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Background: Intrastromal corneal ring segments are commonly implanted in the corneas of eyes with mild-to-moderate keratoconus; however, changes in corneal densitometry (CD) after implantation are a matter of debate in the current literature. We evaluated the changes in CD 1 and 3 months after femtosecond laser-assisted Keraring implantation. Methods: This retrospective, non-comparative, multicenter, case series study included patients with keratoconus who underwent femtosecond laser-assisted implantation of double segments with 90° and 160° arc lengths or two 160° arc length Keraring segments. Demographic and baseline clinical ophthalmic data were recorded. Corneal topography and tomography data acquired using a Pentacam HR Scheimpflug tomography system (Pentacam High Resolution; Oculus, Wetzlar, Germany) with a best-fit sphere were used as a reference surface. Using the Pentacam HR, CD measurements were acquired over a corneal area of 12 mm in total and at four concentric zones (0-2, 2-6, 6-10, and 10-12 mm) of three corneal stromal depths: 120 µm of the anterior corneal stromal layer, 60 µm of the posterior corneal stromal layer, and the central layer of stroma lying between these two layers. Results: We included 40 eyes of 40 patients, including 8 (20%) male and 32 (80%) female individuals, with a mean (standard deviation) age of 21.0 (6.4) years. We observed a significant improvement in the topographic values of steep keratometry (K), flat K, maximum K, and corneal astigmatism (all P < 0.05), but not in the mean K, thinnest corneal pachymetry, corneal thickness at the apex, back elevation, or front elevation (all P > 0.05). The mean total anterior, central, and posterior CD differed significantly among the time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05) and no difference between those of the 1-month and 3-month postoperative visits (all P > 0.05). The mean CD for the anterior layer in the central, paracentral, and mid-peripheral zones, and the central layer in all four zones, differed significantly among time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05), which remained unchanged from the 1-month to the 3-month postoperative visit (all P < 0.05), except for the central 2-6-mm zone, which decreased significantly from the 1-month to the 3-month postoperative visit (P < 0.001). The CD of the central 10-12-mm zone did not differ significantly in each pairwise comparison (all P > 0.05). In contrast, CD for the posterior layer in the paracentral zone decreased significantly from the preoperative to the 1-month and 3-month postoperative visits but increased, to a lesser extent, from the 1-month to the 3-month postoperative visit (all P < 0.05). Conclusions: Femtosecond laser-assisted Keraring implantation significantly changes CD, with improvement in most topography parameters. Further longitudinal studies with larger sample sizes are required to verify these preliminary findings.

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The common disorder, Keratoconus (KC), is distinguished by cumulative corneal slimming and steepening. The corneal ring implantation has become a successful surgical procedure to correct the KC patient's vision. The determination of suitable patients for the surgery alternative is among the paramount concerns of ophthalmologists. To reduce the burden on them and enhance the treatment, this research aims to previse the ocular condition of KC patients after the corneal ring implantation. It focuses on predicting post-surgical corneal topographic indices and visual characteristics. This study applied an efficacious artificial neural network approach to foretell the aforementioned ocular features of KC subjects 6 and 12 months after implanting KeraRing and MyoRing based on the accumulated data. The datasets are composed of sufficient numbers of corneal topographic maps and visual characteristics recorded from KC patients before and after implanting the rings. The visual characteristics under study are uncorrected visual acuity (UCVA), sphere (SPH), astigmatism (Ast), astigmatism orientation (Axe), and best corrected visual acuity (BCVA). In addition, the statistical data of multiple KC subjects were registered, including three effective indices of corneal topography (i.e., Ast, K-reading, and pachymetry) pre- and post-ring embedding. The outcomes represent the contribution of practical training of the introduced models to the estimation of ocular features of KC subjects following the implantation. The corneal topographic indices and visual characteristics were estimated with mean errors of 7.29% and 8.60%, respectively. Further, the errors of 6.82% and 7.65% were respectively realized for the visual characteristics and corneal topographic indices while assessing the predictions by the leave-one-out cross-validation (LOOCV) procedure. The results confirm the great potential of neural networks to guide ophthalmologists in choosing appropriate surgical candidates and their specific intracorneal rings by predicting post-implantation ocular features.

