Intracorneal Ring Segments Research Articles

Keratometric Outcomes after Simultaneous versus Sequential Intracorneal Ring Segment Implantation with Femtosecond Laser and Corneal Collagen Crosslinking in Egyptian Patients with Keratoconus and Ectasia.

Keratoconus (KC) is degenerative corneal disorder, with central and paracentral thinning and corneal ectasia. For KC progressive cases, primary treatment included corneal collagen cross linking (CXL) to stabilize coning and intracorneal rings segment (ICRS) to correct visual acuity. The aim of the study is to assess efficacy and safety of ICRS and CXL on one session (Simultaneous) or two sessions (sequential) with maximum of 1 month apart. This Prospective Intervention Comparative research made at Armed forces hospital, Cairo, Egypt from January 2017 to December 2019. Forty patients (60 eyes) with mild to moderate KC were enrolled. Patients sorted into Simultaneous group includes 21 patients (30 eyes) undergo two procedures (ICRS then CXL) at the same session and Sequential group included 19 patients (30 eyes) undergo ICRS then CXL on two sessions with month apart. Patients followed up at end of 1st, 3rd, and 6th months. Assessment included changes in corrected corneal surface irregularities as minimum keratometric 1 (K1), maximum keratometric readings (K2), and mean keratometric (Km) readings. Improvement of K1, K2, and Km in Simulations and Sequential groups achieved at end of 1st-, 3rd-, and 6th-month postoperative versus preoperative. Maximum improvement in Simulations and Sequential groups in K1 achieved at end of 6th and 1st months, in K2 at end of 3rd and 6th months and in Km at end of 1st and 3rd months. Combined ICRS and CXL act safely in one or two sessions and there are no statistically significant variations between results on both methods in keratometric readings.

Clinical, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment implantations in duck-type keratoconus.

To evaluate the visual, refractive, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment (PT-ICRS) implantation in duck-type keratoconus. This retrospective study included eyes with oval (duck-type) keratoconus treated with PT-ICRS implantation. After the femtosecond laser tunnel creation, one PT-ICRS (Keraring AS 5 with 160° arc length) was implanted along the ectatic, inferior half of the cornea. Data of uncorrected and corrected distance visual acuity (UDVA and CDVA), refraction, asphericity (Q value), and keratometry (K) were compared pre- and postoperatively. Additionally, changes in the topometric indices of corneal irregularity were also evaluated after PT-ICRS implantation. Thirty-one eyes of 30 patients were included in the study with a mean follow-up time of 9.06 months (ranging between 6 and 18 months). UDVA improved from 0.85 ± 0.36 to 0.27 ± 0.14 logMAR (P = 0.001), and CDVA improved from 0.37 ± 0.22 to 0.13 ± 0.11 logMAR (P = 0.001). The mean spherical error decreased from -3.66 ± 2.60 to -1.60 ± 1.42 D (P = 0.001), and the mean cylindrical error decreased from -4.91 ± 2.65 to - 1.41 ± 1.31 D (P = 0.001). All topographic parameters measured from the anterior cornea demonstrated statistically significant improvements after PT-ICRS implantation (P = 0.001). K mean, K maximum, corneal astigmatism, and Q value showed a significant decrease. Besides the index of height asymmetry, all topometric indices were significantly reduced after PT-ICRS implantation. There were no loss of lines and no complications. PT-ICRS implantation in duck-type keratoconus is an effective and safe treatment. This intervention improves the visual acuity, refractive error, topographical, and topometric parameters significantly by decreasing both eccentricity and steepness of the cone.

Intracorneal Ring Segment Implantation Results in Corneal Mechanical Strengthening Visualized With Optical Coherence Elastography.

