The effect of keratoconus on the structural, mechanical, and optical properties of the cornea

Ambekar, Raghu; Toussaint, Kimani C.; Johnson, Amy J. Wagoner

doi:10.1016/j.jmbbm.2010.09.014

Cited by 120 publications

(95 citation statements)

References 86 publications

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“…Because keratoconic corneas invariably show fragmentation of the Bowman layer, 36 we hypothesized that a surgical approach in which the potential functionality of the Bowman layer in stabilizing the cornea could be restored while avoiding the risk factors related to PK and DALK. 15 Although positioning an isolated donor Bowman layer onto a keratoconic cornea (i.e., in its true anatomic position) technically is feasible, it is difficult to obtain sufficient traction force across the cornea to flatten the central cone because the thin donor Bowman layer cannot be fixated with any sutures or glues currently available.…”

Section: Discussionmentioning

confidence: 99%

Bowman Layer Transplantation to Reduce and Stabilize Progressive, Advanced Keratoconus

et al. 2015

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Section: Discussionmentioning

confidence: 99%

Bowman Layer Transplantation to Reduce and Stabilize Progressive, Advanced Keratoconus

et al. 2015

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“…Structural changes in the cornea include thinning of the central stroma and breaks in Bowman's layer as well as a decreased number of collagen lamellae. 1 The mechanisms underlying keratoconus are poorly understood and may involve an inheritable genetic factor, increased protease activity, oxidative stress, and environmental factors such as eye rubbing. 2 Management of keratoconus revolves around visual rehabilitation as well as slowing the disease progression.…”

mentioning

confidence: 99%

Collagen Cross-Linking Using Rose Bengal and Green Light to Increase Corneal Stiffness

Cherfan

Verter

Melki³

et al. 2013

Invest. Ophthalmol. Vis. Sci.

149

164

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PURPOSE. Photochemical cross-linking of corneal collagen is an evolving treatment for keratoconus and other ectatic disorders. We evaluated collagen cross-linking by rose bengal plus green light (RGX) in rabbit eyes and investigated factors important for clinical application.METHODS. Rose bengal (RB, 0.1%) was applied to deepithelialized corneas of enucleated rabbit eyes for 2 minutes. The diffusion distance of RB into the stroma was measured by fluorescence microscopy on frozen sections. RB-stained corneas were exposed to green (532-nm) light for 3.3 to 9.9 minutes (50-150 J/cm 2 ). Changes in the absorption spectrum during the irradiation were recorded. Corneal stiffness was measured by uniaxial tensiometry. The spatial distribution of the stromal elastic modulus was assessed by Brillouin microscopy. Viable keratocytes were counted on H&E-stained sections 24 hours posttreatment. RESULTS.RB penetrated approximately 100 lm into the corneal stroma and absorbed >90% of the incident green light. RGX (150 J/cm 2 ) increased stromal stiffness by 3.8-fold. The elastic modulus increased in the anterior approximately 120 lm of stroma. RB was partially photobleached during the 2-minute irradiation, but reapplication of RB blocked light transmission by >70%. Spectral measurements suggested that RGX initiated cross-linking by an oxygen-dependent mechanism. RGX did not decrease keratocyte viability.CONCLUSIONS. RGX significantly increases cornea stiffness in a rapid treatment (@12 minutes total time), does not cause toxicity to keratocytes and may be used to stiffen corneas thinner than 400 lm. Thus, RGX may provide an attractive approach to inhibit progression of keratoconus and other ectatic disorders.

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“…Keratoconus is an ocular disorder characterized by corneal degeneration due to corneal thinning and bilateral conical protrusion. Similar to myopia, the exact etiology of keratoconus is unknown, but it is more common in patients with atopic conditions, dermatitis, and Down syndrome~Bell, 1993; Mao & Bristow, 2001;Ambekar et al, 2011!. It is generally accepted that the progressive myopia and keratoconus is associated with a lack of synthesis of extracellular matrix components during the development of cornea and sclera. In particular, osteogenesis imperfecta is associated with a collagen type-I defect, Ehlers-Danlos syndrome is associated with collagen type-I and -III defects, and Marfan syndrome and pseudoxanthoma elasticum are associated with elastin defects~Bell, 1993; Mao & Bristow, 2001;Rada et al, 2006;Ambekar et al, 2011!. Stromal thinning and the biomechanical processes of progressive myopia are similar to progressive keratoconus, suggesting the possibility of a novel therapy against progressive myopia.…”

Section: Discussionmentioning

confidence: 99%

“…Keratoconus and myopia are the most prevalent ocular disorders characterized by corneal degeneration due to corneal thinning~Bell, 1993; Mao & Bristow, 2001;Ambekar et al, 2011! and a mismatch between the power and axial length of the eye owing to scleral thinning~Wollensak Wollensak et al, 2005;Wollensak & Iomdina, 2009!, respectively.…”

Section: Introductionmentioning

confidence: 99%

Structural and Biomechanical Effects of Photooxidative Collagen Cross-Linking with Photosensitizer Riboflavin and 370 nm UVA Light on Human Corneoscleral Tissues

et al. 2013

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This study quantitatively investigated the immediate effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin (RF) and 370 nm UVA light in in vitro human corneoscleral collagen fibrils using histology, thickness, scanning electron microscopy, and atomic force microscopy analyses. Twenty 8 x 2 mm corneoscleral strips were dissected sagittally from donor tissue using a scalpel. Four parameters were investigated, including the density, thickness, adhesion force, and stiffness of corneoscleral tissues before and after the collagen cross-linking treatment. The RFUVA-catalyzed collagen cross-linking treatment led to an increase in the density of both corneal (8%) and scleral (23%) stromal collagens. However, there was no difference in corneoscleral thickness. Furthermore, RFUVA-catalyzed collagen cross-linking treatment led to an increased biomechanical response of corneosclera: 25 and 8% increases in corneoscleral stiffness, and 24 and 22% increases in corneoscleral adhesion force. The collagen cross-linking treatment through RF-sensitized photoreaction may cause structural and biomechanical changes in the collagen fibril network of the cornea and the sclera. This is due to narrowing of the interfibrillar spacing and the stromal edema.

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The effect of keratoconus on the structural, mechanical, and optical properties of the cornea

Cited by 120 publications

References 86 publications

Bowman Layer Transplantation to Reduce and Stabilize Progressive, Advanced Keratoconus

Bowman Layer Transplantation to Reduce and Stabilize Progressive, Advanced Keratoconus

Collagen Cross-Linking Using Rose Bengal and Green Light to Increase Corneal Stiffness

Structural and Biomechanical Effects of Photooxidative Collagen Cross-Linking with Photosensitizer Riboflavin and 370 nm UVA Light on Human Corneoscleral Tissues

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