental laboratory study.
METHODS
Healthy human corneas were stripped of Descemet membrane and the endothelium for Descemet membrane endothelial keratoplasty. After epithelium removal, corneas were divided into 2 groups. In Group 1, Bowman layer was ablated with an excimer laser (20 μm thick, 10 mm). In Group 2, Bowman layer was left intact. Then, a lamella was cut from the anterior cornea with an automated microkeratome. Elastic and viscoelastic material properties were analyzed by 2D stress-strain extensometry between 0.03 and 0.70 N.
RESULTS
Twenty-six human corneas were analyzed. The mean lamella thickness was 160 ± 37 μm in corneas with Bowman layer and 155 ± 22 μm in corneas without. No statistically significant differences between flaps with and without Bowman layer were observed in the tangential elastic modulus between 5% and 20% strain (11.5 ± 2.9 kPa vs 10.8 ± 3.7 kPa, P > .278).
CONCLUSIONS
The presence or absence of Bowman layer did not reveal a measurable difference in corneal stiffness. This may indicate that the removal of Bowman layer during photorefractive keratectomy does not represent a disadvantage to corneal biomechanics.
Topics: Biomechanical Phenomena; Cornea; Germany; Humans; Photorefractive Keratectomy; Prospective Studies
PubMed: 33315734
DOI: 10.1097/j.jcrs.0000000000000543 -
Cornea Dec 2022The aim of this study was to review the postoperative course and imaging features of 7 eyes that presented with corneal hydrops after Bowman layer (BL) transplantation...
PURPOSE
The aim of this study was to review the postoperative course and imaging features of 7 eyes that presented with corneal hydrops after Bowman layer (BL) transplantation was performed for advanced keratoconus to determine the potential mechanisms of hydrops formation.
METHODS
A retrospective analysis was performed of 7 eyes of 5 patients with advanced keratoconus that underwent midstromal BL transplantation at 2 tertiary referral centers and developed acute corneal hydrops on average 64 (±30) months (range 14-104 months) postoperatively. Corneal tomography and anterior segment optical coherence tomography (AS-OCT) images were reviewed to document the postoperative and posthydrops course.
RESULTS
For all eyes, the post-BL transplantation course was uneventful until hydrops development. Despite stable postoperative topographies in 5 of 7 eyes, eyes developed hydrops with typical hypodense areas on AS-OCT that were limited to the stromal layers posterior to the BL graft. With AS-OCT (6/7 eyes), 2 eyes showed a break in Descemet membrane, whereas Descemet membrane was intact across the cornea in 2 eyes; in 2 eyes, the images were inconclusive. All patients admitted to continued eye rubbing, and all but 1 had a clinically significant allergy and/or atopic constitution. Most eyes (5/7) showed a relatively quick (visual) recovery within 1 to 4 months after hydrops.
CONCLUSIONS
Hydrops formation in keratoconic corneas after midstromal BL transplantation may indicate that a break in Descemet membrane is secondary to hydrops development (and not vice versa). With a midstromal BL graft in situ limiting hydrops dimensions, resolution of the hydrops seemed relatively quick with recovery to prehydrops visual acuity in most eyes.
Topics: Humans; Keratoconus; Descemet Membrane; Retrospective Studies; Postoperative Complications; Corneal Edema; Tomography, Optical Coherence; Edema
PubMed: 34864795
DOI: 10.1097/ICO.0000000000002920 -
American Journal of Ophthalmology Feb 1966
Topics: Cornea; Epithelium; Eye Diseases; Female; Humans; Male; Middle Aged
PubMed: 5904010
DOI: 10.1016/0002-9394(66)90275-3 -
Biomolecules Apr 2023Bowman's layer is an acellular layer in the anterior stroma found in the corneas of humans, most other primates, chickens, and some other species. Many other species,... (Review)
Review
Bowman's layer is an acellular layer in the anterior stroma found in the corneas of humans, most other primates, chickens, and some other species. Many other species, however, including the rabbit, dog, wolf, cat, tiger, and lion, do not have a Bowman's layer. Millions of humans who have had photorefractive keratectomy over the past thirty plus years have had Bowman's layer removed by excimer laser ablation over their central cornea without apparent sequelae. A prior study showed that Bowman's layer does not contribute significantly to mechanical stability within the cornea. Bowman's layer does not have a barrier function, as many cytokines and growth factors, as well as other molecules, such as EBM component perlecan, pass bidirectionally through Bowman's layer in normal corneal functions, and during the response to epithelial scrape injury. We hypothesized that Bowman's layer represents a visible indicator of ongoing cytokine and growth factor-mediated interactions that occur between corneal epithelial cells (and corneal endothelial cells) and stromal keratocytes that maintain the normal corneal tissue organization via negative chemotactic and apoptotic effects of modulators produced by the epithelium on stromal keratocytes. Interleukin-1 alpha, produced constitutively by corneal epithelial cells and endothelial cells, is thought to be one of these cytokines. Bowman's layer is destroyed in corneas with advanced Fuchs' dystrophy or pseudophakic bullous keratopathy when the epithelium becomes edematous and dysfunctional, and fibrovascular tissue commonly develops beneath and/or within the epithelium in these corneas. Bowman's-like layers have been noted to develop surrounding epithelial plugs within the stromal incisions years after radial keratotomy. Although there are species-related differences in corneal wound healing, and even between strains within a species, these differences are not related to the presence or absence of Bowman's layer.
Topics: Humans; Animals; Dogs; Rabbits; Epithelium, Corneal; Endothelial Cells; Corneal Stroma; Chickens; Cornea; Wound Healing; Cytokines
PubMed: 37238641
DOI: 10.3390/biom13050771