To quantify the mechanical impact of intracorneal ring segment (ICRS) implantation of different dimensions in an ex vivo eye model. A total of 30 enucleated porcine eyes were assigned to ICRS implantation (thickness: 300 µm, angle: 120°, 210°, or 325°), tunnel creation only, or virgin control groups. For mechanical evaluation, each globe was mounted on a customized holder and intraocular pressure (IOP) was increased in steps of 0.5 mm Hg from 15 to 17 mm Hg, simulating physiologic diurnal IOP fluctuations. At each step, an optical coherence tomography volume scan was recorded. Deformations between subsequent scans and the locally induced axial strains were analyzed using a vector-based phase difference method. The effective E-modulus was derived from the overall induced strain as a measure of global mechanical impact. ICRS implantation increased the effective E-modulus from 146 and 163 kPa in virgin and tunnel-only eyes to 149, 192, and 330 kPa in eyes that received a 5-mm optical zone ICRS with 120°, 210°, and 325° arc length, respectively; and to 209 kPa in a 6-mm optical zone ICRS with 325° arc length. The most consistent effect was a shift toward positive strains in the posterior stroma by 0.1% to 0.46% (factor 1.15 to 2.15) after ICRS surgery. ICRS implantation reduces the overall tissue strain under the load of the IOP and provokes posterior tissue relaxation. This effect is more prominent the longer the arc length and the smaller the optical zone of the ICRS is. ICRS have not only a geometrical, but also a mechanical impact on corneal tissue. This behavior might have clinical implications when ICRS implantation is performed in biomechanically weakened keratoconic corneas. [J Refract Surg. 2022;38(7):459-464.].

Current approaches in the management of patients with keratoconus.

Keratoconus is a relatively frequent eye disease, especially in young patients, in which the cornea gradually thins and deforms in a cone shape. In the past, it could be treated only with glasses, rigid contact lenses or, for advanced cases, penetrating corneal transplant. Nowadays, corneal cross-linking, intracorneal ring segments implantation or deep anterior lamellar keratoplasty are available options of treatment, along with the above mentioned ones. Several studies focused on this disease and its management attempted to establish the applicability of these treatment methods in current practice. In the early stages, glasses or soft toric contact lenses are able to correct the astigmatism, but, as the disease progresses, rigid contact lenses are indicated. Corneal cross-linking is done in order to slow down or even stop the progression of the disease. Implanting intracorneal ring segments helps improve visual acuity in patients with low vision that cannot be corrected otherwise. Advanced stages need corneal transplant, either penetrating or anterior lamellar, depending on each patient's ocular characteristics. Thus, keratoconus treatment is individualized for every patient, according to the stage of the disease. Moreover, because of the new developed technology, keratoconus patients can benefit from efficient treatment, in much safer conditions.

Effect of intracorneal ring segments on posterior corneal topography in eyes with keratoconus

PurposeTo analyze the changes in the anterior and posterior corneal surfaces measured with a Scheimpflug imaging device in keratoconus patients implanted with intracorneal ring segments (ICRS) and to correlate those changes with the visual outcomes. MethodsThis prospective interventional case series study included 92 eyes of 60 patients with keratoconus who underwent Kerarings (Mediphacos, Belo Horizonte, Brazil) ICRS implantation. Keratometric (K) readings, corneal asphericity (Q value) and elevations of both anterior and posterior corneal surfaces were evaluated using a Scheimpflug imaging device preoperatively and at 1, 3, 6 and 12 months after surgery. ResultsThe mean best corrected visual acuity (BCVA) improved from 0.61 to 0.19 logMAR at 12 months after surgery. Both anterior and posterior corneal surfaces showed significant flattening with statistically significant reduction of the mean anterior K reading by 3.39 D and the mean posterior K reading by 0.39 D (p<0.001) at 12 months. Statistically significant change of the anterior Q to a less negative value (from -1.05 to -0.36) was observed (p<0.001) with no significant change of the posterior Q value. Improvement of the anterior Q was significantly correlated to better postoperative BCVA (p=0.03). Better postoperative BCVA significantly correlated to better preoperative BCVA, flatter preoperative anterior and posterior K, less prolate anterior Q value and lower anterior elevations. ConclusionsICRS implantation has a significant flattening effect on both anterior and posterior corneal surfaces. Improvement of corneal asphericity is correlated to better visual outcome. Certain preoperative parameters were predictive factors of the postoperative visual improvement.

