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AIM: To compare the consistency of two autorefractors (Tianle RM-9000 and Topcon KR-800) for school-age myopia children, and to provide a basis for largescale data analysis and comparison. METHODS: The refractive error in 909 subjects (age 4–18y) were measured using both autorefractors without cycloplegia. The data were analyzed using Fourier decomposition and the correlation coefficients, intraclass correlation coefficients (ICC), and Bland-Altman limits of agreement (LoA) for each parameter were calculated. RESULTS: There was a strong correlation between the spherical equivalent (SE), sphere diopter (DS), and cylinder diopter (DC) readings of the Tianle RM-9000 and those of the Topcon KR-800, with correlation coefficient values of 0.98, 0.98 and 0.83 and ICC values of 0.99, 0.99 and 0.93, respectively. However, the correlation coefficients and ICC values of J0 and J45 were unreliable (R=-0.004, -0.034; both ICC more...

Visibility deterioration may have negative impacts on aviation safety, particularly in landing and take-off procedures. Beside traditional weather observation methods which are based on human visual estimations, automatic weather observation systems (AWOS) are recently used in airports in order to provide instant measurements of the relevant meteorological parameters. One of the most important sensors is the RVR sensor. In this study, the variability of human visibility and optical instrumental visibility, including the meteorological optical range (MOR) and runway visual range (RVR), along with the probable differences between their values are investigated from December 2019 to February 2020 at Payam Airport, Karaj, Iran. Results indicate that in different weather conditions, the values of MOR and RVR are predominantly greater than human visibility. In this investigation, MOR is about 99% and 96% more than observed visibility for daytime and nighttime, respectively. The probable reasons for such discrepancies between these two sources of data have argued in this paper. However, to overcome the differences between the two methods, an optimized parameter is introduced as visual optical range (VOR). This parameter simulates human's visibility through MOR to gain the benefits of both methods. Using darkness coefficient, the new parameter depends not only on extinction coefficient but also on sky brightness. The value of 0.07 is proposed for VOR calculation instead of 0.05 in the calculation of MOR. Meanwhile, in the new method, RVR value is also taking the greater values of the Allard's visibility and VOR rather than MOR. Applying this method, it is observed that VOR values align between traditional and instrumental visual ranges. Furthermore, the new method gives more reasonable results considering minimum values of the runway's light intensity over nighttime. [ABSTRACT FROM AUTHOR] more...

Aeromagnetic and core drilled data covering parts of southern Nupe Basin was acquired and interpreted with the view of evaluating the mineral potential of the area through interpretation of the structural features in the area, determination of the Curie isotherm depth, and correlation of aeromagnetic outcomes with the core sample data from the area. Two major regional fault trends were interpreted: northeast--southwest (NE-SW) and NNE-SSW with minor northwest--southeast (NW-SE) directions. Two depth sources in the area are delineated, namely zone of shallow seated basement which ranges from 0.42 km to 1.5 km and zone of deeply seated basement ranging from 1.91 to 3.50 km. Results of qualitative interpretation of the total magnetic intensity map (TMI) and residual intensity map reveal that the magnetic intensities range from 7500 to 8460 nano-Tesla (nT) and -220 to 240 nT, respectively. The depths to the centroid and top of the magnetic causative bodies range from 9.00 to 17.10 km and 0.4 to 3.10 km, respectively. There are evidences of oolitic iron ore in some parts of the study area. Juxtaposing the topographical and core drilling data reveal that the oolitic iron ore level follows the topographical level which implies that the topography of the area controls the configuration of the iron ore deposit level. All these deductions are made considering the geology of the area. [ABSTRACT FROM AUTHOR] more...

Background: Adjustment of the ocular accommodative system is an important phenomenon allowing for optimal vision at different distances. Aim: The study compared the refractive behaviour of the human eye under different ambient lighting conditions for different target brightness. Setting: Auto-refraction measurements were taken of the participants in the Department of Optometry at the University of Johannesburg. Methods: Five African participants from a single ethnic group aged between 20 years and 25 years, had 40 successive auto-refractor (Nidek AR 610) measurements taken on the right eye of each participant in a bright and dark room using the illuminated and dark targets (LL and DL); dark target in the illuminated and dark room (LD and DD). Results: A change in the refractive state of all participants was observed on LL and LD, except for one, who experienced myopic shifts. The largest significant difference in the variance-covariances and the means was approximately 2.40 dioptre (D). The other participants' shifts in means were approximately the same and varied between 1.00 D and 1.50 D stigmatic shift. For the DL to DD conditions all participants, except for one, underwent a hyperopic shift of about 0.50 D. Conclusion: The refractive behaviour of the human eye appears to be dependent on ambient light conditions as well as target illumination or luminance. Contribution: The study is scientific and clinical, and focuses on changes in refractive behaviour under different lighting conditions, falling within the scope of the journal. Key insights are that there is a change in the refractive behaviour of the eye under different ambient conditions. [ABSTRACT FROM AUTHOR] more...

Abstract Background To compare the refractive results of hand-held and table-mounted autorefractors. Methods We designed this study as an observational, cross-sectional study. We compared the mean spheric and cylinder power, spherical equivalent, Jackson cross-cylinder values, determined the limits of agreement (LoA), and evaluated the reliability of two autorefractors. Results We evaluated 256 eyes of 256 pediatric patients (mean age, 9.12 ± 2.26 years; range, 5–16 years). 49% of the patients were female, and 51% were male. The Nidek HandyRef-K autorefractor measured relatively more astigmatism (P more...

