The effects of collagen cross-linking on corneal density: a comparison between accelerated and conventional methods

Fard, Ali; Sorkhabi, Rana; Khazaei, Mojtaba; Nader, Nader D.

doi:10.1007/s10792-018-0961-8

Cited by 8 publications

(8 citation statements)

References 18 publications

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“…It also has been described that the corneal clarity depends on the severity of keratoconus: in more advanced keratoconus, due to the increasing corneal damage, higher densitometry values can be measured [ 35 ]. Studies examining corneal densitometry changes after CXL in keratoconus differ in involved patients’ ages: some of these reports strictly contain adults over 18 years [ 12 , 15 , 36 , 37 ], whereas some of them involved patients under 18 years as well [ 11 , 13 , 38 ], although the presented tendencies in densitometry changes are similar. A recent study showed that in juvenile keratoconus patients significantly higher postoperative haziness can be observed after CXL compared to adults [ 39 ].…”

Section: Discussionmentioning

confidence: 99%

“…Since ’Cornea Densito’ software is available, the degree and location of corneal opacities can be quantified objectively in concentric rings and in different depth layers of the cornea. Several studies have demonstrated increased densitometry values after CXL in keratoconus patients [ 11 – 14 ], mainly in the anterior and middle layers and central rings. Previous studies have already evaluated correlations between densitometry values and postoperative outcomes [ 15 , 16 ], however no preoperative predictive factors of postoperative corneal haze formation have been yet identified after conventional CXL.…”

Section: Introductionmentioning

confidence: 99%

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Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study

et al. 2021

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Background Our aim was to determine associations of pachymetry, keratometry, and their changes with haze formation and corneal flattening after collagen cross-linking, and to analyse the relationship between postoperative haze and visual outcome. Methods Retrospective analysis was performed on 47 eyes of 47 patients with keratoconus using the Pentacam HR Scheimpflug camera before and 1, 3, 6 and 12 months after cross-linking. Corneal backscattered light values in grey scale unit were recorded in the anterior, center and posterior corneal layers and in four concentric rings. Surface area- and thickness-corrected grey scale unit values were assessed with an additional calculation. Friedman test with post hoc Wilcoxon signed-rank test was used to analyse changes in visual acuity, pachymetry, keratometry and densitometry. Spearman’s rank correlation test was used to detect correlations of haze formation and corneal flattening with pachymetry, keratometry and their postoperative change. Generalized estimating equations analysis was used to investigate the influence of densitometry values on postoperative visual acuity after controlling for the effect of preoperative keratometry. Results One year after treatment, significant flattening was observed in maximum and mean keratometry readings (p < 0.001). Significantly increased densitometry values were observed in three central rings compared to baseline (post hoc p < 0.0125). According to receiver operating characteristic curve, densitometry value of the anterior layer of 0–2 mm ring was the most characteristic parameter of densitometry changes after cross-linking (area under the curve = 0.936). Changes in haze significantly correlated with preoperative maximum keratometry (R = 0.303, p = 0.038) and with the changes in maximum keratometry (R = -0.412, p = 0.004). Changes in maximum keratometry correlated with preoperative maximum keratometry (R = -0.302, p = 0.038). Postoperative haze had a significant impact on uncorrected and best corrected distance visual acuity (β coefficient = 0.006, p = 0.041 and β coefficient = 0.003, p = 0.039, respectively). Conclusions Our findings indicate that in more advanced keratoconus more significant corneal flattening effect parallel with haze formation can be observed after cross-linking. Despite significant reduction of keratometry, postoperative corneal haze may limit final visual acuity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study

et al. 2021

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“…Higher energy parameters (up to an irradiance of 30 mW/cm 2 ) combined with shorter treatment time (3–10 mins) are utilized in accelerated corneal CXL to obtain the same total radiant energy of standard CXL. This accelerated protocol has shown promising results in stabilization of progressive keratoconus 13,14. The current study evaluated the 12-month results of accelerated CXL with a total dose of 7.2 J/cm 2 for cases of progressive keratoconus.…”

Section: Discussionmentioning

confidence: 99%

<p>Accelerated Epithelium-Off Corneal Collagen Cross-Linking For Keratoconus: 12-Month Results</p>

Omar¹,

Zein²

2019

OPTH

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PurposeThe main aim of the study was to report visual, refractive, topographic, and aberrometric results of accelerated CXL in patients with keratoconus who were followed for 12 months and to highlight the important parameters that can be used in follow-up.SettingsIt was a prospective interventional non-randomized case series study, in which 40 keratoconus eyes of 40 patients were studied in the period between April 2016 and July 2018.MethodsAll eyes were examined preoperatively and post-accelerated CXL to evaluate visual acuity, refractive state, keratometric values, keratoconus indices, and corneal higher order aberrations (HOAs).ResultsThe mean age of the studied patients was 28.4 ± 8.6 years (18–37years). One year after cross-linking, 11.6% of the eyes gained two lines of the UCVA, 26.4% of the eyes gained one line, 49.8% showed no change, 7.1% lost one line, and 5.1% lost two lines. Postoperative BCVA showed 13.7% of the eyes gained at least two lines, 32.5% gained one line, 49.9% had no change, and 3.9% lost one line. The keratometric values changed significantly after CXL; K1 decreased by a mean of 0.41D, K2 by 0.62D while Kmax by 1.57 D. The significant changes in keratoconus indices were in index of vertical asymmetry (IVA), index of surface variance (ISV), and keratoconus index (KI). Vertical coma, spherical aberrations, and trefoil decreased significantly at 12 months compared to baseline values (p = 0.04, 0.017, 0.025, respectively).ConclusionKeratoconus indices especially ISV, IVA, and KI along with HOAsparticularly vertical coma, spherical aberrations, and trefoil can add value beside keratometric readings in the follow-up of eyes treated with accelerated CXL.

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“…The need to compare the results obtained with the different protocols has required the setting of parameters apt to predict if the treatment is successful or not, as the changes in best-corrected visual acuity and K readings [ 20 ] or the changes in corneal density [ 21 ]. A parameter that today seems to satisfy the need of indirect predictor of effectiveness is the demarcation line [ 9 ], and various studies compare the effectiveness of different cross-linking protocols based on the demarcation line [ 11 , 12 , 13 , 22 ].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Demarcation Line after Epithelium-Off Iontophoresis Corneal Collagen Cross-Linking for Progressive Keratoconus

D’Oria

Puzo

Incandela

et al. 2021

JCM

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The aim of the study was to visualize and evaluate the characteristics and depth of the demarcation line with anterior segment optical coherence tomography (AS-OCT) after epithelium-off iontophoresis corneal collagen cross-linking (epi-off I-CXL). In this prospective, consecutive, single center study 18 eyes of 18 patients with keratoconus were involved. One month after epi-off I-CXL, all the patients underwent an AS-OCT scan to search for a demarcation line and its characteristics. The corneal stromal demarcation line was identified in all the eyes. Mean depth of the corneal stromal demarcation line was 261.8 ± 46.7 μm (range: 184 to 362 μm), at 56.7 ± 12% corneal depth. In conclusion, epi-off I-CXL determines a demarcation line that can be visualized with AS-OCT, which seems clearly distinguishable and similar to that created in standard CXL.

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The effects of collagen cross-linking on corneal density: a comparison between accelerated and conventional methods

Cited by 8 publications

References 18 publications

Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study

Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study

<p>Accelerated Epithelium-Off Corneal Collagen Cross-Linking For Keratoconus: 12-Month Results</p>

Evaluation of Demarcation Line after Epithelium-Off Iontophoresis Corneal Collagen Cross-Linking for Progressive Keratoconus

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