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https://www.readbyqxmd.com/read/28445165/non-diverging-analytical-expression-for-the-sensitivity-of-converging-spect-collimators
#1
Jarno van Roosmalen, Marlies C Goorden
Accurate analytical expressions for collimator resolution and sensitivity are important tools in the optimization of SPECT systems. However, presently known expressions for the sensitivity of converging collimators either diverge near the focal point or focal line(s), or are only valid on the collimator axis. As a result, these expressions are unsuitable to calculate volumetric sensitivity for e.g. short-focal length collimators that focus inside the object to enhance sensitivity. To also enable collimator optimization for these geometries, we here present non-diverging sensitivity formulas for astigmatic, cone beam and fan beam collimators that are applicable over the full collimator's field-of-view...
April 26, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28437964/passively-coupled-low-coherence-interferometric-duct-profiling-with-an-astigmatism-corrected-conical-mirror
#2
Helen D Ford, Ralph P Tatam
Duct-profiling in test samples up to 25 mm in diameter has been demonstrated using a passive, low-coherence probe head with a depth resolution of 7.8 μm, incorporating an optical-fibre-linked conical mirror addressed by a custom-built array of single-mode fibres. Zemax modelling, and experimental assessment of instrument performance, show that degradation of focus, resulting from astigmatism introduced by the conical mirror, is mitigated by the introduction of a novel lens element. This enables a good beam focus to be achieved at distances of tens of millimetres from the cone axis, not achievable when the cone is used alone...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437274/axial-length-and-anterior-segment-alterations-in-former-preterm-infants-and-full-term-neonates-analyzed-with-scheimpflug-imaging
#3
Achim Fieß, Ruth Kölb-Keerl, Markus Knuf, Bernd Kirchhof, Christiane Blecha, Isabel Oberacher-Velten, Philipp S Muether, Jacqueline Bauer
PURPOSE: To compare the axial length and anterior segment alterations in preterm infants with and without retinopathy of prematurity with those of full-term infants. METHODS: The Wiesbaden Prematurity Study investigated 503 participants of former gestational age ≤32 weeks and gestational age ≥37 weeks now being aged 4 to 10 years. This study included 485 participants in the prospective controlled cross-sectional, hospital-based study with successful Pentacam Scheimpflug imaging...
April 21, 2017: Cornea
https://www.readbyqxmd.com/read/28435210/incidence-of-interface-fluid-syndrome-after-laser-in-situ-keratomileusis-in-egyptian-patients
#4
Amr A Gab-Alla
PURPOSE: To determine the incidence of interface fluid syndrome (IFS) secondary to steroid-induced elevation of intraocular pressure (IOP) following laser in situ keratomileusis (LASIK) in myopic Egyptian patients. METHODS: This retrospective case series study was conducted at El-Gowhara Private Eye Center. The medical records of 1,807 patients (3,489 eyes), who underwent LASIK to correct myopia from April 2012 to December 2015 were included. The patients were operated on and reviewed by one surgeon (AAG) for IFS after LASIK associated with elevation of IOP (as compared to preoperative values)...
2017: Clinical Ophthalmology
https://www.readbyqxmd.com/read/28430330/long-term-visual-outcomes-in-children-with-primary-congenital-glaucoma
#5
Sanaa A Yassin
PURPOSE: To determine the long-term visual outcomes and risk factors for visual loss in children with primary congenital glaucoma (PCG) who underwent angle surgery over a 21-year period. METHODS: This was a retrospective study of patients who underwent trabeculotomy, trabeculectomy, or combined trabeculotomy-trabeculectomy for PCG. Visual acuity (VA), surgeries, and underlying cause of visual impairment were recorded and compared. Main outcome measures were final best-corrected good VA (20/20 to 20/50), moderate VA (<20/50 to 20/200), or poor VA (<20/200); age at surgery, sex, laterality, type of initial glaucoma surgery, and number of surgeries were recorded...
