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At least 253 records · Page 14Linked to original sources

Myopic astigmatism a substitute for accommodation in pseudophakia.

The power of an intraocular lens can be calculated before surgery to make the eye emmetropic or ametropic. The physiological mechanism of accommodation however, cannot be restored with an inelastic lens. An increased depth of focus in the implanted eye can be predicted through optical principles alone, if the postoperative ametropia of the implanted eye is a simple myopic astigmatism. This increased depth of focus without accommodation was tested in artificial ametropia and found to be used in nature by the seal. To increase the precision of intraocular lens calculation the average change in corneal power induced at surgery is used to predict the postoperative corneal power. By controlled suture release in the postoperative phase, the amount of induced corneal astigmatism is adjusted to obtain a simple myopic astigmatism. Patients with an intraocular lens and a simple myopic astigmatism as a residual ametropia, are spectacle independent most of the time. They need their glasses only for driving or prolonged reading. The methods used to calculate the postoperative cornea, the postoperative anterior chamber depth and the intraocular lens are described with the corresponding calculator programs for the HP 41C calculator. Clinical results and measurements of the depth of focus are shown in a series of 50 successive implant cases.

Accommodation, Ocular↗

The 57 mm thermal clearance probe: a non-invasive tool for measuring subcutaneous blood flow.

1. The segmented thermal clearance probe is a non-invasive instrument which measures heat thermal clearance, a variable directly proportional to superficial blood flow, with a depth sensitivity theoretically proportional to the sensor diameter. We compared an 18 mm sensor and a recently developed 57 mm sensor with the reference technique of xenon washout. 2. The theoretical depth sensitivity of the sensors was assessed using Perspex spacers. Ninety-five per cent of sensitivity had been lost at the respective depths of 3.5 mm and 7.1 mm for the 18 mm and 57 mm sensors. 3. A comparison was made between heat thermal clearance reading and 133Xe decay curves using the two probes for 15 min after injection of 133Xe at 2 mm and 6 mm depths in the anterior thigh in 41 subjects. The 57 mm sensor showed similar correlation with xenon washout at 2 mm injection depth (r = 0.89) and 6 mm injection depth (r = 0.86), whereas the 18 mm sensor showed greater correlation at 2 mm (r = 0.92) than at 6 mm (r = 0.62). 4. The 57 mm sensor was compared with xenon washout at 6 mm in eight insulin-treated diabetic subjects. The relationship was similar to that in non-diabetic subjects (r = 0.79), with no significant difference in slope or intercept. 5. It is concluded that the 57 mm thermal clearance probe may be used to study blood flow at the depth of insulin injection (6 mm) in diabetic and non-diabetic subjects.

Adult↗

A comparison of laser photocoagulation with cryotherapy for threshold retinopathy of prematurity at 10 years: part 2. Refractive outcome.

OBJECTIVE: To compare the refractive outcome of eyes treated with cryotherapy for threshold retinopathy of prematurity (ROP) with eyes treated with laser photocoagulation. DESIGN: Extended follow-up of a randomized controlled clinical trial. PARTICIPANTS: One hundred eighteen eyes from 66 patients were randomly assigned to receive either cryotherapy or laser photocoagulation for threshold ROP. Twenty-five patients (44 eyes treated) were available for follow-up examination 10 years later. INTERVENTION: Cycloplegic autorefraction or retinoscopy was performed. Immersion ultrasound biometry (A-scan) was also performed, and an autokeratometer was used for keratometry. If an A-scan could not be tolerated or the patient was not cooperative, a B-scan through-the-lid biometry was performed. Corneal thickness was measured using optical coherence tomography. MAIN AND SECONDARY OUTCOME MEASURES: Refractive error. In addition, anterior chamber depth, lens thickness, and axial length were measured. Central corneal thickness measurements and keratometric readings were also obtained. RESULT: Eyes treated with cryotherapy were significantly more myopic than those treated with laser photocoagulation. When comparing patients with bilateral treatment, the mean spherical equivalent (SE) of eyes treated with laser was -4.48 diopters (D) compared with a mean SE of -7.65 D for eyes treated with cryotherapy (n = 15 pairs of eyes, P = 0.019). Cryotherapy-treated eyes had a mean axial length of 21.7 mm versus 22.9 mm for laser-treated eyes (P = 0.024, n = 12 pairs of eyes). The anterior chamber depth and lens thickness averaged 2.86 mm and 4.33 mm, respectively, in the cryotherapy-treated eyes compared with 3.42 mm and 3.95 mm in the laser-treated eyes (P < 0.001, n = 12 pairs for both measurements). There were no statistical differences in anterior corneal curvature and central corneal thickness between the two treatment modalities. Crystalline lens power bore the strongest correlation to refractive outcomes in both laser-treated (r = 0.885, P < 0.001) and cryotherapy-treated eyes (r = 0.591, P = 0.026). Although keratometric readings were higher than normal values in these eyes, there was no correlation to the degree of myopia. CONCLUSIONS: Laser-treated eyes were significantly less myopic than cyrotherapy-treated eyes. Lens power seemed to be the predominant factor contributing to the excess myopia.