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Background: Keratoconus (KCN) is an ectatic disorder of the cornea characterized by stromal weakness and apical protrusion of the cornea, and is associated with a gradual and painless reduction in visual acuity. KCN in pediatric patients has certain important characteristics, such as a progressive and aggressive nature. We aimed to analyze the visual, refractive, and topographic outcomes of implanting a single 210° arc-length Keraring segment according to a novel, objective, Q value-based nomogram (Q-N) for the treatment of pediatric versus adult KCN. Methods: This prospective, multicenter, non-randomized, open-label trial included 47 eyes of 47 patients who were allocated to one of two groups. The adult group included 33 eyes of patients ≥ 18 years of age, whereas the pediatric group included 14 eyes of patients aged 14 - 17 years. All patients underwent femtosecond laser-assisted implantation of a single 210° arc-length Keraring segment according to the Q-N and were followed up for 6 months. All eyes underwent visual acuity measurement, cycloplegic refraction, and corneal topography at baseline and 6 months after surgery. Results: The study groups were comparable in terms of sex proportions and KCN grades (both P > 0.05). The adult group exhibited significant postoperative improvements in mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere, cylinder, spherical equivalent (SE), and Kmax (all P < 0.001) with a mean change of -0.56 logarithm of the minimal angle of resolution (logMAR), - 0.40 logMAR, 3.07 diopters (D), 0.70 D, 3.42 D, and - 5.26 D, respectively. The pediatric group exhibited significant postoperative improvements in mean UDVA, CDVA, sphere, SE, and Kmax (all P < 0.05) with a mean change of - 0.62 logMAR, - 0.34 logMAR, 3.18 D, 3.67 D, and - 5.37 D, respectively. There were no significant differences between the groups in terms of the mean change in visual, refractive, and topographic variables (all P > 0.05). No postoperative complications were observed in either group. Conclusions: Use of the objective Q-N was efficient in the treatment of pediatric KCN, with postoperative improvements in the mean visual, refractive, and topographic parameters, comparable to outcomes in adult keratoconus. Q-N achieved good corneal remodeling with subsequent improvements in visual, refractive, and topographic outcomes in both adult and pediatric patients with keratoconus. To verify our preliminary findings, we recommend further multicenter randomized clinical trials using the Q-N nomogram in a larger sample of pediatric patients with KCN as an adjunct treatment before or after CXL.

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PURPOSE: To evaluate and compare visual and refractive outcomes after implantation of the intracorneal continuous ring 360° arc (ICCR) versus the intracorneal ring segment 340° arc (ICRS) using femtosecond laser for central keratoconus. SETTING: Research Department, Oftalmosalud, Instituto de Ojos, Lima, Peru. METHODS: Randomized study that included 40 eyes of 32 patients diagnosed with central keratoconus between November 2014 and March 2015. Twenty eyes had an implantation of ICCR (MyoRing, Dioptex GmbH, Austria) through an intrastromal pocket and 20 eyes had an implantation of ICRS (Keraring, Mediphacos, Brazil) through an intrastromal tunnel. Both procedures were performed with a femtosecond laser (LDV Z6 model, Ziemer Ophthalmic Systems AG). Visual acuity (VA), refraction, and Scheimpflug imaging analysis were performed pre- and postoperatively at 1 month and 1 year. Comparisons of means were performed using the Student's t-test. RESULTS: At 1 year, uncorrected VA improved 0.77 LogMAR (p < 0.001) in the ICCR group and 0.79 LogMAR (p = 0.01) in the ICRS group; mean sphere improvement was 5.13 Diopters (D) in the ICCR group and 6.27 D in the ICRS group (p < 0.001 both); mean Steeper Keratometry improvement was 4.24 D in the ICCR group and 5.53 D in the ICRS group (p < 0.001 both). In the ICCR group, mean decrease in the pachymetry at the thinnest point of the cornea was 32.16 µm (p = 0.01), and in the ICRS group, mean increase was 4.2 µm at 1 year (p = 0.61). CONCLUSION: Intracorneal continuous ring 360° arc (ICCR) and intracorneal ring segment 340° (ICRS) are effective treatments for central keratoconus. No significant differences between rings were found on visual acuity, refraction, and keratometry improvement.

