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refractive surgery thin cornea

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https://www.readbyqxmd.com/read/27926756/cutting-and-decellularization-of-multiple-corneal-stromal-lamellae-for-the-bioengineering-of-endothelial-grafts
#1
Zhiguo He, Fabien Forest, Aurélien Bernard, Anne-Sophie Gauthier, Romain Montard, Michel Peoc'h, Clotilde Jumelle, Emilie Courrier, Chantal Perrache, Philippe Gain, Gilles Thuret
Purpose: Engineered corneal endothelial grafts able to provide numerous functional endothelial cells for the restoration of corneal transparency would be a worthwhile way of replacing donor tissue, which is extremely scarce. The grafts are simply constructed: a biocompatible thin and transparent carrier colonized by a monolayer of cultured endothelial cells (ECs). Here we describe a process able to obtain appropriate carriers by recycling human corneas unsuitable for graft in their original state, but liable to provide multiple thin lamellae when cut with a femtosecond laser as used in refractive surgery...
December 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27621779/central-corneal-thickness-measurement-using-ultrasonic-pachymetry-rotating-scheimpflug-camera-and-scanning-slit-topography-exclusively-in-thin-non-keratoconic-corneas
#2
Mehrdad Mohammadpour, Kazem Mohammad, Nasser Karimi
PURPOSE: To evaluate the agreement among Pentacam, Orbscan and ultrasound (US) pachymetry for measurement of central corneal thickness (CCT) in thin corneas with normal topographic pattern. METHODS: We included 88 eyes of 44 refractive surgery candidates with thinnest pachymetric readings of 500 micrometers (μm) or less on Orbscan, a normal topographic pattern, no sign of keratoconus, and best corrected visual acuity (BCVA) of 20/20. Pentacam, Orbscan and US were performed in one session by the same examiner...
July 2016: Journal of Ophthalmic & Vision Research
https://www.readbyqxmd.com/read/27367533/refractive-regression-and-changes-in-central-corneal-thickness-three-years-after-laser-assisted-subepithelial-keratectomy-for-high-myopia-in-eyes-with-thin-corneas-a-retrospective-study
#3
Dan Fu, Zhen-Yong Zhang, Lin Wang, Xing-Tao Zhou, Zhi-Qiang Yu
This retrospective study aimed to explore refractive regression and central corneal thickness (CCT) following laser-assisted subepithelial keratectomy (LASEK) performed for the correction of high myopia in eyes with thin corneas. Forty patients (19 male, 21 female; mean age, 28.5 years) representing 76 treated eyes were included. The mean optical zone was 6.10 ± 0.32 mm, and the mean ablation depth was 121.53 ± 15.48 µm. CCT was significantly greater three years after surgery than at three months after surgery (425...
July 1, 2016: Seminars in Ophthalmology
https://www.readbyqxmd.com/read/27315289/prevention-of-iatrogenic-keratectasia
#4
C J Rapuano
Iatrogenic corneal ectasia is a rare but devastating complication after refractive surgery. While its incidence appears to be declining, it has not been eliminated. Its cause is probably related to a combination of an intrinsic predisposition to ectasia and an additional anatomical destabilising effect from the refractive surgery. Determining which eyes are intrinsically "weak" and exactly how much additional "weakening" an eye can withstand before developing progressive thinning and protrusion are both difficult tasks...
June 2016: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/27302856/five-year-changes-in-central-and-peripheral-corneal-thickness-the-shahroud-eye-cohort-study
#5
Hassan Hashemi, Soheila Asgari, Mohammad Hassan Emamian, Shiva Mehravaran, Akbar Fotouhi
PURPOSE: To determine five year changes in corneal thickness from the apex to the 8mm periphery and related factors through a longitudinal population-based study of middle-aged Iranians. METHODS: In the first phase, 4670 of the 5190 participants, and in the second phase, 4666 of the 4737 participants were examined with the Pentacam. In this report, analysis was done on right eye data of 2509 people who had no diabetes, pterygium, or history of eye surgery, and their image quality was displayed as "ok"...
October 2016: Contact Lens & Anterior Eye: the Journal of the British Contact Lens Association
https://www.readbyqxmd.com/read/27152485/importance-of-accurately-assessing-biomechanics-of-the-cornea
#6
Cynthia J Roberts
PURPOSE OF REVIEW: This article summarizes the state-of-the-art in clinical corneal biomechanics, including procedures in which biomechanics play a role, and the clinical consequences in terms of error in estimating intraocular pressure (IOP). RECENT FINDINGS: Corneal biomechanical response to refractive surgery can be categorized into either stable alteration of surface shape and thus visual outcome, or unstable biomechanical decompensation. The stable response is characterized by central flattening and peripheral steepening that is potentiated in a stiffer cornea...
