Predictors of Clinical Outcomes after Intrastromal Corneal Ring Segments Implantation
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ABSTRACT Purpose To evaluate the influence of age and severity of keratoconus in the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS). Methods A total of 1,073 eyes of 810 patients, consecutively operated from January 2006 to July 2008, were evaluated. Two independent analysis were made according to the age of patients and keratoconus staging. Four groups were created according to the age of patients: < 20 years old, 20 to 30, 30 to 40 and >40 years old. The patients were also evaluated according to the keratoconus stage (I to IV). The outcome analysis included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry (K), asphericity (Q), corneal volume (CV) and pachymetry. All patients were evaluated using the Pentacam. Results The postoperative increase in UDVA and CDVA was statistically significant in all groups (p < 0.05). The magnitude of improvement of CDVA was larger for patients between 21 and 30-year-old (CDVA = 20/40) and patients with keratoconus grade I (CDVA = 20/35) (p < 0.05). There was a statistically significant increase in CV and pachymetry postoperatively in all groups. The keratometry (3.95D) and asphericity (–0.77) reduction were larger in patients younger than 20-year-old and in patients with keratoconus grade IV (p < 0.05). Conclusion The best clinical outcomes are seen in patients between 20 and 30-year-old and initial cases of keratoconus (grade I). The more advanced the keratoconus, the larger magnitude of K and Q reduction after ICRS implantation. How to cite this article Torquetti L, Ferrara G, Ferrara P. Predictors of Clinical Outcomes after Intrastromal Corneal Ring Segments Implantation. Int J Keratoco Ectatic Corneal Dis 2012;1(1):26-30.Keywords:
Corneal pachymetry
To determine the biomechanical and topographic alterations within the first year after accelerated crosslinking (CXL) treatment in patients with keratoconus.In this prospective study, 52 eyes of 52 patients with progressive keratoconus underwent accelerated CXL were included. All patients had a detailed preoperative ophthalmologic examination, including slit-lamp evaluation, Goldmann tonometry, fundoscopy, topography by Scheimpflug imaging (Sirius), and corneal biomechanical evaluation with a biomechanical waveform analysis device (ORA). Alterations in visual acuity and topographic findings were evaluated before the treatment and at 12 months follow-up. Corneal biomechanical features were obtained before the treatment, and at 1st, 3rd, 6th and 12th months.Uncorrected-visual acuity and best-corrected visual acuity both statistically significantly improved at 12th month (p=0.001). There were no statistically significant differences in keratometry values, whereas maximum K (AKfront) and symmetry index front (SIfront) decreased significantly (p=0.015 and p=0.009, respectively). Corneal thinnest point and volume also decreased significantly at 12th month (p=0.001 for both). Goldmann-correlated intraocular pressure (IOPg) and corneal compensated IOP (IOPcc) values transiently increased in the first three months, while corneal hysteresis (CH) and the corneal resistance factor (CRF) transiently decreased, with the difference not statistically significant (p>0.05). However, central corneal thickness significantly decreased at the end of the 12th month (p=0.001).Accelerated CXL seems to be effective in stopping the progression of keratoconus. Our findings showed transient alterations in biomechanical features, which will end with the preoperative values at the end of the 12th month. Further studies are needed to demonstrate the changes in corneal biomechanics in vivo.
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Purpose To assess the refractive improvements and the corneal endothelial safety of an individualised topography-guided regimen for corneal crosslinking in progressive keratoconus. Methods An open-label prospective randomised clinical trial was performed at the Department of Clinical Sciences, Ophthalmology, Umeå University Hospital, Umeå, Sweden. Thirty-seven patients (50 eyes) with progressive keratoconus planned for corneal crosslinking were included. The patients were randomised to topography-guided crosslinking (photorefractive intrastromal crosslinking (PiXL); n=25) or uniform 9 mm crosslinking (corneal collagen crosslinking (CXL); n=25). Visual acuity, refraction, keratometry (K1, K2 and K max ) and corneal endothelial morphometry were assessed preoperatively and at 1, 3, 6 and 12 months postoperatively. The PiXL treatment involved an asymmetrical treatment zone centred on the area of maximum corneal steepness with treatment energies ranging from 7.2 to 15.0 J/cm 2 ; the CXL treatment was a uniform 9 mm 5.4 J/cm 2 pulsed crosslinking. The main outcome measures were changes in refractive errors and corneal endothelial cell density. Results The spherical refractive errors decreased (p<0.05) and the visual acuity improved (p<0.01) at 3, 6 and 12 months after PiXL, but not after CXL. The between-groups differences, however, were not significant. K2 and K max decreased at 3, 6 and 12 months after PiXL (p<0.01), but not after CXL (p<0.01 when comparing the two treatments). No corneal endothelial cell loss was seen after either treatment. Conclusions Individualised topography-based crosslinking treatment centred on the ectatic cone has the potential to improve the corneal shape in keratoconus with decreased spherical refractive errors and improved visual acuity, without damage to the corneal endothelium. Trial registration number NCT02514200 , Results.