Anterior Chamber↗

Resource allocation in on-line reading by younger and older adults.

Younger and older adults read a series of expository passages for immediate recall by self-pacing the presentation sector-by-sector on a computer screen. Regression analysis of sector reading times (RT) was used to estimate the time allocated by individuals to word-level (i.e., syllable length and mean word frequency), text-level (i.e., number of propositions, number of new concepts introduced, and total Yngve depth), and discourse-level (i.e., serial position) features. Age differences were found in the pattern of reading time allocation that engendered high levels of recall. Specifically, younger adults who achieved high recall were more responsive to word frequency and the introduction of new concepts. By contrast, high recall among the old was related to a greater degree of on-line contextual facilitation (i.e., a steeper serial position effect). These data suggest that there is an age difference in how the allocation of resources at encoding optimizes subsequent memory performance.

Adult↗

The visual and driving performance of monocular and binocular heavy-duty truck drivers.

This study compared the performance of 40 monocular and 40 binocular tractor-trailer drivers on measures of both visual and driving performance. On the visual measures, the mononuclear drivers were significantly deficient in contrast sensitivity, visual acuity under low illumination and glare, and binocular depth perception. They were not significantly deficient in static or dynamic visual acuity, visual field of individual eyes, or glare recovery. Driving measures of visual search, lane keeping, clearance judgment, gap judgment, hazard detection, and information recognition showed no differences between monocular and binocular drivers. Monocular drives were poorer than binocular drivers only in sign reading distance in both daytime and nighttime driving. This decrement correlated significantly with the binocular depth perception measure. There were large individual differences within each group for most of the visual and driving performance measures. It was concluded that monocular drivers have some significant reductions in selected visual capabilities and in certain driving functions dependent on these abilities, compared with binocular drivers. However, monocular drivers are not significantly worse than binocular drivers in the safety of most day-to-day driving functions. Implications of these findings and the large individual differences within each group are discussed.

Adult↗

Effect of a cataract simulation on clinical and real world vision.

AIMS/BACKGROUND: Many reports have indicated that some patients with cataract can retain good visual acuity but complain of significant visual problems. This is the first in a series of papers trying to determine what causes these symptoms and whether other clinical tests can predict the real world vision loss. METHODS: The effect of a cataract simulation with a similar angular distribution of light scatter as real cataract on clinical (visual acuity, contrast sensitivity, and disability glare) and real world vision (face recognition, reading speed, and mobility orientation) was investigated. RESULTS: The simulation had a relatively small effect on visual acuity (6/6 with the simulation), but much larger effects on contrast sensitivity and low contrast acuity with and without glare. The simulation had no effect on high luminance and high contrast real world tasks, such as mobility orientation in room light and optimal reading speed. A small, but significant deterioration was found for the slightly lower contrast task of face and expression recognition. However, under low luminance conditions, substantial defects in mobility orientation were obtained (despite 6/6 acuity). CONCLUSIONS: Although the relative effect of the cataract simulation on acuity and contrast tasks is not typical of the average cataract, it can be found in those cataract patients with visual problems despite good visual acuity. This corroborates the suggestion that it is large amounts of wide angle light scatter (forward and/or backward) which are at least partly responsible for visual disability in cataract patients with good visual acuity. A patient's reported visual disability may depend on the percentage of time he or she spends under low contrast and/or low luminance conditions, such as walking or reading in dim illumination, and walking or driving at night, in fog, or heavy rain.