July 2016: Current Opinion in Ophthalmology
https://www.readbyqxmd.com/read/27143849/ectasia-risk-factors-in-refractive-surgery
#7
REVIEW
Marcony R Santhiago, Natalia T Giacomin, David Smadja, Samir J Bechara
This review outlines risk factors of post-laser in situ keratomileusis (LASIK) ectasia that can be detected preoperatively and presents a new metric to be considered in the detection of ectasia risk. Relevant factors in refractive surgery screening include the analysis of intrinsic biomechanical properties (information obtained from corneal topography/tomography and patient's age), as well as the analysis of alterable biomechanical properties (information obtained from the amount of tissue altered by surgery and the remaining load-bearing tissue)...
2016: Clinical Ophthalmology
https://www.readbyqxmd.com/read/27113884/intraoperative-corneal-thickness-change-and-clinical-outcomes-after-corneal-collagen-crosslinking-standard-crosslinking-versus-hypotonic-riboflavin
#8
Elan Rosenblat, Peter S Hersh
PURPOSE: To determine intraoperative changes in corneal thickness and outcomes of corneal collagen crosslinking (CXL) using 2 intraoperative regimens: riboflavin-dextran or hypotonic riboflavin. SETTING: Cornea and refractive surgery practice, Teaneck, New Jersey, USA. DESIGN: Prospective randomized case series. METHODS: Eyes with keratoconus or corneal ectasia were treated. All eyes received preloading with riboflavin 0...
April 2016: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/26210054/idiopathic-stromal-keratitis-resembling-central-toxic-keratopathy
#9
Vijay Kumar Wagh, Laura de Benito-Llopis, David P S O'Brart
UNLABELLED: A 28-year-old previously emmetropic woman presented with a 2-day history of bilateral photophobia and blurred vision. She had no history of corneal surgery or contact lens use. Snellen uncorrected distance visual acuity (UDVA) was 6/12 bilaterally. Bilateral anterior stromal infiltration of the central cornea was seen, with no overlying epithelial defect and intact sensation. There was a marked hyperopic shift, central corneal thinning, and associated keratometric flattening...
July 2015: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/26098104/customized-finite-element-modelling-of-the-human-cornea
#10
Irene Simonini, Anna Pandolfi
AIM: To construct patient-specific solid models of human cornea from ocular topographer data, to increase the accuracy of the biomechanical and optical estimate of the changes in refractive power and stress caused by photorefractive keratectomy (PRK). METHOD: Corneal elevation maps of five human eyes were taken with a rotating Scheimpflug camera combined with a Placido disk before and after refractive surgery. Patient-specific solid models were created and discretized in finite elements to estimate the corneal strain and stress fields in preoperative and postoperative configurations and derive the refractive parameters of the cornea...
2015: PloS One
https://www.readbyqxmd.com/read/25980780/corneal-cross-linking
#11
REVIEW
J Bradley Randleman, Sumitra S Khandelwal, Farhad Hafezi
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...
November 2015: Survey of Ophthalmology
https://www.readbyqxmd.com/read/25853948/-iatrogenic-keratectasia-a-review
#12
REVIEW
M Kohlhaas
Iatrogenic corneal ectasia is a rare complication but also one of the most feared situations that can occur after uneventful corneal laser surgery. Ectatic changes can occur as early as 1 week or can be delayed up to several years after LASIK. The actual incidence of ectasia is undetermined, an incidence rate of 0.04 to almost 2.8 % has been reported. Ectasia is most common following LASIK; however, cases have been reported following PRK and other corneal refractive procedures. Keratectasia shows progressive myopia, irregular astigmatism, ghosting, fluctuating vision and problems with scotopic vision...
June 2015: Klinische Monatsblätter Für Augenheilkunde
https://www.readbyqxmd.com/read/25709915/a-short-term-study-of-corneal-collagen-cross-linking-with-hypo-osmolar-riboflavin-solution-in-keratoconic-corneas
#13
Shao-Feng Gu, Zhao-Shan Fan, Li-Hua Wang, Xiang-Chen Tao, Yong Zhang, Chun-Qin Wang, Ya Wang, Guo-Ying Mu
AIM: To report the 3mo outcomes of collagen cross-linking (CXL) with a hypo-osmolar riboflavin in thin corneas with the thinnest thickness less than 400 µm without epithelium. METHODS: Eight eyes in 6 patients with age 26.2±4.8y were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution after its de-epithelization. Best corrected visual acuity, manifest refraction, the thinnest corneal thickness, and endothelial cell density were evaluated before and 3mo after the procedure...
2015: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/25538907/corneal-haze-and-visual-outcome-after-collagen-crosslinking-for-keratoconus-a-comparison-between-total-epithelium-off-and-partial-epithelial-removal-methods
#14
Hasan Razmjoo, Behrooz Rahimi, Mona Kharraji, Nima Koosha, Alireza Peyman
BACKGROUND: Keratoconus is an asymmetric, bilateral, progressive noninflammatory ectasia of the cornea that affects approximately 1 in 2000 of the general population. This may cause a significant negative impact on quality of life. Corneal collagen crosslinking (CXL) is one of the recently introduced methods that have been used to decrease the progression of keratoconus, in particular, as well as other corneal-thinning processes. MATERIALS AND METHODS: A total of 44 keratoconic eyes of 22 patients were enrolled in this randomized prospective study, after obtaining informed consent...