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This study aims to determine whether customised peripheral corneal cross-linking (P-CXL) can halt keratoconus progression in ultrathin corneas with stage 3 and 4 keratoconus, with thinnest pachymetry well below 400 μm and therefore excluded from most treatment protocols.This retrospective study included 21 eyes with progressive keratoconus and thinnest pachymetry ranging from 97 to 399 μm (mean 315 μm), who underwent P-CXL between 2007 and 2020. The procedure involved preoperative NSAIDs therapy, tomography-guided customized epithelial debridement, the use of both hypo-osmolar and iso-osmolar riboflavin solutions, and 9.0 mW/cm2 UV-A irradiation for 10 minutes. The outcome measures were best spectacle-corrected visual acuity (BSCVA), mean keratometry, maximum keratometry, and thinnest pachymetry.After a minimum follow-up period of 12 months, P-CXL stabilized or improved mean keratometry and maximum keratometry in 85.7% of eyes (Kavg from 57.48 ± 9.38 to 56.43 ± 8.96 D, p < 0.001; Kmax from 72.77 ± 12.74 to 70.00 ± 11.50 D, p < 0.001), BSCVA in 90.5% of eyes (from 4.48 ± 2.85 to 5.72 ± 3.34 decimals, p < 0.001), and thinnest pachymetry in 81% of eyes (from 315.81 ± 90.05 to 342.33 ± 74.22 μm, p = 0.08). No adverse events and no loss of endothelial cell density occurred.Customised peripheral corneal cross-linking (P-CXL) treated very severe keratoconus with a success rate of 85.7% and improved visual acuity and tomographic indicators in most cases. While a longer follow-up and a larger sample would help to support such conclusions to a greater extent, these results allow to broaden the treatment spectrum for patients with stage 3 and 4 keratoconus and contact lens tolerance.
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The aim of this study is to report the results of 18 months of follow-up after treatment with accelerated (18 mW/cm(2)) corneal cross-linking in patients with progressive keratoconus.Forty-two eyes of 42 patients with progressive keratoconus were included in this retrospective study. All patients underwent accelerated corneal cross-linking at an irradiance of 18 mW/cm(2) for 5 min (total surface dose 5.4 J/cm(2)). Visual acuity, topographic findings (Kflat, Ksteep, Kaverage, and apical keratometry), and central corneal thickness were evaluated during the 18-month follow-up period.The mean ± standard deviation age of the 16 female and 26 male patients was 24.28 ± 6.32 years (range 14-36). Uncorrected distance visual acuity improved clinically significant from 0.52 ± 0.31 to 0.44 ± 0.25 logMAR (P = 0.031), and corrected distance visual acuity improved clinically significant from 0.34 ± 0.21 to 0.28 ± 0.19 logMAR (P = 0.018). At the last examination during the follow-up period, the flat keratometry (Kflat) decreased from a baseline of 45.65 ± 2.71 to 45.41 ± 2.72 diopters (D) (P = 0.001), the steep keratometry (Ksteep) decreased from 49.20 ± 3.54 to 48.96 ± 3.43 D (P = 0.023), and apical keratometry decreased from 56.62 ± 6.43 to 55.19 ± 5.69 D (P = 0.001), all of them were clinically significant at the 18-month visit. The preoperative values of central corneal thickness changed from 458.95 ± 38.79 to 461.85 ± 41.36 μm 18 months after the operation (P = 0.476).The accelerated corneal cross-linking was found to be effective for the stabilization of progressive keratoconus during the 18 months of follow-up visits.
