Visual Ranges Research Articles

Exploring Vision-Related Quality of Life: A Qualitative Study Comparing Patients' Experience of Cataract Surgery with a Standard Monofocal IOL and an Enhanced Monofocal IOL.

PurposeTo explore quality of life related with intermediate vision of patients before and after cataract surgery, and to make patients’ experience available for the design of future scales that assess visual function related with intermediate distance.Patients and MethodsA qualitative research methodology based on thematic content analysis was used to explore vision-related quality of life based on the experiences of patients with cataract. Patients were recruited at the Service of Ophthalmology of the Hospital de Sant Pau (Barcelona, Spain). Data were collected through nineteen semi-structured interviews conducted with patients diagnosed with cataract and implanted with a standard aspheric monofocal intraocular lens (IOL) (Tecnis® ZA9003) (n = 6), an enhanced monofocal IOL (Tecnis® Eyhance ICB000) (n = 6), and patients from the waiting list (n = 7). The data analysis consisted in coding, aggregation, and theme development of the transcribed audios.ResultsPatients on waiting lists reported difficulty and insecurity in performing daily and meaningful tasks related to near visual ranges (eg: threading a needle, reading price tags), intermediate (eg: using a computer or dialling numbers on a smartphone), and distant (eg: recognizing faces, walking on uneven surfaces). Patients after surgery with the standard IOL reported improvement in performing activities mainly in the distant visual range, but also the need for a better communication with clinical staff to adjust their own expectations on the results of the surgery. Finally, patients implanted with the enhanced IOL reported satisfaction and improved visual function in performing daily activities, especially those related to the intermediate visual range.ConclusionOur exploratory study found that patients after cataract surgery with the enhanced IOL reported a better performance in activities that require the intermediate vision. These results will inform the development of scales to assess vision-related quality of life in the intermediate visual range prioritizing outcomes according to patients’ daily and meaningful activities.

Below the horizon-the physics of extreme visual ranges.

Visual ranges of up to 440 km have recently been documented by photographs of ground-based observers. A report from 1948 claimed a record visual range from a plane of more than 530 km and a similar recent observation from 2017 was documented by a photo. Such extreme visual ranges can in principle be explained by the interplay of refraction and light scattering. However, they require optimal atmospheric conditions, and cleverly chosen locations and times.

Visibility in airborne volcanic ash: considerations for surface transportation using a laboratory-based method

All modes of surface transportation can be disrupted by visibility degradation caused by airborne volcanic ash. Despite much qualitative evidence of low visibility on roads following historical eruptions worldwide, there have been few detailed studies that have attempted to quantify relationships between visibility conditions and observed impacts on network functionality and safety. In the absence of detailed field observations, such gaps in knowledge can be filled by developing empirical datasets through laboratory investigations. Here, we use historical eruption data to estimate a plausible range of ash-settling rates and ash particle characteristics for Auckland city, New Zealand. We propose and implement a new experimental set-up in controlled laboratory conditions, which incorporates a dual-pass transmissometer and solid aerosol generator, to reproduce these ash-settling rates and calculate visual ranges through the associated airborne volcanic ash. Our findings demonstrate that visibility is most impaired for high ash-settling rates (i.e. > 500 g m−2 h−1) and particle size is deemed the most influential ash characteristic for visual range. For the samples tested (all < 320 μm particle diameter), visibility was restricted to ~ 1–2 m when ash settling was replicated for very high rates (i.e. ~ 4000 g m−2 h−1) and was especially low when ash particles were fine-grained, more irregular in shape and lighter in colour. Finally, we consider potential implications for disruption to surface transportation in Auckland through comparisons with existing research which investigates the consequences of visual range reduction for other atmospheric hazards such as fog. This includes discussing how our approach might be utilised in emergency and transport management planning. Finally, we summarise strategies available for the mitigation of visibility degradation in environments contaminated with volcanic ash.

