Assessment of the Number of Lamellae in the Central Region of the Normal Human Corneal Stroma at the Resolution of the Transmission Electron Microscope

Bergmanson, Jan P.G.; Horne, Jessica; Doughty, Michael J.; Garcia, M. M. Sola; Gondo, Margaret

doi:10.1097/01.icl.0000165280.94927.0d

Cited by 61 publications

(53 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The differences may be dismissed as artifacts of the preparative methods, but further work is clearly needed to define the collagen fibril characteristics at other regions of the corneal stroma and to establish the full nature of the possible differences reported by others [13,19] . Similarly, any possible age-related changes [14,20] need to be investigated further as part of specific detailed and systematic studies for both the lamellae [2] , as well as the actual fibrils in human corneas. Such studies are currently in progress.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of the Apparent Intra- and Inter-Sample Variability in the Collagen Fibril Diameter in the Posterior Corneal Stroma of Rabbits

Doughty¹,

Bergmanson²

2006

Ophthalmic Res

Self Cite

View full text Add to dashboard Cite

Purpose: To assess the natural variability in the diameter of small collagen fibrils in the lamellae of corneal stroma of healthy young rabbits. Materials and Methods: The corneas of 6 young adult female New Zealand White rabbits (2.1 kg) were prepared for transmission electron microscopy (TEM) by fixation with a cacodylate-buffered 2% glutaraldehyde (pH 7.2–7.4, 320–340 mosm/kg). The corneas were embedded in Epon-Araldite, thin sections prepared from the central region of the posterior corneal stroma and stained with acidic uranyl acetate followed by acidic lead citrate. High magnification (×33,000) micrographs were taken, and fibril diameters (FDs) measured at a final magnification of ×275,000 to a resolution of 2 nm. Results: Assessment of sampling-related errors indicated that the average diameter of the fibrils within any particular micrograph could be estimated to within 1% or better by measures of 100 fibrils. Assessments of the intra-sample variance (6 micrographs taken from the same cornea) indicated a group mean FD of 32.4 ± 3.6 nm, whilst the inter-sample variance (6 micrographs taken from 6 different corneas) yielded an average of 33.1 ± 4.5 nm (n = 100 fibrils/micrograph, ±SD). However, group-averaged data sets of FDs, while unimodal, were not normally distributed, and cumulative averaging indicated a fixed range of FDs across the data sets. Conclusions: Intra- and inter-sample variability in collagen FDs is very similar, but the analysis indicates that the collagen fibrils are not homogeneous and that closely adjacent lamellae can have subtle differences in average FD.

show abstract

Section: Discussionmentioning

confidence: 99%

“…The mammalian corneal stroma is organized into flat sheets called lamellae [1,2] . As revealed many years ago by transmission electron microscopy (TEM), the lamellae are actually composed of collagen fibrils with a relatively small diameter, stated as being between 20 and 50 nm in the earliest papers [3] .…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Apparent Intra- and Inter-Sample Variability in the Collagen Fibril Diameter in the Posterior Corneal Stroma of Rabbits

Doughty¹,

Bergmanson²

2006

Ophthalmic Res

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the human cornea there are distinct anatomical differences between the outermost and the deeper corneal lamellae. The anterior layers have a lamella density some 50% greater than those in the deep layers (Bergmanson et al 2005); they frequently bifurcate and interweave (Radner et al 1998) and are arranged in equal numbers within all orientations within the plane of the cornea. The posterior layers are more hydrated and are stacked rather like plywood, run from limbus to limbus and occur predominantly vertically and horizontally within the eye (Meek et al 1987;Daxer and Fratzl 1997;Aghamohammadzadeh et al 2004).…”

