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Biomedical subjects

Xiaoyi Jiang

Publications and source records attributed to Xiaoyi Jiang.

10 recordsLinked to original sources
PubMed2006

Development of visual pursuit in the first 6 years of life.

BACKGROUND: There are few previous investigations on the development of smooth visual pursuit in children. The aim of this study was to determine normative values for the development of horizontal and vertical smooth pursuit in a large number of normal children. METHODS: Eye movements of 358 healthy children aged 6 weeks through 6 years were recorded using infrared photo-oculography. Visual pursuit was elicited with colored squares of 1.2 degrees of visual angle. The stimulus moved horizontally or vertically with constant velocities of 7.5, 15, or 30 degrees/s. RESULTS: Attention time increased with increasing age from 0.54 to 0.77 (P<0.01) and decreased with increasing stimulus velocities (P<0.01). The ratio of time of smooth pursuit to time of smooth pursuit plus saccades increased with increasing age from 0.63 to 0.78 (P<0.01) and decreased with increasing stimulus velocities (P<0.01). For stimulus velocities of 7.5 degrees/s, no significant difference was found between horizontal and vertical gain values. For stimulus velocities of 15 degrees/s and 30 degrees/s, gains for horizontal movements were larger that for vertical (P<0.05). Increasing stimulus speeds were associated with decreasing gains (P<0.05). CONCLUSIONS: This study provides the following normative values for photo-oculography in healthy children aged 6 weeks through 6 years of age: attention time, smooth pursuit time, and gain for three stimulus velocities presented horizontally and vertically. This normative database should help to diagnose pathologic ophthalmological or neuropediatric conditions, to perform screening interventions, and to initiate therapies.

Child↗
PubMed2006

Influence of the Pulfrich phenomenon on driving performance.

BACKGROUND: The Pulfrich stereoillusion occurs spontaneously in diseases inducing asymmetric visual pathway delays. Its influence on driving performance has never been investigated and was, therefore, assessed using a three-dimensional (3D) computer driving simulation. METHODS: A 3D driving scenery of a road with obstacles was visualised on an autostereoscopic 3D display. Seven normal subjects drove at a speed of 6 m/s using a steering wheel and three angles of view of the scenery (0 degrees, 45 degrees to left, and 90 degrees to left) with different interocular delays (25 ms on the right, 25 ms on the left, and no delay). One subject drove the scenery at an angle of 90 degrees without delay and with a delay of 8 ms, 16 ms, and 25 ms on the right and left, respectively, at speeds of 6 m/s, 12 m/s and 18 m/s. RESULTS: Stereo-illusion only influenced car position if the angle of view was 90 degrees (p<0.05). At this angle, increasing car speeds were associated with larger car displacements (delay on right p<0.001, on left p<0.01) and smaller delays with smaller car displacements (p<0.001). CONCLUSIONS: This study showed that Pulfrich phenomenon has an influence on car position only if the viewing angle is 90 degrees. No influence could be found if the driving direction corresponded to the visual axis of the driver. These findings are in agreement with reports of patients with spontaneous Pulfrich phenomenon who indicate that while driving, distances are only misjudged when looking sideways.

Adult↗
PubMed2006

Lung motion correction on respiratory gated 3-D PET/CT images.

Motion is a source of degradation in positron emission tomography (PET)/computed tomography (CT) images. As the PET images represent the sum of information over the whole respiratory cycle, attenuation correction with the help of CT images may lead to false staging or quantification of the radioactive uptake especially in the case of small tumors. We present an approach avoiding these difficulties by respiratory-gating the PET data and correcting it for motion with optical flow algorithms. The resulting dataset contains all the PET information and minimal motion and, thus, allows more accurate attenuation correction and quantification.

Algorithms↗
PubMed2006

A new 3D monitor-based random-dot stereotest for children.

PURPOSE: Objective testing for random-dot stereovision in preverbal children requires some type of dissociating glasses. Drawbacks of such methods are the alteration of natural visual conditions and sometimes nonacceptance of the glasses. For this reason, a new, natural method for random-dot stereopsis measurement was developed and tested. METHODS: Random-dot circles (diameter 10 cm, crossed disparity of 0.34 degrees ) were generated on an autostereoscopic display and presented to 18 normal children (mean age, 5.1 +/- 1.1 years), 8 with anisometropic amblyopia (mean age, 4.9 +/- 1.3 years), 14 with infantile essential esotropia (mean age, 5.3 +/- 0.7 years), and 16 with primary microstrabismus (mean age, 5.2 +/- 1.4 years). While the position of the stimulus randomly changed among four possible locations, eye positions were recorded by infrared photo-oculography. If two or more consecutive saccades ends corresponded to the stimulus coordinates, a positive response was assumed. The results with the new test were compared with the ability to recognize the Lang I random-dot stereotest. RESULTS: Twenty-four of 26 Lang I-positive children had positive responses (sensitivity of 92.3%), 29 of 30 Lang I-negative children had negative three-dimensional (3D) stimulus responses (specificity, 96.7%). The positive predictive value of the new test was 0.96 (95% CI, 0.79-0.99); the negative predictive value, 0.94 (95% CI, 0.78-0.99); and the overall accuracy, 0.95 (95% CI, 0.85-0.99). CONCLUSIONS: This new 3D monitor-based test allows objective assessment of random-dot stereopsis in children older than 3 years.

Amblyopia↗
PubMed2004

Redundant publications in scientific ophthalmologic journals: the tip of the iceberg?

