Corneal crosslinking by an argon-fluorine excimer laser

2021 ◽  
pp. 35-38
Author(s):  
I.M. Kornilovskiy ◽  
Keyword(s):  
Excimer Laser ◽  
Ablation Threshold ◽  
Objective Assessment ◽  
Corneal Stroma ◽  
Radiation Energy ◽  
Secondary Radiation ◽  
Cross Linking ◽  
Negative Effects ◽  
Corneal Crosslinking ◽  
Clinical Observations

Purpose. To substantiate the expediency of using ablative and subablative energy densities of an argon-fluorine excimer laser for corneal crosslinking. Material and methods. In the period from 1 month to 6 years, the results of more than 500 photorefractive and phototherapeutic operations with saturation of the cornea with riboflavin and the effect of crosslinking were analyzed. To activate riboflavin, secondary radiation was used, induced by the use of ablative and subablative energy densities of an argon-fluorine excimer laser. For an objective assessment of the effect of excimer laser crosslinking, we used the techniques of computed keratotopography, aberrometry, optical coherence tomography, and densitometry. Results. Clinical observations have shown that in most cases of photorefractive surgery of the cornea for the prevention of keratoectasias, it is sufficient to carry out ablation after saturation of the corneal stroma with 0.25% isotonic riboflavin solution for 3-10 minutes, depending on the degree of ametropia and the volume of tissue removed. This provided photoprotective protection of deeper stromal structures from the negative effects of ablation-induced secondary radiation. At the same time, upon completion of ablation, secondary radiation initiated the effect of crosslinking in the adjacent layers, which did not violate the elastic properties of the cornea. In a number of cases, the cross-linking effect was enhanced by additional exposure to energy densities below the ablation threshold and the formation of a Bowman-like membrane structure on the ablation surface. For keratoconus and corneal pathology, without and in combination with keratoectasia, the technology of therapeutic cross-linking was used. This technology provided for the saturation of the stroma with 0.1% or 0.25% isotonic riboflavin solution and its activation by subablative radiation energy densities of an argon-fluorine excimer laser. During therapeutic crosslinking, according to OCT and densitometry, all the classic signs of traditional corneal crosslinking were revealed. Conclusion. The radiation of an argon-fluorine excimer laser with the use of ablative pulse energy densities can be recommended for prophylactic crosslinking in all cases of corneal thinning during photorefractive surgeries, while the use of energy densities below the ablation threshold allows for therapeutic crosslinking in keratoconus and corneal ectasias of various etiology. Key words: excimer laser crosslinking, cornea, keratoconus, photorefractive ablation, riboflavin.

scholarly journals New Possibilities of Refractive Modeling of the Cornea by the Radiation of an Argon-fluorine Excimer Laser

2021 ◽  
pp. 7-18
Author(s):  
I. M. Kornilovskiy
Keyword(s):  
Excimer Laser ◽  
Clinical Studies ◽  
Ablation Threshold ◽  
Objective Assessment ◽  
Corneal Stroma ◽  
Strength Properties ◽  
Secondary Radiation ◽  
Total Radiation Dose ◽  
Corneal Nerves ◽  
Negative Effect

Purpose: To consider new possibilities of refractive modeling of the cornea by the radiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin. Materials and Methods: Experimental (20 pork, 90 rabbit eyes) and clinical studies on photorefractive and phototherapeutic operations with saturation of the corneal stroma with riboflavin (610 operations) were analyzed. To activate riboflavin, secondary radiation induced by exposure to ablative and subablative energy densities was used. A quick transition to energy densities below the ablation threshold without additional calibrations was carried out using a “Microscan Visum-500” excimer laser (Optosystems, Russia). An objective assessment of the refractive keratomodelling effect and visual results was carried out according to the data of complex optometric studies. Results: Experimental and clinical studies have shown the advantages of refractive keratomodeling by theradiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin. Isotonic 0.25% riboflavin solution did not affect the accuracy of refractive ablation and blocked the negative effect of induced secondary radiation on keratocytes and corneal nerves. This reduced the aseptic inflammatory response and the risk of developing an irreversible form of fibroplasia. Ablation with riboflavin initiated a damped crosslinking effect, which increased the photoprotective and strength properties of the thinned cornea. A refractive keratomodelling effect was found when energy densities were applied below the stromal ablation threshold. The magnitude of this refractive effect depended on the total radiation dose and the topography of the affected area. This approach made it possible to implement laser-induced refractive keratomodeling without ablation of the corneal stroma. Conclusion: Refractive modeling of the cornea by the radiation of an argon-fluorine excimer laser in ablative and subablative modes after saturation of the stroma with riboflavin opens up new possibilities in laser correction of ametropia.

Photoablation with riboflavin as an alternative to the application of Mitomycin-C in excimer laser corneal surgery

2021 ◽  
pp. 24-27
Author(s):  
I.M. Kornilovskiy ◽  
Keyword(s):  
Visual Acuity ◽  
Mitomycin C ◽  
Excimer Laser ◽  
Laser Surgery ◽  
Membrane Structure ◽  
Cross Linking ◽  
Ablation Zone ◽  
Corneal Surgery ◽  
Clinical Observations ◽  
Decrease In Visual Acuity