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PURPOSE: To assess potential differences between central and eccentric cones in the aberrometric corneal profile and in visual and keratometric outcomes 6 months after intracorneal ring segment (ICRS) implantation for keratoconus. METHODS: This study compared two groups consisting of 12 patients each, with central or eccentric keratoconus who were treated with femtosecond laser-assisted Keraring implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, keratometric readings and higher order aberrations (HOAs) including high order aberrations root mean square (HOARMS), coma, spherical aberration and trefoil were measured preoperatively and 6 months after ICRS implantation. RESULTS: Trefoil and spherical aberration were significantly reduced after ICRS implantation compared to preoperative values in eccentric keratoconus (Trefoil, p = 0.0049; Spherical aberration, p < 0.0001). In central keratoconus spherical aberration was reduced not significantly after ICRS implantation compared to preoperative values (p = 0.087). Coma showed a significant reduction in central (p = 0.0001) and in eccentric keratoconus (p = 0.0001). The reduction of spherical aberration in central keratoconus was significantly positively correlated to improvement in UDVA (Pearson's correlation coefficient, r = -0.66; p = 0.02). In eccentric keratoconus there was a significant positive correlation between reduction of trefoil and improvement in UDVA (Spearmans R, r = -0.69; p = 0.01). CONCLUSION: Patients both with central and eccentric keratoconus benefit from ICRS implantation. Specifically, our data provide a slightly higher gain in visual performance for eccentric cones 6 month after ICRS implantation, which is accentuated by a greater reduction in spherical aberration and trefoil. Improvements in UDVA are positively correlated with reductions in HOAs.

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PURPOSE: To evaluate clinical outcomes in patients with asymmetric duck phenotype keratoconus implanted with asymmetric progressive thickness intrastromal corneal ring segments (PT-ICRS, Keraring AS, Mediphacos, Belo Horizonte, Brazil), and to demonstrate improved visual acuity and symmetry in corneal flattening. METHODS: This single-center, retrospective, observational study evaluated the clinical outcomes at 1, 3, and 6 months after implantation of PT-ICRS in patients with duck phenotype keratoconus. After creating the intrastromal tunnel with a femtosecond laser, one 160-degree arc length PT-ICRS, either 150/250 µm or 200/300 µm, was implanted. Changes in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction (MR), manifest refraction spherical equivalent (MRSE), mean keratometry (Kmean), maximum keratometry (Kmax), Coma@5mm, and manifest and topographical astigmatism were documented. RESULTS: The study cohort included 23 eyes of 17 patients with a mean age of 24.6 years. From baseline to 6 months following implantation, mean UDVA improved from 0.70 logarithm of the minimum angle of resolution (logMAR) (20/100 Snellen) to 0.22 logMAR (20/33 Snellen), CDVA improved from 0.33 logMAR (20/42 Snellen) to 0.14 logMAR (20/27 Snellen), the mean sphere and MRSE decreased from -1.05 diopters (D) and -2.70 D to -0.25 D and -0.80 D, respectively, and the Kmean and Kmax improved from 46.5 D and 53.7 D to 44.6 D and 48.7 D, respectively. CONCLUSIONS: The Keraring AS ICRS offers a safe, effective means of improving visual acuity while reducing refractive error, mean and max keratometry, and aberrations in patients with duck phenotype keratoconus.

