Correlation of the Corneal Collagen Cross-Linking Demarcation Line Using Confocal Microscopy and Anterior Segment Optical Coherence Tomography in Keratoconic Patients

doi:10.1016/j.ajo.2013.09.010

American Journal of Ophthalmology

Volume 157, Issue 1, January 2014, Pages 110-115.e1

https://doi.org/10.1016/j.ajo.2013.09.010 Get rights and content

Purpose

To evaluate and compare the depth of the corneal stromal demarcation line after corneal collagen cross-linking (CXL) using 2 different methods: confocal microscopy and anterior segment optical coherence tomography (AS OCT).

Design

Prospective, comparative, interventional case series.

Methods

Seventeen patients (18 eyes) with progressive keratoconus were enrolled. All patients underwent uneventful CXL treatment according to the Dresden protocol. One month after surgery, corneal stromal demarcation line depth was measured in all patients by 2 independent observers using confocal microscopy and AS OCT.

Results

Mean corneal stromal demarcation line depth measured using confocal microscopy by the first observer was 306.22 ± 51.54 μm (range, 245 to 417 μm) and that measured by the second observer was 303.5 ± 46.98 μm (range, 240 to 390 μm). The same measurements using AS OCT were 300.67 ± 41.56 μm (range, 240 to 385 μm) and 295.72 ± 41.01 μm (range, 228 to 380 μm) for the first and second observer, respectively. Pairwise comparisons did not reveal any statistically significant difference between confocal microscopy and AS OCT measurements for both observers (P = .3219 for the first observer and P = .1731 for the second observer).

Conclusions

Both confocal microscopy and AS OCT have similar results in evaluating the depth of the corneal stromal demarcation line after CXL.

Section snippets

Methods

Institutional Review Board approval from University of Crete for this prospective study was obtained, and all patients were informed appropriately before their participation in the study and gave written informed consent in accordance with institutional guidelines, according to the tenets of the Declaration of Helsinki.

Results

No intraoperative or postoperative complications were observed in any of the patients. Mean patient age was 27.76 ± 7.43 years (range, 20 to 45 years). Mean keratometric readings of the patients before surgery were 44.37 ± 3.25 D (range, 36.74 to 50.92 D) and 48.54 ± 3.79 D (range, 41.9 to 55.42 D) for flat and steep keratometric readings, respectively. Mean preoperative corneal pachymetry was 457.1 ± 28.88 μm (range, 405 to 525 μm). Corneal depth of the transition area between the acellular

Discussion

CXL is a minimally invasive surgical treatment used to strengthen the tissue of the ectatic cornea and to halt the keratoconus progression.1, 2 CXL treatment is based on a photochemical reaction between riboflavin (vitamin B₂) and UVA. Riboflavin is a photosensitizer that is excited into its triplet state when irradiated, generating reactive oxygen species.¹ Reactive oxygen species can react further with various molecules, inducing chemical covalent bonds bridging amino groups of collagen

George D. Kymionis, MD, PhD, is an Assistant Professor in University of Crete, Department of Ophthalmology and voluntary Assistant Professor at the University of Miami, Bascom Palmer Eye Institute. He was the first who introduced combined transepithelial phototherapeutic keratectomy during corneal collagen cross-linking technique (Cretan Protocol). He also performed the first DMEK in Greece and the first bilateral pediatric DSEK worldwide.