Effect of Visual Range on Driving Speed on Low-grade Highway

Visual range from road alignments plays an important role in traffic safety since it is a key factor for drivers to adopt an appropriate speed. It is especially true to low-grade highways where speeds tend to reach a high value when sections have a relatively good linearity. High speeds on low-grade highway are considered a main contributor to traffic accidents. This paper studied the relationship of maximum visual range and driving speed on low-grade highways to put forward a suggested visual range for safe driving. Four typically mountainous highway models with the same driving environment but different visual ranges were constructed to analyze the effect of visual range on driving speed. A driving simulator with eight degrees of freedom was used to carry out the experiments. Data of driving speed, acceleration and deceleration were collected to study the speed and acceleration trends. The conclusion drawn is that the appropriate value of maximum visual range on low-grade highways is recommended to be 80m to ensure safety driving.

A qualitative investigation of visual tasks with which to assess distance-specific visual function

The ability to perform many daily tasks relies on good visual acuity at various distances. A review of existing measures of visual function revealed gaps in task content, particularly tasks that rely on intermediate vision. This research sought to extend the content base and visual range coverage of tasks used to assess visual function. Ophthalmology patients (n = 72) with myopia, hyperopia, presbyopia, astigmatism, cataracts, and/or glaucoma were involved in various qualitative sub-studies, including life event journaling, telephone interviews, and both on-line and face-to-face focus groups. The resulting journal entries and transcripts were thematically analyzed to identify visual tasks that rely on visual acuity in the near, intermediate, and distant visual ranges. A wide variety of distance-specific visual tasks were identified. Certain types of tasks relied on distance vision, such as; ambulation, driving, leisure and sports, and social functions. Other task groupings such as technology use and activities of daily living relied primarily on near and intermediate vision. Two new content areas were identified, technology use and safe task performance. This thematic analysis provides a rich body of information about tasks that affect daily life and are made more difficult by poor visual acuity at various distance ranges.

Algorithm Development of a Visibility Monitoring Technique Using Digital Image Analysis

Atmospheric visibility is one of the indicators used to evaluate the status of air quality. Based on a conceptual definition of visibility as the maximum distance at which the outline of the selected target can be recognized, an image analysis technique is introduced here and an algorithm is developed for visibility monitoring. Although there are various measurement techniques, ranging from bulk and precise instruments to naked eye observation techniques, each has their own limitations. In this study, a series of image analysis techniques were introduced and examined for in-situ application. An imaging system was built up using a digital camera and was installed on the study sites in Incheon and Seoul separately. Visual range was also monitored by using a dual technology visibility sensor in Incheon and transmissometer in Seoul simultaneously. The Sobel mask filter was applied to detect the edge lines of objects by extracting the high frequency from the digital image. The root mean square (RMS) index of variation among the pixels in the image was substantially correlated with the visual ranges in Incheon and Seoul with correlations of <TEX>$R^2$</TEX>=0.88 and <TEX>$R^2$</TEX>=0.71, respectively. The regression line equations between the visual range and the RMS index in Incheon and Seoul were VR=<TEX>$2.36e^{0.46{\times}(RMS)}$</TEX> and VR=<TEX>$3.18e^{0.15{\times}(RMS)}$</TEX>, respectively. It was also confirmed that the fine particles (<TEX>$PM_{2.5}$</TEX>) have more impacts to the impairment of visibility than coarse particles.

Determination of visual range during fog and mist using digital camera images

During the winter of 2008, daily time series of images of five "unit-cell chequerboard" targets were acquired using a digital camera. The camera and targets were located in the Majura Valley approximately 3 km from Canberra airport. We show how the contrast between the black and white sections of the targets is related to the meteorological range (or standard visual range), and compare estimates of this quantity derived from images acquired during fog and mist conditions with those from the Vaisala FD-12 visibility meter operated by the Bureau of Meteorology at Canberra Airport. The two sets of ranges are consistent but show the variability of visibility in the patchy fog conditions that often prevail in the Majura Valley. Significant spatial variations of the light extinction coefficient were found to occur over the longest 570 m optical path sampled by the imaging system. Visual ranges could be estimated out to ten times the distance to the furthest target, or approximately 6 km, in these experiments. Image saturation of the white sections of the targets was the major limitation on the quantitative interpretation of the images. In the future, the camera images will be processed in real time so that the camera exposure can be adjusted to avoid saturation.