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OBJECTIVE: To evaluate changes in visual acuity and corneal tomographic outcomes at 6 months after femtosecond-laser assisted implantation of two different types of intracorneal implants in keratoconus. METHODS: A total of 39 keratoconus eyes implanted with two segments KeraRing (n = 22 eyes) or MyoRing (n = 17 eyes) were enrolled. Tomographic data (Pentacam system, Oculus) were analyzed and correlated with enhancement in uncorrected (UDVA) and corrected distance visual acuity (CDVA). The tomographic indices were front maximum keratometry (Kmax), corneal asphericity (Q-value) on both surfaces, average pachymetric progression indices (PPI), maximum Ambrosio relational thickness (ARTmax), Belin-Ambrósio enhanced ectasia total deviation index (BAD-D), index of surface variance (ISV), vertical asymmetry (IVA), height asymmetry (IHA) and height decentration (IHD). RESULTS: LogMAR UDVA and CDVA improved 2.1 (p = 0.003) and 0.7 (p = 0.074) lines with KeraRing, and 8 and 2.5 lines with MyoRing (p = 0.001). The highest and lowest mean differences in the tomographic indices between both groups were related to ISV and IHD, respectively. Changes in all indices differed significantly between two groups except for changes in front corneal astigmatism, ARTmax, ISV, IVA, IHD and IHA (p > 0.05). Correlation of changes in CDVA with changes in other parameters was statistically significant only for IHD in the KeraRing group, while changes in in UDVA were significantly correlated with changes in spherical equivalent, back Q-value, ISV, IVA, and IHA only in the MyoRing group. CONCLUSION: Both implants promote corneal shape regularization and an enhancement in UDVA in keratoconus. A considerable flattening effect and reduction in prolateness in the front corneal surface were observed with MyoRing.

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The short-term safety and efficacy of intracorneal ring segment (ICRS) implantation in keratoconus eyes of children are investigated in this study. A retrospective interventional case series study including a total of 33 keratoconus eyes (age 8 to 17 years) that had undergone ICRS (Keraring segments, Mediphacos) implantation was conducted. Information about visual, refractive, pachymetric, corneal topographic and aberrometric, and corneal endothelial changes during a 3-month follow-up were extracted and analysed. A significant improvement was observed in logMAR corrected distance visual acuity (p = 0.005), combined with a statistically significant reduction in keratometric readings (p < 0.001). A reduction in the magnitude of corneal astigmatism of ≥1 D was observed in 52.8% of eyes. No significant changes were observed in corneal endothelial density (p = 0.317). Significant changes were found in the anterior vertical coma component (p = 0.002) as well as in the spherical aberration of the posterior corneal surface (p = 0.004). Only two relevant complications were described: one corneal microperforation with penetration of the ring segment into the anterior chamber (1 eye, 2.8%), and a case of ring extrusion (1 eye, 2.8%). ICRS implantation in children keratoconus eyes allows a reduction of corneal astigmatism, irregularity, and aberrations, leading to a significant visual improvement.

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PURPOSE: To analyze the impact of the depth of implantation of intracorneal ring segments on morphological, biomechanical, and clinical outcomes in ectatic corneas. METHODS: This prospective longitudinal study enrolled 40 eyes of 29 patients (age 20-51 years) with corneal ectasia that underwent intracorneal ring segments implantation (KeraRing, Mediphacos). Changes in visual acuity, refraction, corneal tomography, and corneal biomechanics (Ocular Response Analyzer, Reichert) were evaluated during a 6 month follow-up. Likewise, changes in ring segment implantation depth measured by optical coherence tomography (Visante OCT, Carl Zeiss Meditec) were also evaluated. RESULTS: Mean relative depth of implantation was 71.6 ± 5.8%, 71.5 ± 6.5%, and 71.9 ± 6.3% at 1, 3, and 6 months after surgery, respectively (p = 0.827). The difference between the real relative depth of implantation and the theoretical attempted value of 70% was not statistically significant (p = 0.072). Differences in spherical equivalent during the follow-up changed significantly depending on the level of relative depth of implantation (p = 0.036), with an increase of 0.114 D per each 1% increase in relative depth of implantation. Likewise, a decrease of -0.194 D in the steepest keratometric reading was found per each decrease of 1% in relative depth of implantation (p = 0.026). Changes in corneal thickness (p = 0.092) and biomechanics (p = 0.080) were not related to relative depth of implantation. CONCLUSION: The effect on visual acuity and refraction of intracorneal ring segments when implanted in corneal ectasia is less clinically relevant when the implantation is done at a very deep plane. The variability of the depth of intracorneal ring segments implantation when using femtosecond laser technology is minimal and with no clinically significant effect on clinical outcomes.

