Evaluation of Corneal Stromal Demarcation Line Depth in Epithelium-Off Standard, Epithelium-Off Accelerated and Transepithelial Cross-Linking in Keratectasia

Aim. This is a prospective interventional clinical trial to assess the depth of the demarcation line in transepithelial versus epithelium-off accelerated corneal cross-linking (AXL) in keratoconus patients. Methods. This prospective clinical trial was conducted on 40 eyes of 20 patients. Each patient had transepithelial AXL in one eye and epithelium-off AXL in the contralateral eye applying UVA light with an irradiance of 45 mW/cm2 for 2.4 minutes and 30 mW/cm2 for 4 minutes. The depth of the demarcation line was measured using anterior segment OCT (Topcon 3D OCT-2000) one month postoperative for both eyes. Results. The demarcation line was patchy in 50% of the transepithelial AXL eyes, the other half showing a demarcation line at a mean depth of 183 ± 41.6 μm. In the epithelium-off AXL technique, the demarcation line was well defined in all cases with a mean depth of 219 ± 27.3 μm. There was a statistically significant difference in corneal demarcation line depth between transepithelial and epithelium-off techniques (P = 0.008 and P < 0.05). The shallower demarcation line in the transepithelial group suggests that it is less effective. Conclusion. Based on the depth of the demarcation line, the cross-linking effect of epi-off AXL seems more efficacious than after transepithelial AXL. The future will show if the biomechanical effect will be sufficient to stop progression of keratoconus similarly after standard CXL. This trial is registered with NCT04045626.

Download Full-text

Intraobserver reproducibility and interobserver agreement of demarcation line depth measurements following corneal cross linking

European Journal of Ophthalmology ◽

10.1177/1120672119835116 ◽

2019 ◽

Vol 30 (4) ◽

pp. 635-642

Author(s):

Argyrios Tzamalis ◽

Riccardo Vinciguerra ◽

Vito Romano ◽

Esmaeil Arbabi ◽

Mark Batterbury ◽

...

Keyword(s):

Medical Students ◽

Confidence Interval ◽

Correlation Coefficient ◽

Intraclass Correlation Coefficient ◽

Intraclass Correlation ◽

Cross Linking ◽

Demarcation Line ◽

Line Depth ◽

Collagen Cross Linking ◽

Corneal Collagen

Purpose: The aim of this study was to evaluate the intraobserver reproducibility of demarcation line depth measurement in keratoconic patients after epithelium-off corneal collagen cross linking and assess the interobserver variability/agreement among examiners of various experience levels. Methods: 56 eyes of 56 patients undergoing corneal collagen cross linking for progressive keratoconus were enrolled. After 4 weeks, all patients underwent an anterior segment optical coherence tomography (AS-OCT; CASIA SS-1000; Tomey, Nagoya, Japan) in the cross-linked eye by four masked examiners (two medical students (S1 and S2) and two corneal fellows (F1 and F2)) in order to identify and measure the demarcation line depth in experienced and non-experienced users. The intraclass correlation coefficient and the coefficient of variation were calculated. Agreement between raters was evaluated using Bland–Altman plots, intraclass correlation coefficient and weighted-kappa statistics comparing raters in pairs. Results: The average demarcation line depth of all measurements was 254.34 ± 72.3 μm, varying from 84 to 459 μm. The intraclass correlation coefficient evaluating the reproducibility of measurements for F1 was 0.9379 (95% confidence interval (CI) =0.9035–0.9619), for the second (F2), it was 0.9837 (95% confidence interval = 0.9743–0.9901), while intraclass correlation coefficient between medical students was calculated 0.844. The overall intraclass correlation coefficient among all four observers was 0.8706 (95% confidence interval = 0.8061–0.9185). The coefficient of variation for repeated measurements was 5.981 μm (95% confidence interval = 3.966–7.471) and 3.312 μm (95% confidence interval = 2.468–3.981) for F1 and F2 raters, respectively. The percentage of demarcation line detection was 90.32%. Conclusion: The reproducibility of demarcation line measures although very good (intraclass correlation coefficient > 0.9), yielded a difference between the two experienced raters. Furthermore, the novice raters did not reach an excellent level of agreement with the expert ones showing greater variability in their recordings.

Download Full-text

Correlation of Demarcation Line Depth With Medium-Term Efficacy of Different Corneal Collagen Cross-Linking Protocols in Keratoconus

Cornea ◽

10.1097/ico.0000000000001733 ◽

2018 ◽

Vol 37 (12) ◽

pp. 1511-1516 ◽

Cited By ~ 3

Author(s):

Ali Mesen ◽

Banu Bozkurt ◽

Umit Kamis ◽

Suleyman Okudan

Keyword(s):

Cross Linking ◽

Medium Term ◽

Demarcation Line ◽

Term Efficacy ◽

Line Depth ◽

Collagen Cross Linking ◽

Corneal Collagen

Download Full-text

Corneal Collagen Cross-Linking Mushroom Shape Demarcation Line Profile After Limited Bowman’s Membrane Removal by Phototherapeutic Keratectomy

The Open Ophthalmology Journal ◽

10.2174/1874364101509010017 ◽

2015 ◽

Vol 9 (1) ◽

pp. 17-19 ◽

Cited By ~ 3

Author(s):

George D Kymionis ◽

Michael A Grentzelos ◽

Nektarios E Klados ◽

Niki A Xanthopoulou ◽

Theodore A Paraskevopoulos ◽

...

Keyword(s):

Line Profile ◽

Anterior Segment ◽

Cross Linking ◽

Demarcation Line ◽

Phototherapeutic Keratectomy ◽

Early Postoperative Complications ◽

One Year ◽

Line Depth ◽

Collagen Cross Linking ◽

Corneal Collagen

Purpose :To report a corneal collagen cross-linking (CXL) mushroom shape demarcation line profile after limited Bowman’s membrane removal by phototherapeutic keratectomy (PTK).Methods :Case report.Results :A twenty-one-year-old male with progressive keratoconus underwent mechanical epithelial debridement (at an 8.5 mm zone) followed by PTK (at a 5.0 mm zone and in a 10 μm depth) and CXL. No intra- or early postoperative complications were found. Evaluation of the corneal stromal demarcation line depth using anterior segment optical coherence tomography revealed a mushroom shape profile.Conclusion :It seems that removal of the Bowman’s layer leads to greater depth of the corneal stromal demarcation line.

Download Full-text