1,721,677 research outputs found
Customized Corneal Cross-Linking
No full textPersonalized accelerated crosslinking nomograms for the management of corneal ectasia were conceived after comparative analysis of demarcation lines and cell viability observed after customized accelerated epithelium-off crosslinking CXL treatments by spectral domain corneal OCT and scanning laser in vivo confocal microscopy matching all the clinical and instrumental data with mathematical models. Accelerated high-fluence Topography-guided CXL at 30 mW/cm2 UV-Power and Accelerated epithelium-off CXL with 9 and 15 mW/cm2 UV-A power with standardized Fluence of 5.4 J/cm2 were safe and effective demostrating a keratocytes apoptosis and demarcation line depth between 280 and 340 μm. The 30 mW ACXL showed a penetration with continuous and pulsed light between 150 and 200 μm. No endothelial damage was reported in any case. In vivo morphological studies demonstrated that Accelerated CXL allow a pachymetry-guided cutomization of CXL maintainig the standard Fluence of 5.4 J/cm2 and a total treatment time under 20 min. Moreover a pachymetry-guided ACXL nomogram (M nomogram) developed by Mazzotta C and Friedman M matching the physical and mathematical calculations with the miscostructural IVCM and OCT observations of demarcation lines depths allow an efficacous CXL management of primary and iatrogenic ectatic corneas also allowing a safe management of thin ectatic corneas
Review of SIRIO interferometer experimental results
Full text linkThe SIRIO (Scanning InfraRed Interferometer) interferometer [1], recently disassembled together with the FTU (Frascati Tokamak Upgrade) experiment [2], worked continuously from 2004 to 2019. An extremely important contribution was made in all the experiments conducted on this tokamak. By virtue of its characteristics, in terms of spatial (1 cm) and temporal resolution (density profiles every 62 μs), combined with its capability to scan the entire plasma column. This interferometer produced all the density feedbacks for operations. Above all, it collected accurate density measurements in plasma physics, among the best data of all tokamak interferometers. In this review, it is reported the highly valuable experimental work of this powerful diagnostics. Indeed, high density observations were analyzed, as well as fast variations were measured; some examples: the detection of plasma instabilities (MARFE), the trace and the speed of the pellets, the measurement of the particle transport efficiencies in important transients etc. In order to improve the knowledge for future interferometry in plasma density measurements projects, some topics related to data analysis are also exposed, as well as local density reconstruction methods
Customized epithelial debridement for thin ectatic corneas undergoing corneal cross-linking: epithelial island cross-linking technique
Full text linkCosimo Mazzotta,1 Vincenzo Ramovecchi2 1Unità Operativa Complessa di Oculistica, Siena University Hospital, Siena, Italy; 2Unità Operativa Complessa di Oculistica, San Severino Marche Hospital, San Severino Marche, Italy Abstract: Thin corneas with a minimum corneal thickness less than 400 µm after epithelial removal represent a contraindication to standard epithelium-off cross-linking (CXL) treatment due to a significant endothelial cell density decrease and potentiality of permanent haze development. Preoperative swelling of the cornea with hypoosmolar riboflavin solutions broadens the spectrum of CXL indications to thin corneas. However the iatrogenic swelling effect might not be durable throughout the CXL procedure increasing the risk of postoperative complications. The transepithelial CXL technique proposed for thin corneas demonstrated poor clinical results and mid- to long-term keratoconus instability. The epithelial island CXL technique with customized pachymetry-guided epithelial debridement was evaluated by means of in vivo laser scanning confocal microscopy, corneal topography, and clinical examination in a 1-year follow-up, in order to assess if it may be considered an alternative surgical option for keratoconic patients with thin corneas undergoing corneal collagen CXL. According to our clinical and in-vivo micro-morphological results the technique results safe, and efficacious in stabilizing progressive keratoconus and may be considered a valid option in the treatment of thin ectatic corneas alone or in combination with hypoosmolar or dextran-free riboflavin solutions. Keywords: cross-linking, keratoconus, thin corneas, epithelial island, surgical techniqu