Purpose. To substantiate the advantages of photoablation with riboflavin as an alternative to the use of Mitomycin-C in excimer laser surgery of the cornea. Material and methods. The work is based on clinical observations of the results of 598 photorefractive and phototherapeutic operations. In all cases, keratoablation was performed after drip, aerosol, or combined saturation of the stroma with 0.1% or 0.25% isotonic riboflavin solution. Corneal OCT was performed on RTVue 100 and RTVue XR100 devices. Keratotopographic and densitometric studies were performed on a TMS-5 device. Results. With photokeratoablation of the stroma saturated with riboflavin, the response aseptic inflammatory and regenerative reactions, the severity and duration of the corneal syndrome decreased. In densitometry and OCT studies, an increase in optical density was noted with the formation of a membrane structure on the ablation surface and the effect of cross-linking in the stromal layers adjacent to the ablation zone. Shielding of induced secondary radiation by riboflavin and the formation of a Bowman-like membrane structure made it possible to avoid the development of an irreversible form of fibroplasia and a decrease in visual acuity. The formed membrane structure with cross-linking in the underlying stromal layers was a barrier between pro-inflammatory epithelial and stromal cytokines, which predetermine the development of fibroplasia during photokeratoablation. Conclusion. Photokeratoablation with riboflavin prevents the development of an irreversible form of fibroplasia and can be considered as an alternative to the use of Mitomycin-C in photorefractive and phototherapeutic operations on the cornea by radiation from an argon-fluorine excimer laser. Key words: Mitomycin-C, riboflavin, fibroplasia, excimer laser corneal surgery, laser-induced crosslinking.

scholarly journals Severe Corneal Morphological Alterations after Excimer Laser Surface Ablation for a High Astigmatism

2021 ◽  
pp. 492-496
Author(s):  
Anna M. Roszkowska ◽  
Giovanni W. Oliverio ◽  
Giuseppe A. Signorino ◽  
Mario Urso ◽  
Pasquale Aragona
Keyword(s):  
Excimer Laser ◽  
Corneal Stroma ◽  
Corneal Topography ◽  
Laser Surface ◽  
Slit Lamp ◽  
Slit Lamp Examination ◽  
Morphological Alterations ◽  
Surface Ablation ◽  
Confocal Images

We report long-term alterations of anterior corneal stroma after excimer laser surface ablation for a high astigmatism. The patient claimed progressive visual loss in his right eye (RE) during the last 3 years after bilateral laser-assisted subepithelial keratectomy (LASEK) surgery. His examination comprised visual acuity (UDVA and CDVA), slit-lamp examination, corneal topography and tomography, AS-OCT, and confocal microscopy. The UDVA was 0.1 in his RE and 1.0 in the left eye. The CDVA in the RE was 0.8. The slit-lamp examination showed a stromal lesion in the inferior paracentral corneal zone, with multiple vertical tissue bridges and severe thinning. Corneal topography and tomography showed central flattening with inferior steepening and severe alteration in elevation maps. AS-OCT showed void areas in the anterior stroma with thinning of the underlying tissue, and confocal images were not specific. In this case, progressive corneal steepening and thinning that manifest topographically as inferior ectasia occurred in correspondence to the singular stromal alterations after LASEK.

scholarly journals Amnwiotic Membrane Transplantation as a Treatment for Sterile Infiltration and Corneal Melting after Corneal Crosslinking for Keratoconus

2018 ◽  
Vol 9 (1) ◽  
pp. 185-189 ◽  
Author(s):  
Takanori Sasaki ◽  
Takeshi Ide ◽  
Ikuko Toda ◽  
Naoko Kato
Keyword(s):  
Visual Acuity ◽  
Diclofenac Sodium ◽  
Corneal Stroma ◽  
Amniotic Membrane Transplantation ◽  
Eye Drops ◽  
Epithelial Defect ◽  
Persistent Epithelial Defect ◽  
Corneal Crosslinking ◽  
Corneal Epithelial Defect ◽  
Corneal Melting

We report a case of corneal melting through sterile infiltration presumably due to excessive use of nonsteroidal anti-inflammatory eye drops after corneal crosslinking (CXL). It was treated using steroids combined with amniotic membrane transplantation (AMT). A 33-year-old man with progressing keratoconus underwent left eye CXL. We prescribed betamethasone and levofloxacin eye drops 5 times daily and diclofenac sodium eye drops 3 times daily for 3 days. Three days after CXL, there was a persistent epithelial defect and the left corneal stroma was clouded. His visual acuity remained unchanged. We prescribed betamethasone hourly and 20 mg prednisolone daily. At 1 week after CXL, the corneal epithelial defect and infiltration were unchanged. He had not stopped using diclofenac at the prescribed time. On day 17, we performed AMT and his cornea and visual acuity improved. AMT may be effective against persistent epithelial defects and corneal melting after CXL.

scholarly journals Corneal Cross-linking in Combination with Intracorneal Ring Segments

2017 ◽  
Vol 6 (2) ◽  
pp. 92-96
Author(s):  
Aylin Kiliç
Keyword(s):  
Visual Acuity ◽  
Cross Linking ◽  
Corneal Crosslinking ◽  
Distance Visual Acuity ◽  
Corrected Distance Visual Acuity ◽  
Ring Segment

ABSTRACT The goal of ring segment surgery is to reduce the degree of myopia and astigmatism, improving uncorrected and corrected distance visual acuity. The crosslinking is a procedure used for stabilizing the cornea in patients with progressive keratoconus. Corneal crosslinking surgery and combination of an intracorneal ring segments seems to be as effective for corneal stability and refractive improvement in keratoconic eyes. How to cite this article Kiliç A. Corneal Cross-linking in Combination with Intracorneal Ring Segments. Int J Kerat Ect Cor Dis 2017;6(2):92-96.

Outcomes of Simultaneous and Sequential Cross-linking With Excimer Laser Surface Ablation in Keratoconus

2018 ◽  
Vol 34 (10) ◽  
pp. 690-696 ◽  
Author(s):  
Ahmed Shalaby Bardan ◽  
Hanbin Lee ◽  
Mayank A. Nanavaty
Keyword(s):  
Excimer Laser ◽  
Laser Surface ◽  
Cross Linking ◽  
Surface Ablation
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