Adult↗

Acquired monocular vision: functional consequences from the patient's perspective.

PURPOSE: The study is conducted to determine the effect of acquired monocular vision (enucleation, phthisis) on the daily activities of patients. METHODS: Sixty-five patients in a case series completed a 30-question survey evaluating the functional consequences of monocular vision. RESULTS: Patients with sudden visual loss adapted more slowly than those with gradual loss (8.8 versus 3.6 months). Difficulties with depth perception and cosmesis were prevalent. Unexpected consequences included neck pain, strain with reading, employment change, depression, car accidents, and alcoholism. Ninety-one percent of patients had no formal training to help them adapt. CONCLUSIONS: More than previously appreciated, there are many obstacles that patients face in making the transition to monocular vision. Few patients receive any formal instruction to help them adapt, yet many indicate that it would be beneficial.

Activities of Daily Living↗

Light curing unit effectiveness assessed by dental radiometers.

OBJECTIVES: The purpose of this investigation was to assess the effectiveness of five commercially available hand-held dental radiometers and a computer-based experimental radiometer. METHODS: Light intensity of five visible light activation units was determined using the dental radiometers. The influence of curing light intensity on depth of cure of a hybrid composite material was determined using a digital penetrometer. RESULTS: The radiometers evaluated varied with respect to sensor aperture diameter, scale readings (analogue or digital) and the units of measurement (arbitrary or mW cm2). The experimental computer-based radiometer allowed continuous recording of intensity against time; thus the light output could be monitored over the entire irradiation period. CONCLUSIONS: When light intensity readings were normalized with regard to a standardized light sensing device aperture of 4 mm diameter, a linear relationship was found between depth of cure and the logarithm of the intensity of the light. The results of this investigation support the use of dental radiometers for periodically monitoring visible light activation units.

Composite Resins↗

Radiographic measurements of alveolar bone loss in the rat.

A new method to evaluate alveolar bone loss in rodents is described. The palatal and lingual halves of maxillae and mandibles were radiographed. On enlarged positive prints, 5 vertical distances were drawn at defined sites from the cemento-enamel junction to points revealing fully intact bone structure. These were either located on the alveolar crest or at the depth of intrabony defects. These distances were recorded with a trace-reading pen coupled to a computer. Results were expressed in mm for each site separately and totals (left plus right values) for either maxillae or mandibles were calculated. This technique was compared to other methods for evaluating alveolar bone loss, using the jaws of rats subjected to a gnotobiotic regime in which the degree of bone loss was low. It was demonstrated that the measurement of vertical distances based on radiography by which also intrabony defects were defined was accurate, reproducible and more sensitive than other means of evaluating bone loss.

Actinomycosis↗

Evaluation of one-step amplicon-based targeted enrichment for SARS-CoV-2 whole-genome sequencing using the Midnight amplicon scheme.

Genomic surveillance proved invaluable during the COVID-19 pandemic for tracking SARS-CoV-2 variants and guiding outbreak responses, underscoring the ongoing need to reduce whole-genome sequencing (WGS) costs and improve workflow efficiency to ensure accessibility in resource limited settings. Here, we evaluated a one-step reverse transcription polymerase chain reaction (RT-PCR) approach using the Midnight V2 primer scheme for targeted amplification of the SARS-CoV-2 genome, assessed its compatibility with Illumina sequencing, and compared its performance to a well-established two-step method. Initially, we determined optimal RT-PCR reaction conditions using the Midnight V2 primer panel for the one-step RT-PCR kit and scaled reaction volumes for both RT-PCR and library preparation. Clinical specimens (n&#x202f;=&#x202f;53) that had undergone routine WGS for surveillance purposes using the established two-step RT-PCR method were compared using the one-step RT-PCR assay. For samples with genome completeness greater than 70%, both methods gave comparable results with similar sequence coverage and 100% concordance for lineage assignment. Further investigation revealed a higher percentage of reads aligning to the SARS-CoV-2 genome with a greater depth of coverage using the one-step method compared to the two-step method. Finally, analysis of scaled one-step and library reaction volumes revealed significant cost savings for samples undergoing WGS. Overall, the results presented here verify the accuracy and reproducibility of one-step targeted amplification and offer an efficient and cost-effective workflow for routine SARS-CoV-2 genomic surveillance.

