Corneal biomechanical outcome of collagen cross-linking in keratoconic patients evaluated by Corvis ST

2020 ◽  
pp. 112067212094479
Author(s):  
Mahmoud Jabbarvand ◽  
Zahra Moravvej ◽  
Kianoush Shahraki ◽  
Hessam Hashemian ◽  
Hamed Ghasemi ◽  
...  
Keyword(s):  
Amplitude Ratio ◽  
Corneal Thickness ◽  
Case Series ◽  
Cross Linking ◽  
Corvis St ◽  
Significant Difference ◽  
Biomechanical Changes ◽  
The Mean ◽  
Prospective Case Series ◽  
Collagen Cross Linking

Purpose: A 6-month evaluation of the topographic and biomechanical changes induced by corneal collagen cross-linking (CXL) in keratoconic eyes using Pentacam and Corvis ST. Design: Longitudinal prospective case series. Methods: In this study, 67 eyes of 67 patients with progressive keratoconus (KCN) treated with “Epithelium-off” CXL were evaluated. Patients with stages 1 or 2 of KCN and a corneal thickness of at least 400 μm at the thinnest point were included. Standard ophthalmologic examinations were carried out for all patients. The topographic and biomechanical measurements of the cornea were obtained by Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 6-month postoperatively. Results: The mean age of the participants was 21.68 ± 4.23 years. There was significant difference in mean spherical equivalent (SE) before and 6 months after CXL. Uncorrected and best corrected visual acuity improved postoperatively, although not statistically significant. The mean and maximum keratometry showed a significant decrease 6 months after CXL (0.93 ± 0.38 D and 1.43 ± 0.62 D, respectively p < 0.001). Among Corvis ST parameters, first applanation length and velocity (AL1 and AV1) showed statistically significant changes. The radius at highest concavity changed significantly (0.13 ± 0.37 mm mean increase after CXL; p < 0.001). A significant increase was observed in stiffness parameter A1 (SP-A1; p < 0.001) and significant decreases were noted in integrated radius (IR) and deformation amplitude ratio (DAR; p < 0.001). Conclusion: Analyzing biomechanical changes after corneal cross-linking can provide basis for efficient KCN treatment. Corvis ST parameters demonstrated changes in corneal biomechanical characteristics indicative of stiffing after CXL.

Long term results of accelerated corneal collagen cross-linking in pediatric keratoconus

2021 ◽  
pp. 112067212110183
Author(s):  
Yasin Cinar ◽  
Cagla Cilem Han ◽  
Alparslan Sahin ◽  
Zeba A Syed
Keyword(s):  
Visual Acuity ◽  
Corneal Thickness ◽  
University Hospital ◽  
Long Term Results ◽  
Cross Linking ◽  
Distance Visual Acuity ◽  
The Mean ◽  
Collagen Cross Linking ◽  
Corneal Collagen

Purpose: To evaluate the long term visual, refractive, and corneal tomographic outcomes of epithelium-off accelerated corneal collagen cross-linking (ACXL) in the management of pediatric keratoconus (KC). Methods: This retrospective study included patients under 18 years old with progressive KC who underwent ACXL between 2012 and 2019 at Dicle University Hospital. Complete ophthalmic examination was performed including uncorrected distance visual acuity (UDVA), best spectacle-corrected distance visual acuity (CDVA), manifest refraction, and corneal tomography. Evaluations were performed preoperatively and at 6 months intervals postoperatively. Results: Forty-nine eyes of 49 patients were included in the study. The mean age of patients at the time of ACXL was 14.2 ± 1.8 (range: 9.5–17.3) years. Mean follow up was 4.61 ± 1.90 (range: 2.0–8.1) years. The mean LogMAR UDVA improved from 0.94 ± 0.41 to 0.81 ± 0.43, 0.69 ± 0.41, and 0.67 ± 0.33 after 1, 3, and 5 years respectively ( p = 0.001). The mean LogMAR CDVA improved from 0.58 ± 0.36 to 0.46 ± 0.31, 0.34 ± 0.23, and 0.39 ± 0.27 after 1, 3, and 5 years respectively ( p = 0.015). The mean refractive cylinder improved significantly from 6.01 ± 2.07 diopters (D) to 5.46 ± 1.87, 5.38 ± 2.18, and 5.02 ± 2.31 D after 1, 3, and 5 years respectively ( p = 0.005). As compared to preoperative values, steep keratometry and maximum keratometry were not significantly different ( p = 0.805 and 0.448, respectively) following ACXL, while flat keratometry significantly improved after ACXL ( p = 0.012). Although central corneal thicknesses decreased significantly ( p = 0.029), the decrease in thinnest corneal thickness was not statistically significant ( p = 0.205). Conclusion: Epithelium-off ACXL seems to be effective for halting KC progression with long term clinical benefits in pediatric patients.