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Citation Excerpt :
However, these studies did not focus on correlations between early mid-stromal densitometry changes and intermediate-term therapeutic outcomes. Our findings support those in the existing literature regarding the intermediate-term improvement in corneal HOAs after CXL, with significant improvements in coma, spherical aberration, and total HOAs.2,9,5,18 Corneal HOAs have been independently correlated with visual acuity; however, the degree of change has not been correlated with the improvement in visual acuity.8,9,19
To characterize changes in densitometry after corneal crosslinking (CXL) and correlate it with visual outcomes.
Tertiary referral academic medical center, New York, New York, USA.
Retrospective case series.
Patients with progressive keratoconus or post-laser in situ keratomileusis ectasia had CXL following the Dresden protocol. The corrected distance visual acuity (CDVA) and Pentacam imaging were obtained at baseline and follow-up visits.
Fifty-seven patients were followed for a mean of 15 months (range 1 to 24 months) after CXL. The CDVA improved significantly from baseline to 6, 12, 18, and 24 months postoperatively. The change in densitometry of the mid-stromal layer, 2.0 to 6.0 mm annulus, at 6 months was correlated with the improvement in CDVA at 6, 12, and 24 months (all P < .10). The increase in densitometry of the mid-stromal layer, centermost 0.0 to 2.0 mm annulus, at 6 months was significantly associated with the decrease in maximum keratometry (K) at 6 and 12 months (both P < .05). Last, the change in densitometry at 6 months was significantly correlated with the decrease in specific higher-order aberrations (HOAs) (P < .05).
Although the greatest and most durable post-CXL densitometry change was in the anterior layer, the degree of increased densitometry haze in the mid-stromal layer was most associated with and possibly predictive of improvement in CDVA, maximum K, and HOAs. The persistence of corneal haze at 6 months, measured by increased densitometry, might be a prognostic marker for CXL effectiveness.
Mechanical versus transepithelial phototherapeutic keratectomy epithelial removal followed by accelerated corneal crosslinking for pediatric keratoconus: Long-term results
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Citation Excerpt :
In the transepithelial PTK epithelium removal group, the demarcation line was of a similar depth. Recently, there has been a debate on whether the depth of the corneal stromal demarcation line is a true indicator of the efficacy of CXL.30 In the present study, we did not measure the demarcation line in either group, which could be a limitation of our study.
To compare the 36-month outcomes of mechanical or transepithelial phototherapeutic keratectomy (PTK) epithelial removal before accelerated corneal crosslinking (CXL) for pediatric keratoconus.
Atatürk Training and Research Hospital, Ankara, Turkey.
Retrospective case series.
Eyes that had accelerated CXL after mechanical (Group 1) or transepithelial PTK (Group 2) epithelial removal were evaluated preoperatively and 12, 24, and 36 months postoperatively. The uncorrected (UDVA) and corrected distance visual acuities, spherical equivalent (SE), manifest astigmatism, and corneal tomographic and aberrometric parameters were assessed.
The study included 40 eyes of 35 consecutive keratoconus patients younger than 18 years with a 36-month follow-up. Group 1 comprised 15 patients, and Group 2 comprised 20 patients. Both groups had a significant improvement in UDVA (P = .001 and P = .02, respectively) and a significant decrease in maximum keratometry (K) and thinnest corneal thickness (all P < .001) 36 months postoperatively. The improvements in maximum K, topographic astigmatism, and spherical aberration were greater in Group 2 than in Group 1 at 12 months (P = .03, P = .01, and P = .04, respectively). After 12 months, the outcomes in the 2 groups were more similar.
The initial visual and topographic outcomes of transepithelial PTK ablation were better than those of mechanical epithelium removal before accelerated CXL in pediatric patients with keratoconus. Over the long-term, the results were similar between the 2 groups.
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Original articleCorrelation of the Corneal Collagen Cross-Linking Demarcation Line Using Confocal Microscopy and Anterior Segment Optical Coherence Tomography in Keratoconic Patients

Purpose

Design

Methods

Results

Conclusions

Section snippets

Methods

Results

Discussion

Am J Ophthalmol

Ophthalmology

Ophthalmology

Am J Ophthalmology

J Cataract Refract Surg

J Cataract Refract Surg

J Cataract Refract Surg

J Cataract Refract Surg

Crosslinking treatment of progressive keratoconus: new hope

Curr Opin Ophthalmol

Original article
Correlation of the Corneal Collagen Cross-Linking Demarcation Line Using Confocal Microscopy and Anterior Segment Optical Coherence Tomography in Keratoconic Patients