Corneal asphericity changes after implantation of single intracorneal corneal ring segment vs implantation of double intracorneal segments in the cornea for treatment of keratoconus

Corneal asphericity changes after implantation of single intracorneal corneal ring segment vs implantation of double intracorneal segments in the cornea for treatment of keratoconus

Efecto de los segmentos anulares intracorneales en la topografía corneal posterior en ojos con queratocono

PurposeTo analyze the changes in the anterior and posterior corneal surfaces measured with a Scheimpflug imaging device in keratoconus patients implanted with intracorneal ring segments and to correlate those changes with the visual outcomes. MethodsThis prospective interventional case series study included 92 eyes of 60 patients with keratoconus who underwent Kerarings (Mediphacos, Belo Horizonte, Brazil) intracorneal ring segments implantation. Keratometric (K) readings, corneal asphericity (Q value) and elevations of both anterior and posterior corneal surfaces were evaluated using a Scheimpflug imaging device preoperatively and at one, 3, 6 and 12 months after surgery. ResultsThe mean best corrected visual acuity (BCVA) improved from 0.61 to 0.19 logMAR at 12 months after surgery. Both anterior and posterior corneal surfaces showed significant flattening with statistically significant reduction of the mean anterior K reading by 3.39 D and the mean posterior K reading by 0.39 D (P<.001) at 12 months. Statistically significant change of the anterior Q to a less negative value (from −1.05 to −0.36) was observed (P<.001) with no significant change of the posterior Q value. Improvement of the anterior Q was significantly correlated to better postoperative BCVA (P=.03). Better postoperative BCVA significantly correlated to better preoperative BCVA, flatter preoperative anterior and posterior K, less prolate anterior Q value and lower anterior elevations. ConclusionsImplanted with intracorneal ring segments implantation has a significant flattening effect on both anterior and posterior corneal surfaces. Improvement of corneal asphericity is correlated to better visual outcome. Certain preoperative parameters were predictive factors of the postoperative visual improvement.

Evaluation of long-term outcomes of simultaneous corneal collagen cross-linking and femtosecond laser-assisted intracorneal ring segment implantation for keratoconus

Background Intracorneal ring segment (ICRS) implantation in combination with corneal collagen cross-linking (CXL) has shown promising results in improving the visual acuity and reducing refractive errors, but long-term results are lacking. Aim To evaluate the long-term outcomes (&gt;5 years) of simultaneous CXL and femtosecond laser-assisted intracorneal stromal ring segment implantation for management of keratoconus. Design This was a noncomparative, noncontrolled retrospective single-center study. Patients and methods The study included 50 eyes of 37 patients with keratoconus who underwent simultaneous CXL and ICRS implantation and were followed up for at least 5 years regarding visual acuity, refraction, and corneal imaging. Results Best-corrected visual acuity showed statistically significant improvement, with mean changed from 1.07±0.41 to 0.40±0.30 LogMAR. The results showed significant improvement also after 5 years. The spherical equivalent also was significantly improved from a mean of −4.61±4.37 D to a mean of −1.41±−1.49 D. Keratometric readings also showed improvement of both K1 and K2. The mean K1 improved from a mean of 49.6±6.76–47.78±6.17 D, and the mean K2 improved from 55.04±7.34 to 52.67±7.38. The results were stable, with no statistically significant change after 5 years. Conclusions Simultaneous CXL and femtosecond laser-assisted ICRS is effective and stable for both visual outcome and refraction in patients with keratoconus.

Management of Anterior Stromal Necrosis After Polymethylmethacrylate ICRS: Explantation Versus Exchange With Corneal Allogenic Intrastromal Ring Segments.