Section: Corneal Lamellaementioning

confidence: 99%

Corneal collagen—its role in maintaining corneal shape and transparency

2009

View full text Add to dashboard Cite

Corneal collagen has a number of properties that allow it to fulfil its role as the main structural component within the tissue. Fibrils are narrow, uniform in diameter and precisely organised. These properties are vital to maintain transparency and to provide the biomechanical prerequisites necessary to sustain shape and provide strength. This review describes the structure and arrangement of corneal collagen from the nanoscopic to the macroscopic level, and how this relates to the maintenance of the form and transparency of the cornea.

show abstract

“…However, for cuts deeper than 31%, VisionGraft corneas clearly have less ridges (ridge scores ranged 1.92 to 2.25) than fresh corneas (ridge scores ranged 3.30 to 3.83) 8 . It has been suggested that in fresh corneas, the anterior corneal lamellae have more bridging fibers between them that increase shear strength, and these are relatively lacking in the posterior stroma, 20, 21 the less compactly arranged posterior stromal fiber wrinkled by external pressure such as the action of applanation lens might possibly be one of reasons for ridges on fresh cadaver corneas. We speculated the stronger interlamellar cohesion of VisionGraft corneas could decrease the stromal fiber wrinkling induced by applanation and lead to less ridges on the interface compared with those on fresh corneas.…”

Section: Discussionmentioning

confidence: 99%

Laboratory Evaluation of Femtosecond Laser Lamellar Cuts in Gamma-Irradiated Corneas

Zhang¹,

Liu

Tang

et al. 2015

Cornea

View full text Add to dashboard Cite

PURPOSE To evaluate the stromal interface quality after femtosecond laser full lamellar cuts in Gamma-irradiated corneas (VisionGraft Sterile Cornea) and determine the limits of cut depth using VisionGraft as donor corneas for laser-assisted lamellar anterior keratoplasty. METHODS Fourteen VisionGraft corneas underwent full lamellar cuts using femtosecond laser. The percent cut depth was 17-21% (100μm, n=2), 31-35% (n=3), 38-40% (n=3), 45-48% (n=3) and 50% (n=3) of total stromal thickness (not including epithelium). The cap and stromal bed surfaces were imaged with scanning electron microscope (SEM). The quality of cut surfaces was graded by 2 masked observers based on two indices: ridge and roughness. The ridge grading indicated macroscopic irregularity. The roughness grading indicated microscopic irregularity. The grading was on a subjective integer scale of 1-5 (1=best, 5=worst), which was used previously in a published study of cut quality in fresh corneas. RESULTS The ridge grading ranged from 1.50 for the shallowest cut to 2.25 for the deepest cut and was weakly (r=0.279) but significantly (P=0.037) correlated with percent cut depth. The roughness grading ranged from 2.63 to 2.56 and bore no trend with percent cut depth (r=0.006, P=0.968). CONCLUSION Compared to previously published results in fresh corneas, where ridge grading exceeded 3 for cuts deeper than 31%, the cut quality was better for VisionGraft. Even at depths up to 48% of total stromal thickness, ridge grading was not worse than shallow cuts. Thus Gamma irradiated corneas could provide smoother interface than fresh eye bank cornea for laser-assisted lamellar anterior keratoplasty.

show abstract

Assessment of the Number of Lamellae in the Central Region of the Normal Human Corneal Stroma at the Resolution of the Transmission Electron Microscope

Abstract: When assessed at the resolution of the transmission electron microscope, the number of stromal lamellae in the central region of the human cornea are higher (at approximately 240 per cornea) than most previous estimates reported from light microscopy studies.

Cited by 61 publications

References 19 publications

Assessment of the Apparent Intra- and Inter-Sample Variability in the Collagen Fibril Diameter in the Posterior Corneal Stroma of Rabbits

Assessment of the Apparent Intra- and Inter-Sample Variability in the Collagen Fibril Diameter in the Posterior Corneal Stroma of Rabbits

Corneal collagen—its role in maintaining corneal shape and transparency

Laboratory Evaluation of Femtosecond Laser Lamellar Cuts in Gamma-Irradiated Corneas

Contact Info

Product

Resources

About