Effectiveness of intracorneal ring segments for keratoconus

Park, Se Eun; Tseng, Michael; Lee, Jimmy K.

doi:10.1097/icu.0000000000000582

Cited by 35 publications

(29 citation statements)

References 62 publications

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“…Among keratoconus (KC) treatments, intracorneal ring segments (ICRS) have widely demonstrated their efficacy in improving clinical parameters and reshaping the cornea [ 1 ]. Through the last decades, the indications, geometry, and materials of ICRS have changed, looking for better biocompatibility and results [ 2 ]. Today, the most frequently implanted ICRS for keratoconus are made of polymethyl methacrylate (PMMA), have a triangular shape, and are available in different thicknesses and arc lengths [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model

et al. 2021

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Purpose To evaluate the local geometric effects of a unilateral intrastromal ring segment with a combined variation of ring thickness and base width in a finite element simulation, and to compare it against the isolated effect of thickness or base width variation alone. Methods A two-dimensional finite-element model of a transversely isotropic cornea was created assuming either axisymmetric stress or plane strain condition. The model geometry was composed of a three-layered corneal tissue (epithelium, anterior and posterior stroma) fixed at the limbus. The implantation of a triangular-shape asymmetric ring segment with varying ring thickness (150 to 300 μm) and base width (600 to 800 μm) was simulated. Also, changes induced by thickness or base width alone were studied and compared their combined effect in the asymmetric ring segment. Geometrical deformation of the simulated cornea and sagittal curvature were the main parameters of study. Results Increasing ring thickness and base width along the arc of the asymmetric ring segment produced a more pronounced flattening in this part of the ring. The asymmetric design did find a good balance between maximizing corneal flattening at one end and minimizing it at the other end, compared to the isolated effect of ring thickness and width. Ring thickness was the most robust parameter in flattening both, the central and peripheral cornea. Conclusion The finite-element model permitted a theoretical study of corneal deformation undergoing implantation of realistic and hypothetical ring geometries. Intracorneal asymmetric ring segments with varying thickness and base width can be a good alternative in corneas with asymmetric keratoconus phenotypes.

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Section: Introductionmentioning

confidence: 99%

Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model

et al. 2021

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“…Post-LASIK ectasia requiring intervention has been reported to be as low as 0.033% [ 10 ] which is similar to our findings when one considers the incidence of patients who underwent CXL in addition to PK during the study period. Scleral contact lens technology [ 30 ], CXL [ 19 , 31 ], and intracorneal ring segments [ 32 ] can provide excellent outcomes and obviate the need for PK. Other LASIK complications besides ectasia include chronic dry eye syndrome, visual aberrations and decentered ablations, diffuse lamellar keratitis, epithelial downgrowth, infectious keratitis, and various flap complications.…”

Section: Discussionmentioning

confidence: 99%

Complications Leading to Keratoplasty among Contact Lens Users and LASIK Patients: A 10-Year Cross-Sectional Analysis

Rush

Bulla

Rush

2021

Journal of Ophthalmology

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Purpose. To determine the incidence and outcomes in patients who underwent penetrating keratoplasty (PK) resulting from complications related to contact lens (CL) use and laser in situ keratomileusis (LASIK) in a metropolitan area of the United States. Methods. Population data was obtained from the United States Census Bureau and the Centers for Disease Control. A retrospective, cross-sectional chart review was performed on all patients who underwent keratoplasty in a specific metropolitan geographic area over a ten-year period. The main outcome was best-corrected visual acuity (BCVA) at 2 years in patients who underwent PK secondary to complications related to CL use and LASIK. The secondary outcome was the relative risk of undergoing PK secondary to a complication related to CL use versus LASIK. Results. The study’s geographic area had 46,545 CL users in one or both eyes during any given year and 10,285 patients who underwent LASIK in one or both eyes during the study interval. There were 24 CL users (0.52 per 1,000) and 3 post-LASIK patients (0.29 per 1,000) who underwent PK secondary to complications during the study interval (OR 1.77 [0.53–5.87, 95% CI]; p = 0.35 ). BCVA at 2 years was 1.45 [1.0–1.90] logMAR (20/564 Snellen) in the CL using cohort and 0.07 [−1.19–1.33] logMAR (20/23 Snellen) in post-LASIK cohort following PK ( p = 0.04 ). Conclusions. Patients who underwent PK secondary to complications related to CL use had worse visual outcomes at 2 years compared to those related to LASIK. Complications leading to PK were rare in both cohorts, but the incidence of undergoing PK secondary to CL use trended higher than LASIK.

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“…Concerning the management of keratoconus, corneal collagen crosslinking (CXL) is an effective option to control its progression, with an increased risk of evolution of the disease associated to a higher economic burden if this surgical option is delayed when signs of progression are evident [2] . Intracorneal ring segments (ICRS) have been also investigated during many years as a therapeutic option for the management of keratoconus and other corneal ectatic diseases [3][4][5][6] . ICRS implantation in keratoconus significantly reduces the level of corneal high order aberrations and irregularity, leading to an improvement in visual quality [3][4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus

Fernández¹,

Peris-Martínez

Pérez-Rueda

et al. 2021

Int J Ophthalmol

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AIM: To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data. METHODS: This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients (age 18-62y) with keratoconus diagnosis from two Spanish centers. Ferrara ring segment (AJL Ophthalmic) implantation was performed in all cases, using the mechanical procedure in 25 eyes (28.4%) and a femtosecond laser-assisted procedure in 63 eyes (71.6%). The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations. Visual, refractive, corneal topographic, aberrometric, and pachymetric changes after surgery were evaluated during a 3-month follow-up. RESULTS: The implants induced a significant refractive change as well as an improvement in uncorrected (UDVA) and corrected distance visual acuity (CDVA; P<0.001). Postoperative CDVA of 0.10 logMAR or better was achieved in 28.4% and 46.5% of eyes, respectively. Two eyes (2.3%) lost two or more lines of CDVA whereas a total of 53.5% of eyes gained lines of CDVA. A significant central anterior and posterior corneal flattening was induced (P≤0.003), with a significant reduction of anterior (P<0.001) and posterior corneal astigmatisms (P=0.048), and a change in anterior asphericity (P<0.001). Total primary coma (6 mm pupil) change was also statistically significant (preoperative 3.66±3.04 µm vs postoperative 2.33±2.26 µm, P<0.001). No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques (P≥0.101). CONCLUSION: The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus, with a relevant control of primary coma aberration.

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Effectiveness of intracorneal ring segments for keratoconus

Cited by 35 publications

References 62 publications

Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model

Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model

Complications Leading to Keratoplasty among Contact Lens Users and LASIK Patients: A 10-Year Cross-Sectional Analysis

Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus

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