Evaluation of corneal hysteresis and corneal resistance factor after corneal cross-linking for keratoconus

Gkika, Maria; Labiris, Georgios; Giarmoukakis, Athanassios; Koutsogianni, Anna; Kozobolis, Vassilios

doi:10.1007/s00417-011-1897-0

Cited by 60 publications

(52 citation statements)

References 31 publications

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“…It has been repeatedly shown that crosslinking halts the progression of keratoconus, and the effects from corneal crosslinking have been convincingly demonstrated in vitro by biochemical (Spoerl et al 2004b;Brummer et al 2011), biomechanical (Wollensak et al 2003b;Knox Cartwright et al 2012;Dias et al 2013), structural (Wollensak et al 2004;Beckman Rehnman et al 2011) and thermomechanical (Spoerl et al 2004a) investigations. Demonstrating an increased biomechanical strength in vivo after CXL treatment using the Ocular Response Analyser (ORA), has been more difficult (Vinciguerra et al 2010;Spoerl et al 2011;Gkika et al 2012;Goldich et al 2012), but it is generally accepted today that CXL acts through an increase in corneal biomechanical strength (Beshtawi et al 2013).…”

Section: Discussionmentioning

confidence: 99%

Initial results from mechanical compression of the cornea during crosslinking for keratoconus

Rehnman

Behndig

Hallberg

et al. 2014

Acta Ophthalmologica

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ABSTRACT.Purpose: To compare refractive changes after corneal crosslinking with and without mechanical compression of the cornea. Methods: In a prospective, open, randomized case-control study conducted at the Department of Ophthalmology, Ume a University Hospital, Sweden, sixty eyes of 43 patients with progressive keratoconus aged 18-28 years planned for corneal crosslinking and corresponding age-and sex-matched control subjects were included. The patients were randomized to conventional corneal crosslinking (CXL; n = 30) or corneal crosslinking with mechanical compression using a flat rigid contact lens sutured to the cornea during treatment (CRXL; n = 30). Subjective refraction and ETDRS best spectacle-corrected visual acuity (BSCVA), axial length measurement, keratometry and pachymetry were performed before and 1 and 6 months after treatment. Results: The keratoconus patients had poorer BSCVA, higher refractive astigmatism and higher keratometry readings than the control subjects at baseline (p < 0.01). In the CXL group, BSCVA increased from 0.19 AE 0.26 to 0.14 AE 0.18 logMar (p = 0.03), and the spherical equivalent improved from À1.9 AE 2.8 D to À1.4 AE 2.4 D (p = 0.03). Maximum keratometry readings decreased after CXL from 53.1 AE 4.9 D to 52.6 AE 5.2 D (p = 0.02), and the axial length decreased in the CXL group, likely due to post-treatment corneal thinning (p = 0.03). In the CRXL group, all the above variables were unaltered (p > 0.05). Conclusion: At 6 months, the refractive results from CRXL did not surpass those of conventional CXL treatment. Rather, some variables indicated a slightly inferior effect. Possibly, stronger crosslinking would be necessary to stabilize the cornea in the flattened configuration achieved by the rigid contact lens.

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Section: Discussionmentioning

confidence: 99%

Initial results from mechanical compression of the cornea during crosslinking for keratoconus

Rehnman

Behndig

Hallberg

et al. 2014

Acta Ophthalmologica

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“…This enables in vivo measurement of CH and the CRF [10]. In KCN corneas, CH and the CRF have been shown to be significantly decreased when compared with non-KCN corneas [11,22,23,24]. …”

Section: Corneal Biomechanical Propertiesmentioning

confidence: 99%

Corneal Collagen Crosslinking: A Systematic Review

Sorkin

Varssano²

2014

Ophthalmologica

166

122

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Keratoconus (KCN) is an ectatic disorder with progressive corneal thinning and a clinical picture of corneal protrusion, progressive irregular astigmatism, corneal fibrosis and visual deterioration. Other ectatic corneal disorders include: post-LASIK ectasia (PLE) and pellucid marginal degeneration (PMD). Corneal crosslinking (CXL) is a procedure whereby riboflavin sensitization with ultraviolet A radiation induces stromal crosslinks. This alters corneal biomechanics, causing an increase in corneal stiffness. In recent years, CXL has been an established treatment for the arrest of KCN, PLE and PMD progression. CXL has also been shown to be effective in the treatment of corneal infections, chemical burns, bullous keratopathy and other forms of corneal edema. This is a current review of CXL - its biomechanical principles, the evolution of CXL protocols in the past, present and future, indications for treatment, treatment efficacy and safety.

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“…31 A number of publications, in which ORA was used, report on changes in ocular biomechanical properties in keratoconus eyes. 17,26,27,32,33 Statistically, CH and CRF are significantly lower in keratoconus eyes compared to normal eyes, but both parameters have low sensitivity and specificity for distinguishing between the groups, thus alone are not suitable for establishing the diagnosis. 32,33 Although CorVis ST analyses corneal deformations due to air puff applanation as well, parameters obtained by the two equipments cannot be compared.…”

Section: 811mentioning

confidence: 99%

Repeatability of Ocular Biomechanical Data Measurements With a Scheimpflug-Based Noncontact Device on Normal Corneas

Németh¹,

Hassan²,

Csutak³

et al. 2013

J Refract Surg

116

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any of the instruments used in this study. Flattest and steepest keratometric data and also IOP showed highly significant correlation with the ten specific CorVis ST parameters. Conclusions:The novel technique measuring ocular biomechanical properties showed high repeatability for only IOP and pachymetric data determined in our study. Single measurements are not reliable in case of the ten device-specific parameters. The equipment allows for conducting clinical examinations, and screenings of surgeries altering ocular biomechanical properties with some form of averaging of multiple measurements.

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Evaluation of corneal hysteresis and corneal resistance factor after corneal cross-linking for keratoconus

Abstract: ORA parameters demonstrate significant differences between KC and non-KC eyes. Both CH and CRF present significant correlations with visual acuity and corneal parameters. CXL exerts a non-significant impact on ORA measurements.

Cited by 60 publications

References 31 publications

Initial results from mechanical compression of the cornea during crosslinking for keratoconus

Initial results from mechanical compression of the cornea during crosslinking for keratoconus

Corneal Collagen Crosslinking: A Systematic Review

Repeatability of Ocular Biomechanical Data Measurements With a Scheimpflug-Based Noncontact Device on Normal Corneas

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