One way to optimize Corneal Cross linking (CXL) !!

One way to optimize Corneal Cross linking (CXL) !!

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  one way tooptimize corneal cross linking !! Dr.Diyar jaafer C.A.B.(Ophth),FICO Ibn Alhaitham Teaching Eye Hospital
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  Financial Disclosure 2 There areno financial disclosures relevant to this presentation
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  CROSSLINKING (CXL) is atechnique which uses UV light and aphotosensitizer to strengthen chemical bonds in the cornea. In 1998, corneal collagen cross-linking was first proposed as a treatment modality to stabilize the ectatic cornea. The standard Dresden protocol entails UV-A treatment over a central 9 mm zone at an irradiance of 3.0 mW/cm2 for 30 min, delivering a fluence of 5.4 J/cm2 3
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  Patient Characteristics Predictiveof Corneal Flattening After Cross-linking ▪ For the same cross-linking parameters, variability in the change in Kmax predicted by: • Initial Kmax • Cone Location 5 Significant corneal flattening observed in 40% of cases. The only factor that was independently predictive of flattening was baseline Kmax of greater than 54.00 D Koller T, Pajic B, Vinciguerra P, et al. Flattening of the cornea after collagen crosslinking for keratoconus. J Cataract Refract Surg. 2011;37(8):1488–92. The only evaluated factors independently predictive of improvement after CXL were CDVA of 20/40 or worse, or KMax of 55.00 D or greater. Greenstein S a, Hersh PS. Characteristics influencing outcomes of corneal collagen crosslinking for keratoconus and ectasia: Implications for patient selection. J Cataract Refract Surg. 2013;39(8):1133–40 Baseline KMax was not predictive of cross- linking outcome in this study. However, a more eccentric cone was associated with steeper keratometry at 1 year follow-up. Wisse RPL, Godefrooij D a, Soeters N, et al. A Multivariate Analysis and Statistical Model for Predicting Visual Acuity and Keratometry One Year After Cross-linking for Keratoconus. Am J Ophthalmol. 2014;157(3):519–525.e2
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  Major drawback : ▪1. Time ▪ 2. Epi. Off related complication 6
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  Epi. off VSEpi. on 7 Gray
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  But Epi. Onstill in mind….. 8
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  1. chemical modificationsto riboflavin, such as addition of enhancers (EDTA, benzalkonium chloride or 20% alcohol),Ricrolin TE®, which combines two enhancers: amino alcohol and EDTA. 2. the iontophoresis technique, a noninvasive procedure during which a low-intensity electric current is applied to enhance the penetration of riboflavin into the stroma, stands out as being as efficient as conventional application of riboflavin, based on a pre-clinical study 9
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  Giuliano Scarcelli, PhD,and colleagues who evaluated the mechanical properties of keratoconic corneas using tissue removed during keratoplasty Using Brillouin optical microscopy, they showed mechanical loss was generally localized to the area of the cone, whereas outside the cone the Brillouin shift was similar to that measured in healthy control eyes concept of performing customized CXL arose from findings of biomechanical modeling undertaken by Abhijit Sinha Roy, PhD, and William J. Dupps Jr., MD, PhD, who proposed that the biomechanical change in keratoconus is focal, not generalized 10
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  12 One way tooptimize corneal CXL : Customize it
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  Customized CXL isa tomography-guided procedure that focuses the treatment on the weak area of the keratoconic cornea. The procedure, which Avedro has been marketing as CuRV, is performed using a proprietary adjustable ultraviolet A light device (Mosaic System, Avedro) that features an integrated eye tracker and enables projection of customized irradiation patterns with customized energy profiles onto the cornea . In C-CXL, the corneal stroma is soaked with a riboflavin solution before exposure to a uniform beam of UV-A radiation. Targeting the CXL procedure to stiffen this area specifically represents an interesting strategy to redistribute biomechanical stresses in the cornea Transition headline 13
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  Customized CXL for treatment ofKeratoconus Prof.Theo Seiler Prospective evaluation of customized CXL versus conventional cross-linking 10 minute VibeX Rapid Soak 10mW/cm2 continuous illumination in custom group Concentric superimposed circular zones applied Treatment zone centered on posterior float Treatment doses ranging from 5.4 to 10 J Dresden CXL in conventional group 14
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  ▪ inner circle:total energy applied 10J/cm2 – shortest diameter of PF – 0.5mm intermediate circle: total energy applied 7.2J/cm2 – average diameter of outer/inner circle outer circle: total energy applied 5.4J/cm2 - maximal diameter of PF + 1.0 mm . 15
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  16 p-valuestandard CXL customized CXL 0.03-0.9 ± 1.3-1.7± 2.0Δ Kmax [D] 0.034.1 ± 3.15.2 ± 2.7regularization index [D] 0.023.19 ± 0.732.56 ± 0.5epithelial healing time [days] 0.22-0.04 ± 0.14-0.07 ± 0.20Δ -logMAR significant differences in 1 year changes between groups
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  Evolutive keratoconus treatedby customized topography-guided corneal cross-linking: clinical results Author:M.Cassagne FRANCE CoAuthor(s): K.Pierne S.Galiacy P.Fournie F.Malecaze Acustomized CXL technique for keratoconus that concentrates on the area of the cone shows promise for stabilizing the cornea and for improving vision. François Malecaze, MD, PhD; and Kévin Pierné, FRCOphth 17 Customized CXL for treatment of Keratoconus Cosimo Mazzotta, Antonio Moramarco, Claudio Traversi, Stefano Baiocchi, Alfonso Iovieno, and Luigi Fontana Italian Multicenter Study of Customized CXL for Treatment of Keratoconus
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  Look For : 18 1.Epithelial healing 2. Maximum keratometry Mean change in Kmax for the customized and standard groups was –1.7 D and –0.9 D
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  3. Corneal reshaping.the mean regularization index values for the two groups were 5.2 D and 4.1 D, 4. Visual acuity .CDVA improved to 0.2648 ±0.2574 logMAR (P=.104) in the C-CXL eyes, compared with 0.2162 ±0.2495 logMAR (P<.05) in the TG-CXL eyes 5. Safety 6. Nerve and cell density 7. demarcation line depth 19
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  20 PiXL customized crosslinking induceschanges in corneal curvature by adding strength. The application of customized U-VA illumination patterns for the treatment of refractive error through zone-specific crosslinking has been termedphotorefractive intrastromal crosslinking, or PiXL
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  21 AT A GLANCE •Biomechanical analyses of keratoconic corneas have shown that weakening is concentrated within the area of the cone. • Targeting the CXL procedure to stiffen the area of the keratoconic cone specifically represents one strategy to redistribute biomechanical stresses in the cornea. • Topography-guided CXL has been shown to induce a flattening effect that is greater than the effect of conventional CXL and also produce a gradient in the biological response to treatment from the area of the cone to the surrounding area.
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