Changes in Collagen Orientation and Distribution in Keratoconus Corneas

Meek, Keith Michael Andrew; Tuft, Stephen; Huang, Yifei; Gill, Paulvinder S.; Hayes, Sally; Newton, Richard; Bron, Anthony J.

doi:10.1167/iovs.04-1253

Cited by 441 publications

(346 citation statements)

References 51 publications

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“…Despite the considerable variability known to exist between keratoconus corneas in terms of the extent of stromal collagen disruption, 14 X-ray scattering and scanning electron microscopy studies are in agreement that the severity of disruption decreases with distance from the cone apex. 13,14,18,19 In contrast to most keratoconus corneal buttons, the majority of the failed-graft tissue appeared normal in terms of collagen orientation and mass distribution, with regions of abnormality being limited to the inferior aspect of the peripheral cornea and coinciding in each case with the location of the original graft-host interface. The most marked abnormalities were observed in the grossly vascularised infero-nasal quadrant of the peripheral cornea, where the normal tangential alignment of collagen was replaced by radially orientated collagen and the lamellae appeared indistinct and disordered when viewed by electron microscopy.…”

Section: Discussionmentioning

confidence: 99%

“…The findings were compared with our previously published work (using the same experimental protocol as here), which examined six normal corneas 12 and six keratoconus corneas. 13,14 Measurements of fibril diameter in the failed-graft corneal tissue were compared with those obtained from an 8.5-mm button excised from a normal post-mortem cornea stored for 23 days in culture medium and then de-swelled for 2 days in dextran (obtained from the Corneal Transplant Service Eye Bank, Bristol, UK). Our previously published results from five healthy corneas 15 were used to confirm the normal range of fibril diameters in the human cornea.…”

Section: Specimen Informationmentioning

confidence: 99%

“…These findings are consistent with our previously published data from six keratoconus corneas of varying disease severity, cone shape, and location. 13,14 Collagen distribution…”

Section: Predominant Orientation Of Corneal Collagenmentioning

confidence: 99%

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A structural investigation of corneal graft failure in suspected recurrent keratoconus

Hayes

Young

Boote

et al. 2009

Eye

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Purpose Penetrating keratoplasty was performed on the right eye of a 51-year-old patient diagnosed with advanced bilateral keratoconus. Thirteen years later, an 8.5 mm regraft was required as a result of gross vascularisation, a poor epithelium, and suspected recurrent keratoconus. To learn more about the structural basis for graft failure, we examined the removed tissue for the presence of abnormalities in the stroma and limiting membranes. Methods X-ray scattering and electron microscopy were used to study the failed-graft tissue to provide information on the integrity of the limiting membranes and the diameter, dominant orientation, and distribution of collagen within the corneal stroma. The findings were compared with similar structural data from normal and keratoconus corneas. Results In contrast to the keratoconus cornea, a normal orientation and distribution of collagen was seen throughout most of the failed-graft tissue, although abnormalities were observed in the infero-nasal quadrant at the original graft/ host junction. The average diameter of collagen fibrils in the failed-graft button did not differ from that of normal corneas. Conclusions The structural abnormalities identified in this case of graft failure were not consistent with those typically seen in keratoconus. The clear demarcation of the graft/ host boundary 13 years after surgery suggests that a normal stromal collagen arrangement may never be fully achieved in corneal graft wounds.

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Section: Discussionmentioning

confidence: 99%

Section: Specimen Informationmentioning

confidence: 99%

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A structural investigation of corneal graft failure in suspected recurrent keratoconus

Hayes

Young

Boote

et al. 2009

Eye

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“…These changes allow more contact between the collagen sheets and the proteoglycans, thus altering the stroma organization where alterations in interlamellar proteoglycans might contribute to slippage of the lamellae. 81 Meek et al, 82 using synchrotron X-ray scattering patterns, confirmed that a gross rearrangement of vertical and horizontal collagen lamellae occurs in keratoconus. Tissue degradation alone does not account for that systematic realignment of fibrils, and so the authors suggested that both slippage and remodeling have a role.…”

Section: Corneal Stroma Compositionmentioning

confidence: 92%

Keratoconus: an inflammatory disorder?

Galvis

Sherwin

Tello

et al. 2015

Eye

301

199

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Keratoconus has been classically defined as a progressive, non-inflammatory condition, which produces a thinning and steepening of the cornea. Its pathophysiological mechanisms have been investigated for a long time. Both genetic and environmental factors have been associated with the disease. Recent studies have shown a significant role of proteolytic enzymes, cytokines, and free radicals; therefore, although keratoconus does not meet all the classic criteria for an inflammatory disease, the lack of inflammation has been questioned. The majority of studies in the tears of patients with keratoconus have found increased levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase (MMP)-9. Eye rubbing, a proven risk factor for keratoconus, has been also shown recently to increase the tear levels of MMP-13, IL-6, and TNF-α. In the tear fluid of patients with ocular rosacea, IL-1α and MMP-9 have been reported to be significantly elevated, and cases of inferior corneal thinning, resembling keratoconus, have been reported. We performed a literature review of published biochemical changes in keratoconus that would support that this could be, at least in part, an inflammatory condition.

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“…Structural abnormalities were occurred in the central part of Bowman's layer (BM) in the form of a sharp edge defects and interruption in the BM resulting from collagen bundle separation. 3 Computer-assisted videokeratography (corneal topography) was one of the recent methods of diagnosis of keratoconus which depends on screening for keratoconic corneal shape changes. It depends on Rabinowitz diag nostic indices for diagnosis of keratoconus.…”

Section: Introductionmentioning

confidence: 99%

Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt

Sayed¹,

Ali²,

Barbara³

2017

International Journal of Keratoconus and Ectatic Corneal Diseases

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Background: Keratoconus (KC) is a progressive, non-inflammatory bilateral but (usually asymmetrical) ecstatic corneal disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion. The reported incidence and prevalence of KC varies widely depending upon the geographic location, diagnostic criteria used and the cohort of patients selected. Materials and methods:This study as designed as a prospective surveillance study. All clinical records in the computerized database from pentacam with the clinical diagnosis of KC and / or suspected were included and statistically analyzed. Results:Data from 2116 cases with the average 28.8 ± 6.5 years old were analyzed over the span of 1 year starting from March 2013 to March 2014. Based on topographic images of the pentacam 36 eyes were diagnosed as KC. The incidence of KC was 1.7% ( 95% confidence interval, 0.55-1.45). In keratoconic patients, the mean age was 28.1 years, the mean K1 and K2 were 45.18±3.44 D and 49.49 ± 4.28 D respectively. The mean minimal pachymetry value was 463± 6.51um, the mean index of surface variance (ISV) was 61± 32, the mean index of vertical asymmetry (IVA) was 0.63±0.38, the mean keratoconus indices (KI) was 1.08±0.14. Conclusion:This study provides the first population-based estimate of the incidence of keratoconus in Beni suef governorate in the upper Egypt. According to this study incidence rate of KC is comparable to the rate among the Caucasian people in middle Asia e.g. Iran while incidence rate is much higher among Malaysia and Kingdom of Saudi Arabia citizens.

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Changes in Collagen Orientation and Distribution in Keratoconus Corneas

Cited by 441 publications

References 51 publications

A structural investigation of corneal graft failure in suspected recurrent keratoconus

A structural investigation of corneal graft failure in suspected recurrent keratoconus

Keratoconus: an inflammatory disorder?

Incidence and Indices of Keratoconus in Patients presenting for LASIK in Egypt

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