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PURPOSE: To assess the 3-year safety and efficacy of femtosecond laser-assisted intrastromal corneal ring segments' (ICRS) implantation followed or accompanied by transepithelial accelerated corneal collagen cross-linking (TE-ACXL) as a treatment of keratoconus in children with vernal keratoconjunctivitis (VKC). PATIENTS AND METHODS: Fifty two eyes of 28 children with keratoconus and vernal VKC were included in this study. Cases were divided into 2 groups; the first group had been treated with femtosecond laser-assisted ICRS (Keraring) implantation accompanied or followed by TE-ACXL, while the second group had been treated by TE-ACXL only and all cases completed a follow-up period of 3 years. RESULTS: In group 1: the mean uncorrected (UCVA) and best-corrected (BCVA) visual acuity, spherical equivalent, K-max and Q-value improved markedly from 0.97 ± 0.19, 0.67 ± 0.18, -8.75 ± 4.55, 60.41 ± 4.98, and -1.18 ± 0.54 preoperatively to 0.61 ± 0.27, 0.39±0.21, -3.25 ± 3.56, 55.22 ± 5.72, and -0.44 ± 0.68 postoperatively respectively. While in group 2: the preoperative mean UCVA, BCVA, spherical equivalent, K-max and Q-values were 0.68 ± 0.28, 0.38 ± 0.24, -2.84 ± 2.59, 50.29 ± 4.04, and-0.58 ± 0.23 respectively while their corresponding postoperative values were 0.58 ± 0.34, 0.19 ± 0.17, -2.35 ± 2.07, 49.58 ± 3.26, and -0.57 ± 0.25. Only one case in group 1 required repeat cross-linking. CONCLUSION: Although the long-term safety and efficacy of femtosecond laser-assisted ICRS implantation accompanied or followed by TE-ACXL in children with keratoconus and VKC is high, some cases still may need repeat cross-linking.

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Purpose: To assess the preoperative visual, refractive, corneal topo/tomographic, aberrometric and biomechanical parameters as predictive factors of a successful outcome 6 months following intrastromal corneal ring segments implantation. Methods: Sixty-eight keratoconus eyes implanted with Keraring using femtosecond laser technology were assessed. The preoperative assessed parameters included uncorrected and corrected distance visual acuity (UDVA & CDVA), refraction, placido-disk based topography using TMS-4, Scheimplfug tomography using Pentacam HR, corneal biomechanical assessments using Ocular Response Analyzer (ORA) and the wavefront analysis using i-Trace aberrometer. Other variables were type of astigmatism based on orientation of the steep meridian, keratoconus staging based on the Amsler-Krumeich classification and the difference between the axes of refractive astigmatism, topographic astigmatism and comatic aberration based on a difference less or more than 30°. The success criterion was defined based on CDVA, a post-operative CDVA improvement at least two lines were considered as a success and otherwise were recognized as a failure following Keraring implantation. Results: Only UDVA, coincidence of the most elevated points on the front and back corneal surfaces and the difference between UDVA and CDVA showed significant difference between the eyes with successful outcomes and those with unsuccessful results (P < 0.05). Although corneal curvature and astigmatism were higher and corneal thickness was lower in the unsuccessful group, differences were not statistically significant. Conclusion: It is expected that the greater difference between the preoperative uncorrected and corrected distance visual acuity (Δ UDVA-CDVA) and more coincidence of the most elevated points in the two corneal surfaces on the elevation maps increase the rate of successful outcome following the Keraring implantation. Abbreviations: ICRS: intrastromal corneal ring segments; UDVA: uncorrected distance visual acuity; CDVA: corrected distance visual acuity; logMAR: logarithm of minimum angle of resolution; SE: spherical equivalent; IOP: intra-ocular pressure; Km: mean keratometry; CA: corneal astigmatism; WTR: with-the-rule; ATR: against-the-rule; OBL: oblique; SB: symmetric bow-tie; AB: asymmetric bow-tie; IS: inferior steepening; SRAX: skewed radial axis; Q: asphericity (Q-value); CCT: central corneal thickness; CTP: corneal thinnest point; ORA: ocular response analyzer; CH: corneal hysteresis; CRF: corneal resistance factor; HOAs: higher-orders aberrations; RMS: root mean square; SD: standard deviation; CI: confidence interval.