Detecting subclinical keratoconus by biomechanical analysis in tomographically regular keratoconus fellow eyes

2021 ◽  
pp. 112067212110637
Author(s):  
Victor A Augustin ◽  
Hyeck-Soo Son ◽  
Isabella Baur ◽  
Ling Zhao ◽  
Gerd U Auffarth ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Case Series ◽  
Biomechanical Analysis ◽  
Corvis St ◽  
Corrected Visual Acuity ◽  
The Mean ◽  
Best Corrected Visual Acuity ◽  
Fellow Eyes

Purpose To analyze the tomographically non-affected second eyes of keratoconus patients using the Corvis ST to detect any biomechanical abnormalities or subclinical keratoconus. Methods In this retrospective, single-center, consecutive case series 244 eyes of 122 keratoconus patients were analyzed between November 2020 and February 2021. Fourteen fellow eyes fulfilled the inclusion criteria and showed no clinical or tomographic signs of keratoconus. Main outcome measures included best-corrected visual acuity, tomographic and biomechanical analyses using Scheimpflug imaging: Pentacam and Corvis ST (Oculus, Wetzlar, Germany). Tomographic analyses included anterior and posterior simulated keratometry, K-Max, central corneal thickness, thinnest corneal thickness, Belin/Ambrosio Ectasia Display, and the ABCD grading system. For biomechanical analyses, the corneal biomechanical index (CBI) and tomographic biomechanical index were used. Results The mean best-corrected visual acuity was 0.01 ± 0.10 logMAR. Mean K-Max was 43.79 ± 1.12 D, mean central corneal thickness 529 ± 25 µm, mean thinnest corneal thickness 524 ± 23 µm, and mean Belin/Ambrosio Ectasia Display 1.0 ± 0.32. The mean CBI was 0.30 ± 0.21. Regular CBI values were found in six of 14 patients. The mean tomographic biomechanical index was 0.47 ± 0.22 with regular values observed in only two of 14 patients. No signs of tomographic or biomechanical abnormalities were shown in only one of 14 keratoconus fellow eyes, with regular ABCD, Belin/Ambrosio Ectasia Display, CBI and tomographic biomechanical index values. Conclusions Tomographically normal fellow eyes of keratoconus patients are rare. In these cases, a biomechanical analysis of the cornea may help detect a subclinical keratoconus. The tomographic biomechanical index was the most sensitive index to verify a mild ectasia.

scholarly journals Long-term Follow-up of Pachymetric and Topographic Alterations after Corneal Collagen Cross-Linking for Keratoconus

2012 ◽  
Vol 1 (1) ◽  
pp. 22-25
Author(s):  
Paraskevi G Zotta ◽  
Diamantis D Almaliotis ◽  
George D Kymionis ◽  
Vasilios F Diakonis ◽  
Kostas A Moschou ◽  
...  
Keyword(s):  
Corneal Thickness ◽  
Case Series ◽  
Cross Linking ◽  
Retrospective Case ◽  
Time Intervals ◽  
Long Term Follow Up ◽  
Collagen Cross Linking ◽  
Corneal Collagen