To evaluate management of keratoconic eyes with anterior stromal necrosis overlying the intracorneal ring segment (ICRS), by either ICRS explantation alone or exchange with corneal allogenic intrastromal ring segments (CAIRS). Among 643 Intacs SK (Additional Technology, Inc) inserted at one institutional center, 16 eyes (15 patients) with overlying spontaneous anterior stromal necrosis were identified. Data included size of stromal defect and refractive and topographical findings before ICRS insertion, before anterior stromal necrosis, and 6 months after intervention. The 10-year incidence of anterior stromal necrosis after femtosecond laser-assisted ICRS insertion was 5.5%. Eight eyes underwent ICRS removal only and 8 eyes had ICRS exchanged with CAIRS. In the first group, CDVA worsened from 0.14 before melt to 0.28 logMAR after removal (P = .10), simulated keratometry (SimK) and maximum axial keratometry (Kmax) increased from 44.73 to 46.34 diopters (D) (P = .14) and from 49.23 to 52.26 D (P = .14), respectively, and coma worsened from 0.87 to 1.52 D (P = .02). In the CAIRS group, CDVA of 0.16 before melt improved to 0.11 logMAR postoperatively (P > .99), and topographic indices stabilized with SimK, Kmax, and coma mildly altering from 45.31 to 45.44 D (P > .99), from 49.25 to 49.64 D (P > .99) and from 0.87 to 0.81 D (P > .99), respectively. Whether the ICRS were explanted or exchanged, the visual and topographic mean values were better than those reported before ICRS implantation, whereas higher order aberrations in eyes without CAIRS regressed to levels before ICRS insertion. At the site of melt, thinnest residual stromal thickness averaged 327 µm with ICRS removal and 490 µm with CAIRS. Eyes with larger melt areas resulted in less optimal results with CAIRS implantation. Early experience in the management of anterior stromal necrosis by exchange of polymethylmethacrylate ICRS with CAIRS seems to avoid stromal thinning and confer better visual and topographic results, which were more pronounced with thicker segments. The benefit of CAIRS in large stromal melts needs to be investigated. [J Refract Surg. 2022;38(4):256-263.].

The Effect of Intracorneal Ring Segments Implantation for Keratoconus on In Vivo Corneal Biomechanics Assessed With the Corvis ST.

To evaluate the effect of the implantation of intracorneal ring segments (ICRS) in keratoconus on the dynamic corneal response (DCR) parameters obtained with the Corvis ST (Oculus Optikgeräte GmbH). This prospective clinical study included patients who underwent ICRS implantation for keratoconus over a period of 1 year. On the day of the surgery and at least 1 month after ICRS implantation, the following measurements were made: corrected and uncorrected distance visual acuity, corneal tomography indices with the Pentacam (Oculus Optikgeräte GmbH), biomechanically corrected intraocular pressure (bIOP), Corvis ST DCR parameters, integrated inverse concave radius (1/R), deformation amplitude ratio (DA ratio), stiffness parameter at first applanation (SP-A1), stress-strain index (SSI), and highest concavity radius (HRC). Fifty-one eyes of 40 patients were included with a median follow-up time of 3 months (interquartile ratio [IQR]: 2 to 6 months). Statistical analysis showed that ICRS implantation did not affect corneal biomechanical measurements evaluated with the Corvis ST, which was demonstrated by non-significant changes in the SP-A1 (P = .637), 1/R (P = .647), HRC (P = .177), DA ratio (P = .735), and SSI (P = .501). Additionally, the results showed that bIOP measurements were not significantly affected by ICRS implantation (P = .113). ICRS implantation does not affect corneal biomechanical measurements in early follow-up. [J Refract Surg. 2022;38(4):264-269.].

Optical Evaluation of Intracorneal Ring Segment Surgery in Keratoconus.

PurposeThe purpose of this study was to assess the impact of different intracorneal ring segments (ICRS) combinations on corneal morphology and visual performance on patients with keratoconus.MethodsA total of 124 eyes from 96 patients who underwent ICRS surgery were analyzed and classified into 7 groups based on ICRS disposition and the diameter of the surgical zone (5- and 6-mm). Pre- and postoperative complete ophthalmological examinations were conducted. Corneal geometry, volume, and symmetry were studied. Zernike polynomials were used to build a virtual ray-tracing model to evaluate optical aberrations and the Visual Strehl (VS).ResultsICRS induced significant flattening across the cornea, being more pronounced on the anterior (+0.38 mm, P < 0.001) than on the posterior (+0.15 mm, P < 0.001) corneal radius. Asphericity experienced a larger change for a 6-mm surgical zone diameter (from −1.23 ± 1.1 to −1.86 ± 1.2, P < 0.001) than for a 5-mm zone (from −1.99 ± 1.1 to −2.10 ± 1.5, P = 0.536). Mean astigmatism was reduced by 2.05 D (P < 0.001). Combination four was the most effective in reducing astigmatism. Coma decreased by 30% on average and combination one produced an average reduction by 51% (P < 0.05). Patients experienced significant improvement in visual performance, best corrected visual acuity increased from 0.57 ± 0.21 to 0.69 ± 0.21 and VS changed from 0.049 ± 0.02 to 0.065 ± 0.041.ConclusionsICRS combinations implanted within 5 mm diameter zone are more effective in flattening the cornea, whereas those implanted on 6 mm diameter are as effective in reducing astigmatism and are a good choice if the asymmetry and the intended flattening are smaller. Combinations with asymmetrical implants are the best option to regularize corneal surface.Translational RelevanceThis study uses methods and metrics of optical research applied to daily clinical practice.