Robert W Arnold,1 Samuel J Martin,2 Joshua R Beveridge,3 Andrew W Arnold,4 Stephanie L Arnold,4 Nathanael R Beveridge,5 Kyle A Smith1,6 1Alaska Blind Child Discovery, Alaska Children’s EYE & Strabismus, Anchorage, AK, 99508, USA; 2Loma Linda Medical School, Loma Linda, CA, USA; 3Idaho College of Osteopathic Medicine, Boise, ID, USA; 4Ascension Genesys Residency Program, Grand Blanc, MI, USA; 5US Airforce Academy, Colorado Springs, CO, USA; 6Accurate Vision, Anchorage, AK, USACorrespondence: Robert W ArnoldAlaska Children’s EYE & Strabismus, 3500 Latouche Street #280, Anchorage, AK, 99508, USATel +1(907)561-1917Fax +1 9075635373Email eyedoc@alaska.netBackground: Handheld devices can automatically give an estimate of refraction. The established method for refraction comparison using spherical equivalent (M) and J0, J45 vector transformations by Bland–Altman analysis is too complex for non-eye doctors involved with vision screening and remote vision clinics. Therefore, a simpler comparison technique was developed.Methods: Based on the spectacle limit to resolve grade A 1 logMAR, B 3 logMAR and C 6 logMAR blur, J0, J45, and M are combined into the Alaska Blind Child Discovery (ABCD) composite ellipsoid GRADE system. Pediatric eye patients had confirmatory examination after dry refraction with three portable autorefractors: Plusoptix, 2WIN and Retinomax. The refractions were then compared using both Bland–Altman and ABCD composite. Performance to detect AAPOS amblyopia risk factors was also assessed.Results: A total of 202 children, mean age seven years, 28% high spectacle need and 43% AAPOS 2013 amblyopia risk factors showed high correlation with cycloplegic refraction (intraclass correlation 0.49 to 0.90) for sphere, J0 and J45 spectacle components. Plusoptix had more (10%) inconclusives due to patients out-of-range. The Retinomax was unable to screen some younger children and was less reliable for sphere but gave more precise astigmatism estimates. The proportion of autorefractions expected to give GRADE A/B high-need patients acuity improvement to 20/40 would be 41% for Plusoptix, 39% for 2WIN and 65% for Retinomax. Sensitivity/specificity for amblyopia risk factor detection was 80%/83% for Plusoptix, 72%/88% for 2WIN and 84%/73% for Retinomax.Conclusion: The simplified spectacle comparison resembled Bland–Altman and could assist lay vision screeners and non-eye doctors attempting remote spectacle donation worldwide.Keywords: spectacles, remote dispensing, autorefractors, validation more...

Introduction: More than 400 million people suffer from visual impairment globally, with more than half due to uncorrected refractive error. Autorefraction (AR) is the most common examination performed prior to prescribing glasses. As technology advances, so has the accuracy and number of portable autorefractors available. Portable technology has become acutely important with the coronavirus disease 2019 pandemic and the conversion of in-person clinical evaluations to remote telemedicine encounters. Patients and providers want to do as much as possible remotely. The aim of this study was to conduct a systematic literature review of the accuracy and effectiveness of available portable automated refractors compared to the current standard of care, subjective refraction (SR).Methods: A literature search of PubMED, Embase and ClinicalTrials.gov 97 unique publications in English on portable autorefractors. Twelve studies comparing a portable AR device to at least one form of SR were systematically included in this review.Results: There were four portable autorefractors (Netra, Quicksee, Retinomax and SVOne) studied against SR. There was high patient acceptance of glasses prescriptions by the Quicksee alone, with 87% subjects seeing the same or better than SR. Quicksee was more accurate than Netra and Retinomax. SVOne was preferred over Netra and outperformed Retinomax in multiple measures, despite Retinomax being the fastest test.Discussion: There are numerous portable autorefractors available, but few were compared against SR. Quicksee and SVOne are the most accurate and patient-preferred devices. Quicksee was the most accurate, and it performed clinically the same as SR in some reports. [ABSTRACT FROM AUTHOR] more...

Purpose: To determine, through simulations, the effect of lateral misalignment of the Grand‐Seiko WR‐5100K autorefractor on peripheral refraction. Methods: Using a Navarro schematic eye, into‐ and out‐of‐the eye raytracing was done for a Grand‐Seiko autorefractor simulation. For comparison, conventional out‐of‐the eye raytracing simulated the use of a Hartman‐Shack aberrometer. Peripheral refractions were determined out to ±40° along the horizontal visual field with lateral misalignments up to ±1 mm. Results: The effects are high, and greater when misalignment and the visual field are in opposite directions than when they are in the same direction. For example, 1 mm nasal misalignment causes mean sphere errors of −2.7 D and +1.3 D at 30° temporal field and 30° nasal field, respectively. These effects are approximately twice those occurring in a previous experimental study. Effects are small with the Hartmann‐Shack simulation, with mean sphere errors not exceeding 0.03 D with 1 mm instrument misalignment. Conclusion: Misalignment of the Grand‐Seiko WR‐5100K autorefractor is predicted to cause considerable errors in peripheral refraction. The simulation produces about twice the errors found in an experimental study, and the reason for this is unknown. [ABSTRACT FROM AUTHOR] more...

Purpose: To determine, through simulations, the likely validity of Grand‐Seiko autorefractors with annular targets in peripheral refraction. Methods: Using a physical model eye, the distance inside the eye to which the Grand Seiko AutoRef/Keratometer WAM‐5500 beam was converging and the effective size of its outer diameter at the cornea were determined. Grand‐Seiko refraction was calculated from Rx = (θ + α)/h1, where θ is the angle of the ingoing radiation beam, h1 is the height of the beam at the anterior cornea and α is the angle of the beam emerging from the eye following reflection at the retina. Two eye models were used: a Navarro schematic eye and a Navarro schematic eye with a contact lens having a highly positive aspheric front surface. Results: The instrument beam was determined to be converging towards the eye to a distance of 24.4 mm behind the corneal vertex, with a 2.46 mm effective size outer diameter of the beam at the anterior cornea. The Grand‐Seiko refractions provided accurate estimates of peripheral refraction for the model eyes. The results were closer to Zernike refractions than to Zernike paraxial refraction. Spherical aberration influenced refraction by up to 0.5 D, and peripheral coma had limited influence. Conclusion: Grand‐Seiko autorefractors in current use, and having a circular annulus with an ingoing effective outer diameter at the front of the eye of about 2.4 mm, are likely to give valid peripheral refractions. [ABSTRACT FROM AUTHOR] more...