Humans↗

Integrating stage and continuum models to explain processing of exercise messages and exercise initiation among sedentary college students.

Concepts from the transtheoretical model (J.O. Prochaska, C.C. DiClemente, & J.C. Norcross, 1992), theory of planned behavior (I. Ajzen, 1985), and the elaboration likelihood model (R.E. Petty & J.T. Cacioppo, 1986b) were used to examine how exercise readiness impacted processing of exercise messages and exercise initiation. Sedentary college students (n = 147) were assessed for exercise attitude, intent, behavior, and stage of change. Students also listed their thoughts after reading messages with either strong or weak arguments for exercise. Attitude predicted depth of message processing, but stage of change did not. Stage of change and intent at baseline predicted exercise adoption at 1- to 3-month follow-up (n = 134), with baseline activity moderating the effect of intent. Tailoring messages to recipients' depth of processing and interactive effects of intent and behavior on exercise adoption should be considered in future research.

Adult↗

Assessment of Micral-Test microalbuminuria test strip in the laboratory and in diabetic outpatients.

We have evaluated a semi-quantitative dry immunochemical screening method (Micral-Test) for the detection of low concentrations of albumin in urine. The stability of Micral-Test strips on storage was good, especially with regard to temperature, light and humidity. Changes in urine osmolality (urea and creatinine concentration), pH and sodium and potassium concentration did not have a significant analytical effect on the Micral-Test measurement; extremes of temperature altered the rate of colour development. The depth of dipping the strip into the sample and the timing of reading colour development were critical. We measured the albumin concentration in 184 urine samples from diabetic outpatients by the Micral-Test and by our in-house immunoturbidimetric method; a Micral-Test result of 20 mg/L had a sensitivity of 91% and specificity of 97% to predict a discriminating urine albumin concentration greater than 30 mg/L by the in house method. The Micral-Test is suitable for use by non-laboratory personnel and is capable of producing analytically acceptable results for use in diabetes clinics and by general practitioners.

Albuminuria↗

Occupancy modeling of coverage distribution for whole genome shotgun DNA sequencing.

Expected-value models have long provided a rudimentary theoretical foundation for random DNA sequencing. Here, we are interested in improving characterization of genome coverage in terms of its underlying probability distributions. We find that the mathematical notion of occupancy serves as a good model for evolution of the coverage distribution function and reveals new insights related to sequence redundancy. Established concepts, such as "full shotgun depth," have been assumed invariant, but actually depend on project size and decrease over time. For most microbial projects, the full shotgun milestone should be revised downward by about 30%. Accordingly, many already-completed genomes appear to have been over-sequenced. Results also suggest that read lengths for emerging high-throughput sequencing methods must be increased substantially before they can be considered as possible successors to the standard Sanger method. In particular, gains in throughput and sequence depth cannot be made to compensate for diminished read length. Limits are well approximated by a simple logarithmic equation, which should be useful in estimating maximum coverage-based redundancy for future projects.

Algorithms↗

Effect of interocular delay on disparity-selective v1 neurons: relationship to stereoacuity and the pulfrich effect.