April 20, 2017: European Journal of Ophthalmology
https://www.readbyqxmd.com/read/28430322/prewound-assisted-technique-for-hydrophobic-foldable-intraocular-lens-implantation
#6
Takuya Shiba, Hiroshi Tsuneoka
PURPOSE: To describe a technique for intraocular lens (IOL) implantation that lessens the degree of surgical invasiveness by implanting a tightly rolled IOL through a small incision without touching the eye with the cartridge tip. METHODS: An IOL was inserted through an incision by first allowing the leading haptic to protrude slightly from the cartridge tip. It was then injected through the incision without allowing any part of the cartridge to touch the eye during IOL implantation...
April 7, 2017: European Journal of Ophthalmology
https://www.readbyqxmd.com/read/28426715/acute-hypoxia-influences-collagen-and-matrix-metalloproteinase-expression-by-human-keratoconus-cells-in-vitro
#7
Tina B McKay, Jesper Hjortdal, Shrestha Priyadarsini, Dimitrios Karamichos
Keratoconus (KC) is a progressive corneal ectasia linked to thinning of the central cornea. Hard contact lenses, rigid gas permeable lenses, and scleral lenses are the primary treatment modalities for early to mid- stages of KC to correct refractive error and astigmatism that develops as a result of an irregular corneal structure. These treatments are associated with significant drawbacks, including reduced availability of the tear film and oxygen to the corneal epithelium and stroma. However, it remains unknown whether hypoxia affects corneal integrity in the KC pathobiology...
2017: PloS One
https://www.readbyqxmd.com/read/28424534/corneal-flap-thickness-with-the-moria-m2-single-use-head-90-microkeratome-in-72-consecutive-lasik-procedures
#8
Yunus Karabela, Orkun Muftuoglu, Faruk Kaya
PURPOSE: This study aimed to evaluate the accuracy and consistency of corneal flap thickness in laser-assisted in situ keratomileusis (LASIK) with the Moria M2 single-use head 90 microkeratome. METHODS: The central corneal thickness of 72 (37 right, 35 left) eyes of 37 patients was measured by ultrasonic pachymetry preoperatively and intraoperatively after flap cut. The Moria M2 single-use head 90 microkeratome was used to create a superior hinged flap in all eyes...
2017: Clinical Ophthalmology
https://www.readbyqxmd.com/read/28423020/refractive-error-change-and-vision-improvement-in-moderate-to-severe-hyperopic-amblyopia-after-spectacle-correction-restarting-the-emmetropization-process
#9
Ji Woong Chang
PURPOSE: The aims of the study were to develop guidelines for prescribing spectacles for patients with moderate to severe hyperopic amblyopia and to demonstrate how emmetropization progresses. METHODS: Children with hyperopic amblyopia who had a spherical equivalent of ≥ +4.0 diopters (D) or more were included, while those who had astigmatism of > 2.0 D or anisometropia of > 2.0 D were excluded. The patients were divided into a full correction group and an under-correction group according to the amount of hyperopia correction applied...
2017: PloS One
https://www.readbyqxmd.com/read/28422801/interrater-and-test-retest-reliability-of-the-beery-visual-motor-integration-in-schoolchildren
#10
Erin M Harvey, Tina K Leonard-Green, Kathleen M Mohan, Marjean Taylor Kulp, Amy L Davis, Joseph M Miller, J Daniel Twelker, Irene Campus, Leslie K Dennis
PURPOSE: To assess interrater and test-retest reliability of the 6th Edition Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI) and test-retest reliability of the VMI Visual Perception Supplemental Test (VMIp) in school-age children. METHODS: Subjects were 163 Native American third- to eighth-grade students with no significant refractive error (astigmatism <1.00 D, myopia <0.75 D, hyperopia <2.50 D, anisometropia <1.50 D) or ocular abnormalities...