Anterior acute uveitis report in a sars-cov-2 patient managed with adjunctive topical antiseptic prophylaxis preventing 2019-ncov spread through the ocular surface route
Full text linkPurpose: To report the clinical-epidemiological association between acute anterior uveitis and acute bilateral follicular conjunctivitis in a 30-year-old female patient who had tested positive for the SARS-CoV-2 RT-PCR. Methods: A 30-year-old female visited emergency ophthalmology care at the Siena Crosslinking Centre, Italy, for a bilateral eye redness lasting two weeks, associated with unilateral photophobia and blurred vision in her right eye. She visited on the 23rd of March 2020 in the full pandemic period and presented chills and fever with a temperature of 39.0°C, associated with complete loss of taste. Since eye examination findings, systemic symptoms and epidemiological criteria correlated with SARS-CoV-2 infection, she was referred to Siena University Hospital, Italy, for the SARS-CoV-2 nasopharyngeal buffer and haemato-logical examinations for uveitis. Results: Eye examination revealed bilateral conjunctival hyperaemia with acute follicular conjunctivitis associated with right eye acute anterior uveitis characterized by diffuse pigmentary and whitish immune precipitates over the anterior capsule of the crystalline lens and initial anterior lens opacity explaining the blurred vision. Adjunctive prophylactic eye topical treatment, included in the acronym SHYPIO (0.02% sodium hypochlorite solution, 0.6% povidone iodine eye-drops and 10.50% ozonized oil eye-drops), was associated with conventional uveitis therapy to prevent the virus spread through the ocular surface route. Conclusion: Our report demonstrates that complicated acute anterior uveitis (iridocyclitis) with blurred vision could be associated with SARS-CoV-2 infection, being potentially sight-threatening for early complicated lens opacity. Ophthalmologists examining suspected or asymptomatic patients should be aware of the risk of 2019-nCoV infection
Accelerated CXL: present and future
No full textConventional and accelerated CXL protocols have demonstrated medium- to long-term improvement in visual acuity and topographic and aberrometric parameters; however, the results are often variable and unpredictable due to the uneven biologic response of collagen to photodynamic reaction.
Early diagnosis of corneal ectasia is mandatory, especially in pediatric patients who generally demonstrate faster progression.
Today, the CXL therapeutic window allows treatment in about 20 minutes, with a good balance between efficacy and tolerability for the patient, optimizing the time of surgery without affecting treatment efficacy
Intraoperative corneal thickness measurement by optical coherence tomography in keratoconic patients undergoing corneal collagen cross-linking
No full textPurpose: To assess intraoperative variation of corneal thinnest point in keratoconic patients undergoing riboflavin/ultraviolet type A (UV-A) cross-linking treatment using noncontact time-domain optical pachymetry. • Design: Prospective, noncomparative interventional study. • Methods: Ten patients underwent epithelium-off riboflavin/UV-A corneal cross-linking at Siena University Hospital; corneal thickness was measured using optical coherence tomography at the following times: preoperatively with epithelium on; after removal of a 9-mm-diameter disc of epithelium; immediately after instillation of 2 drops of riboflavin 0.1%-dextran T 500 20% solution; after repeated instillation of riboflavin 0.1%-dextran T 500 20% solution every 2.5 minutes, at 10, 20, and 30 minutes of soaking time; at the end of the treatment after 30 minutes of UV-A exposure with the