Complete corneal ring (MyoRing) implantation versus MyoRing implantation combined with corneal collagen crosslinking for keratoconus: 3-year follow-up

Bikbova, Guzel; Kazakbaeva, Gyulli; Бикбов, М.М.; Usubov, E.L.

doi:10.1007/s10792-017-0593-4

Cited by 22 publications

(16 citation statements)

References 29 publications

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“…The present study showed that, after KeraRing and MyoRing implantation, CCT does not generally change; however, the CCT decreased at central 4 mm after MyoRing implantation, and this change was statistically significant. This effect might be due to the special design of the ring and its depth of implantation, as also mentioned in another study [ 19 ]. The study by Zare indicated that, after Intacs implantation, the cornea thickness increased within the first month after surgery [ 17 ].…”

Section: Discussionmentioning

confidence: 78%

Intracorneal Stromal Ring Can Affect the Biomechanics of Ectatic Cornea

Bamdad

Sedaghat

Yasemi

et al. 2020

Journal of Ophthalmology

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Purpose. The biomechanical properties of ecstatic cornea undergo changes. This study evaluates the biomechanical changes of ecstatic cornea after implantation of two types of intracorneal stromal ring (ICR). Methods. For doing this prospective cross-sectional study, 32 patients with keratoconus (KCN) were randomly divided into two 16-member groups (group I: MyoRing, group II: KeraRing). The main inclusion criteria were transparent cornea with no scar in the central part, corneal thickness >450 µ in the incision region, keratometry within 48–52 diopters, and progressive course of corneal thinning. Biomechanics of the cornea was evaluated by “ORA” and “Corvis” devices. All of the data were recorded and analyzed before implantation of the rings and 6 months thereafter. Results. The mean ages of patients of groups I and II were 26 ± 6.55 and 33.86 ± 8.5, respectively. The postoperative change of sphere refraction was significant in both groups. However, reduction in the astigmatism was significant only in group I. In addition, the change of flat meridian keratometry (Kf) was significant before and after ring implantation in group I, unlike group II. The changes in CH and CRF parameters (ORA) were not significant in either group before and after the operation. Besides, only HRC parameter (Corvis) decreased significantly in both groups before and after the operation. Conclusion. Both MyoRing and KeraRings have positive effects on the biomechanics of cornea at least during the first year after implantation. Comparison of these two types of ICR did not show significant differences in Corvis and ORA parameters.

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Section: Discussionmentioning

confidence: 78%

Intracorneal Stromal Ring Can Affect the Biomechanics of Ectatic Cornea

Bamdad

Sedaghat

Yasemi

et al. 2020

Journal of Ophthalmology

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“…Using microkeratome pocket maker, Myoring significantly enhanced UCVA and CDVA from 1.06 to 0.49 logarithm of minimum angle of resolution (LogMAR) to 0.3 and 0.28 after 36 months respectively. SE, as well, was significantly decreased from −7.8 to −1.6 D and the average k readings similarly were reduced from 50.2 to 40.8 D [ 20 ].…”

Section: Discussionmentioning

confidence: 99%

Combined Corneal Cross-Linking and Myoring Implantation in Advanced Keratoconus: Femtosecond Laser versus Manual Dissection

Basiony

Elsawy

Ismail

et al. 2021

Journal of Ophthalmology

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Background. Intrastromal corneal ring segments are widely adopted for keratoconus management. However, the complete ring (Myoring) was proposed to be superior in advanced cases. Myoring can be implanted either via femtoassisted or manual dissection techniques. A comparison between both techniques can delineate any differences in the outcomes. Methods. This was a prospective interventional case series study. Sixty-four eyes with progressive advanced keratoconus were enrolled: 36 and 28 had femtoassisted or manual Myoring, respectively. Uncorrected visual acuity (UCVA), corrected distance visual acuity (CDVA), maximal keratometry (Kmax), spherical equivalent (SE) and corneal thinnest location were measured in all eyes preoperatively and at one, six, and 12 months postoperatively. Epi-off corneal cross-linking (CXL) was performed eight weeks after Myoring implantation for all cases. Results. Femtoassisted Myoring dissection significantly improved UCVA and CDVA from 0.1 ± 0.06 and 0.18 ± 0.1 preoperatively to 0.29 ± 0.08 and 0.43 ± 0.1 at 12 months. Also, manual technique similarly enhanced UCVA and CDVA from 0.11 ± 0.05 and 0.2 ± 0.1 preoperatively to 0.27 ± 0.2 and 0.4 ± 0.2 at 12 months. In terms of safety, while no cases of ring extrusion were encountered with the femtoassisted technique, six (21.4%) cases of extrusion were encountered in the manual group. Conclusion. Femtoassisted or manual Myoring technique followed by CXL is an effective choice for advanced progressive keratoconus. Although it did not reach a statistical significance, the high extrusion rate with manual dissection is a red flag to be considered.

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“… 19 – 21 Nevertheless, other authors outlined the need for additional evidence to confirm this claim. 22 …”

Section: Introductionmentioning

confidence: 99%

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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Complete corneal ring (MyoRing) implantation versus MyoRing implantation combined with corneal collagen crosslinking for keratoconus: 3-year follow-up

Cited by 22 publications

References 29 publications

Intracorneal Stromal Ring Can Affect the Biomechanics of Ectatic Cornea

Intracorneal Stromal Ring Can Affect the Biomechanics of Ectatic Cornea

Combined Corneal Cross-Linking and Myoring Implantation in Advanced Keratoconus: Femtosecond Laser versus Manual Dissection

Corneal Biomechanics After Intrastromal Ring Surgery: Optomechanical In Silico Assessment

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