ABSTRACT Purpose To determine the long-term alterations of corneal thickness, along with topographic outcomes, after corneal collagen cross-linking treatment (CXL) for keratoconus. Materials and methods In this retrospective case series, 46 patients (52 eyes), 32 males and 14 females, with progressive keratoconus were included. All eyes underwent CXL in accordance with the standard protocol (Dresden) for the treatment of their ectatic corneal disorder between January 2006 and June 2007. Pachymetric and topographic outcomes were evaluated preoperatively and at 1, 3, 6, 12, 24 and 36 months postoperatively. Results Mean follow-up was 28.08 ± 8.39 months (range, from 12 to 36 months). A statistically significant decline in corneal pachymetric values (at the thinnest location) when compared with preoperative values (467.65 ± 41.08 µm) was demonstrated at 1 (437.63 ± 50.57 µm), 3 (439.08 ± 52.27 µm), 6 (449.37 ± 52.73 µm), 12 (449.63 ± 83.53 µm) and 24 (459.97 ± 47.32 µm) months after CXL (p < 0.05, for all mentioned time intervals). Return to preoperative pachymetric values (469.52 ± 40.52 µm) was revealed 36 months post-CXL (p > 0.05). With respect to topographic (flat and steep keratometric values, keratoconus index), no statistically significant differences between preoperative and all postoperative intervals were found (p > 0.05, for all values for all time intervals). Conclusion Corneal pachymetric values reduce significantly up to 24 months after CXL treatment, while a return to preoperative values was revealed 36 months after the procedure. No significant changes’ concerning topographic outcomes was demonstrated after CXL, indicating stability of these parameters. How to cite this article Zotta PG, Almaliotis DD, Kymionis GD, Diakonis VF, Moschou KA, Karampatakis VE. Long-term Follow-up of Pachymetric and Topographic Alterations after Corneal Collagen Cross-Linking for Keratoconus. Int J Keratoco Ectatic Corneal Dis 2012;1(1):22-25.

scholarly journals Transepithelial versus Epithelium off Crosslinking for Treating Keratoconus among Jordanians

2019 ◽  
Vol 13 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Khalid Al Zubi ◽  
Yaser Albakar ◽  
Rana Nasser
Keyword(s):  
Corneal Thickness ◽  
Tertiary Care ◽  
Cross Linking ◽  
Corrected Distance Visual Acuity ◽  
Corneal Collagen Crosslinking ◽  
The Mean ◽  
Group 2 ◽  
Collagen Cross Linking ◽  
Corneal Collagen ◽  
Group 1

Background: The progression of keratoconus is stabilized with the help of corneal collagen cross-linking (CXL) supported through photosynthesized riboflavin. Objective: This study aims to compare the effectiveness of the transepithelial procedure and epithelium off procedure of corneal collagen crosslinking among keratoconus patients in Jordan. Methods: The study recruited 80 patients suffering from progressive keratoconus, from a tertiary care setting in Jordan. These participants were randomly divided into two groups; group 1 with 40 participants subjected to transepithelial (Corneal collagen cross-linking) CXL; and 40 participants in group 2 received conventional epithelium off CXL. Results: Improvement was observed in the mean contact lens, which corrected distance visual acuity (CDVA) from logMAR 0.332 ± 0.09 (group 1), 0.35 ± 0.09 (group 2) to 0.241 ± 0.07 (group 1), 0.21 ± 0.07 (group 2), respectively at the end of follow-up (12 months). The mean pachymetry improved from 429.81 ± 18.96 μm (group 1), 430.08 ± 17.05 μm (group 2) to 436.5 ± 15.49 μm (group 1), 436.44 ± 12.53 μm (group 2), respectively, after twelve months. Additionally, the mean Sim K astigmatism declined from 7.0 ± 2.0 (group 1), 6.73 ± 1.98 (group 2) to 5.97 ± 1.88 (group 1), 5.53 ± 0.08 (group 2) respectively at twelve months post-treatment. Majority of the patients in group 2 experienced more pain as compared to group 1 participants. Conclusion: The effectiveness of a cross-linking procedure related to keratometry readings and corneal thickness showed that conventional (epithelium off) CXL method is more effective than transepithelial CXL.

scholarly journals Corneal Collagen Cross-Linking for Keratoconus: Systematic Review

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Hidenaga Kobashi ◽  
Shi Song Rong
Keyword(s):  
Systematic Review ◽  
Visual Acuity ◽  
Corneal Thickness ◽  
Cross Linking ◽  
Control Group ◽  
Significant Heterogeneity ◽  
Eligibility Criteria ◽  
Significant Difference ◽  
One Year ◽  
Collagen Cross Linking