riboflavin biofilm in situ; and finally after washing the riboflavin biofilm. • Results: The most significant decrease in thinnest point measurement was detected meanly in the first 10 minutes of corneal soaking. In this interval, the minimum recommended in various studies, a mean reduction of -79.28 μm (-17.61% of initial thinnest point value after removal of the epithelium) was recorded. No adverse events were recorded. • Conclusions: The study demonstrates a statistically significant intraoperative reduction in corneal thinnest point value during epithelium-off cross-linking procedure using standard riboflavin 0.1%-dextran 20% solutions. Intraoperative optical pachymetry evaluation during cross-linking should be recommended before starting UV-A irradiation, and if a thickness under 380 μm is detected, the stroma should be reexpanded with hypotonic dextran-free riboflavin solutions
Confocal microscopy in corneal cross-linking
No full textConventional riboflavin ultraviolet A (UVA) corneal cross-linking (CXL) represents an evolving therapy for the conservative treatment of progressive keratoconus and secondary corneal ectasia. 1, 2 The physiochemical basis 3, 4 of conventional CXL lies in the photodynamic type I to II reactions induced by the interaction between 0.1% riboflavin molecules absorbed in corneal tissue and UVA rays delivered at a 5.4 J/cm2 energy dose for 30 minutes, releasing reactive oxygen species that mediate cross-link formation between and within collagen fibers, increasing biomechanical corneal resistance against ectasia and intrinsic anticollagenase activity. 5-7 Since 3mW/cm2 for 30 minutes conventional CXL procedure 8 requires a long time (about 50-60 minutes), 6 new high irradiance accelerated CXL (ACXL) treatment protocols based on the physical principles stated in Bunsen-Roscoe law of reciprocity have been recently investigated. According to the “equal-dose” principle stated in the Bunsen-Roscoe law, 10 mW/cm2 for 9 min, 18 mW/cm2 for 5 min, 30 mW/cm2 for 3 min or 45 mW/cm2 for 2 min at constant energy (E) dose of 5.4 J/cm2 may have the same photochemical impact as conventional CXL at 3 mW/cm2 for 30 minutes
Progressive high-fluence epithelium-on accelerated corneal crosslinking: a novel corneal photodynamic therapy for early progressive keratoconus
Full text linkPurpose: To assess the preliminary clinical results of a new, progressively higher fluence-pulsed light Epi-On accelerated crosslinking nomogram (PFPL M Epi-On ACXL) in the treatment of progressive keratoconus (KC). Setting: Siena Crosslinking Center, Siena, Italy. Methods: A prospective pilot open, non-randomized interventional study, including 32 eyes of 32 young-adult patients over 26 years old with Stages I-III progressive KC undergoing PFPL M Epi-On ACXL, was conducted. Riboflavin loading was performed by using Paracel I 0.25% for 4 min and Paracel II 0.22% for 6 min. The Avedro KXL System (Glaukos-Avedro, Burlington, USA) was used for pulsed-light accelerated crosslinking (ACXL) at air room 21% oxygenation and 13 min of UV-A irradiation. The treatment fluence was set at 7.2 J/cm2, 8.6 J/cm2, and 10.0 J/cm2 in corneas with baseline pachymetry <420 μm (group 1: 8 eyes), ≥ 420 μm <460 μm (group 2, 11 eyes), and ≥ 460 μm (group 3, 13 eyes), respectively. Uncorrected distance visual acuity (UDVA), best-spectacle corrected visual acuity (BSCVA), Scheimpflug corneal tomography, and anterior segment OCT (AS-OCT) data were collected at baseline and postoperatively at 1, 3, and 6 months. Results: UDVA and BSCVA improved in all groups (P ≤ 0.05). Maximum keratometry values (K max) showed a significant decrease in the 10.0 J/cm2 group (Δ −1.68 D). The coma (HOAs) value improved significantly by the sixth month in all groups. OCT average demarcation lines were 211 ± 19 μm in group 1, 245 ± 23 μm in group 2, and 267 ± 21 μm in group 3. Conclusions: The preliminary results show that pachymetry-based PFPL M Epi-On ACXL nomogram stabilizes ectasia progression. Higher fluence Epi-On ACXL increases CXL penetration, with better functional outcomes in the absence of complications
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