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Refractive errors

Yo Ping Huang, Avichandra Singh, Li Ju Lai
INTRODUCTION: We aimed to determine the prevalence and severity of myopia in suburban schoolchildren. The refractive error, best corrected visual acuity (BCVA) and other ocular indices of 6069 schoolchildren (aged 6 to 15 years) from elementary and junior high schools in Chiayi County, Taiwan were examined in 2013-2015. MATERIALS AND METHODS: Spherical equivalent (SE) was stratified into 4 categories: emmetropia, mild myopia, moderate myopia, and high myopia for underlying analysis...
July 2018: Annals of the Academy of Medicine, Singapore
Ibrahim Olanrewaju Alade, Aliyu Bagudu, Tajudeen A Oyehan, Mohd Amiruddin Abd Rahman, Tawfik A Saleh, Sunday Olusanya Olatunji
BACKGROUND AND OBJECTIVES: The refractive index of hemoglobin plays important role in hematology due to its strong correlation with the pathophysiology of different diseases. Measurement of the real part of the refractive index remains a challenge due to strong absorption of the hemoglobin especially at relevant high physiological concentrations. So far, only a few studies on direct measurement of refractive index have been reported and there are no firm agreements on the reported values of refractive index of hemoglobin due to measurement artifacts...
September 2018: Computer Methods and Programs in Biomedicine
Andrew S Camp, Thomas S Shane, Julia Kang, Benjamin Thomas, Cameron Pole, Richard K Lee
PURPOSE: Uncorrected refractive error is the leading cause of visual impairment worldwide and has significant quality of life and economic implications. Treatment with subjective refraction and custom-made spectacles requires expensive equipment and highly trained personnel. We examine several alternatives. METHODS: Patients were taught to self-refract using two devices: AdSpecs and the I-test Vision Screener. Ready-made spectacles were fit to the self-refraction and visual acuity (VA) was measured...
August 17, 2018: Ophthalmic Epidemiology
Huaxia Deng, Fei Wang, Jin Zhang, Guoce Hu, Mengchao Ma, Xiang Zhong
For vision measurement at high temperature, pixel error from light refraction by high temperature is a problem that cannot be neglected. The refractive index distribution is nonlinear around the high-temperature component, leading to the light deflection. In this paper, the influence of measurement parameters on the deflection of imaging light and the accuracy after binocular reconstruction are systematically analyzed. The heat transfer theory is used to simulate the air temperature distribution near the measured component, and the corresponding refractive index distribution of air is obtained according to the refractive index formula...
July 10, 2018: Applied Optics
Lin Zhu, Qingshan Xu, Chen Cheng, Xiongwei Sun, Pengfei Wu, Lei Yang
The water-leaving radiances for shortwave infrared (SWIR) channels can be negligible, and these channels also contain information on aerosol particle size. Therefore, the satellite-based data of SWIR channels can be used to estimate aerosol particle size over inland waters [Appl. Opt.39, 887 (2000)APOPAI0003-693510.1364/AO.39.000887]. Supposing the actual atmospheric aerosol size distribution is based on the Junge power law, in this paper an iterative algorithm is used to simultaneously determine the aerosol optical depth (AOD) and the exponent of the Junge power law from Aqua MODIS L1B reflectance data of channels 1...
August 1, 2018: Applied Optics
Kaustubh Banerjee, Pouya Rajaeipour, Çağlar Ataman, Hans Zappe
We introduce a transmissive refractive adaptive optics system featuring a deformable transparent optofluidic wavefront modulator and a sensorless wavefront error estimation algorithm. The wavefront modulator consists of a cavity filled with an optical liquid which is sealed by a deformable elastic polymer membrane. Deformation of the membrane is achieved through electrostatic actuation using 25 transparent indium tin oxide electrodes buried in the cavity. Modulation of the two-dimensional phase distribution generated by the system is performed using open loop control both with and without active wavefront sensing...
August 1, 2018: Applied Optics
Xiuqin Wang, Yue Ma, Min Hu, Ling Jin, Baixiang Xiao, Ming Ni, Hongmei Yi, Xiaochen Ma, Congyao Wang, Beatrice Varga, Yiwen Huang, Scott Rozelle, Nathan Congdon
IMPORTANCE: Uncorrected refractive error causes 90% of poor vision among Chinese children. BACKGROUND: Little is known about teachers' influence on children's glasses wear. DESIGN: Cohort study. PARTICIPANTS: Children at 138 randomly-selected primary schools in Guangdong and Yunnan provinces, China, with uncorrected visual acuity (VA) ≤6/12 in either eye correctable to >6/12 in both eyes, and their teachers. METHODS: Teachers and children underwent VA testing and completed questionnaires about spectacles use and attitudes towards children's vision...