Quality control of age data at the Alaska Fisheries Science Center

The Alaska Fisheries Science Center operates a 14-person Age and Growth Program that specialises in the ageing of various groundfish species using otoliths. In 1983, a quality control programme was established whereby a random subsample of 20% of the total of aged samples is re-aged by a second age reader. The purpose of this programme is to assure, to the greatest extent possible, that ages used in stock assessment are based on consistent ageing criteria. This age data is entered into our AGEDATA Microsoft ACCESS™ database where it can be easily updated, corrected and analysed. VISUAL BASIC computer programmes AGREE (a precision estimating programme) and RANGES (an outlier searching programme) were written to routinely analyse age data before data are released to end-users. The statistical relationship between average percentage error and coefficient of variation is described, as well as an interpretation of Bowker’s test for symmetry. Discrepancies between the reader and tester are reconciled while viewing the problematic otoliths using a dual-headed microscope, and reconciled ages are assigned. When necessary, all questionable otoliths in a troublesome sample may be re-aged.

Measurement of Slant Visual Range in Laser Radar Operation Considering the Spread of Transmitted Laser Beam Caused by Small Particles in the Atmosphere.

In bad weather conditions, e.g. rainy, foggy, and snowy conditions, exact slant visual ranges should be obtained for safe landings at airports. However, no equipment for achieving this has been installed in airports yet. In this study, the laser radar system is refined for estimating the slant visual range. It is found that the empirical data in bad weather conditions do not correspond to predictions with the current laser radar equation. Therefore, a new laser radar equation, which considers the divergence of the transmitting laser beam, is proposed. The slopes of this equation correspond well to the empirical data in various weather conditions. The visibilities estimated by this equation also correspond with those obtained by the slant transmittance system. Also, the extent of the divergence is examined by means of classifying the empirical data by weather conditions. As a result, it is found that the divergence of the transmitted laser beam increases in the order of rain, fog, misty rain, and snow.

A revised model of visual range in fish

Abstract Models of visual range and location distances are crucial for quantification of vision based feeding opportunities and predation risk in the pelagic habitat. We compare an earlier published model with measurements of the reactive distance of Gobiusculus flavescens relative to two species of copepods. Although this model gave reasonable predictions at low light intensities, the measurements of reactive distance at higher intensities were much lower than those predicted by the model. We modified the model to account for saturation at high light intensities. With this additional feature, the correspondence with the G.flavescens observations was significantly improved. Furthermore, the revised model is consistent with earlier published data on fish contrast thresholds obtained over a wide range of target sizes and irradiance levels. Given the values of only two parameters, one sensitivity threshold and one saturation parameter, the model is capable of predicting visual ranges for relatively large intervals of light intensity, prey size and turbidity. Other published visual range models are briefly reviewed and compared with our model.

大気中の微小粒子による送信ビームの広がりを考慮したレーザレーダによる斜め視程測定法

In bad weather conditions e. g. rainy, foggy and snowy conditions, exact slant visual ranges should be obtained for safe landings at airports. However no equipment for achieving this has been installed in airports yet.In this study, the laser radar system is developed for estimating the slant visual range. It is found that the practical data in bad weather conditions do not correspond to the predictions of the current laser radar equation. Therefore, the new laser radar equation, which considered the divergence of transmitting laser beam, is proposed. The slopes of this equation correspond well to the practical data in various weather conditions. The visibilities estimated by this equation also coincide with those obtained by the slant transmittance system. And the extent of the divergence is examined by means of classifying the practical data by weather conditions. As a result, it is found that the divergence of the transmitted laser beam increases in the order of rain, fog, misty rain, and snow.