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BACKGROUND: Intracorneal ring segment implantation is an effective and safe method of visual improvement in patients with keratoconus. The aim of our study was to evaluate the long-term clinical outcomes after Keraring implantation for keratoconus in patients older than 40 years. METHODS: Eleven eyes from 11 patients with keratoconus who underwent femtosecond laser-assisted Keraring implantation for keratoconus were included in this retrospective study. The uncorrected visual acuity (UCVA), corrected visual acuity, keratometric readings, central corneal thickness and thinnest corneal pachymetry were evaluated preoperatively and 6 months after the Keraring implantation. RESULTS: UCVA, BCVA and keratometric readings improved at 6 months postoperatively. CONCLUSION: Our data showed significant keratometric amelioration and visual improvement after Keraring implantation for keratoconus in patients older than 40 years at 6 months postoperatively.

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@#AIM: To evaluate the clinical effectiveness of intrastromal corneal ring segments among the patients suffering from keratoconus. <p>METHODS: A retrospective and comparative interventional design had been utilized on the basis of postoperative follow up among 56 keratoconus patients. Visual acuity was significantly assessed during complete ophthalmic examination of the patients. The femtosecond laser had been used to create the corneal tunnels in 15 eyes; whereas, the corneal tunnels were created in 72 eyes mechanically. <p>RESULTS: The ranges and standard deviations had been used to obtain results. It had been revealed through ophthalmic assessment that the mean preoperative uncorrected visual acuity observed was 1.38±0.37 Logarithm of Minimal Angle of Resolution. Moreover, a significant improvement was observed postoperatively in visual acuity by 0.58±0.32 during the fourth month. The improvement was also witnessed in the 16^th month by 0.48±0.30. <p>CONCLUSION: The implantation of intrastromal corneal ring segments is an efficient and effective surgical intervention for the treatment of keratoconus. Thus, identified intervention seems to be associated with appropriate visual outcomes and safety after the development of femtosecond as well as mechanical tunnels.

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PURPOSE: We attempted to evaluate the efficacy of femtosecond laser-assisted intrastromal corneal ring segment implantation in patients with keratoconus (KC). PATIENTS AND METHODS: A retrospective interventional consecutive clinical study was conducted on patients with KC who were treated with femtosecond laser Keraring implantation. All procedures were performed at Ebsar Eye Center in the period from January 5, 2015, to February 28, 2016. RESULTS: Thirty eyes of 20 patients were included in this study. The mean age of patients was 27.43±3.57 years. Eleven patients (55%) were female and nine patients (45%) were male. Keraring segments were successfully implanted in all eyes. There were no complications or need for ring repositioning. The follow-up period was 6 months postoperatively. There was a significant improvement in the mean logarithm of the minimum angle of resolution (LogMAR) of uncorrected visual acuity (UCVA) after Keraring segment implantation from 1.5±0.23 preoperatively to 0.54±0.16 at 6 months postoperatively (P=0.001). The preoperative mean LogMAR of best-corrected visual acuity (BCVA) was 0.85±0.17. At 1 month postoperatively, it was 0.35±0.15; at 3 months postoperatively, it was 0.26±0.11, and at 6 months postoperatively, it was 0.14±0.07 (P=0.001). The mean preoperative maximum keratometric value for 3 mm pupil in diopters (K max) significantly decreased from 55.85±5.44 preoperatively (N=30) to 44.05±1.64 D at 6 months postoperatively (P=0.001). There was a statistically significant reduction in the mean preoperative spherical equivalent from -5.43±1.76 D preoperatively to -2.43±0.95 D at 6 months postoperatively. No statistically significant differences were detected between 1 and 3 months of follow-up regarding the visual and refractive outcomes. CONCLUSION: Analysis of the outcomes after Keraring ICRS implantation showed a significant postoperative corneal flattening with a subsequent increase in UCVA and BCVA. Using the femtosecond laser for tunnel creation made the procedure easy and fast with an accurate precise depth of implantation and reduced the risk of operative and postoperative complications.