OBJECTIVE: The number of scientific publications is often used to measure scientific achievement. This practice can motivate unethical conduct, such as redundant or duplicate publications, defined as publication of the same scientific contents in more than 1 journal. The aim of this study was to estimate the amount of redundant publications in ophthalmologic journals. DESIGN: Retrospective analysis of published literature. METHODS: We developed an electronic search engine for redundancies to estimate the amount of duplicate publications in scientific journals. When redundancies reached a given degree (matching score), the articles were screened manually based on authors, titles, and abstracts. We applied this method to the 22 433 articles that were published between 1997 and 2000 in 70 ophthalmologic journals indexed by MEDLINE. MAIN OUTCOME MEASURES: The number of duplicate publications with a matching score of 0.6 or more, the number of involved journals, and the number of authors. RESULTS: Redundancies reached a matching score of 0.6 or more in 13 967 pairs of articles. Out of them, a sample of 2210 was reviewed manually. We found 60 redundant articles and estimated that 1.39% of the publications were redundant. Thirty-two journals and an estimate of 1092 authors were involved. In 5% of cases, the scientific conclusions were modified. CONCLUSIONS: Because of the restrictive selection process, the impracticability of detecting all redundant publications, and the estimated amount of duplicates increases with lower matching scores, we regard our estimate to be the tip of the iceberg. Duplicate publications have several negative impacts, but neither peer reviewers nor editors can protect their journal from them completely. Several deterrents for duplicate publications are possible, but as long as publications remain the central requirement for academic advancement, a solution seems unlikely. Nevertheless, it is the responsibility of all those who care about objective research and evidence-based medicine to address this problem-not only in ophthalmology.

Algorithms↗
PubMed2003

[A new objective visual acuity test: an automated preferential looking].

BACKGROUND: The Preferential Looking test using Teller acuity cards is widely used for preverbal children but has some weaknesses, in particular because it is examiner dependent and at best half-objective. We tested a new automated method in a pilot study. PATIENTS AND METHODS: In our preferential looking setting we project separate images into the left and right eye. This permits measuring each eye without having to cover the other. An infrared oculography system documents objectively and reproducibly whether or not the stimulus is seen. A square is shown which moves consecutively in a square formation on a background that has the same average brightness. Charting an XY-plot of the eye position results in a square with two diagonals, if the stimulus is seen. By using a specific baby examination unit, this test is already feasible in babies. In this study, the new setting was tested on two children. RESULTS: In two healthy children we found a good correlation between visual acuities determined with the new method and Teller visual acuity charts. Fogging one eye in each of the children resulted in fixation loss of the stimulus when the required visual acuity rose above the fogging value. CONCLUSIONS: This new technique permits one to perform an objective preferential looking test without the need of verbal answers. Larger studies have to validate these preliminary results.

Attention↗
PubMed2003

[A new objective test for random-dot stereopsis in preverbal children].

BACKGROUND: The Lang-Stereotest is at best half-objective in testing stereovision in preverbal children. We developed a new method which might objectively measure random-dot stereopsis in preverbal children. PATIENTS AND METHODS: We project two separate random-dot images into the left and right eye using a 3D-monitor. If both eyes are perfectly aligned and random stereopsis is present, the child perceives a stimulus. Four different stimulus positions are shown at random. An infrared oculography system objectively detects whether the stimuli are seen. By using a specific baby examination unit, testing is already feasible in infants. RESULTS: We present the plots of two children with a positive (normal) and two with a negative (pathologic) response to random-dot stimuli. CONCLUSIONS: This new examination technique allows an objective assessment of random-dot stereopsis in non-verbal children. It permits us for the first time to study the development of stereovision under natural conditions. In future, the method may also be used to screen preverbal children for visual abnormalities. Larger studies are required to determine the positive and negative predictive values of this new test.

Child, Preschool↗
PubMed2002

[Ophthalmology "Made in Switzerland" -- Swiss papers listed in Medline].

BACKGROUND: Publications are one of the most important tools to measure scientific production in a particular sphere. Hence, the aim of this study was to identify the quantitative and (through Journal Impact Factor) qualitative amount of ophthalmological articles coming from Switzerland. MATERIALS AND METHODS: With a specifically developed software we searched 70 ophthalmological Journals indexed by Medline for articles from Switzerland. RESULTS: Not counting the publications related to the annual meeting of the Swiss Ophthalmological Society, the amount of Swiss papers in ophthalmological journals indexed by Medline, increased between 1988 and 1999 by a factor of four. In proportion to the global amount of ophthalmological publications we calculated an increase by a factor of 2.6. The amount of publications grew particularly during the analysed time period in journals with high impact factors. In 1999 a total of 1.8 % of the indexed ophthalmological articles originated from Swiss research institutes and hospitals. The average amount of authors of Swiss publications increased, thereby following an international trend. CONCLUSIONS: The increased amount of publications may rely on the growing role of Swiss research in ophthalmology as well as on a broadened and deepened international orientation of Swiss ophthalmology. The increased number of authors can be explained by the growing complexity and interdisciplinary nature of research projects. Both, the amount of publications and the number of authors, can be linked to the "publish or perish" paradigm.

Forecasting↗
PubMedDate not supplied

Automated analysis of eye tracking movements.

OBJECTIVE: To present a quick algorithm to automatically analyze the raw data acquired by a photo-oculography (POG) system. METHODS: We developed a simple algorithm for POG data analysis based on an extrapolation of missing values due to blinking and on exclusion of outliers using the robust mean and standard deviation. RESULTS: POG curves of 4 children aged between 1.5 and 7 years are shown before and after automatic analysis. After applying our algorithm, the curves are much smoother. CONCLUSION: Our algorithm allows a quick data analysis and will help to better interpret and analyze POG data.

Algorithms↗