Purpose: To study the optical principles and properties of autorefractors that use the image‐size principle in which the size of the reimaged retinal image determines refraction. Methods: The retinal illumination and reimaging of the retinal image were described, as were variations in the basic system. Imaging was determined for systems in which the light source is either diverging or converging as it passes into the eye. Equations were determined to describe the dependence of refraction on the heights and angles of incoming and outgoing beams, and refraction error was determined when eye position was not correct. Results: The fundamental refraction equation is DE=±(α+θ)/h1 where DE is refraction, h1 is the beam height entering the eye, and θ and α are the angles of the incoming and outgoing beams, respectively. The negative sign outside the brackets applies if the beam focuses before entering the eye, while the positive sign applies if the beam focuses after entering the eye. When light is diverging as it reaches the anterior eye, hyperopia produces greater retinal image sizes than myopia. The opposite is the case when light is converging as it reaches the anterior eye. The effect of incorrect ocular longitudinal position on the measured refraction was determined; this produced errors identical to those for vertex errors with ophthalmic lenses. Conclusion: For image‐size principle autorefractors, simple equations describe the dependence of measured refraction on the height and angle of the instrument beam as it enters the eye and the angle of the light, reflected back from the retina, after it exits the eye. Further work will investigate the validity of such instruments for determining peripheral refraction. [ABSTRACT FROM AUTHOR] more...

Background: To compare the refractive results of hand-held and table-mounted autorefractors.Methods: We designed this study as an observational, cross-sectional study. We compared the mean spheric and cylinder power, spherical equivalent, Jackson cross-cylinder values, determined the limits of agreement (LoA), and evaluated the reliability of two autorefractors.Results: We evaluated 256 eyes of 256 pediatric patients (mean age, 9.12 ± 2.26 years; range, 5-16 years). 49% of the patients were female, and 51% were male. The Nidek HandyRef-K autorefractor measured relatively more astigmatism (P < 0.001) and less hyperopia (P = 0.024). The mean differences and 95% LoA were 0.06 D ± 0.47 D (- 0.82 D to 0.98 D) in spherical power, 0.08 D ± 0.28 D (- 0.47 D to 0.64 D) in cylindrical power, 0.11 D ± 0.47 D (- 0.81 D to 1.01 D) in spherical equivalent, 0.02 D ± 0.36 D (- 0.73 D to 0.69 D) in Jackson cross-cylinder power at 0°, 0.005 D ± 0.54 D (- 1.07 D to 1.06 D) in Jackson cross-cylinder power at 45°. We found the difference within 0.50 D in 244 (95%) eyes for spherical power, in 245 (96%) eyes for cylindrical power, 228 (89%) eyes for spherical equivalent, 224 (87%) eyes for Jackson cross-cylinder power at 0°, 213 (83%) eyes for Jackson cross-cylinder power at 45°. When comparing devices, there were strong correlations for spherical power (Spearman's rho = 0.99, P < 0.001), cylindrical power (Spearman's rho = 0.88, P < 0.001), and spherical equivalent (Spearman's rho = 0.98, P < 0.001).Conclusion: Two autorefractors showed clinically applicable agreement limits; excellent reliability for spherical power and spherical equivalent and good reliability for cylindrical power; high positive percent agreement for spherical and cylindrical power, spherical equivalent, Jackson cross-cylinder power at 0°and 45°. These results showed that both devices might be used interchangeably for screening of refractive error in children. [ABSTRACT FROM AUTHOR] more...

Copyright of Review of Medicine / Przeglad Lekarski is the property of Wydawnictwo Przegld Lekarski / Publisher Medicine Review and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Background: What constitutes an appropriate vision screening protocol is controversial, because the tests or methods are expected to be cost-effective, expedient and easy but efficient in detecting visual anomalies among children. Aim: This review intends to compare the different vision screening tests for children and methods in the interest of identifying the most effective screening method from the standpoint of validity, public acceptance, expediency and cost. Method: The literature search was performed for this review using the Medline, Science Direct and EBSCOhost databases. The search terms used were vision screening methods or tests, children’s vision screenings, computer software programs and vision screening instruments. The inclusion criteria for the articles reviewed were all types of articles related to vision screening methods. The exclusion criteria were all articles for which full text was not available and those not available in English. Eighty articles were analysed, of which 33 were found to have complied with the inclusion criteria and were selected. From the first round of articles retrieved, additional references were identified by a manual search among the cited references. Results: Evidence from the literature reviewed demonstrated that the conventional vision screening method (isolated and combination tests) is the method commonly used to detect a range of relevant visual anomalies among the schoolgoing age group (≥ 6 years) and drew attention to the need for training of vision screening personnel. However, in addition to the conventional method, other vision screening methods include instruments as an adjunct for screening preschoolers and those difficult to screen (≤ 6 years). Conclusion: Inconsistencies in what constitutes an appropriate vision screening method still exist, especially with the booming market of using computer software programs, which still needs to be validated. more...

Background: The use of patient simulators in ophthalmic education appears limited. This study examines the effects of the addition of the 'Virtual Refractor' patient simulator learning activity into a short unit preparing students to determine the power of the spectacle lenses required by patients in a clinic.Methods: Twenty-four year one optometry students were randomly assigned to either the simulator-intervention group (n = 12) or the non-intervention group. All students attended tutorials on refraction and the use of a refractor-head. Simulator-intervention students additionally attended a tutorial on the Virtual Refractor. All answered a questionnaire concerning time spent studying, perceived knowledge and confidence. Twenty-four short-sighted patients were recruited. Two refractions per student were timed and the accuracy compared with that of an experienced optometrist.Results: Ten students from each group completed the study. Students who used the simulator were significantly (p < 0.05) more accurate at a clinical level (within 0.22 ± 0.22 DS, 95 per cent CI 0.12-0.32) than those who did not (within 0.60 ± 0.67 DS, 95 per cent CI 0.29-0.92) and 13 per cent quicker (4.7 minutes, p < 0.05). Students who used the simulator felt more knowledgeable (p < 0.05) and confident (p < 0.05), but had spent more time reading about refraction and practised on the Virtual Refractor at home for 5.7 ± 1.3 hours.Conclusion: The Virtual Refractor has many features of high-fidelity medical simulation known to lead to effective learning and it also offers flexible independent learning without a concomitant increase in the student time-burden. The improved accuracy and speed on first patient encounters found in this study validates the use of this patient simulator as a useful bridge for students early in training to successfully transfer theoretical knowledge prior to entering the consulting room. The translational benefits resulting from compulsory learning activities on a patient simulator can lead to reduced demands on infrastructure and clinical supervision. [ABSTRACT FROM AUTHOR] more...