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PURPOSE: To compare the outcome measures following implantation of two types of ICRS. METHODS: Forty-four eyes of keratoconic patients (aged 18-50 years) were randomly assigned to femtosecond laser-assisted Keraring ICRS (Group A) or MyoRing (Group B) implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, keratometry (K), and aberrations were compared preoperatively, at 3 and 6 months postoperatively. A survey was conducted to assess patient's satisfaction, 6 months postoperatively. RESULTS: In Groups A (n = 26) and B (n = 18), UDVA was increased (P < 0.05), but CDVA increased only in Group A (P < 0.05) 6 months postoperatively. The mean K was reduced by 4.55 D (P < 0.0001) in Group A and 6.51 D (P < 0.001) in Group B. Six months postoperatively, the mean refraction spherical equivalent (MRSE) decreased by 2.90 and 3.60 D in Groups A and B, respectively (P < 0.0001). Between groups, coma was more reduced (P = 0.035) in Group B than A, 6 months postoperatively. On motivation for surgery, 88.9% of patients' ranked "desire to improve unaided vision" and "relief from glasses" (77%) topmost. Seventy-seven (77%) of Group A and 89% of Group B patients were satisfied with their unaided vision at the final visit, after 6 months. CONCLUSIONS: KeraRing (A) and MyoRing (B) corneal implants both performed well in improving vision and stabilising the cornea. Implantation of the MyoRing caused greater reduction in coma and better patient satisfaction, but CDVA improved only in the Keraring group, at the final visit.

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PURPOSE: To compare complete versus incomplete ring implantation for keratoconus correction. METHODS: We investigated 25 eyes of keratoconic patients, of which 15 had femtosecond-assisted MyoRing corneal implantation (Group 1) and 10 had femtosecond-assisted Keraring segments (Group 2). Uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), mean K (K m), sphere, topographic cylinder, and corneal asphericity value (Q-value) were measured in all eyes preoperatively and at 4 weeks postoperatively (1 month). RESULTS: In Group 1, the K m change was -6.15±2.16 D, with a mean change in sphere of 4.45±2.18 D and a mean change in refractive cylinder of 2.32±3 D. UCVA change was -0.57±0.273 logarithm of the minimum angle of resolution (LogMAR), BCVA change was -0.2±0.27 (LogMAR), and the Q-value change was 0.43±2.6. In Group 2, the K m change was -3.15±1.68 D, UCVA change was -0.48±0.37 (LogMAR), BCVA change was -0.09±0.15 (LogMAR), and the Q-value change was 0.5±0.21. Changes in the means did not significantly differ between groups, except for the K m change, which was significantly greater in Group 1 than in Group 2 (P=0.05). CONCLUSION: Both complete ring and ring segment implantation are effective for improving corneal and visual parameters in keratoconus. Complete ring implantation may have a greater flattening effect on the anterior corneal surface.

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PURPOSE: To report the results of intrastromal corneal ring segment (KeraRing; Mediphcose, Belo Horizonte, Brazil) implantation relative to depth of insertion in keratoconic patients. METHODS: In this retrospective, observational study, we evaluated 29 eyes of 27 patients with keratoconus who underwent implantation of KeraRing SI-5 with mechanical tunnel creation. In the mean follow-up of 8.8 months, all eyes underwent scheimpfluge image of pentacam (Oculus, Germany) to determine insertion depth. Based on the measured implantation depth, cases were categorized into: 40-59% thickness group, 60-79% thickness group, and ≥80% thickness group. Visual, refractive, and shape outcomes were evaluated relative to implantation depth. RESULTS: The mean insertion depth was 61.7%.We had 41.4% of cases were in the 40-59% thickness group, 51.7% in the 60-79% group, and 6.9% in the >80% group. Results were similar in 40-59% and 60-79% thickness groups: uncorrected visual acuity (UCVA) and best spectacle corrected VA (BSCVA) improved 3 and 2 lines, respectively, maximum keratometry (Kmax) decreased 2.6 D, refractive cylinder improved 2.04 D, and Q value 8 mm anterior changed by 0.35. In the ≥80% thickness group, UCVA and BSCVA improved less than 1 lines, Kmax change was less than 0.5 D, and RC decreased less than 0.25 D. CONCLUSION: Implantation of KeraRing with mechanical tunnel creation in 40-80% of stromal thickness despite the variable insertion depth is effective.