Current clinical approach to pediatric keratoconus patients

Introduction Due to structural differences between pediatric and adult corneas, keratoconus (KC) is considered more aggressive in pediatrics than in adults. It is controversial whether therapeutic intervention in pediatric KC should differ from adult KC. Areas covered We investigate if there is a substantial difference between pediatric and adult KC regarding disease severity and progression rate, factors important for treatment timing and prognosis. Then, feasibility of current treatment modalities is discussed based on current evidence. Expert opinion Despite several conflicting reports, pediatric KC is more severe at initial diagnosis with faster progression. Therefore, pediatric patients should be followed closely for evidence of progression. This can be tracked in a variety of ways, including with the Belin ABCD progression system. Controlling ocular allergy and eye rubbing is the first step in treatment. The epithelium-off Dresden protocol remains the gold standard CXL approach to stop progression in pediatric KC, whereas epithelium-off accelerated CXL might be an alternative. In pediatric patients, both penetrating and lamellar keratoplasty can be challenging; however, lamellar keratoplasty seems to offer the advantage of lower graft rejection rate. Epithelium-on CXL, intracorneal ring segment implantation, excimer laser ablation and CXL protocols are not recommended in pediatric KC. Nevertheless, there remains a need for evidence-based clinical practical guidelines in pediatric KC.

Corneal Strain Induced by Intracorneal Ring Segment Implantation Visualized With Optical Coherence Elastography.

To record the axial strain field in the cornea directly after creating a stromal tunnel and implanting an intracorneal ring segment (ICRS). Freshly enucleated porcine eyes were obtained and assigned to either ICRS implantation, tunnel creation only, or virgin control groups. Immediately after manual tunnel creation and ICRS positioning, the entire eye globe was mounted on a customized holder and intraocular pressure (IOP) was adjusted to 15 mm Hg. Then, IOP was inreased to 20 mm Hg, in steps of 1 mm Hg. At each step, an optical coherence tomography volume scan was recorded. Displacements between subsequent scans were retrieved using a vector-based phase difference method. The induced corneal strain direction was determined by taking the axial gradient. In addition, corneal surface was detected and sagittal curvature maps computed. Corneal tissue presented a localized compressive strain in the direct vicinity of the stromal tunnel, which was independent of IOP change. The central and peripheral (exterior to the ICRS) cornea demonstrated compressive strains on IOP increase, and tensile strains on IOP decrease. ICRS implantation induced an annular-shaped tensile strain at its inner border, particularly during IOP increase. The compressive strains close to the tunnel remained after ICRS implantation. Corneal curvature changes were concentrated on regions where strain was induced. ICRS implantation induces localized strains in the regions subjected to refractive changes, suggesting that corneal strain and curvature are directly related. Studying corneal strain in response to surgical intervention may provide new insights on underlying working principles. [J Refract Surg. 2022;38(3):210-216.].

Morphological characterization and clinical effects of stromal alterations after intracorneal ring segment implantation in keratoconus

