Clinical assessment of visual function with particular emphasis on testing methods for young children

Research during the last decades has emphasised the importance of visual stimulation during the first months of life. It is consequently of great importance to identify children with subnormal vision as early as possible in order to start treatment and habilitation. A prerequisite is that reliable testing methods are available and can reveal visual defects as early as possible. The aim of the study was to evaluate different methods for testing visual acuity in young children. The possibility of using the Preferential Looking (PL)-method as a screening test for the detection of amblyopia was assessed in 28 adult patients with strabismic amblyopia. PL regularly overestimated the visual acuity. The method is not sensitive enough for the detection of amblyopia and approximately 30% of the cases would have been missed. Contrast sensitivity could be a suitable method for the detection of amblyopia. Seven different contrast sensitivity tests were assessed in 20 adult patients with strabismic amblyopia to determine various parameters of the contrast sensitivity function. Depending on the parameters applied, all the tests investigated could be used in the detection of amblyopia Various acuity tests, have been assessed in 151 children 0-6 years of age with assumed normal vision, ocular disease usually connected with visual impairment, and strabismus.The children were divided into three age groups: 0-1 1/2 years, 1 1/2-3 years and 9 month, and 3 years and 9 months -6 years. The acuity tasks were divided into three subtypes according to the kind of stimulus used; detection acuity, resolution acuity, and recognition acuity. Children under the age of 1 1/2 years were tested with the Stycar Rolling Balls, PL (the acuity card procedure) and the detection of raisins, puffed rice and black and white sugar strands on a white and black background. It was found impossible to reliably detect subnormal vision in this age group with the tests presently available, representing detection and resolution acuities. Children aged 1 1/2 - 6 years were examined with several tests. Detection acuity with the Stycar Rolling Balls highly overestimated visual acuity, and only gave a very rough estimate of the visual function. Resolution acuity, PL, regularly led to an overestimation of the acuity values in all the three groups, especially the strabismic children. Good correlation was found between the different recognition tests in line. Slightly better values were obtained with single optotypes, a sign of crowding. Different acuity values were obtained depending on whether detection, resolution, or recognition acuity was tested. Reliable visual acuity values can only be obtained when visual acuity can be assessed with a recognition test using lines of letters or symbols. However, the detection and resolution acuities give valuable information about the childs total visual behaviour. Contrast sensitivity function was assessed, in children 3 years and 9 months - 6 years, with the LH contrast test, and the ability to detect raisins, puffed rice, and sugar strands. It was found that a separation between the subjects with subnormal vision due to ocular disease and strabismic amblyopia in comparison with the subjects with normal vision could be made with the LH - contrast test, but not with the other tests. Key words: amblyopia, children, contrast sensitivity, crowding, detection acuity, linear tests, ocular disease, preferential looking, recognition acuity, resolution acuity, single tests, strabismus, visual acuity, visual impairmen

Screening for Dyslexia Using Eye Tracking during Reading

<div><p>Dyslexia is a neurodevelopmental reading disability estimated to affect 5–10% of the population. While there is yet no full understanding of the cause of dyslexia, or agreement on its precise definition, it is certain that many individuals suffer persistent problems in learning to read for no apparent reason. Although it is generally agreed that early intervention is the best form of support for children with dyslexia, there is still a lack of efficient and objective means to help identify those at risk during the early years of school. Here we show that it is possible to identify 9–10 year old individuals at risk of persistent reading difficulties by using eye tracking during reading to probe the processes that underlie reading ability. In contrast to current screening methods, which rely on oral or written tests, eye tracking does not depend on the subject to produce some overt verbal response and thus provides a natural means to objectively assess the reading process as it unfolds in real-time. Our study is based on a sample of 97 high-risk subjects with early identified word decoding difficulties and a control group of 88 low-risk subjects. These subjects were selected from a larger population of 2165 school children attending second grade. Using predictive modeling and statistical resampling techniques, we develop classification models from eye tracking records less than one minute in duration and show that the models are able to differentiate high-risk subjects from low-risk subjects with high accuracy. Although dyslexia is fundamentally a language-based learning disability, our results suggest that eye movements in reading can be highly predictive of individual reading ability and that eye tracking can be an efficient means to identify children at risk of long-term reading difficulties.</p></div

Box plots of features selected in 1000 (100%) training folds by the best performing classification model.

<p>The box plots show the distribution of values, normalized to range between 0 and 1, by feature and group HR (<i>n</i> = 97) and LR (<i>n</i> = 88).</p

Example of eye movement analysis where the horizontal (CH) and vertical (CV) eye movement signal is plotted over time.

<p>Light green stripes represent saccades, light gray areas represent fixations. Light blue stripes represent sweeping movements (most commonly return sweeps) and red stripes represent transients. Plot <b>A</b> represents a subject from the HR group and plot <b>B</b> a subject from the LR group. The analysis was performed using a dynamic dispersion threshold algorithm based on the physiological properties of the foveal and parafoveal fields of vision. The algorithm analyzes the tracking signal sample by sample and switches between four mutually exclusive states: distortions, transients, fixations, and saccades. A distortion state is detected if the horizontal or vertical signal is missing for both eyes. A transient state is detected if the horizontal and vertical position is within a threshold distance of 0.5 degrees + signal noise (2.5 × RMS error of the last 25 samples) from the average of the samples in the current state. A fixation state is detected when the eyes have remained stable for at least 50 ms, and a saccade state when the eyes have moved beyond the threshold distance. Once a change of state is detected, the samples of the previous state are identified as a new event.</p

Prediction accuracy as a function of the numbers of features selected during training.