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A 49-year-old man with an uncorrected visual acuity (UCVA) of 20 / 1000, a best spectacle-corrected visual acuity (BSCVA) of 20 / 400, keratometric readings of K1 = 59.88 × 82° / K2 = 45.88 × 172°, and an inferior steepening that was consistent with keratoconus in his left eye was treated with clear-cornea phacoemulsification and an intraocular lens (IOL) implantation after insertion of keraring intrastromal corneal ring segments for severe keratoconus and cataract. An asymmetrical pair of kerarings was implanted with the assistance of a femtosecond laser in September 2008; the one segment was 250 µm and the other was 150 µm and both were placed at 70°. Three months after the kerarings were implanted, clear-cornea phacoemulsification and IOL implantation were performed on the left eye. After surgery, both the UCVA and the BSCVA of the left eye improved by eight lines. Postoperative central keratometry showed a decrease of 7.35 diopters in the left eye. Both the postoperative refraction (-0.75 -0.75 × 60°) and the keratometric reading (K1 = 50.05 × 93° / K2 = 48.83 × 3°) remained stable one month following the procedures. Thus, the sequential order of intrastromal corneal rings implantation and cataract surgery can be considered as a treatment option in patients with severe keratoconus and cataract.

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A 49-year-old man with an uncorrected visual acuity (UCVA) of 20 / 1000, a best spectacle-corrected visual acuity (BSCVA) of 20 / 400, keratometric readings of K1 = 59.88 x 82degrees / K2 = 45.88 x 172degrees, and an inferior steepening that was consistent with keratoconus in his left eye was treated with clear-cornea phacoemulsification and an intraocular lens (IOL) implantation after insertion of keraring intrastromal corneal ring segments for severe keratoconus and cataract. An asymmetrical pair of kerarings was implanted with the assistance of a femtosecond laser in September 2008; the one segment was 250 microm and the other was 150 microm and both were placed at 70degrees. Three months after the kerarings were implanted, clear-cornea phacoemulsification and IOL implantation were performed on the left eye. After surgery, both the UCVA and the BSCVA of the left eye improved by eight lines. Postoperative central keratometry showed a decrease of 7.35 diopters in the left eye. Both the postoperative refraction (-0.75 -0.75 x 60degrees) and the keratometric reading (K1 = 50.05 x 93degrees / K2 = 48.83 x 3degrees) remained stable one month following the procedures. Thus, the sequential order of intrastromal corneal rings implantation and cataract surgery can be considered as a treatment option in patients with severe keratoconus and cataract.

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PURPOSE: To report the outcomes after the implantation of intrastromal corneal ring segments (KeraRing(R)) by manual tunnel creation for the correction of keratoconus. METHODS: The present retrospective case series was comprised of 12 eyes of 11 consecutive keratoconic patients. Intrastromal corneal ring segments (KeraRing(R)) were implanted for keratoconus correction after manual tunnel creation. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive outcome, and complete ophthalmologic examinations were performed before and after surgery at 1 day, 1 week, 3 months, and 6 months. Corneal topography was measured before surgery, 6 months after surgery and during any necessary follow-up visits. RESULTS: Intrastromal corneal ring segments (KeraRing(R)) implantation significantly increased BCVA from logMAR 0.47 +/- 0.19 to logMAR 0.28 +/- 0.17 (P < 0.05) and decreased the spherical equivalent from -6.03 +/- 3.24 D to -2.24 +/- 1.96 D. The simulated keratometric value in the Orbscan IIz significantly decreased in K maximum from 50.7 +/- 2.93D to 47.65 +/- 3.15 D and in K minimum from 47.65 +/- 3.15 D to 44.92 +/- 2.80 D. CONCLUSIONS: Intrastromal corneal ring segments implantation (KeraRing(R)) by manual tunnel creation appears to be effective in improving BCVA and reducing corneal astigmatism and keratometric value in keratoconic patients. KeraRing(R) may delay or prevent the need for a corneal graft, and reduce the contact lens intolerance.

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