PurposeTo analyze the histological and (ultra)structural stromal tissue changes after femtosecond (Fs) laser–assisted intracorneal ring segment (ICRS) implantation and their refractive and topographic effects in patients with keratoconus.MethodsThis monocentric retrospective case series included 15 consecutive patients with clinical peri-segmental lamellar channel deposits after treatment with Fs-ICRS implantation for keratoconus. The stromal changes were investigated using in vivo confocal microscopy. Two patients underwent a penetrating keratoplasty after the Fs-ICRS implantation; the explanted corneas were processed for histopathology and transmission electron microscopy (TEM). Refractive and topographic effects were investigated comparing the uncorrected (UDVA) and corrected (CDVA) distance visual acuity, spherical equivalent (SE), flat (K1), steep (K2), and steepest (Kmax) keratometry before and after detection of lamellar channel deposits.ResultsIn vivo confocal microscopy revealed diffuse linear and focal granular hyperreflective structures. Histologically, there was mild proliferation of fibroblasts and fibrosis. TEM demonstrated focal accumulations of degenerated keratocytes with cytoplasmic lipid inclusions. There were no significant changes for UDVA (Δ = 0.0 ± 0.2 logMAR; p = 0.67), CDVA (Δ = 0.0 ± 0.1 logMAR; p = 0.32), SE (Δ 0.1 ± 0.9 D; p = 0.22), K1 (Δ = 0.3 ± 1.0 D; p = 0.28), K2 (Δ = 0.1 ± 0.9 D; p = 0.51), and Kmax (Δ = 0.3 ± 1.5 D; p = 0.17).ConclusionsTwo types of structural stromal changes were identified: (1) diffuse peri-segmental fibrosis and (2) lamellar channel deposits. These structural changes showed no evidence of a relevant refractive or topographic effect.

Combined corneal wavefront-guided transepithelial photorefractive keratectomy and accelerated corneal collagen cross-linking following intracorneal ring segment implantation in management of moderate keratoconus.

PURPOSE:Keratoconus (KC) leads to gradual progressive loss of vision in young and adult patients. For the purpose of visual rehabilitation and for hindering KC progression in patients, we designed this study. The main aim of this study is to help the KC patients to improve and stabilize their vision.METHODS:This prospective consecutive uncontrolled study includes 36 eyes of 36 patients with moderate degree of KC. All patients underwent combined wavefront-guided transepithelial photorefractive keratectomy (TPRK) and accelerated corneal collagen cross-linking (ACXL) after intracorneal ring segment (ICRS) implantation. Different measures will be evaluated at baseline, after ICRS implantation, and at one, 3, 6, and 12 months after combined (TPRK and ACXL). These measurements are uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, and higher-order aberrations (HOAs) based on (Sirius, Schwind) tomography.RESULTS:There were significant improvements in logMAR (UDVA and CDVA) and reduction in sphere, manifest cylinder, MRSE, maximal keratometry, and mean keratometry after ICRS implantation in the first stage. After TPRK and ACXL as the second stage, there were significant improvements in visual acuity of both logMAR UDVA and CDVA. Reduction in refractive outcomes, including MRSE, sphere, and manifest cylinder. All corneal indices including steep, flat, mean, and maximal keratometries had been decreased. Furthermore, there were significant improvements in the final root mean square, HOAs, and coma aberrations from baseline.CONCLUSION:In moderate KC, triple therapy of ICRS implantation followed by combined TPRK and ACXL appears to be a safe and effective approach. This approach provides an improvement in visual acuity, refraction, corneal indices, and HOAs. These improvements were maintained for 1 year postoperatively. It also halts KC progression.

The use of two 90-degree arc intracorneal ring segments in management of crab-claw topographic pattern

BackgroundKeratoconus and pellucid marginal degeneration (PMD) are bilateral, progressive, and ectatic corneal disorders characterized by thinning of the cornea.AimTo assess the visual and refractive outcome of using two 90-degree arc intrastromal corneal ring segments (ICRS) in the management of crab-claw topographic pattern.Patients and methodsThis study included 17 eyes of nine patients with crab-claw topographic patterns, either pellucid-like KC or PMD, needing ICRS. Preoperative evaluation included detailed ocular history, full ophthalmic examination, including uncorrected visual acuity (UCVA), manifest refraction, best spectacle-corrected visual acuity, and Pentacam.ResultsRegarding visual outcome, the mean UCVA improved significantly from 0.12 ± 0.09 to 0.86 ± 0.16 postoperatively (P < 0.001). The UCVA improved in all eyes (100%). The mean best spectacle-corrected visual acuity in LogMAR improved significantly from 0.31 ± 0.18 to 0.91 ± 0.11 postoperatively (P < 0.001). The mean cylinder was −8.00 ± 1.30 preoperatively that improved to −1.50 ± 1.00 at the end of the follow-up (P < 0.001), while the mean sphere improved nonsignificantly from + 2.00 ± 1.00 to + 2.50 ± 1.00 postoperatively.ConclusionTwo 90-degree arc ICRS implantations are a safe and efficient surgical option in the management of patients with crab-claw topographic patterns, which was either PMD or pellucid-like KC with a good visual and refractive outcome.