August 16, 2018: Clinical & Experimental Ophthalmology
Jae Keun Chung, Jae Min Wi, Kwan Bok Lee, Byung Heon Ahn, Young Hoon Hwang, Mijin Kim, Jong Jin Jung, Young Cheol Yoo
PURPOSE: To compare long-term postoperative refractive outcomes between phacotrabeculectomy and phacoemulsification, both with posterior chamber intraocular lens implantation. SETTING: Department of Ophthalmology, Konyang University, Kim's Eye Hospital, Myung-Gok Eye Research Institute, Seoul, South Korea. DESIGN: Retrospective comparative study. METHODS: Postoperative refractive outcomes were compared between patients with cataract and coexisting primary or secondary open-angle glaucoma (OAG) who had phacotrabeculectomy (combined group) and patients with cataract with or without coexisting OAG who had phacoemulsification alone (phaco-only group)...
August 2018: Journal of Cataract and Refractive Surgery
Mehdi Shajari, Carolin M Kolb, Kerstin Petermann, Myriam Böhm, Michael Herzog, Nina de'Lorenzo, Sabrina Schönbrunn, Thomas Kohnen
PURPOSE: To evaluate the accuracy of 9 formulas (Barrett Universal II, Haigis, Hill-Radial Basis Function [RBF], Hoffer Q, Holladay 1, Holladay 2, Olsen, Sanders-Retzlaff-Kraff/theoretical [SRK/T], and T2) calculating the power of the quadrifocal Acrysof IQ Panoptix TFNT00 intraocular lens (IOL). SETTING: Department of Ophthalmology, Goethe University, Frankfurt, Germany. DESIGN: Retrospective case series. METHODS: The study included patients having cataract surgery with insertion of a quadrifocal IOL over 15 months...
August 2018: Journal of Cataract and Refractive Surgery
Victoria Barnett, Allon Barsam, Jonathan Than, Sathish Srinivasan
A 73-year-old woman with bilateral previous radial keratotomies (RK) and symptomatic cataracts was referred. The uncorrected distance visual acuity (UDVA) was 0.24 logarithm of the minimum angle of resolution (logMAR) in the left eye and 0.32 logMAR in the left eye. The American Society of Cataract and Refractive Surgery calculator for eyes with previous RK was used for intraocular lens (IOL) power calculation. The dominant left eye had uneventful cataract extraction with monofocal IOL implantation. For the nondominant right eye, a small-aperture posterior chamber IOL with the highest available power was used; this was followed by planned secondary piggyback sulcus IOL implantation for the expected residual refractive error...
August 2018: Journal of Cataract and Refractive Surgery
Annelies Postelmans, Ben Aernouts, Wouter Saeys
A shape dependent method for particle size distribution (PSD) estimation based on bulk scattering properties was elaborated. This method estimates the parameters of a particle size distribution with predefined shape from the bulk scattering spectra. The estimation routine was validated on simulated data of polystyrene in water suspensions. To investigate the effect of measurement errors on PSD estimates, a sensitivity analysis was performed. The influence of spectral resolution and range was rather limited...
June 11, 2018: Optics Express
Stephanie Kearney, Lisa O'Donoghue, Laura K Pourshahidi, Patrick Richardson, Eamon Laird, Martin Healy, Kathryn J Saunders
BACKGROUND: Conjunctival ultraviolet autofluorescence (CUVAF) has been used as a biomarker of time spent outdoors. Smaller CUVAF area is associated with myopia in southern hemisphere cohorts. Further research is required to determine if this association is replicated in northern latitudes and whether average CUVAF intensity is a valuable metric. This prospective study explored the association between myopia, CUVAF (area and intensity) and additional indicators of sun exposure (vitamin D3 and self-reported sun exposure preferences) across seasons at a location of 55° north...
August 16, 2018: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
Tianliang Yan, Dong Liu, Xue Shen, Yuhao Zhou, Zhongming Zang, Tu Shi, Chong Liu
An iterative algorithm based on optical path difference (OPD) and ray deflection is proposed to obtain the DT (deuterium-tritium)-layer refractive index and thickness of the ICF (inertial confinement fusion) target simultaneously. Starting from an assumed initial value, the refractive index and thickness are solved back and forth until the iteration stopping criterion is reached. Simulations show that the relative retrieval error of the DT-layer refractive index is better than 0.05% after finite iterations, and that of the thickness is better than 0...