Purpose: To determine repeatability and agreement of the ARK-30 handheld autorefractor with retinoscopy under cycloplegic and noncycloplegic conditions in children.Methods: >Three consecutive autorefractor measurements (with and without cycloplegia) and retinoscopy were performed and compared in 30 randomized eyes of 30 children (mean age of 6.7 ± 2.7 years with spherical equivalent [SE] refraction from ‒4.01 to +7.38 D) in a cross-section and masked study. Bland-Altman analysis of autorefractor measurements (with and without cycloplegia) and agreement with retinoscopy were calculated with conventional notation (sphere [Sph] and cylinder [Cyl]) and vector notation (SE, J0, and J45coefficients).Results: ARK-30 measurements without cycloplegia were lower than under cycloplegic conditions (Sph: ‒0.52 ± 2.37 D vs + 0.86 ± 2.60 D, P < 0.01; Cyl: ‒0.83 ± 0.80 D versus ‒0.78 ± 0.77 D, P = 0.37; and SE: ‒0.94 ± 2.19 D vs + 0.47 ± 2.44 D, P < 0.01, respectively) and statistically different (P < 0.03) from retinoscopy (Shp: +0.83 ± 2.66 D; Cyl: ‒0.71 ± 0.87 D; SE: +0.51 ± 2.49 D). Without statistical differences were in J0and J45coefficients. Cyloplegic autorefraction measures were not found to be statistically significantly different to retinoscopy measures. ARK-30 under cycloplegia shows better repeatability with lower limits of agreement (LoA) in Sph (LoA: ‒0.66 to +0.69 D), and SE (LoA: ‒0.66 to +0.65 D) than without cycloplegia (LoA: ‒1.45 to +1.77 D, and ‒1.38 to +1.74 D, respectively).Conclusion: Under noncycloplegic conditions, ARK-30 autorefractor has low repeatability and a tendency toward minus over correction in children. However, repeatability and agreement with retinoscopy under cycloplegic conditions allow use of ARK-30 in children to estimate refraction but not to substitute gold standard retinoscopic refraction. [ABSTRACT FROM AUTHOR] more...

Purpose: To study the effect of cycloplegia on astigmatism measurements in pediatric patients with amblyopia. Methods: This was a prospective comparative clinical study. Participants 4 to 17 years old were recruited from the patient population at the Arkansas Children's Hospital eye clinic after informed consent was obtained. Autorefractor measurements were used to obtain values of refractive error in amblyopic and non-amblyopic patients before and after cycloplegia. The groups were subdivided into myopia and hyperopia and with and without underlying amblyopia. The refractive error was expressed as sphere, cylinder, axis of astigmatism, and spherical equivalent. The treatment effect was summarized as the mean difference (95% confidence interval) for each outcome. Results: No statistically significant difference was found on the axis and power of astigmatism before and after cycloplegia in the patients with amblyopia (P = .28 and .99, respectively). Conclusions: Non-cycloplegic autorefraction measurements may be considered safe for refining astigmatism power and axis in pediatric patients with amblyopia. [ABSTRACT FROM AUTHOR] more...

INTRODUCTION: We evaluated the reproducibility of two portable, self-administered autorefractors (Netra and SVOne Pro) to assess the time course of visual changes on the ISS. METHODS: We measured cycloplegic refractive error at 5 visits at least a week apart in 13 subjects (6 women, 7 men, 30 ± 9 yr) using both devices seated and also prone with lower body positive pressure (LBPP) applied. Axial length was measured with an optical biometer. Subjects completed a questionnaire on device preferences. RESULTS: The SVOne seated intrasession reproducibility coefficient (RPC) was 0.37 diopters (D), while the Netra's was 0.41 D. Intersession seated results were: RPC = 0.67 D for the SVOne and RPC = 0.54 D for the Netra. The average seated to prone LBPP differences were significantly different from zero for both the SVOne and Netra. The SVOne was preferred in four out of five categories on the questionnaire and took half the time to complete a measurement set compared to the Netra. DISCUSSION: Users preferred the SVOne and it took less time. An SVOne refraction change of 0.67 D from baseline would happen by chance less than 5% of the time. If multiple separate measurements were taken, the detection limit could be reduced (e.g., three repeated measurements could reduce it to 0.38 D). Since astronauts with visual changes show spherical equivalent changes of 0.5 to 1.0 D, in-flight autorefractors could help determine the time course of refractive changes in space from which changes in axial length could be inferred. [ABSTRACT FROM AUTHOR] more...

Purpose: We aim to determine the association of the types of lamp for homework including incandescent lamp, fluorescent lamp, and light-emitting diode (LED) lamp with the prevalence of myopia in Chinese children. Methods: 2346 grade 7 students from ten middle schools (93.5% response rate) aged 13 to 14 years in Mojiang, a small county located in Southwestern China, participated in the study. Refractive error was measured with cycloplegia using an autorefractor by optometrists or trained technicians. An IOL Master was used to measure ocular biometric parameters including axial length (AL). Information regarding the types of lamp for homework af``ter schools was collected by questionnaires. Results: Of all the study participants, 693 (29.5%) were affected by myopia, with the prevalence estimates being higher in girls (36.8%; 95% confidence interval [CI]: 34.0, 39.6) than in boys (22.8%; 95% CI: 20.4, 25.1) (P < 0.001). After adjusting for potential confounders such as gender, height, parental history of myopia, time on computer use, time on watching TV, time outdoors, and time on reading and writing, participants using LED lamps for homework had a more myopic refractive error and a longer AL compared with those using incandescent or fluorescent lamps. There were no significant differences in myopia prevalence between children using incandescent and fluorescent lamps for homework. The population attributable risk percentage for myopia associated with using LED lamps for homework after schools was 11.2%. Conclusions: Using LED lamps for homework after schools might contribute to the development of myopia among school-aged children. [ABSTRACT FROM AUTHOR] more...