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PURPOSE: To evaluate the safety and efficacy of Intacs inserts in keratoconic eyes to alter corneal shape and refractive power and stabilize the progression of corneal ectasia. SETTING: Service d'Ophtalmologie, Bordeaux, France. METHODS: In this prospective study, 57 eyes with clear central corneas that were diagnosed with keratoconus and contact lens intolerant were followed for up to 1 year. The primary objectives were to assess the safety of Intacs and the visual outcomes by measuring uncorrected visual acuity (UCVA), best corrected visual acuity, manifest refraction spherical equivalent, keratometry, intraocular pressure (IOP), pachymetry, and patient satisfaction. The stability of the refraction, keratometry, and visual acuity measurements was also assessed. RESULTS: At the 6-month examination, 78% of patients showed improvement of 2 lines or more in UCVA (P<.001). Best corrected visual acuity of 20/40 or better improved from 53% of patients preoperatively to 74% of patients (P≤.033). Manifest refraction spherical equivalent improved to 3.1 ± 2.5 diopters (D) (P<.001) compared with the preoperative examination. Keratometry decreased a mean of −4.3 ± 2.8 D from the preoperative readings (P≤.002). These changes appeared to be stable over time. At 6 months, there were no adverse events, no clinically significant increase in IOP, and no decrease in central corneal thickness. In 7 of 57 eyes (12%), the Intacs were removed due to dissatisfaction with visual symptoms. There were no adverse effects or complications associated with the Intacs removal. CONCLUSIONS: Intacs were safe and effective for treating keratoconus. All patients demonstrated improved objective visual outcomes; functional vision was restored in most patients. Intacs were removed without permanent sequelae.
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To assess the efficacy and tolerance of corneal collagen cross-linking with corneal epithelium debridement in the stabilizing treatment of primary or secondary corneal ectasia.Prospective, comparative, single-center study of patients presenting with progressive primary or secondary corneal ectasia. The control group, comprising the fellow eye of patients with bilateral involvement, was followed up for 6 months and then treated. The parameters examined were the biomicroscopic examination, visual acuity [best spectacle-corrected visual acuity (BSCVA) and uncorrected visual acuity (UCVA)], keratometry of the central 3 mm, intraocular pressure, central pachymetry, endothelial density, and macular profile.Fifty-five eyes of 39 patients were treated; the mean follow-up period was 20.8 ± 6.8 months (range, 12-36 months). The control group comprised 16 eyes. UCVA and BSCVA were significantly improved between 3 and 12 months, reaching their minimum at 6 months, varying from 0.12 UCVA to 0.07 BSCVA (P < 0.05). These values and the keratometry values did not vary significantly after 36 months of follow-up. In contrast, analysis of the control group revealed significant keratometric deterioration of +1.2 diopters at 6 months (P < 0.05), with no further significant variation after treatment. Analysis of the subgroups of patients with post-laser in situ keratomileusis ectasia confirmed these results. At the end of the study, intraocular pressure, pachymetry, and endothelial density were not significantly modified, and no macular profile modification was observed.This study shows that corneal collagen cross-linking can stabilize progressive corneal ectasia, both primary and secondary, with no induced iatrogenic effects.
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To assess the changes in visual acuity and topographic indices after implantation of single-segment Intacs.Forty-two keratoconic eyes received Femtosecond-assisted single-segment Intacs. Uncorrected distance visual acuity (UDVA) and best spectacle corrected visual acuity (BSCVA), refractive error, keratometry (K1, K2, Km, and KMax.), and seven Pentacam measured topographical indices; index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD), and minimum radius of curvature (R Min) were assessed 4 months after surgery. Correlations between changes of visual acuity and topographical indices changes were evaluated.UDVA increased from 0.92 ± 0.35 to 0.49 ± 0.31 logMAR (P < 0.001), and BSCVA increased from 0.39 ± 0.15 to 0.23 ± 0.11 logMAR (P < 0.001). Subjective refraction spherical equivalent (SRSE) decreased from -3.92 ± 1.66 diopters (D) to -2.00 ± 1.51 D (P < 0.001). Mean central Keratometry decreased 2.16 ± 1.09 D from the preoperative readings (P < 0.001). All Pentacam topographical indices except CKI significantly improved (for IHA P = 0.046, for five others P < 0.001). The correlation between improvement in topographical indices and visual acuity improvements was not week.Intacs implantation in keratoconic eyes increased visual acuity and made corneal shape less irregular. However, the improvements of visual acuity and corneal shape were not strongly correlated.