May 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28422132/haploinsufficiency-for-ankrd11-flanking-genes-makes-the-difference-between-kbg-and-16q24-3-microdeletion-syndromes-12-new-cases
#11
Francesca Novara, Berardo Rinaldi, Sanjay M Sisodiya, Antonietta Coppola, Sabrina Giglio, Franco Stanzial, Francesco Benedicenti, Alan Donaldson, Joris Andrieux, Rachel Stapleton, Astrid Weber, Paolo Reho, Conny van Ravenswaaij-Arts, Wilhelmina S Kerstjens-Frederikse, Joris Robert Vermeesch, Koenraad Devriendt, Carlos A Bacino, Andrée Delahaye, S M Maas, Achille Iolascon, Orsetta Zuffardi
16q24 deletion involving the ANKRD11 gene, ranging from 137 kb to 2 Mb, have been associated with a microdeletion syndrome characterized by variable cognitive impairment, autism spectrum disorder, facial dysmorphisms with dental anomalies, brain abnormalities essentially affecting the corpus callosum and short stature. On the other hand, patients carrying either deletions encompassing solely ANKRD11 or its loss-of-function variants were reported in association with the KBG syndrome, characterized by a very similar phenotype, including mild-to-moderate intellectual disability, short stature and macrodontia of upper incisors, with inter and intrafamilial variability...
April 19, 2017: European Journal of Human Genetics: EJHG
https://www.readbyqxmd.com/read/28421654/short-term-outcomes-of-small-incision-cataract-surgery-provided-by-a-regional-population-in-the-pacific
#12
Riyaz Bhikoo, Hans Vellara, Salome Lolokabaira, Neil Murray, Biu Sikivou, Charles McGhee
BACKGROUND: To describe patient demographics, visual and surgical outcomes of a cohort undergoing Small Incision Cataract Surgery (SICS) at a Pacific regional ophthalmic training facility. DESIGN: Prospective, longitudinal study conducted at the Pacific Eye Institute, Fiji. PARTICIPANTS: 156 patients underwent SICS. METHODS: Preoperatively, a complete ophthalmic examination, including pachymetry and macular Optical Coherence Tomography (OCT) performed by two independent investigators...
April 19, 2017: Clinical & Experimental Ophthalmology
https://www.readbyqxmd.com/read/28421140/comparison-of-corneal-power-and-astigmatism-between-simulated-keratometry-true-net-power-and-total-corneal-refractive-power-before-and-after-smile-surgery
#13
Yishan Qian, Yan Liu, Xingtao Zhou, Rajeev Krishnan Naidu
Purpose. To compare the mean corneal power (Km) and total astigmatism (Ka) estimated by three methods: simulated keratometry (simK), true net power (TNP), and total corneal refractive power (TCRP) before and after femtosecond laser small incision lenticule extraction (SMILE) surgery. Methods. A retrospective, cross-sectional study. SimK, TNP, and TCRP from a Scheimpflug analyzer were obtained from 144 patients before and 6 months after SMILE surgery. Km and Ka were recorded as the mean of individual paracentral rings of 1...
2017: Journal of Ophthalmology
https://www.readbyqxmd.com/read/28419129/factors-related-to-axial-length-elongation-and-myopia-progression-in-orthokeratology-practice
#14
Bingjie Wang, Rajeev K Naidu, Xiaomei Qu
PURPOSE: To investigate which baseline factors are predictive for axial length growth over an average period of 2.5 years in a group of children wearing orthokeratology (OK) contact lenses. METHODS: In this retrospective study, the clinical records of 249 new OK wearers between January 2012 and December 2013 from the contact lens clinic at the Eye and ENT Hospital of Fudan University were reviewed. The primary outcome measure was axial length change from baseline to the time of review (July-August 2015)...
2017: PloS One
https://www.readbyqxmd.com/read/28412800/-visual-quality-comparison-after-multifocal-toric-intraocular-lens-or-monofocal-toric-intraocular-lens-implantation
#15
K Feng, H K Guo, Y L Zhang, Z Wu
Objective: To compare visual quality and satisfaction after multifocal toric intraocular lens (Acrysof IQ Restor toric, ART) and monofocal toric intraocular lens implantation in patients. Methods: It was a prospective nonrandomized Phase Ⅲ clinical trial. Patients with age-related cataract and corneal astigmatism were enrolled and accepted phacoemulsification combined with implantation of intraocular lens (IOL) in Henan Provincial Eye Hospital during March 2013 to December 2014. Fifty-six cases were divided into two groups according to which IOL they chose...