Purpose: Variant myopia (VM) presents as a discrepancy of >1 diopter (D) between subjective and objective refraction, without the presence of any accommodative dysfunction. The purpose of this study is to create a clinical profile of VM.Methods: Fourteen eyes of 12 VM patients who had a discrepancy of >1D between retinoscopy and subjective acceptance under both cycloplegic and noncycloplegic conditions were included in the study. Fourteen eyes of 14 age- and refractive error-matched participants served as controls. Potential participants underwent a comprehensive orthoptic examination followed by retinoscopy (Ret), closed-field autorefractor (CA), subjective acceptance (SA), choroidal and retinal thickness, ocular biometry, and higher order spherical aberrations measurements.Results: In the VM eyes, a statistically and clinically significant difference was noted between the Ret and CA and Ret and SA under both cycloplegic and noncycloplegic conditions (multivariate repeated measures analysis of variance, P < 0.0001). A statistically significant difference was observed between the VM eyes, non-VM eyes, and controls for choroidal thickness in all the quadrants (Univariate ANOVA P < 0.05). The VM eyes had thinner choroids (197.21 ± 13.04 μ) compared to the non-VM eyes (249.25 ± 53.70 μ) and refractive error-matched controls (264.62 ± 12.53 μ). No statistically significant differences between groups in root mean square of total higher order aberrations and spherical aberration were observed.Conclusion: Accommodative etiology does not play a role in the refractive discrepancy seen in individuals with the variant myopic presentation. These individuals have thinner choroids in the eye with variant myopic presentation compared to the fellow eyes and controls. Hypotheses and clinical implications of variant myopia are discussed. [ABSTRACT FROM AUTHOR] more...

AIM:To compare noncycloplegic and cycloplegic results of Retinomax measurements with findings achieved after cycloplegia using table-top autorefractor and retinoscopy.METHODS: The study included 127 patients (mean age 96.7mo, range 21 to 221). Retinomax (Rmax) (Nikon Inc., Japan) was used to obtain noncycloplegic refraction. Under cycloplegia, refraction was measured with Rmax, table-top autorefractor (TTR) (Nikon NRK 8000, Inc., Japan) and retinoscopy. The values of sphere, spherical equivalent, cylinder and axis of cylinder were recorded for Rmax, TTR and retinoscopy in each eye. All results were analyzed statistically.RESULTS: The mean spheric values (SV), spherical equivalent values (SEV) and cylindrical values (CV) of the noncycloplegic Rmax (SV:0.64 D, SEV:0.65 D and CV:0.03 D, respectively) were found to be significantly lower than cycloplegic TTR (1.43 D, 1.38 D and 0.3 D; P=0.012, P=0.011 and P=0.04, respectively) and retinoscopy (1.34 D, 1.45 D and 0.23 D; P=0.04, P=0.002 and P=0.045, respectively). Mean cycloplegic SV, SEV, CV were not significantly different between Rmax and TTR, Rmax and retinoscopy, TTR and retinoscopy. Cycloplegic or noncycloplegic axis values were not different between any method.CONCLUSION: Rmax may be used successfully as a screening tool but may not be accurate enough for actual spectacle prescription. Cycloplegic Rmax measurements may be able to identify refractive error in children because of approximate results to retinoscopy. more...

Abstract: Purpose: Multifocal or multi‐zone contact lenses are increasingly being fit to young eyes in an attempt to control myopia progression. However, success in achieving this aim may depend on how much the eye accommodates. The purpose of the current work was to evaluate the ability of an open‐field clinical autorefractor to measure on‐axis refractive state and accommodation in eyes fit with multifocal contact lenses (CLs). Methods: Refractive state was measured with a Grand Seiko WAM‐5500 autorefractor ( www.grandseiko.com) and a clinical Shack‐Hartmann Complete Ophthalmic Analysis System (COAS) aberrometer ( www.wfsci.com) in subjects fit bilaterally with single vision aspheric contact lenses, centre distance, and centre near zonal multifocal CLs, and an experimental myopia control multi‐zone bifocal CLs (MiSight). Autorefractor measurements were obtained when aligned with the pupil centre, pupil margin, and mid‐periphery. Accuracy of refractive state measurements was evaluated using a fully presbyopic (62‐year‐old) dilated (pupil diameter = 7.1 mm) eye measured through known added spherical powers (trial lenses) of +1.00 D to +6.00 D. Refractive state and accommodation were measured for seven young myopic eyes (23.71 ± 2.87 years) with six target vergences ranging from −0.33 D to −5.00 D. Results: Irrespective of the CL fitted, measured changes in refractive state of the calibration eye were within ≤0.25 D of the added sphere power and the slope (measured refractive state/trial lens power) was approximately −1.0 D/D for both Shack‐Hartmann (COAS) aberrometer and Grand Seiko instruments. Also, the Grand Seiko data were highly repeatable (mean measurement standard deviation = 0.04 D) as long as measurements occurred at the same pupil location, but exhibited a hyperopic bias that increased to +1.00 D when eyes were fit with CLs containing significant negative spherical aberration. Centre and marginal refractive states could differ by >3.00 D due to the combined spherical aberration contained in the eye plus the different CL designs. Measured refractive states of young accommodating eyes also varied with measurement location in the pupil. The accommodation gains were similar at each pupil location, irrespective of contact lens design. Conclusions: With consistent sampling at the same pupil location, the open field Grand Seiko clinical autorefractor proved an effective tool for assessing the on‐axis refractive state and accommodative responses of eyes fit with multi‐zone bifocal and multifocal CLs. [ABSTRACT FROM AUTHOR] more...