2014: Advanced Biomedical Research
https://www.readbyqxmd.com/read/25331075/screening-for-keratoconus-suspects-among-candidates-for-refractive-surgery
#15
REVIEW
Charles W McMonnies
This review examines methods for estimating the risk of post-surgical ectasia in candidates for refractive surgery by establishing a diagnosis of keratoconus suspect as a contraindication for proceeding with surgery. Notwithstanding the desirability of achieving 100 per cent sensitivity, any associated reduction in specificity and increased numbers of false positives might deny some candidates the opportunity to proceed with refractive surgery. The introduction of a model for the risk of ectasia involving both pre- and post-surgical findings has been followed by a plethora of attempts to achieve the same purpose based on topographic and/or tomographic evaluation before surgery...
November 2014: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
https://www.readbyqxmd.com/read/25232339/management-of-extreme-ametropia-after-penetrating-keratoplasty-a-series-of-surgical-procedures-for-high-myopia-and-astigmatism
#16
Jorge E Valdez-Garcia, Juan J Cueto-Gómez, Juan F Lozano-Ramírez, Alejandro E Tamez-Peña
A series of surgical interventions - relaxing corneal incisions, intraocular lens, and intrastromal rings - were used to correct a case of extreme ametropia in a thin cornea after a penetrating keratoplasty in an 18-year-old patient who presented with a -10.25 -8.50 × 120 preoperative refraction and 20/200 best-corrected visual acuity (BCVA). After a series of surgical procedures, the patient's BCVA in his left eye improved to 20/30 with +0.50 -1.00 × 170, the slit lamp examination showed no significant findings, and the patient's visual complaints disappeared...
May 2014: Case Reports in Ophthalmology
https://www.readbyqxmd.com/read/24857438/biomechanical-and-optical-behavior-of-human-corneas-before-and-after-photorefractive-keratectomy
#17
COMPARATIVE STUDY
Paolo Sánchez, Kyros Moutsouris, Anna Pandolfi
PURPOSE: To evaluate numerically the biomechanical and optical behavior of human corneas and quantitatively estimate the changes in refractive power and stress caused by photorefractive keratectomy (PRK). SETTING: Athineum Refractive Center, Athens, Greece, and Politecnico di Milano, Milan, Italy. DESIGN: Retrospective comparative interventional cohort study. METHODS: Corneal topographies of 10 human eyes were taken with a scanning-slit corneal topographer (Orbscan II) before and after PRK...
June 2014: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/24774009/biomechanics-of-corneal-ectasia-and-biomechanical-treatments
#18
REVIEW
Cynthia J Roberts, William J Dupps
UNLABELLED: Many algorithms exist for the topographic/tomographic detection of corneas at risk for post-refractive surgery ectasia. It is proposed that the reason for the difficulty in finding a universal screening tool based on corneal morphologic features is that curvature, elevation, and pachymetric changes are all secondary signs of keratoconus and post-refractive surgery ectasia and that the primary abnormality is in the biomechanical properties. It is further proposed that the biomechanical modification is focal in nature, rather than a uniform generalized weakening, and that the focal reduction in elastic modulus precipitates a cycle of biomechanical decompensation that is driven by asymmetry in the biomechanical properties...
June 2014: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/24636364/past-and-present-of-corneal-refractive-surgery-a-retrospective-study-of-long-term-results-after-photorefractive-keratectomy-and-a-prospective-study-of-refractive-lenticule-extraction
#19
Anders Højslet Vestergaard
UNLABELLED: Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become possible. Two new procedures were developed, ReLEx flex (FLEX) and ReLEx smile (SMILE). Until this thesis, only a few long-term studies of PRK with a relatively limited number of patients had been published; therefore, this thesis intended to retrospectively evaluate long-term outcomes after PRK for all degrees of myopia for a large number of patients...
March 2014: Acta Ophthalmologica
https://www.readbyqxmd.com/read/24364803/intacs-after-laser-in-situ-keratomileusis-a-preliminary-report
#20
EDITORIAL
D S Durrie, T L Vande Garde
PURPOSE: To assess the corneal topographic and refractive results and feasibility of placing Intacs in eyes with a history of previous laser in situ keratomileusis (LASIK) surgery. METHODS: This was a prospective study on 25 eyes with residual myopia between -0.75 and -3.00 D. Residual myopia in these patients was secondary to regression or planned undercorrection due to preoperative thin corneas. RESULTS: Main outcome measures included uncorrected visual acuity, preservation of best spectacle-corrected visual acuity, refractive predictability, corneal topographic changes, and evaluation of surgical complications...
March 2, 2000: Journal of Refractive Surgery
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