Purpose. To evaluate the efficacy of collagen cross-linking (CXL) one year after treatment for keratoconus compared to no treatment by summarizing randomized controlled trials (RCTs) using a systematic review. Methods. Trials meeting the selection criteria were quality appraised, and the data were extracted by two independent authors. The outcome parameters included maximum keratometry (Kmax), corneal thickness at the thinnest point, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), spherical equivalent (SE) refraction, and cylindrical refraction one year after CXL. We compared the changes in the above parameters with the control group. Results. We identified five RCTs involving 289 eyes that met the eligibility criteria for this systematic review. The changes in BSCVA from baseline to one year exhibited a significant difference between the two groups. There was no statistically significant difference between the two groups for changes in corneal thickness and cylindrical refraction. We did not conduct a meta-analysis in Kmax, UCVA, and SE refraction because their I2 values were greater than 50%. Conclusions. According to the systematic review, CXL may be effective in halting the progression of keratoconus for one year under certain conditions, although evidence is limited due to the significant heterogeneity and paucity of RCTs.

scholarly journals Corneal Parameters in Healthy Subjects Assessed by Corvis ST

2020 ◽  
Author(s):  
Ramin Salouti ◽  
Mansoureh Bagheri ◽  
Anis Shamsi ◽  
Mohammad Zamani ◽  
Maryam Ghoreyshi ◽  
...  
Keyword(s):  
Linear Regression Analysis ◽  
Corneal Thickness ◽  
Case Series ◽  
Biomechanical Properties ◽  
Radius Of Curvature ◽  
Corvis St ◽  
Deformation Amplitude ◽  
Study Results ◽  
The Mean ◽  
The Right

Purpose: To evaluate corneal biomechanics using Corvis ST in healthy eyes from Iranian keratorefractive surgery candidates. Methods: In this prospective consecutive observational case series, the intraocular pressure (IOP), central corneal thickness (CCT), and biomechanical properties of 1,304 eyes from 652 patients were evaluated using Corvis ST. Keratometric readings and manifest refraction were also recorded. Results: The mean (±SD) age of participants was 28 ± 5 years, and 31.7% were male. The mean spherical equivalent refraction was –3.50 ± 1.57 diopters (D), the mean IOP was 16.8 ± 2.9 mmHg, and the mean CCT was 531 ± 31 μm for the right eye. The respective means (±SD) corneal biomechanical parameters of the right eye were as follows: first applanation time: 7.36 ± 0.39 milliseconds (ms); first applanation length: 1.82 ± 0.22 mm; velocity in: 0.12 ± 0.04 m/s; second applanation time: 20.13 ± 0.48 ms; second applanation length: 1.34 ± 0.55 mm; velocity out: –0.67 ± 0.17 m/s; total time: 16.84 ± 0.64 ms; deformation amplitude: 1.05 ± 0.10 mm; peak distance: 4.60 ± 1.01 mm; and concave radius of curvature: 7.35 ± 1.39 mm. In the linear regression analysis, IOP exhibited a statistically significant association with the first and second applanation times, total time, velocity in, peak distance, deformation amplitude, and concave radius of curvature. Conclusion: Our study results can be used as a reference for the interpretation of Corvis ST parameters in healthy refractive surgery candidates in the Iranian population. Our results confirmed that IOP is a major determinant of Corvis parameters.

scholarly journals Two-Year Accelerated Corneal Cross-Linking Outcome in Patients with Progressive Keratoconus

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Arleta Waszczykowska ◽  
Piotr Jurowski
Keyword(s):  
Visual Acuity ◽  
Corneal Thickness ◽  
Long Term Results ◽  
Cross Linking ◽  
Mean Values ◽  
Significant Difference ◽  
Uncorrected Visual Acuity ◽  
The Mean

Purpose. To evaluate the long-term results of accelerated corneal cross-linking (CXL) in patients with progressive keratoconus.Methods. Sixteen patients underwent accelerated CXL at 6 mW/cm2for 15 minutes in one eye. The follow-up visits were scheduled on 7 days, 14 days, and 3, 12, and 24 months after the treatment.Results. There were no significant differences (P>0.05) between preoperative and 2-year postoperative mean values, respectively, in terms of uncorrected visual acuity, best spectacle-corrected visual acuity, maximum keratometryKmax⁡, minimum keratometryKmin⁡, corneal astigmatism, and corneal eccentricity index. We noted a significant flattening of the cornea in 18.7% of patients with a higher preoperativeKmax⁡value (>50 D) and its steepening in patients with a lowerKmax⁡value (<50 D) (6.25%). There was no significant difference in the central corneal thickness and the apical corneal thickness preoperatively and 2 years postoperatively. The mean demarcation line depth was282±11 μm. Persistent corneal haze was noted in 25% of patients.Conclusions. Accelerated CXL appears to be a relatively effective procedure for the treatment of keratoconus in 2-year follow-up.