By embracing 21st century design technology, the dialyte telescope concept now offers apochromatic performance using inexpensive glass types, with the benefits of low cost, very lightweight, rapid cool-down times, and atmospheric dispersion control. Much larger apertures than with traditional technologies are now feasible. [ABSTRACT FROM AUTHOR] more...

Purpose: To assess prevalence and associated factors of myopia and high myopia in schoolchildren in Greater Beijing. Methods: The school-based, cross-sectional Greater Beijing School Children Myopia study was carried out in the year 2016 in 54 schools randomly selected from 15 districts in Beijing. Non-cycloplegic auto-refractometry of the right eyes was performed. Results: The study included 35,745 (99.4%) out of 35,968 eligible pupils with a mean age of 12.6±3.4 years (range 6–18 years). Prevalence of myopia defined as myopic refractive error of ≥-0.50 diopters (D),≥-1D,≥-6D,≥-8D and ≥-10D was 70.9%(95% confidence intervals (CI):70.5,71.4), 60.9% (95%CI:60.4,61.4), 8.6%(95%CI:8.4,8.9), 2.2%(95%CI:2.0,2.4), and 0.3% (95%CI:0.3,0.4), respectively. The frequency of high myopia (≥-6D, ≥-8D, ≥-10D) increased from 1.5% (95%CI:1.0,2.0), 0.4% (95%CI:0.1,0.6) and 0.1% (95%CI:0.00,0.02), respectively in 10-year-olds to 19.4% (95%CI:17.3,21.6), 5.2% (95%CI:4.0,6.4) and 0.9% (95%CI:0.4,1.5), respectively, in 18-year-olds. Mean refractive error in the 18-year-olds was -3.74±2.56D (median:-3.63D;range:-19.6D to + 6.25D). Higher prevalence of high myopia (≥-6D and ≥-8D) was correlated (all P<0.001) with older age (OR:1.18, and 1.15, respectively), female gender (OR: 1.44 and 1.40, respectively), higher body mass index (OR: 1.02 and 1.03, respectively), taller body height (OR: 1.03 and 1.02, respectively), urban region of habitation (OR: 1.26 and 1.33, respectively) and higher school type (OR:1.57 and 2.22, respectively). Prevalence of severe high myopia (≥-10D) was associated only with older age (P<0.001; OR: 1.44; 95%CI: 1.31, 1.59) but not with any education-related parameter such as higher school type (P = 0.48), urban region of habitation (P = 0.07) or female gender (P = 0.37). Conclusion: In this most recent survey, prevalence of high myopia (≥-6D:19.4%;≥-8D:5.2%;≥-10D:0.9%) in 18-year-old school children was higher than in previous surveys from mainland China. In contrast to minor high myopia and moderate high myopia (defined as myopic refractive error of <-10D), severe high myopia (myopic refractive error ≥-10D) was not strongly correlated with educational parameters. [ABSTRACT FROM AUTHOR] more...

A formalism is presented for dark-field X-ray microscopy using refractive optics. The new technique can produce three-dimensional maps of lattice orientation and axial strain within millimetre-sized sampling volumes and is particularly suited to in situ studies of materials at hard X-ray energies. An objective lens in the diffracted beam magnifies the image and acts as a very efficient filter in reciprocal space, enabling the imaging of individual domains of interest with a resolution of 100 nm. Analytical expressions for optical parameters such as numerical aperture, vignetting, and the resolution in both direct and reciprocal spaces are provided. It is shown that the resolution function in reciprocal space can be highly anisotropic and varies as a function of position in the field of view. Inserting a square aperture in front of the objective lens facilitates disjunct and space-filling sampling, which is key for three-dimensional reconstruction and analysis procedures based on the conservation of integrated intensity. A procedure for strain scanning is presented. Finally the formalism is validated experimentally at an X-ray energy of 17 keV. [ABSTRACT FROM AUTHOR] more...

The far field refractor problem with a discrete target is solved with a numerical scheme that uses and simplify ideas from Caffarelli et al. (1999). A numerical implementation is carried out and examples are shown. [ABSTRACT FROM AUTHOR] more...

Based on photographic and CCD observations with the Pulkovo 26-inch refractor, radial velocity measurements with the 1.5-m RTT-150 telescope (TUBITAK National Observatory, Turkey), and highly accurate observations published in the WDS catalog, we have obtained the orbits of ten wide visual double stars by the apparent motion parameter method. The orientation of the orbits in the Galactic coordinate system has been determined. For the outer pair of the multiple star HIP 12780 we have calculated a family of orbits with a minimum period P = 4634 yr. Two equivalent solutions with the same period have been obtained for the stars HIP 50 ( P = 949 yr) and HIP 66195 ( P = 3237 yr). We have unambiguously determined the orbits of six stars: HIP 12777 ( P = 3327 yr), HIP 15058 ( P = 420 yr), HIP 33287 ( P = 1090 yr), HIP 48429 ( P = 1066 yr), HIP 69751 ( P = 957 yr), and HIP 73846 ( P = 1348 yr). The orbit of HIP 55068 is orientated perpendicularly to the plane of the sky, P >1000 yr. The star HIP 48429 is suspected to have an invisible companion. [ABSTRACT FROM AUTHOR] more...