July 9, 2018: Optics Express
Yanin Suwan, Samantha Rettig, Sung Chul Park, Apichat Tantraworasin, Lawrence S Geyman, Keith Effert, Luis Silva, Ravivarn Jarukasetphorn, Robert Ritch
PURPOSE: In a myopic population, we investigated the occurrence of circumpapillary retinal nerve fiber layer (RNFL) segmentation errors that required manual correction in optical coherence tomography (OCT) and its effect on glaucoma diagnostic capability of OCT. MATERIALS AND METHODS: Myopic subjects (spherical equivalent refractive error <-3 diopters) with and without primary open-angle glaucoma were recruited. Three circumpapillary RNFL scans with diameters of 3...
August 14, 2018: Journal of Glaucoma
Shole Golmohammady, Masoud Yousefi, Ahmad Mashal, Bijan Ghafary
In this paper, on the basis of the extended Huygens-Fresnel principle, a semi-analytical expression for describing the on-axis scintillation index of a partially coherent flat-topped laser beam through non-Kolmogorov maritime and terrestrial atmospheric environments on a slant path is derived. Consequently, by using the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The effects of source factors (such as wavelength, order of flatness, and beam width) and the non-Kolmogorov turbulent atmosphere parameters (such as the Kolmogorov inner scale, the spectral power-law exponent, and the turbulence structure constant) on propagation behavior of the scintillation index, and hence on the BER, are studied in detail...
August 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Rémi Bouteloup, Didier Mathieu
Understanding the impact of atmospheric aerosols on the global radiative balance requires knowing the refractive index (RI) of their components. Currently available methods to estimate this property from molecular structure are mostly empirical and exhibit significant errors (>10%). This work reports a more physically sound model leading to predictions within ±5% from experiment. The root mean square relative error is <1% for general organic compounds, and <2% for oxygen-rich compounds of special interest in aerosol chemistry...
August 15, 2018: Physical Chemistry Chemical Physics: PCCP
Mehdi Naderi, Siamak Sabour, Soheila Khodakarim, Farid Daneshgar
BACKGTOUND: Photorefractive keratectomy (PRK) is used for a wide range of refractive errors such as low to moderate myopia, hyperopia and astigmatism. While many improvements have been made in laser application and accuracy as well as the modes of corneal flap removal, and although the results are somewhat predictable, regression of refractive errors is still a common complaint among the patients undergoing refractive surgery with Excimer Laser. We aimed to determine related factors of regression following photorefractive keratectomy (PRK) in different types of refractive errors...
August 14, 2018: BMC Ophthalmology
S H Gan, L L Deng, X J Zhou, J L Yi, Q Q Zhou, Y P Li, R Zhou
Objective: To assess the prevalence of visual impairment and the influencing factors among rural residents aged 60 years and above in Yugan county, Jiangxi province. Researchers analyzed influencing factors and provided scientific rationale for blindness prevention and control. Methods: Stratified cluster random sampling was used in randomly selecting 3 789 rural residents aged ≥ 60 in Yugan county. Eligible residents were invited to receive ophthalmic examinations and epidemiological investigations. Multivariate logistic regression was performed to analyze any influencing factors...
August 11, 2018: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
Y Wan, N L Wang, J Hao, Z Dong, Y Zhang, K Cao
Objective: To assess the utilization of eye care services in the rural area of Handan, China under the New Rural Cooperative Medical Scheme, and to analyze the factors associated with the uptake of these services. Methods: In a cohort population-based study, subjects who joined both the baseline (2006-2007) and follow-up (2012-2013) were included. Information of demographic characteristics, participation in the New Rural Cooperative Medical Insurance and use of eye care services, comprehensive ophthalmic examinations, blood pressure and fasting was collected...
August 11, 2018: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
J L Zhao
Eye health is a new concept that has been put forward in recent years as a result of the long term practice of prevention and treatment of blindness. The full understanding of the origin, goal and value of eye health is of great significance for promoting the prevention and treatment of eye diseases and the development of ophthalmology in China. In the past several decades, China has made great achievements in the development of eye health, while some challenges still remained. We should learn the actual requirements of the prevention of blindness and visual impairment and the public eye care, focus effectively on the major tasks, set explicit goals, gradually promote the development of eye health cause...
August 11, 2018: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
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