<p>Accuracy is shown for classifiers based on recursive feature elimination (solid blue line), random feature selection (dashed red line), and chance (dotted green line). Chance-level accuracy is based on Y-randomization of training data. Accuracy is the percentage of correctly identified HR and LR subjects averaged over 100 × 10-fold cross-validation. Maximum accuracy, 95.6%, (± 4.5%), is obtained using recursive feature elimination to select 48 features from the original feature set of 168 features. Shaded regions indicate mean ± 1 standard deviation over the 100 repetitions. Performance at chance level, averaged over the feature subset sizes, is 49.3%.</p

Experimental test protocol based on repeated cross-validation with internal feature selection.

<p>The entire dataset is randomly divided into 10 subsets, setting aside one subset (10% of all subjects) as a test sample and the remaining nine subsets (90% of all subjects) as a training sample. A feature selection algorithm is applied on the training sample to select a subset of <i>n</i> features. Using this feature subset, a classification algorithm is applied on the training sample, producing a parametrized classifier as output. This classifier is then used to classify the subjects in the test sample and the predicted results are compared to the actual identity (HR or LR) of the test subjects. This step is iterated 10 times, with a different training and test set for each iteration. After one completed run of 10-fold cross validation, each subject in the entire dataset has been tested exactly once, while we still have maintained a strict separation between training and test subjects. To reduce the variance of the cross-validated performance estimate, the whole process is repeated 100 times with different initial random splits of the original dataset. The final estimate of the expected predictive performance is calculated by averaging the cross-validation performance over all 100 repetitions. This estimate represents the expected prediction accuracy of the final model. The final model–the one we would deploy in practice–is the classifier we would build from the entire dataset using feature selection method <i>m</i> to select <i>n</i> features.</p

Frequency of features selected during training of the best performing classification model grouped by progressive/regressive fixation- and saccade features.

<p>The Y-axis shows the number of times a feature in the original feature set was selected by the recursive feature elimination algorithm (SVM-RFE) during the 10 x 100 cross-validation with internal feature selection. The X-axis shows the features (represented by their index in the dataset) grouped by progressive/regressive fixation- and saccade features.</p

Behandling av alkohol- och narkotikaproblem : En evidensbaserad kunskapssammanställning

Utvärderingens syfteMissbruk och beroende av alkohol är ett av de största folkhälsoproblemen. Narkotikamissbruk är mindre vanligt men har stora medicinska konsekvenser för de berörda. De sociala och juridiska aspekterna är betydande. En kritisk genomgång av litteraturen vad avser behandling av abstinens, protraherad abstinens, behandling i syfte att förhindra återfall, psykologiska och sociala behandlingar för att minska återfallsrisken, behandlingsprogram och institutionsvårdens roll, samt behandling av missbruk under graviditet. Dessutom en granskning av mini-intervention i primärvård och annan vård vars syfte är att minska konsumtionen hos högkonsumenter av alkohol. Nyligen gjorda meta-analyser inom området värderas och särskild vikt fästs vid interventioner som finns eller lätt kan introduceras i den svenska vårdorganisationen. Behandlingsprogram för patienter med samtidig annan psykisk störning värderas.Så kallat lågdosberoende av bensodiazepiner och andra lugnande medel eller sömnmedel behandlas inte. Inte heller belyses effekten av behandlingar vars primära mål är kroppsliga komplikationer av missbruket, och inte heller granskas metoder att minska tillgänglighet.TillvägagångssättStrukturerad översikt, kostnadsanalyser.Insamling av primärdataSystematisk sökning i relevanta databaser, litteraturlistor i påträffade studier samt i aktuella monografier. Ingen bakre tidsbegränsning och sökning i databaser till och med februari 1999.Utgångspunkt för urval av dataHuvudsakligen randomiserade, kontrollerade, dubbelblinda studier, samt metaanalyser som baseras på sådana studier. Vad gäller långtidsförlopp och ekonomiska analyser även kohortstudier och andra naturalistiska studier.Genomgång av publikationenSamtliga studier värderas med hjälp av en i gruppen utarbetad, och med övriga psykiatriprojekt gemensam, kvalitetsmall. Alla centrala studier läses av minst två i gruppen.Färdiga manuskript värderas av styrelse, expertgrupp samt externa granskare

Final Report of CBRNEmap : A better preparedness and response for European citizens facing CBRNE Threats

CBRNEmap was a pre-study to the upcoming CBRNE technology demonstrator. Accordingly, considerable efforts were used to describe the feasibility and to sort out a number of basic requirements of the contemplated demonstrator object. This report deals with two areas deemed important when constructing a civilian CBRNE system of systems, its limitations and some suggested specifications: A useful CBRNE system of systems will improve and connect important societal functions vital before, during and after a CBRNE accident and/or attack. CBRNEmap identifies three clusters of activities as the most important when making our society resilient to CBRNE. These are, the cluster of activities making up the response function, the cluster of activities defining the function to protect identified targets and the cluster of societal investments enabling Europe to become more resilient. As examples and as a source of inspiration the three societal functions described above (response, protect and enabling) were used to discuss the CBRNE technology demonstrator. The demonstrator objects were populated by technologies and thereafter discussed with respect to choice of scenarios, choice of parameters to be used for its validation and with respect to its market value. Based on its conclusions, its working process and its interaction with external partners CBRNEmap recommends that: The use of Integrated Project Teams will be given priority when evaluating the upcoming demonstrator objects. The European Commission does everything possible to ensure that the results of previous “EU project” get integrated into the upcoming demonstrator object. Appropriate limitations and projections are made to the CBRNE system of systems perspective, in order to produce a CBRNE demonstrator serving the societal functions responsible or operational active. Considerable efforts are given to validating the improvements and/or added value of the demonstrator object. The cluster of societal investment we refer to as the enabler is further investigated in a future SSA