Purpose To study whether the accommodation response to Badal optometer is equivalent to the response for real space targets. Methods Accommodative responses were measured for 28 young eyes with the WAM-5500 autorefractometer in eight configurations for 0.17 D, 2.0 D and 5.0 D accommodation stimuli. Parameters that might contribute to differences in response were systematically isolated: stimulation method (real space vs Badal targets), field of view, instrument's cover proximity, the looming effect, and the peripheral interposition of objects in depth. Results Mean accommodative response differences between a natural view configuration and a configuration with a Badal Optometer were 0.50 ± 0.43 D and 0.58 ± 0.53 D for 2.0 D and 5.0 D stimulation, respectively ( p < 0.001), with accommodation lags for the latter condition. Of the isolated parameters that might contribute to these differences, varying the interposition of objects in depth affected accommodation response more markedly. Conclusions It is likely that Badal optometers affect accommodation through a combination of some or all of the studied parameters. We conclude that accommodation response to closed-view Badal optometers is not equivalent to real space target response. [ABSTRACT FROM AUTHOR] more...

Purpose To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked examples using these equations. Methods Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings. Results Several examples applying equations are provided. Features of these examples include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed. Conclusions Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed. [ABSTRACT FROM AUTHOR] more...

The purpose of this study is to examine the potential relationship between tonic accommodation (TA), near work induced TA-adaptation and the steady state closed-loop accommodation response (AR). Forty-two graduate students participated in the study. Various aspects of their accommodation system were objectively measured using an open-field infrared auto-refractor (Grand Seiko WAM-5500). Tonic accommodation was assessed in a completely dark environment. The association between TA and closed-loop AR was assessed using linear regression correlations and t-test comparisons. Initial mean baseline TA was 1.84diopter (D) (SD±1.29D) with a wide distribution range (-0.43D to 5.14D). For monocular visual tasks, baseline TA was significantly correlated with the closed-loop AR. The slope of the best fit line indicated that closed-loop AR varied by approximately 0.3D for every 1D change in TA. This ratio was consistent across a variety of viewing distances and different near work tasks, including both static targets and continuous reading. Binocular reading conditions weakened the correlation between baseline TA and AR, although results remained statistically significant. The 10min near reading task with a 3D demand did not reveal significant near work induced TA-adaptation for either monocular or binocular conditions. Consistently, the TA-adaptation did not show any correlation with AR during reading. This study found a strong association between open-loop TA and closed-loop AR across a variety of viewing distances and different near work tasks. Difference between the correlations under monocular and binocular reading condition suggests a potential role for vergence compensation during binocular closed-loop AR. [ABSTRACT FROM AUTHOR] more...

The sunspot observations of Rudolf Wolf form the core of the Wolf series of sunspot relative numbers, or Wolf numbers, since his observations define the original scale of the series and also the main course of solar activity from 1849 to 1893. Unfortunately, the raw data for the years 1856 to 1869 were never published in full detail. The heritage group of the Rudolf Wolf Society in Switzerland digitized parts of the hitherto unpublished original source book of the Wolf series and put it on its website . Now, the Wolf numbers from 1849 to 1876, as provided by the World Data Center for Solar Index and Long-term Solar Observations (WDC-SILSO), can be reconstructed in every detail, since the source book contains all the raw sunspot group and individual spot numbers as well as the implemented calibration and interpolation methods. Thus, the observations made by Rudolf Wolf with the 83/1320 mm Fraunhofer refractor and with the 40/700 mm Parisian refractor as well as those made by Heinrich Schwabe can be identified and separated now. In this article, we describe Wolf's instruments and methods of observation. An inspection of the source book and other published sources reveals that the calibration factor of the 40/700 mm Parisian refractor should probably be lowered. Since no appropriate comparison observations are available, the scale transfer from Heinrich Schwabe to Rudolf Wolf has to be analyzed further. [ABSTRACT FROM AUTHOR] more...

We consider the parallel refractor problem when the planar radiating source lies in a medium having higher refractive index than the medium in which the target is located. We prove local C 1 , α estimates for parallel refractors under suitable geometric assumptions on the source and target, and under local regularity hypotheses on the target set. We also discuss existence of refractors under energy conservation assumptions. [ABSTRACT FROM AUTHOR] more...

Objectives: Objective of this study is to investigate whether there is any effect of accommodation on Autoref reading before and after cycloplegia and to check out which age and type of refractive error is more effected by accommodation. Methods: An informed consent was obtained describing the detail of study and its implication. Therefore the subject was assured of their confidentially of information and outcome. Four groups were selected and effect of accommodation on patients autoref reading were measured. Autorefractor reading was noted before and after cycloplegia. Autoref reading was taken without cycloplegia in different age groups and then by using cyclopentolate to relax the accommodation and by repeating the autoref reading to find out difference in reading before and after cycloplegia. 110 patients of age group 3 to 60 were assessed by that method. Results: Accommodation affects different age groups except old age. Accommodation effects on refractive error more in age 3-15 years because accommodation is stronger in children. There was significant difference between morning and evening amplitude of accommodation as p<0.005. Conclusions: Accommodation affects different age group and the effect is maximum between 3-15 years and decreases with increasing age. Autoref overestimate myopia and under estimate hyperopia without cycloplegia. By using cycloplegia exact refractive error can be measured. [ABSTRACT FROM AUTHOR] more...

Background: Previous research demonstrates that visual impairment (VI) is associated with increased all-cause mortality risk and is also associated with reduced physical activity participation. Although physical activity is reduced among those with VI, no studies have examined the relationship between physical activity and all-cause mortality across different visual function statuses, which is noteworthy of investigation as physical activity is linked with greater survival.Methods: Data from the 2003-2006 NHANES were employed, with physical activity assessed via accelerometry and visual function assessed using the ARK-760 autorefractor.Results: For those with normal vision, and after adjustments, for every 60min increase in physical activity, normal-sighted adults had an 18% (HR=0.82; 95% CI: 0.72-0.93) reduced risk of all-cause mortality. Similarly, after adjustments and for every 60min increase in physical activity for those with uncorrected refractive error and VI, respectively, there was a 15% (HR=0.85; 95% CI: 0.72-1.00) and 35% (HR=0.65; 95% CI: 0.43-0.98) reduced risk of all-cause mortality. Among all three visual status groups, sedentary behavior was not associated with mortality status.Conclusion: Among those with varying degrees of visual loss, sedentary behavior was not associated with mortality, but physical activity demonstrated survival benefits. [ABSTRACT FROM AUTHOR] more...