The temporal properties of disparity-sensitive neurons place important temporal constraints on stereo matching. We examined these constraints by measuring the responses of disparity-selective neurons in striate cortex of awake behaving monkeys to random-dot stereograms that contained interocular delays. Disparity selectivity was gradually abolished by increasing interocular delay (when the delay exceeds the integration time, the inputs from the 2 eyes become uncorrelated). The amplitude of the disparity-selective response was a Gaussian function of interocular delay, with a mean of 16 ms (+/-5 ms, SD). Psychophysical measures of stereoacuity, in both monkey and human observers, showed a closely similar dependency on time, suggesting that temporal integration in V1 neurons is what determines psychophysical matching constraints over time. There was a slight but consistent asymmetry in the neuronal responses, as if the optimum stimulus is one in which the right stimulus leads by about 4 ms. Because all recordings were made in the left hemisphere, this probably reflects nasotemporal differences in conduction times; psychophysical data are compatible with this interpretation. In only a few neurons (5/72), interocular delay caused a change in the preferred disparity. Such tilted disparity/delay profiles have been invoked previously to explain depth perception in the stroboscopic version of the Pulfrich effect (and other variants). However, the great majority of the neurons did not show tilted disparity/delay profiles. This suggests that either the activity of these neurons is ignored when viewing Pulfrich stimuli, or that current theories relating neuronal properties to perception in the Pulfrich effect need to be reevaluated.

Action Potentials↗

Contribution of area MT to stereoscopic depth perception: choice-related response modulations reflect task strategy.

Due to the diversity of tuning properties in sensory cortex, only a fraction of neurons are engaged in a particular task. Characterizing the tuning properties of neurons that are functionally linked to behavior is essential for understanding how activity is "read out" from sensory maps to guide decisions. We recorded from middle temporal (MT) neurons while monkeys performed a depth discrimination task, and we characterized the linkage between MT responses and behavioral choices. Trial-to-trial response fluctuations of MT neurons with odd-symmetric ("Near," "Far") disparity tuning were predictive of monkeys' choices, whereas responses of neurons with even-symmetric tuning were not. This result cannot be explained by neuronal sensitivity or any other response property of MT neurons that we examined but is simply explained by the task strategy that monkeys learned during training. We suggest that this approach provides a physiological means to explore how task strategies are implemented in the brain.

Animals↗

Population-scale detection of methylation outliers from long-read genome sequencing.

BACKGROUND: Aberrant DNA methylation can mediate the functional effects of rare genetic variation and contribute to imprinting disorders, repeat expansion diseases, and other pathogenic regulatory mechanisms. Long-read sequencing technologies now enable genome-wide detection of CpG methylation alongside genetic variation from a single assay. However, methods for systematic identification and interpretation of methylation outliers from long-read sequencing data remain limited. METHODS: We developed METAFORA, a computational workflow for detecting methylation outlier regions from PacBio and Oxford Nanopore long-read sequencing data. METAFORA constructs population-level methylation references, segments the genome into correlated CpG blocks, infers technical and biological sources of variation through hidden factor estimation, models uncertainty due to variable depth sequencing, and computes covariate-adjusted methylation outlier scores for individual samples. We applied METAFORA across large long-read sequencing cohorts and integrated methylation outliers with multi-omic data. METAFORA is implemented as a snakemake workflow available at https://github.com/tjense25/METAFORA. RESULTS: METAFORA identified methylation outlier regions associated with rare structural variants, tandem repeat expansions, and imprinting abnormalities. We found outlier regions were enriched for molecular outliers across transcriptomic and chromatin accessibility datasets, supporting their functional relevance in gene regulation. In a representative case, METAFORA identified an imprinting defect affecting the GNAS locus associated with an STX16 deletion. CONCLUSIONS: METAFORA enables scalable detection and interpretation of methylation outliers from long-read sequencing data and provides a framework for integrating epigenetic outliers with genomic and multi-omic analyses. These approaches may improve interpretation of rare regulatory variation and support discovery of clinically relevant epigenetic abnormalities in genomic medicine.

DNA methylation↗

Intensive remedial instruction for children with severe reading disabilities: immediate and long-term outcomes from two instructional approaches.