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

The aims of this meta-analysis were to evaluate the results of intracorneal ring segments (ICRSs) and MyoRing in the management of corneal ectasia and to compare the clinical outcomes and complication rates between mechanical and femtosecond (FS) laser-assisted surgery. An online electronic search was performed for pre-post studies published until April 2020. Uncorrected distance visual acuity, corrected distance visual acuity, sphere, cylinder, spherical equivalent, steep, flat, and mean keratometry values were considered as outcomes. Weighted mean difference with 95% confidence interval was used as a pooled estimation of intervention efficacy. Of 1484 potentially related studies, 115 studies were finally included in the meta-analysis. Findings of this meta-analysis demonstrated considerable improvement in visual, refractive, and keratometric outcomes in all ICRS models and MyoRing. Intrastromal tunnel creation with both methods yielded similar results. Complication rates were without exception higher when mechanical dissection was used. ICRS and MyoRing are appropriate treatment options for patients with corneal ectasia. Both techniques for tunnel creation are efficacious in achieving good visual, keratometric, and refractive results. Mechanical intrastromal tunnel creation is associated with much higher complication rates when compared with FS laser-assisted technique.

Intrastromal fibrosis and lipid deposits twenty years after intracorneal ring segments implantation for treatment of mild myopia

La mesure de l’épaisseur cornéenne centrale (ECC) permet une évaluation des changements physiologiques et pathologiques de la cornée ; elle permet également un ajustement de la pression intra-oculaire (PIO) mesurée. Le but de notre travail était de déterminer les valeurs moyennes de l’ECC chez les enfants de 0 à 72 mois et d’examiner les facteurs pouvant les modifier.il s’est agi d’une étude hospitalière transversale qui s’est déroulé de février à décembre 2019 dans le service d’ophtalmologie du CHU-YO. Elle a inclus les yeux sains des enfants de 0–72 mois examinés sous anesthésie générale. L’ECC a été mesurée par pachymètre ultrasonique. Les variables étudiées étaient l’âge, le sexe, l’ECC, les diamètres cornéens, la pression intraoculaire, le rapport cup/disc.Cent vingt-sept yeux sains de 78 enfants de 0–72 mois ont constitué notre population d’étude. La moyenne de l’âge était de 22 mois. La moyenne de l’ECC était de 554,01 ± 34,21 μm. Elle était de 556,58 μm chez les patients de 0–36 mois ; et de 536,12 μm chez les patients de plus de 36 mois (p = 0,02). L’ECC moyenne était de 555,96 ± 32,96 μm chez les garçons et 551,80 ± 36,16 μm chez les filles (p = 0,50). Chez les patients qui ont bénéficié d’une mesure bilatérale de l’ECC, la moyenne de l’ECC était de 554,74 ± 35,67 μm à l’œil droit et de 549,76 ± 24,08 μm à l’œil gauche (p = 0,42). Les PIO les plus basses étaient retrouvées chez les sujets ayant une cornée épaisse (p = 0,00).L’ECC de l’enfant de plus de 36 mois est proche de celle de l’adulte mélanoderme.Central corneal thickness measurement permits an evaluation of physiological and pathological corneal changes. It allows for an intra-ocular pressure correction factor. Our purpose was to determine the mean central corneal thickness in children aged 0 to 72 months and to examine factors that might affect it.This was a cross-sectional hospital study which took place from February to December 2019 in the ophthalmology service of YO University Medical Center. It included healthy eyes of children 0–72 months of age examined under general anesthesia. Ultrasonic pachymetry was used to measure the central corneal thickness. The studied variables were age, sex, CCT, corneal diameter, intraocular pressure, and cup/disc ratio.One hundred and twenty-seven healthy eyes of 78 children 0–72 months of age were included. The mean age was 22 months. The overall mean CCT was 554.01 ± 34.21 μm. It was 556.58 μm for children from 0 to 36 months of age and 536.12 μm for subjects over 36 months. The mean CCT was 555.96 ± 32.96 μm in boys and 551.80 ± 36.16 μm in girls. In patients who underwent bilateral CCT measurement, the mean CCT was 554.74 ± 35.67 μm in the right eye and 549.76 ± 24.08 μm in the left eye. Lower IOP's were found in patients with thicker corneas (p = 0.00).The CCT values for black children over 36 months of age was similar to the CCT in black adults.