Background: The PlusOptix photoscreeners (PlusOptix GmbH, Nuremberg, Germany) is used in many vision screening programs. The purpose of the present study was to further explore the accuracy of the PlusOptix A09 photoscreener in children with ametropia (myopia or hyperopia).Methods: A total of 70 eyes (35 children) were prospectively included. Before administration with the cycloplegia treatment 1 % cyclopentolate hydrochloride, children underwent refraction measurement with the PlusOptix A09. A refraction was then performed after cycloplegia with either Retinomax hand-held or Nidek autorefractor before and after 3 years old, respectively.Results: The median (interquartile range) age was 58 (18 to 86) months. The mean (SD) spherical equivalent differed between PlusOptix A09 and cycloplegic autorefraction (+0.54 [1.82] D vs +1.06 [2.04] D, p = 0.04). PlusOptix A09 refraction was positively correlated with cycloplegic autorefraction (r = 0.81, p < 0.001) with higher coefficient in myopic than in hyperopic children (r = 0.91, p = 0.0002 and r = 0.52, p = 0.01, respectively). The mean (SD) difference between PlusOptix A09 and cycloplegic autorefraction was higher with hyperopia than myopia (0.73 [1.34] vs 0.05 [0.66], p = 0.01). The proportion of children with < 1-D difference between cycloplegic and PlusOptix A09 refraction was 68.8 %, higher with myopia than hyperopia (90 % vs 54.5 %, p = 0.01).Conclusion: The spherical equivalent value with non-cycloplegic PlusOptix A09 refraction is closer to that with cycloplegic autorefraction than non-cycloplegic autorefraction. The PlusOptix A09 photoscreener underestimated the hyperopia of 0.73 D and slightly overestimated myopia of 0.05 D. The PlusOptix A09 could be used for screening with higher accuracy in myopic than hyperopic children. [ABSTRACT FROM AUTHOR] more...

The article focuses on history of the refractor of instrument-making firm Thomas Cooke & Sons that belonged to Port Elizabeth, South Africa. Topics discussed include role of J. Bently, resident of Port Elizabeth, to form an observatory society for research in astronomy; and a decline in Schmidt-Cassegrain telescopes and Dobsonian reflectors with decreased interest in astronomy. more...

Purpose The association between myopia and cognitive dysfunction among elderly adults was assessed by applying a Propensity Score Matching ( PSM) approach. This is a statistical method which allows investigators to estimate causal treatment effects using observational or nonrandomised data. Methods The study was designed as a community-based cross-sectional study based on a Chinese cohort aged 60 years or older in China. Objective refraction was measured using an autorefractor and subjective refraction was used to refine vision, using the results of the objective refraction as the starting point. Myopia was defined as a spherical equivalent value of less than −0.50 dioptre (D) in the right eye. The Abbreviated Mental Test ( AMT) was used for cognitive assessment. The propensity scores for myopia were formulated using 13 potential confounders. We matched the propensity scores for subjects with and without myopia within a caliper of 0.01 of logit function of propensity scores. Results About 4123 elderly adults who successfully completed the AMT were included in this analysis. The odds ratio ( OR) of cognitive dysfunction for myopia before matching was 1.98 (95% confidence interval [ CI] 1.61, 2.44; p < 0.001). There were significant covariate imbalances between comparison groups and after propensity score matching, covariate imbalance was significantly reduced. After propensity score matching, the OR of cognitive dysfunction was marginally significant and the magnitude of association was reduced ( OR: 1.31 95% CI 1.00, 1.71; p = 0.05). Traditional multivariate logistic regression modelling found an OR of 1.52 (95% CI 1.23, 2.06; p < 0.001) after adjusting for the 13 potential confounders. Conclusions Myopia was associated with a higher prevalence of cognitive dysfunction among elderly Chinese aged 60 years or older in China. The PSM approach may be a useful method to address selection bias in observational studies when randomised trials cannot ethically be conducted. [ABSTRACT FROM AUTHOR] more...

Background: The aim was to assess non-cycloplegic objective refraction in darkness using an open-field auto-refractor, and furthermore to compare it with distance cycloplegic subjective refraction and distance cycloplegic retinoscopy in the light, in children and young adults.Methods: Twenty-three, visually-normal, young-adults (46 eyes) ages 23 to 31 years, and five children (10 eyes) ages five to 12 years, participated in the study. The spherical component of their refraction ranged from -2.25 D to +3.75 D with a mean of +1.80 D, and a mean cylinder of -0.70 D. Three techniques were used to assess refractive error. An objective measure of the non-cycloplegic refractive state was obtained using an open-field autorefractor (WAM-5500) after five minutes in the dark to allow for dissipation of accommodative transients and relaxation of accommodation. In addition, both distance retinoscopy and subjective distance refraction were performed following cycloplegia (Cyclopentolate, 1%) using conventional clinical procedures. All measurements were obtained on the same day within a single session. The spherical component of the refraction was compared among the three techniques in both the children and adults.Results: There was no significant difference in spherical refraction among the three techniques: non-cycloplegic objective refraction in the dark, distance cycloplegic retinoscopy and distance cycloplegic subjective refraction, in either the adults [F(2, 137) = 0.79, p = 0.45] or the children [F(2, 27) = 0.47, p = 0.62]. Mean difference in the spherical component between refraction in the dark and the cycloplegic distance retinoscopy was -0.34 D (r = 0.89) in the adults and +0.14 D (r = 0.96) in the children. The mean difference in spherical component between refraction in the dark and the cycloplegic distance subjective refraction was -0.25 D (r = 0.92) in the adults and -0.05 D (r = 0.95) in the children.Conclusion: Comparison of the spherical refractive component between the three techniques was not significantly different and furthermore, they were highly correlated in both the children and adults in this pilot study. Non-cycloplegic refraction in the dark may provide a reliable adjunct or alternative to conventional cycloplegic refraction in both children and young adults. [ABSTRACT FROM AUTHOR] more...