Efficacy of complete rings (MyoRing) in treatment of Keratoconus: a systematic review and meta-analysis

Janani, Leila; Tanha, Kiarash; Najafi, Fereshteh; Jadidi, Khosrow; Nejat, Farhad; Hashemian, Seyed Javad; Dehghani, Mohsen; Sadeghi, Mahvash

doi:10.1007/s10792-019-01121-9

Cited by 11 publications

(19 citation statements)

References 38 publications

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“…Janani et al conducted a metaanalysis about efficacy of MyoRing and considered studies until August 2017. 12 We were able to consider further studies, which were published until April 2020. 9,21,[24][25][26] This metaanalysis demonstrated that all ICRS types and MyoRing showed an improvement in visual, keratometric, and refractive values during the 1-year observation period.…”

Section: Discussionmentioning

confidence: 99%

Femtosecond Laser and Mechanical Dissection for ICRS and MyoRing Implantation: A Meta-Analysis

Struckmeier

Hamon

Flockerzi

et al. 2021

Cornea

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Section: Discussionmentioning

confidence: 99%

Femtosecond Laser and Mechanical Dissection for ICRS and MyoRing Implantation: A Meta-Analysis

Struckmeier

Hamon

Flockerzi

et al. 2021

Cornea

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“…Also, optical results for generic rings were in good agreement with different clinical studies in which little difference between healthy and keratoconic outcomes at a population level was reported. 5 , 8 , 10 , 17 , 44 , 45 Unfortunately, clinical studies often report mixed ring typologies, corneal geometries, and degrees of pathology, and therefore results for keratoconic corneas would require of an in silico population study to fully support this conclusion.…”

Section: Discussionmentioning

confidence: 99%

“…Surgical outcomes are characterized by a high variability, 8 thus controlling the postoperative biomechanics is a challenging issue, although several authors 4 , 5 , 9 , 10 reported that the smaller refractive correction owing to the larger diameter is not in contrast with the other observed effects. For example, the shape and size of the cross-section of the implant, its diameter and arc length (in the case of IRS), as well as its implantation position affect the postsurgical shape of the cornea and the respective refractive correction.…”

Section: Introductionmentioning

confidence: 99%

“… 10 The mechanical principle underlying this treatment remains poorly understood and is difficult to extract only from clinical studies. 8 As clinical studies often present mixed populations with different degrees of myopia, KC severity, or implant typology, it is not possible to isolate the contribution of each parameter on the refractive outcomes. In addition, mechanical properties of the cornea play an important role in the procedure but, unfortunately, it is not possible to characterize corneal biomechanics in vivo with current clinical devices.…”

Section: Introductionmentioning

confidence: 99%

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Corneal Biomechanics After Intrastromal Ring Surgery: Optomechanical In Silico Assessment

Ariza-Gracia

Flecha-Lescún

Büchler

et al. 2020

Trans. Vis. Sci. Tech.

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Purpose To provide a biomechanical framework to better understand the postsurgical optomechanical behavior of the cornea after ring implantation. Methods Calibrated in silico models were used to determine the corneal shape and stresses after ring implantation. After mechanical simulations, geometric ray-tracing was used to determine the change in spherical equivalent. The effect of the surgical procedure, circadian variation of intraocular pressure, or the biomechanical weakening introduced by keratoconus (KC) were evaluated for each intrastromal ring. Results Models predicted the postsurgical optomechanical response of the cornea at a population level. The localized mechanical effect of the additional intrastromal volume introduced by the implants (size and diameter) drives the postsurgical corneal response. However, central corneal stresses did not increase more than 50%, and thus implants did not strengthen the cornea globally. Because of the biomechanical weakening introduced by laser pocketing, continuous implants in a pocket resulted in higher refractive corrections and in the relaxation of the anterior stroma, which could slow down KC progression. Implants can move within the stroma, acting as a dynamic pivot point that modifies corneal kinematics and flattens the corneal center. Changes in stromal mechanical properties did not impact on refraction for normal or pathological corneas. Conclusions Implants do not stiffen the cornea but create a local bulkening effect that regularizes the corneal shape by modifying corneal kinematics without canceling corneal motion. Translational Relevance In silico models can help to understand corneal biomechanics, to plan patient-specific interventions, or to create biomechanically driven nomograms.

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“…Clinical studies have shown that ICRS is a safe option for regulating corneal shape by inducing an arcshortening effect, reducing myopic refraction, and delaying corneal transplantation [6,7]. It has also been stated that the complete corneal rings can act as a second limbus and increase the integrity of the corneal structure [8].…”

Section: Introductionmentioning

confidence: 99%

Effects of intracorneal ring segments on the biomechanical response of the ectatic cornea to air-puff: A patient-specific numerical analysis

Bagheri

Mosaddegh

Kadkhodaei

2021

Mathematics and Mechanics of Solids

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The assessment of the underlying factors that influence the biomechanics and dynamics of the cornea is essential for preserving the safety and efficacy of refractive surgeries. In the present work, the operated cornea with intracorneal ring segments (ICRSs) in a patient-specific finite-element model (FEM) was subjected to the air-puff. Then, the dynamic deformation parameters predicted by the FEM were obtained and compared with the corresponding values in clinical measurements. In this study, the effects of ICRS design, position, and implementation procedure in six different surgical scenarios were examined on the induced corneal stresses, deformation behavior, and shape regularization. While surgical scenarios with arc lengths of 160° (single and double segment), 355° implemented with the tunnel incision method provided similar maximum apical displacement (MAD) and highest concavity radius of curvature HCR), they induced significantly different flattening effects. The surgical scenarios with the segment of 160° arc-length implemented in nasal–temporal direction showed an approximately 15% higher reduction in mean corneal power ([Formula: see text]) value than the superior–inferior direction. From a solid-mechanics perspective, the study of ICRS mechanics in the cornea also confirmed the importance of the implementation position to achieve satisfactory flattening outcomes. Comparison of the two types of ICRS implementation procedures showed that, although the pocket method demonstrated a 10.23% higher MAD, it induced a higher reduction in the HCR of 21.65% compared with tunnel incision. The developed numerical model demonstrated the direct correlation of the ICRS insertion site with induced contact stresses and ICRS position stability. The study hypothesizes the significant influence of ICRS implementation position and procedure on the corneal biomechanical and dynamical behaviors. The proposed approach can be assessed as a robust and novel framework for planning optimized corneal refractive surgeries.

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Efficacy of complete rings (MyoRing) in treatment of Keratoconus: a systematic review and meta-analysis

Cited by 11 publications

References 38 publications

Femtosecond Laser and Mechanical Dissection for ICRS and MyoRing Implantation: A Meta-Analysis

Femtosecond Laser and Mechanical Dissection for ICRS and MyoRing Implantation: A Meta-Analysis

Corneal Biomechanics After Intrastromal Ring Surgery: Optomechanical In Silico Assessment

Effects of intracorneal ring segments on the biomechanical response of the ectatic cornea to air-puff: A patient-specific numerical analysis

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