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To investigate the long-term clinical outcomes and changes in crystalline lens transparency after accelerated (45 mW/cm2) transepithelial corneal cross-linking (ATE-CXL) using the Pentacam imaging system in patients with progressive keratoconus.The study prospectively included 44 keratoconus eyes of 40 patients (mean age: 24.39 ± 5.61 years) who underwent ATE-CXL. The examinations, including assessment of uncorrected distance visual acuity, corrected distance visual acuity, corneal topography, and corneal endothelial cell density count, were conducted preoperatively and 1 month, 3 months, 6 months, 1 year, and 5 years postoperatively. Measurement of crystalline lens density using Pentacam images was also performed pre- and postoperatively.All surgeries were uneventful with no postoperative complications. All keratometry values and corneal thickness remained stable during the 5-year follow-up period (all p > 0.05). There were no significant differences in corneal endothelial cell density count, visual acuity, and anterior average lens density in the 0.5-, 1.0-, and 1.5-mm depth zones during the 5-year follow-up period compared with the preoperative values (all p > 0.05).The results of this study suggest that ATE-CXL at 45 mW/cm2 is safe and effective for the treatment of progressive keratoconus in terms of both crystalline lens density and endothelial cell density.
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PURPOSE: To report the mean refractive and topographic changes in progressive keratoconus
(KC) patients post corneal collagen crosslinking (CXL) to assess the progression of corneal
irregularity indices and their relationship with best spectacle-corrected visual acuity (BSCVA).
SETTING: Ocular Microsurgery Institute (IMO) of Barcelona, Spain.
METHODS: This is a retrospective uncontrolled study in eyes with progressive KC. In all 62
eyes from 48 patients, BSCVA, mean K, corneal irregularity at 3 mm and 5 mm were measured
before CXL, at six months, and then annually until the last visit. For data analysis, patients were
divided into three groups according to their mean preoperative K: group 1 included 12 patients
with mean K value less than 43.9 D, group 2 included 41 patients with mean K value between
44-47.9 D, and group 3 included 10 patients with mean K value greater than 48 D.
RESULTS: All patients showed an improvement in BSCVA from 0.13 to 0.06 (p < 0.001) and
a statistically significant decrease in maximum keratometry (Kmax) from 48.22 to 47.25 D
(p < 0.001) and minimum keratometry (Kmin) from 45.7 to 44.89 D (p < 0.001). Measurement
of corneal irregularity also showed a statistically significant decrease at 3 mm from 4.71 to 4.25
(p < 0.001) and at 5 mm from 4.87 to 4.51 (p < 0.007). No statistically significant results were
found according to study group.
CONCLUSION: The improvement in ocular surface regularity indices was statistically
significant in all patients studied, with a possible association between changes in corneal
irregularity, corneal flattening and other topographic changes and the improvement in vision
observed in KC patients undergoing CXL.
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To evaluate the visual, refractive, and topographic outcomes of accelerated corneal collagen cross-linking (CXL) in the pediatric age group.In this retrospective case series study, 89 eyes of 56 patients with progressive keratoconus (KCN) who were under or equal to 18 years old at the time of surgery were included. All patients underwent accelerated corneal CXL. A thorough baseline and follow-up ophthalmic examination including uncorrected distance visual acuity, best corrected visual acuity (BCVA), slit-lamp and fundus examination, and corneal tomography by Scheimpflg camera Pentacam (Oculus, Wetzlar, Germany) were performed.The mean age of patients was 16.2 ± 1.8 years. Mean follow-up was 16.46 ± 11.6 months (range, 6-40 months). The mean BCVA improved significantly from 0.26 ± 0.26 to 0.16 ± 0.19 (logMAR) after accelerated CXL (P < 0.001). The mean corneal astigmatism based on refraction decreased from 3.69 ± 2.12 to 3.15 ± 1.86 after the intervention (P = 0.016). The mean maximum keratometry (Kmax) reduced significantly from 53.23 ± 6.07 diopter (D) to 52.23 ± 6.33 D (P = 0.047). The mean flat keratometry (K1) reduced from 46.37 ± 3.69 to 45.95 ± 3.65 after the intervention (P = 0.119).Our study shows that accelerated CXL increases visual acuity and stabilizes or improves keratometric indices in pediatric patients with progressive KCN without any serious complication for a mean follow-up time of 16 months.
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