Optimization Model for UV-Riboflavin Corneal Cross-linking

Schumacher, Silvia; Mrochen, Michael; Wernli, Jeremy; Bueeler, Michael; Seiler, Theo

doi:10.1167/iovs.11-8059

Cited by 80 publications

(72 citation statements)

References 24 publications

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“…ACXL with pulsed (PL-ACXL) and continuous UV-A light illumination (CL-ACXL) reached the anterior midpart of the corneal stroma until a maximum of 240 mm and 200 mm of depth, respectively, measured from epithelium surface. This aspect assumes a physicochemical relevance because, as reported in literature, 31 the most important biomechanical effect related to crosslinking is concentrated in the anterior mid-stroma. To date, we do not know exactly the optimal interactions between UV-A energy, riboflavin concentration, and exposure time in order to obtain the maximum crosslinking effect ensuring a long-lasting (possibly a definitive) keratoconus biomechanical stability and the better functional outcome, even if the necessity to improve and shorten the procedure are highly desirable.…”

Section: Discussionmentioning

confidence: 91%

Pulsed vs continuous light accelerated corneal collagen crosslinking: in vivo qualitative investigation by confocal microscopy and corneal OCT

Mazzotta

Traversi

Caragiuli

et al. 2014

Eye

114

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Purpose To assess qualitative corneal changes and penetration of pulsed and continuous light accelerated crosslinking by in vivo confocal microscopy and corneal OCT. Methods A total of 20 patients affected from progressive keratoconus were enrolled in the study. Ten eyes of 10 patients underwent an epithelium-off pulsed-light accelerated corneal collagen crosslinking (PL-ACXL) by the KXL UV-A source (Avedro Inc.) with 8 min (1 s on/1 s off) of UV-A exposure at 30 mW/cm 2 and energy dose of 7.2 J/cm 2 ; 10 eyes of 10 patients underwent an epitheliumoff continuous-light accelerated corneal collagen crosslinking (CL-ACXL) at 30 mW/cm 2 for 4 min. Riboflavin 0.1% dextran-free plus hydroxyl-propyl-methylcellulose solution (VibeX Rapid, Avedro Inc.) was used for a 10-min corneal soaking. Treated eyes were examined by in vivo scanning laser confocal analysis and spectral anterior segment OCT at 1, 3, and 6 months. Results Epithelial stratification and nerves regeneration improved in time, being complete at month 6 in both groups without endothelial damage. Keratocyte apoptosis in PL-ACXL was estimated at a mean depth of B200 mm, whereas an uneven demarcation line was detectable by confocal microscopy at a mean depth of 160 mm in CL-ACXL. Conclusion In vivo confocal microscopy and corneal OCT allowed a precise qualitative analysis of the cornea after epithelium-off PL-ACXL and CL-ACXL treatments. Apoptotic effect was higher in pulsed than in continuous light treatments, exceeding 200 mm in corneal stroma. According to different morphological data, the clinical efficacy of ACXL needs to be determined in a long-term follow-up and large cohort of patients.

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Section: Discussionmentioning

confidence: 91%

Pulsed vs continuous light accelerated corneal collagen crosslinking: in vivo qualitative investigation by confocal microscopy and corneal OCT

Mazzotta

Traversi

Caragiuli

et al. 2014

Eye

114

View full text Add to dashboard Cite

show abstract

“…This aspect assumes a physicochemical relevance because, as reported in the literature [26], the most important biomechanical effect related to crosslinking is concentrated in the anterior midstroma. Anyway the penetration of accelerated crosslinking remains under the value of conventional procedure (300 μ m) at 3 mW/cm 2 for 30 minutes of UV-A exposure.…”

Section: Discussionmentioning

confidence: 99%

Pulsed Light Accelerated Crosslinking versus Continuous Light Accelerated Crosslinking: One-Year Results

Mazzotta

Traversi

Paradiso

et al. 2014

Journal of Ophthalmology

115

100

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Purpose. To compare functional results in two cohorts of patients undergoing epithelium-off pulsed (pl-ACXL) and continuous light accelerated corneal collagen crosslinking (cl-ACXL) with dextran-free riboflavin solution and high-fluence ultraviolet A irradiation. Design. It is a prospective, comparative, and interventional clinical study. Methods. 20 patients affected by progressive keratoconus were enrolled in the study. 10 eyes of 10 patients underwent an epithelium-off pl-ACXL by the KXL UV-A source (Avedro Inc., Waltham, MS, USA) with 8 minutes (1 sec. on/1 sec. off) of UV-A exposure at 30 mW/cm2 and energy dose of 7.2 J/cm2; 10 eyes of 10 patients underwent an epithelium-off cl-ACXL at 30 mW/cm2 for 4 minutes. Riboflavin 0.1% dextran-free solution was used for a 10-minutes corneal soaking. Patients underwent clinical examination of uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA), corneal topography and aberrometry (CSO EyeTop, Florence, Italy), corneal OCT optical pachymetry (Cirrus OCT, Zeiss Meditec, Jena, Germany), endothelial cells count (I-Conan Non Co Robot), and in vivo scanning laser confocal microscopy (Heidelberg, Germany) at 1, 3, 6, and 12 months of follow-up. Results. Functional results one year after cl-ACXL and pl-ACXL demonstrated keratoconus stability in both groups. Functional outcomes were found to be better in epithelium-off pulsed light accelerated treatment together with showing a deeper stromal penetration. No endothelial damage was recorded during the follow-up in both groups. Conclusions. The study confirmed that oxygen represents the main driver of collagen crosslinking reaction. Pulsed light treatment optimized intraoperative oxygen availability improving postoperative functional outcomes compared with continuous light treatment.

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“…The Lambert-Beer law states that the amount of light that penetrates through a substance is reduced along the distance the light travels due to the absorption of the material (described by the extinction coefficient). 25,26 Consequently, the CXL effect is diminished in the posterior cornea when compared to the anterior cornea. 10,27,28 Because of this, the stiffness gradient along the corneal thickness might be an important consideration when performing excimer ablation on previously cross-linked corneas.…”

Section: Discussionmentioning

confidence: 99%

Determination of the Excimer Laser Ablation Rate in Previously Cross-linked Corneas

Richoz¹,

Arba-Mosquera²,

Kling³

et al. 2014

J Refract Surg

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Optimization Model for UV-Riboflavin Corneal Cross-linking

Abstract: This theoretical model predicts the spatial distribution of increased stiffness by corneal cross-linking and, as such, can be used to customize treatment, according to the patient's corneal thickness and medical indication.

Cited by 80 publications

References 24 publications

Pulsed vs continuous light accelerated corneal collagen crosslinking: in vivo qualitative investigation by confocal microscopy and corneal OCT

Pulsed vs continuous light accelerated corneal collagen crosslinking: in vivo qualitative investigation by confocal microscopy and corneal OCT

Pulsed Light Accelerated Crosslinking versus Continuous Light Accelerated Crosslinking: One-Year Results

Determination of the Excimer Laser Ablation Rate in Previously Cross-linked Corneas

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