April 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28412798/-intraocular-lens-power-calculation-for-high-myopic-eyes-with-cataract-comparison-of-three-formulas
#16
X J Zhu, W W He, Y Du, D J Qian, J H Dai, Y Lu
Objective: To compare the accuracy of three different formulas for intraocular lens power calculation in high myopic eyes with cataract and analyze their influencial factors. Methods: One hundred and three high myopic patients of cataract (103 eyes), with average age of 60.2±8.8 years old (39.0-77.0), including 45 male and 54 female and with axial length ≥ 26 mm were enrolled in this retrospective case-series study. All of them underwent routine ocular examination and IOLMastermeasurement preoperatively and then underwent phacoemulsification through temporal clear-corneal incision with implantation of HumanOptic posterior chamber Intraocular lens (IOL)...
April 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28412070/evaluation-of-femtosecond-laser-intrastromal-incision-location-using-optical-coherence-tomography
#17
Li Wang, Lai Jiang, Katie Hallahan, Zaina N Al-Mohtaseb, Douglas D Koch
PURPOSE: To use optical coherence tomography (OCT) to evaluate the femtosecond laser intrastromal incisions made during cataract surgery to reduce corneal astigmatism. DESIGN: Retrospective case series. PARTICIPANTS: Seventy-seven eyes of 77 patients. METHODS: Paired intrastromal incisions were created using the Catalys femtosecond laser (Abbott Medical Optics, Inc., Santa Ana, CA). The planned intrastromal incision parameters were 20% uncut anterior, 20% uncut posterior, midpoint depth of 50%, and 90° side cut angle...
April 12, 2017: Ophthalmology
https://www.readbyqxmd.com/read/28410727/transection-and-explantation-of-intraocular-lenses-using-femtosecond-lasers
#18
Chandra Bala, Ushasree Pattamatta, Thomas Chan, Jeffrey Shi, Kerrie Meades
We present 2 cases in which a femtosecond laser was used in vitro to transect hydrophilic acrylic intraocular lenses (IOLs). At 8 μJ with 3 μm spot separation and 6 μm line separation, no charring occurred and there was no increase in total organic carbon. In vivo, the IOLs were successfully transected in the capsular bag (Case 1, opaque IOL) and the sulcus (Case 2, subluxated IOL post-pneumatic displacement of submacular hemorrhage) and explanted through a clear corneal incision (∼3.0 mm). At 3 months, in Case 1, the corrected distance visual acuity (CDVA) improved from 6/24 to 6/5, astigmatism improved by 0...
March 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28410722/visual-outcomes-of-laser-vision-correction-in-eyes-with-preoperative-amblyopia
#19
Nir Sorkin, David Varssano, David Smadja, Ainat Klein, Michael Mimouni, Amir Rosenblatt
PURPOSE: To evaluate the visual outcomes of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in amblyopic eyes. SETTING: Care Vision Refractive Clinic, Tel Aviv, Israel. DESIGN: Retrospective case series. METHODS: Amblyopic eyes of patients with a preoperative corrected distance visual acuity (CDVA) of 20/33 or worse had PRK or LASIK. Postoperative visual outcomes (uncorrected distance visual acuity, CDVA) and correlations with age, preoperative CDVA, refractive error type, astigmatism grade, procedure type, laser suite model, amblyopia grade, and amblyopia type were analyzed...
March 2017: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/28410715/comparison-of-astigmatic-prediction-errors-associated-with-new-calculation-methods-for-toric-intraocular-lenses
#20
Tiago B Ferreira, Paulo Ribeiro, Filomena J Ribeiro, João G O'Neill
PURPOSE: To compare the prediction errors in residual astigmatism associated with new calculation methods for toric intraocular lenses (IOLs). SETTING: Hospital da Luz, Lisbon, Portugal. DESIGN: Retrospective case series. METHODS: In eyes having cataract surgery with toric IOL implantation (Acrysof IQ), the predicted residual astigmatism by each calculation method was compared with the manifest refractive astigmatism...
March 2017: Journal of Cataract and Refractive Surgery
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