One-Year Outcomes of Intracorneal Ring-Segment Insertion Assisted by Femtosecond Laser Simultaneously Performed with Corneal Collagen Cross-Linking for Treatment of Keratoconus.

PurposeTo assess the results of simultaneously performed femtosecond laser–assisted Keraring intrastromal corneal ring–segment insertion and corneal collagen cross-linking for the treatment of keratoconus.Patients and MethodsIn this retrospective, noncomparative, interventional study, 30 eyes of 24 progressive-keratoconus patients of both sexes aged 18–36 years old with poor best-corrected visual acuity (BCVA) and intolerance to contact lenses were included. All patients had been subjected to complete preoperative and postoperative ophthalmological examinations — unaided VA, BCVA, refraction, Pentacam, and contrast sensitivity examinations at 3-month, 6-month, and 1-year follow-ups.ResultsMean unaided VA had changed significantly from 0.649±0.239 logMAR preoperatively to 0.514±0.222 (P=0.014), 0.419±0.162 (P<0.001), and 0.379±0.142 (P<0.001) logMAR at the three follow-up visits, respectively. Mean BCVA had changed significantly from 0.326±0.144 logMAR preoperatively to 0.231±0.140 (P=0.006) at 1-year follow-up. Mean spherical equivalent refraction had decreased significantly at 6-month (P=0.0298) and 1-year follow-up (P=0.0081). Mean steep keratometry (K2) had also significantly reduced from 51.89±3.81 D to 49.87±4.57 D (P=0.034) at 6 months and 49.40±4.39 D (P=0.011) at 1 year. Mean refractive and keratometric astigmatism had significantly decreased at all follow-up visits.ConclusionAt 1-year follow-up, keraring intrastromal corneal ring–segment insertion assisted by femtosecond laser performed simultaneously with corneal collagen cross-linking resulted in an improvement in visual, refractive, and topographic outcomes, which may suggest it is an effective treatment of keratoconus.

Интрастромальная кератопластика с имплантацией роговичных сегментов как самостоятельный метод зрительной реабилитации у пациентов с кератоконусом

Purpose. To assess the possibility of using intrastromal keratoplasty with intracorneal ring segments implantation as an independent technique to achieve visual rehabilitation in patients with keratoconus of the stages I and II. Material and methods. There were examined and operated 14 eyes (10 patients) with keratoconus of the stages I and II (classification by Izmailova SB, 2014). Patients were divided into two groups depending on the keratoconus stage. All patients underwent intrastromal keratoplasty with intracorneal ring segments implantation using the femtosecond technology. The on average follow-up was 5.7 months. Results. In the first group: the average UCVA value increased with from 0.31±0.21 to 0.81±0.31 (p&lt;0.05); the BCVA increased from 0.89±0.08 to 0.94±0.10 (p&gt;0.05); the spherical component of refraction decreased from 0.96±1.25 to 0.08±0.20 (p&lt;0.05); the cylindrical component of refraction decreased from 4.25±1.73 to 0.50±1.22 (p&lt;0.05). In the second group: UCVA increased from 0.51±0.40 to 0.61±0.28 (p&lt;0.05); the BCVA increased from 0.70±0.17 to 0.81±0.26 (p&gt;0.05); the spherical component of refraction decreased from 4.88±2,61±0.53±0.63 (p&lt;0.05); the cylindrical component of refraction decreased from 2.69±1.65 to 1.41±1.02 (p&lt;0.05). Conclusion. 1. After implantation of intracorneal ring segments, both in patients with I and in patients with the II stage of keratoconus, there was an increase in the UCVA and BCVA, as well as a significant reduction in maximal keratometry and coma, which provides the improving of the quality of vision. 2. In all cases the UCVA and BCVA that were obtained after the treatment reached a sufficiently high level to ensure the possibility of performing their professional functions, without resorting to additional surgical treatment techniques. That characterizes this method as an independent and sufficient to achieve high visual acuity in patients with I and II stages of keratoconus. Key words: keratoconus, corneal intrastromal segments, femtosecond laser, visual rehabilitation.