A Critical Assessment of Atmospheric Visibility and Aerosol Measurements in the Eastern United States

As part of a study examining the technical basis for a secondary national ambient air quality standard for fine particulate matter to protect visibility, we reviewed available data on atmospheric aerosol and visibility in the eastern U.S. This paper presents the results of that visibility and aerosol characterization. Analysis of airport visibility data indicates that the annual median visual ranges in the East are in the 16-25 km range. In the absence of a reference method, limited measurements of visibility using various types of instruments provide data generally in agreement with the airport visibility estimates when a contrast threshold of 0.05 is assumed in calculating visual range from the instrumental measurements. Both long- and short-term aerosol measurements have yielded consistent results; however, because of the differences in instrumentation and laboratory analytical techniques among various studies, data often are not directly comparable. The measured annual average fine particulate matte...

Statistical Comparisons between Teleradiometer-Derived and Slide-Derived Visibility Parameters

An automated scanning densitometer system developed to estimate visibility-related parameters from photographic slides was tested in comparison to similar teleradiometric measurements. Parameters such as target-sky contrast, visual range, atmospheric light extinction coefficient, and plume and layered contrast can be estimated using this system; however, only target-sky radiance ratios and standard visual ranges were compared. More than 1600 concurrent densitometer and teleradiometer data pairs from eight National Park Service air quality and visibility monitoring locations in the western United States were analyzed using the techniques of correlation, linear regression, average bias and difference calculation, and cumulative frequency distribution generation. Correlation coefficients were good, especially with middle-range camera vistas around 50 km distant. Regression slopes approached unity with intercepts near zero. Average bias introduced into the determination of radiance ratios from slides ranged f...

Site specific factors influencing the visual range calculated from teleradiometer measurements

This paper presents conclusions and recommendations on the interpretation of data gathered from teleradiometers. As part of Project VIEW (Visibility Investigation Experiment in the West), multiwavelength teleradiometers were used to measure apparent target contrast in 14 southwestern national parks and monuments. Statistical results show that the accurate measurement of visual ranges by teleradiometer in an atmosphere containing significant amounts of aerosol depends on observer-target distance and observation angle, and in clean atmospheres on inherent contrast. Target illumination, sun angle, and mean altitude of the sight path may also affect visual range. The relative contribution of each of these factors to the variance in calculated visual range at different sites as a function of air pollution levels is examined through the use of principal component and regression analysis.

Existing and natural background levels of visibility and fine particles in the rural east

An investigation is conducted into existing and natural background levels of visibility and fine particles in nonurban areas of the eastern U.S. An analysis of data for 100 airports nationwide indicates that nonurban areas of the East experience relatively low visibilities; specifically, rural areas east of the Mississippi and south of the Great Lakes generally exhibit annual median visual ranges of 15–25 km. A review of data from eight monitoring programs indicates that ambient fine (</ 2.5 μm) particle concentrations presently average approximately 29 μg m −3 in the rural East. The largest components are water ( ~ 11 μg m −3), sulfates ( ~ 9 μg m −3), and organics ( ~ 4 μg m −3). The majority of the water is thought to be attached to hygroscopic sulfate aerosols. Currently, sulfates and fine particles exhibit a pronounced maximum in the summer quarter, when visibility shows a pronounced minimum. This seasonal pattern is a new phenomenon historically; prior to the 1960s, visibility was distinctly higher during the summer then during the remainder of the year. An investigation of natural background conditions suggests that the natural line aerosol concentrations would average 5 1 2 ± 2 1 2 μg m −3 in the East, with the largest components being organics and water. Natural background visual range for the East is estimated to be 95 ± 45 km. It is not currently possible to check this estimate of natural background visual range through an analysis of historical visibility trends from the 1930s to the 1970s because of limitations in historical emission trend data, uncertainties in airport visibility trend data and the confounding effects of meteorology. The best check would be to collect simultaneous measurements of fine particle mass, fine particle chemical composition, and visibility in remote continental areas of the Southern Hemisphere.

