A Review of Collagen Cross-Linking in Cornea and Sclera

Zhang, Xiao; Tao, Xiangchen; Zhang, Jian; Li, Zhiwei; Xu, Yong; Wang, Yumeng; Zhang, Chunxiao; Mu, Guoying

doi:10.1155/2015/289467

Cited by 29 publications

(27 citation statements)

References 108 publications

(123 reference statements)

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“…CXL is a rapidly emerging clinical treatment for keratoconus that stiffens the cornea and prevents or minimizes further degeneration (Wollensak et al, 2003a; Zhang et al, 2015). While CXL has been proposed as a treatment for other ocular pathologies such as keratitis (Iseli et al, 2008), its main use remains the treatment of keratoconus.…”

Section: Introductionmentioning

confidence: 99%

Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

Han

Singh

et al. 2017

Journal of the Mechanical Behavior of Biomedical Materials

107

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The biomechanical properties of the cornea play a critical role in forming vision. Diseases such as keratoconus can structurally degenerate the cornea causing a pathological loss in visual acuity. UV-A/riboflavin corneal collagen crosslinking (CXL) is a clinically available treatment to stiffen the cornea and restore its healthy shape and function. However, current CXL techniques do not account for pre-existing biomechanical properties of the cornea nor the effects of the CXL treatment itself. In addition to the inherent corneal structure, the intraocular pressure (IOP) can also dramatically affect the measured biomechanical properties of the cornea. In this work, we present the details and development of a modified Rayleigh-Lamb frequency equation model for quantifying corneal biomechanical properties. After comparison with finite element modeling, the model was utilized to quantify the viscoelasticity of in situ porcine corneas in the whole eye-globe configuration before and after CXL based on noncontact optical coherence elastography measurements. Moreover, the viscoelasticity of the untreated and CXL-treated eyes was quantified at various IOPs. The results showed that the stiffness of the cornea increased after CXL and that corneal stiffness is close to linear as a function of IOP. These results show that the modified Rayleigh-Lamb wave model can provide an accurate assessment of corneal viscoelasticity, which could be used for customized CXL therapies.

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Section: Introductionmentioning

confidence: 99%

Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

Han

Singh

et al. 2017

Journal of the Mechanical Behavior of Biomedical Materials

107

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“…Previous studies have shown that the stiffness of sclera surrounding the optic nerve head is related to glaucoma by significantly influencing the neural tissue (Burgoyne et al , 2005; Langman et al , 2005; Pavlatos et al , 2016; Sigal et al , 2005). Keratoconus is a visual distortion created by the change in corneal rigidity, causing the cornea to bulge from its normal shape (Zhang et al , 2015; Ruberti et al , 2011). Lastly, presbyopia is the loss of the ability of the eye to change focus onto near objects; most of the previous studies investigated age-related stiffening of the crystalline lens (Charman, 2008; Weale, 2000; Glasser et al , 2001; Heys et al , 2004; Pau and Kranz, 1991; Wu et al , 2015; Yoon et al , 2013; Glasser, 2008).…”

Section: Introductionmentioning

confidence: 99%

The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

et al. 2017

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Intraocular pressure (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic wave velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic wave velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear wave elasticity imaging. To generate and then image the elastic wave propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic wave velocity in the cornea increased from 0.96 ± 0.30 m/s to 6.27 ± 0.75 m/s as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic wave velocity in the crystalline lens with the minimum and the maximum speeds of 1.44 ± 0.27 m/s and 2.03 ± 0.46 m/s, respectively. This study shows that ultrasound shear wave elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.

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“…UVA activates riboflavin into a triplet which, in turn, produces reactive oxygen species (ROS). ROS reacts with collagen fibril molecules in the cornea stroma and enhances the mechanical strength of the cornea to arrest the progression of keratoconus and keratectasia (15). The present study reports a case of keratectasia occurring 12 years following LASIK, and the use of riboflavin/UVA cross-linking to arrest disease progression, and ICL to correct high refractive error.…”

Section: Introductionmentioning

confidence: 75%

Combining corneal crosslinking and phakic toric Implantable Collamer Lenses for the treatment of keratectasia: A case report

Zhang

Tao

et al. 2016

Experimental and Therapeutic Medicine

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Abstract. The present study reports the use of a phakic toric Implantable Collamer Lens (ICL) that improved the refraction correction of high myopia and astigmatism in a case of keratectasia following corneal cross-linking. A 31-year-old male was diagnosed with keratectasia 12 years after laser-assisted in situ keratomileusis (LASIK). Following LASIK, the manifest refraction was -3.50-2.25x90 [0.1 logarithmic expression (LogMAR) best corrected visual acuity (BVCA)] in the right eye and -8.00-3.50x175 (0.3 LogMAR BCVA) in the left eye, with a LogMAR uncorrected distance visual acuity (UDVA) of 0.8 and a 'counting fingers' value of 3 ft (CF @3 ft) in the left and right eyes, respectively. Riboflavin/ultraviolet A light (UVA) corneal crosslinking (CXL) was conducted on both eyes. Seven months after cross-linking, LogMAR UDVA was 0.4, the manifest refraction was -2.75-2.50x85 and LogMAR BCVA was 0.1 in the right eye. In the left eye, LogMAR UDVA was CF @3 ft, the manifest refraction was -15.00 and LogMAR BCVA was 0.3. The corneal topography was stable 7 months after CXL. Phakic toric ICL was implanted to correct the refractive error, following which the LogMAR UDVA improved to 0.1 in the right eye and 0.3 in left eye, and visual acuity remained stable for 6 months after ICL implantation. In conclusion, combining riboflavin/UVA corneal cross-linking and phakic toric ICL implantation may be an alternative in the correction of high refractive error in patients with keratectasia.

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A Review of Collagen Cross-Linking in Cornea and Sclera

Cited by 29 publications

References 108 publications

Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model

The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

Combining corneal crosslinking and phakic toric Implantable Collamer Lenses for the treatment of keratectasia: A case report

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