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

Richoz, Olivier; Arba-Mosquera, Samuel; Kling, Sabine; Hammer, Arthur; Magnago, Thomas; Bosch, Martina M.; Hafezi, Farhad

doi:10.3928/1081597x-20140815-03

Cited by 13 publications

(5 citation statements)

References 38 publications

(41 reference statements)

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“…3) showed an intercept of −1.2213D consistent with the mean deviation from target of +1.09 ± 2.36D. These results may eventually be explained by the effects of CXL therapy on progressive corneal flattening, but also the potential effects of the CXLed tissue on ablation rate 31, 32, 33. Some groups31, 32 have reported reduced ablation rate in CXL corneas opposed to our clinical findings 33 .…”

Section: Discussionsupporting

confidence: 77%

“…These results may eventually be explained by the effects of CXL therapy on progressive corneal flattening, but also the potential effects of the CXLed tissue on ablation rate 31, 32, 33. Some groups31, 32 have reported reduced ablation rate in CXL corneas opposed to our clinical findings 33 . Another explanation could be that the flattening of the cornea is simply due to the conus ablation which may not be well computed by the programme as it is complex to forecast this data.…”

Section: Discussionmentioning

confidence: 58%

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Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

Camellin¹,

Guidotti²,

Arba-Mosquera

2017

Journal of Optometry

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PurposeTo evaluate the efficacy and safety of Corneal-Wavefront guided transepithelial photorefractive keratectomy (TransPRK) after corneal collagen cross linking (CXL) in keratoconic patients.MethodsIn this retrospective, non-comparative, consecutive case series, 39 keratoconic eyes underwent Corneal-Wavefront guided TransPRK for the correction of aberrations at least 4 months after conventional CXL at SEKAL Rovigo Microsurgery Centre, Rovigo, Italy. Two eyes (5%) underwent a secondary laser retreatment for the improvement of post-operative visual acuity and were not included in this retrospective analysis. The mean age of the patients was 35 ± 12 years (19–64 years) at the time of the surgery. Keratron-Scout (Optikon) topographer was used for diagnostic tests and a flying-spot laser (AMARIS; SCHWIND eye-tech-solutions) was used for the refractive surgery. Complete ophthalmic examinations were performed before and after the surgery (4–36 months postoperatively with a mean follow up time of 10 ± 8 months).ResultsPreoperatively, eyes showed irregular astigmatism up to 8D. At last postoperative follow-up, 21 eyes (57%) had UDVA better than 20/40, and six eyes (16%) had UDVA of 20/20. Twenty-three eyes (62%) were within 1.50D of attempted correction in spherical equivalent (mean deviation from target was +1.09 ± 2.36D, range −2.50 to +7.38D). No eye lost 2 Snellen lines of CDVA, and 15 eyes (41%) had an increase of more than 2 lines.ConclusionsCorneal-Wavefront guided transepithelial PRK ablation profiles after conventional CXL yields to good visual, optical, and refractive results. These treatments are safe and efficacious for the correction of refracto-therapeutic problems in keratoconic patients.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 58%

Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

Camellin¹,

Guidotti²,

Arba-Mosquera

2017

Journal of Optometry

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“…Both groups found similar reductions of the ablation rate per pulse of 9% 20 and 12%,109 for the first 200 µm of stromal tissue. These results should allow for nomogram adjustments for cross-linked corneas 120. …”

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confidence: 94%

Corneal cross-linking

Randleman

Khandelwal

Hafezi

2015

Survey of Ophthalmology

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164

113

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Since its inception in the late 1990s, corneal cross-linking has grown from an interesting concept to a primary treatment for corneal ectatic disease worldwide. Using a combination of ultraviolet-A light and a chromophore (vitamin B2, riboflavin), the cornea can be stiffened, usually with a single application, and progressive thinning diseases such as keratoconus arrested. Despite being in clinical use for many years, some of the underlying processes, such as the role of oxygen and the optimal treatment times, are still being worked out. More than a treatment technique, corneal cross-links represent a physiological principle of connective tissue, which may explain the enormous versatility of the method. We highlight the history of corneal cross-linking, the scientific underpinnings of current techniques, evolving clinical treatment parameters, and the use of cross-linking in combination with refractive surgery and for the treatment of infectious keratitis.

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“…Whether the wavefront-guided approaches are performed as total wavefront or (anterior) corneal wavefront procedures depend on the individual tomography and the amount of tissue ablation needed. It is important to note that laser ablation depth in cross-linked stromal tissue is 12% less than in noncross-linked tissue [61]. Some surgeons prefer to perform both procedures in a single session (laser surgery, followed by CXL [62][63][64][65][66][67], whereas others prefer to perform the CXL procedure first, then wait (at least 6 months) to perform the laser procedure, after manifest and keratometric astigmatism have stabilized [62,68,69].…”

Section: Corneal Cross-linking Combined With Laser Surgerymentioning

confidence: 99%

Section: Corneal Cross-linking Combined With Laser Surgerymentioning

confidence: 99%

Expanding indications for corneal cross-linking

Hafezi

Torres-Netto

Hillen

2023

Current Opinion in Ophthalmology

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Purpose of reviewThe aim of this study was to summarize the recent developments in corneal cross-linking (CXL) and its indications, including corneal ectasias, refractive surgery and infectious keratitis. Recent findingsAdvances in CXL technology, such as the use of higher-intensity LED ultraviolet (UV) light sources and a better understanding of the UV-riboflavin photochemical reaction, have enabled safer and more effective methods of cross-linking thin and ultra-thin corneas, and more effective accelerated transepithelial/'epi-on' CXL procedures that are beginning to supplant the Dresden protocol as the 'gold standard' CXL method. CXL is also being used in combination with laser surgery, not only to expand the patient base who can receive refractive surgery, but also to help rehabilitate vision in patients with ectasia. CXL, and CXL combined with photorefractive keratectomy (PRK), can result in corneal flattening of 1--2 D, and corneal regularization of 4--5 D, respectively. Finally, photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) has been shown to be an effective therapy for infectious keratitis, both alone, and in combination with antimicrobial drugs. SummaryCXL has evolved from a single technique to treat a single corneal ectasia, keratoconus, to several techniques with several indications, spanning a spectrum of corneal ectasias, as well as visual rehabilitation, refractive procedures and infectious keratitis treatment.

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

Abstract: PURPOSE: To evaluate the need for and quantify the extent of nomogram adjustments to compensate for potential changes in the amount of effective corneal stroma ablated in previously cross-linked corneas.

Cited by 13 publications

References 38 publications

Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

Corneal cross-linking

Expanding indications for corneal cross-linking

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