The effects of non-standard conditions on visibility measurement

The effects of non-standard visibility observation conditions upon computed visual range (meteorological range) were investigated using data from an eastern U.S. visibility study sponsored by the Electric Power Research Institute. Data collected by multi-wavelength telephotometry was specially marked in the field when non-standard conditions were observed. The non-standard conditions explored were those which violate the assumptions implicit in routine visual range calculations. These conditions include bright and dark clouds behind the target, bright haze, shadowed targets, and snow-covered targets. The errors caused by non-standard conditions were evaluated by comparing derived visual ranges and observed luminances along affected and non-affected viewing paths. The factors introducing error into visual range calculations during bright haze and bright cloud conditions were found to depend strongly on the relative degrees of light scattering in front of and behind the target. Large errors were noted in visual ranges derived for snow-covered targets if an intrinsic contrast of − 1.0 was assumed; a method for approximating intrinsic sky/target contrast was applied to correct these errors. Recommendations are provided for recognition of non-standard conditions and field flagging of data.

Analog visibility computer

A simple, inexpensive, all solid-state analog computer has been developed for calculating the visual range. Using an input signal from a transmissometer, the computer calculates the visual range by repeatedly solving the Allard and Koshmieder visibility laws. It is accurate to +/-2.0% for visual ranges of between 500 ft (150 m) and 5000 ft (1500 m).

Visual range and size of atmospheric particles

The product of visual range in the atmosphere and mass concentration of aerosol is constant for a given distribution of particle size; if the distribution is broken down into a set of size ranges the contributions of each are additive with respect to the reciprocal of the visual range. Using this rule, the manner in which the visual range in an atmospheric aerosol depends on the size distribution is illustrated by examples. Study of experimental observations shows that sampling mists with cascade impactors does not catch droplets with radii below 0–5 μm which may make a significant contribution to reducing the visual range. Aitken nuclei may also be present with mist droplets. Failure to include fine droplets and particles accounts for measured visual ranges sometimes being lower than calculated values. There is no indication of failure of the Koschmieder law and Middleton's contrast equation.

IV—Visual Range and the Degree of Risk

The visual sense supplies a major part of the information necessary for avoiding traffic accidents and fog impedes this channel of information, even though the invention of radar has removed the limitation to a considerable extent. The closure of airports is caused mainly by reduced visual range and partly by low cloud, or by typhoons in Japan. The length of signal sections on the Japan National Railway (600 m) was determined from a study of the frequency of visual ranges. Nishikura and others have studied the influence of visibility on the probability of marine traffic accidents and conclude that the ratio of the collision danger with a visibility less than 1 km and more than 1 km is in the range of from 30 to 100. Wheatley et al. have also shown the risk of traffic accidents to be high in bad visibility in the Dover Strait.

人間の目による網糸の水中規程の研究-II

The visual ranges of dyed and transparent twines and also of knots of the net were measured succesively in tank water, illuminated by diffused light from flourescent lamps for varying the physical conditions, namely, colour and reflectance of an object, turbidity of water and brightness which might have direct effects upon underwater visibility. The measurements of the visual range were made through three light filters; blue, green and orange. The visual rangs of the yellow twine was the largest under less turbid conditions but decreased remarkably with the increase of turbidity. Transparent twines were less visible than dyed opaque twines. The visual range was longer than that of twine for knots in brighter surface irradiance but both values become almost the same with the increase of burbidity. The slopes of the curves of the visual range of niyed twines plotted against the wave-length of maximum transmittance of three light filters provided a means to classify them into two types. Twines belonging to the first type are more visible under long wave-legths, such as, yellow, green, and blue twines and those of the other type are most visible in the wave-length, 530 mμ, such as, red, violet, brown, kacchi and grey twines.