Sixty children with severe reading disabilities were randomly assigned to two instructional programs that incorporated principles of effective instruction but differed in depth and extent of instruction in phonemic awareness and phonemic decoding skills. All children received 67.5 hours of one-to-one instruction in two 50-minute sessions per day for 8 weeks. Both instructional programs produced very large improvements in generalized reading skills that were stable over a 2-year follow-up period. When compared to the growth in broad reading ability that the participants made during their previous 16 months in learning disabilities resource rooms, their growth during the intervention produced effect sizes of 4.4 for one of the interventions and 3.9 for the other. Although the children's average scores on reading accuracy and comprehension were in the average range at the end of the follow-up period, measures of reading rate showed continued severe impairment for most of the children. Within 1 year following the intervention, 40% of the children were found to be no longer in need of special education services. The two methods of instruction were not differentially effective for children who entered the study with different levels of phonological ability, and the best overall predictors of long-term growth were resource room teacher ratings of attention/behavior, general verbal ability, and prior levels of component reading skills.

Awareness↗

Depression: cost-of-illness studies in the international literature, a review.

BACKGROUND: Depression is one of the most ancient and common diseases of the human race and its burden on society is really impressive. This stems both from the epidemiological spread (lifetime prevalence rate, up to 30 years of age, was estimated as greater than 14.4% by Angst et al.) and from the economic burden on healthcare systems and society, but also as it pertains to patient well-being. AIMS OF THE STUDY: The scope of this review was to examine studies published in the international literature to describe and compare the social costs of depression in various countries. METHODS: A bibliographic search was performed on international medical literature databases (Medline, Embase), where all studies published after 1970 were selected. Studies were carefully evaluated and only those that provided cost data were included in the comparative analysis; this latter phase was conducted using a newly developed evaluation chart. RESULTS: 10 abstracts were firstly selected; 46 of them underwent a subsequent full paper reading, thus providing seven papers, which were the subject of the in-depth comparative analysis: three studies investigated the cost of depression in the USA, three studies in the UK and one study was related to Italy. All the studies examined highlight the relevant economic burden of depression; in 1990, including both direct and indirect costs, it accounted for US$ 43.7 billion in the US (US$ 65 billion, at 1998 prices) according to Greenberg and colleagues, whilst direct costs accounted for £417 million in the UK (or US$ 962.5 million, at 1998 prices), according to Kind and Sorensen. Within direct costs, the major cost driver was indeed hospitalization, which represented something in between 43 and 75% of the average per patient cost; conversely, drug cost accounted for only 2% to 11% in five out of seven studies. DISCUSSION: Indeed, our review suggests that at the direct cost level, in both the United States and the United Kingdom, the burden of depression is remarkable, and this is confirmed by a recent report issued by the Pharmaceutical Research and Manufacturers Association (PhRMA) where prevalence and cost of disease were compared for several major chronic diseases, including Alzheimer, asthma, cancer, depression, osteoporosis, hypertension, schizophrenia and others: in this comparison, depression is one of the most significant diseases, ranked third by prevalence and sixth in terms of economic burden. Moreover, in terms of the average cost per patient, depression imposes a societal burden that is larger than other chronic conditions such as hypertension, rheumatoid arthritis, asthma and osteoporosis. The application of economic methods to the epidemiological and clinical field is a relatively recent development, as evidenced by the finding that, out of the seven studies examined, three refer to the US environment, three to the UK and one to Italy, while nothing was available about the cost of depression for large countries such as France, Germany, Spain, Japan and others. IMPLICATION FOR HEALTH CARE PROVISION AND USE: The high incidence of hospitalization, and the finding that drug cost represents only a minor component of the total direct cost of the disease, suggests that room is still available for disease management strategies that, while effectively managing the patient's clinical profile, could also improve health economic efficiency. IMPLICATION FOR HEALTH POLICIES: Disease management strategies, with particular emphasis on education, should be targeted not only at patients and medical professionals but also at health decision makers in order "to encourage effective prevention and treatment of depressive illness". IMPLICATIONS FOR FURTHER RESEARCH: Cost of illness studies are a very useful tool allowing cost data comparisons across countries and diseases: for this reason, we suggest that further research is needed especially in some western European countries to assess the true economic burden of depression on societies.

Journal Article↗