scholarly journals The Effect of Corneal Collagen Cross-Linking on Higher Order Aberrations in Keratoconus

2021 ◽  
pp. 1-8
Author(s):  
Ahmed M. Moharam ◽  
Mohammad M. Khater ◽  
Hisham A. Saad ◽  
Khaled A. Nagy
Keyword(s):  
Wave Front ◽  
Corneal Thickness ◽  
Corneal Topography ◽  
Cross Linking ◽  
Baseline Evaluation ◽  
The Mean ◽  
Postoperative Improvement ◽  
Collagen Cross Linking ◽  
High Order Aberrations ◽  
Corneal Collagen

Purpose: To assess the changes in ocular high order aberrations after collagen cross linking for keratoconus. Patients and Methods: This study included 30 eyes with confirmed KCN. Baseline evaluation focused on: UDVA and BSCVA using logMAR notation, MRSE, corneal topography using Orbscan IIZ and wave-front aberrometry using Zywave II. CXL was performed per ‘Dresden protocol’ through a 30-minutes exposure to 370 nm UVA with an irradiance of 3 mW/cm 2. Patients had comprehensive ophthalmic evaluation after 6 months with special attention to: UDVA, BSCVA, MRSE, corneal topography and wave-front aberrometry changes.  Results: The mean age was 25.5±5.84 (20:31) years. After 6 months, there was a significant decrease in corneal thickness from 493.2± 24.17µ to 486.7±24.26µ (P<0.05) and a significant decrease in K max from 47.4±1.17D to 46.1±1.17D (P<0.05). BSCVA improved from preoperative value (0.00:0.5 logMAR (median 0.3)) to 6 months’ value (0.1:1.00 logMAR (median 0.2) (P <0.05). Preoperative MRSE was -7.25: -0.5D (median -2.85D) and at 6 months was -6.25: -0.5D (median - 2.125D) (P<0.05). A significant correlation was found at 6 months between changes in both BSCVA and: K max (P<0.001), corneal thickness (P<0.05), vertical coma (P<0.001) and trefoil (P<0.001).  Conclusions: Improvement in HOA was detected after CXL for KCN. The changes in total, vertical coma and vertical trefoil aberrations were significantly correlated with postoperative improvement in BSCVA. Thus, improvement in HOA profile after CXL is one of the explanations of improvement in visual function after CXL in KCN.

scholarly journals Corneal Collagen Cross-Linking with Hypoosmolar Riboflavin Solution in Keratoconic Corneas

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Shaofeng Gu ◽  
Zhaoshan Fan ◽  
Lihua Wang ◽  
Xiangchen Tao ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Corneal Thickness ◽  
Cross Linking ◽  
Ultraviolet A ◽  
Uva Irradiation ◽  
Manifest Refraction ◽  
Corrected Distance Visual Acuity ◽  
The Mean ◽  
Collagen Cross Linking ◽  
Corneal Collagen

Purpose. To report the 12-month outcomes of corneal collagen cross-linking (CXL) with a hypoosmolar riboflavin and ultraviolet-A (UVA) irradiation in thin corneas.Methods. Eight eyes underwent CXL using a hypoosmolar riboflavin solution after epithelial removal. The corrected distance visual acuity (CDVA), manifest refraction, the mean thinnest corneal thickness (MTCT), and the endothelial cell density (ECD) were evaluated before and 6 and 12 months after CXL.Results. The MTCT was 413.9 ± 12.4 μm before treatment and reduced to 381.1 ± 7.3 μm after the removal of the epithelium. After CXL, the thickness decreased to 410.3 ± 14.5 μm at the last follow-up. Before treatment, the meanK-value of the apex of the keratoconus corneas was 58.7 ± 3.5 diopters and slightly decreased (57.7 ± 4.9 diopters) at 12 months. The mean CDVA was 0.54 ± 0.23 logarithm of the minimal angle of resolution before treatment and increased to 0.51 ± 0.21 logarithm at the last follow-up. The ECD was 2731.4 ± 191.8 cells/mm2before treatment and was 2733.4 ± 222.6 cells/mm2at 12 months after treatment.Conclusions. CXL with a hypoosmolar riboflavin in thin corneas seems to be a promising method for keratoconic eyes with the mean thinnest corneal thickness less than 400 μm without epithelium.

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