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Innovation in the diagnosis of central visual processing dysfunctions in children

Projectomschrijving

Vanwege het toenemend aantal kinderen met complexe visuele stoornissen is er behoefte aan vroegdiagnostiek die de kwaliteit en kwantiteit van visuele informatieverwerking in kaart brengt.

Werkwijze

In dit project hebben we bij een groep kinderen met het vermoeden van visuele informatieverwerkingsproblemen de oogbewegingen in reactie op verschillende visuele stimuli gemeten met een ‘eye tracker’. De kinderen werden gevolgd over een periode van 3 jaar. De uitkomstmaten (reactietijd en fixatienauwkeurigheid) werden vergeleken met resultaten van visuele functie- en perceptie testen. Langere reactietijden en lagere fixatie nauwkeurigheid waren gerelateerd aan de aanwezigheid van hersenschade, maar niet aan leeftijd of de aanwezigheid van nystagmus.

Conclusie

De belangrijkste conclusie is dat door het meten van visueel gestuurd kijkgedrag normale en afwijkende ontwikkeling van visuele informatieverwerking kan worden gevolgd bij kinderen vanaf 6 maanden oud.

English summary

The increase in the number of children with complex visual impairments has led to a need for diagnosis of cerebral visual impairment at young age.

In this project we have assessed the quantity and quality of visual information processing by measuring eye movements in response to various visual stimuli in a group of children at risk of cerebral visual processing problems. The outcome measures were compared to results from commonly used visual function and perception tests. Children were tested once a year, for a total duration of three years. Eye movement parameters (longer reaction times and impaired fixation accuracy) were related to the degree of cerebral damage, but not to age or nystagmus.

The main conclusion is that this method gives quantifiable measures of visual performance starting at six months of age and can differentiate between typically developing children and children with visual impairments. Currently the method will be implemented in Dutch visual rehabilitation centres.

Verslagen


Samenvatting van de aanvraag

Problem definition The number of children with visual impairments related to cerebral damage is steadily increasing (Hoyt and Frederick, 1998, Dutton and Bax, 2010). Improved perinatal care in the Netherlands and other Western World countries is an important reason, which has led to an increased survival rate, but also to a higher neurological comorbidity (Stephens and Vohr, 2009). There is also an increase in the number of children with cerebral visual information processing (CVIP) impairments seen at visual advisory and rehabilitation centres. Accurate assessment of cerebral visual function as early as possible is essential, as failure to do so has a major impact on the visual development of the child and affect his/her performance during daily activities. Nowadays, diagnosis is primarily based visual function tests (VFO;> 0 years) and neuropsychological tests (NPO; > 6 years). Most tests require active cooperation, are time consuming and depend on the experience of the observer. This makes it difficult to make a differential diagnosis in children < 4 years. In recent years the insight has grown that CVIP impairments also occur in many children with motor and/or intellectual disabilities. From a professional and patient perspective there is a need for a method to make an early diagnosis of CVIP that is not dependent on verbal communication skills. Such method is of large benefit for the patients because an early diagnosis helps to adjust daily support and to provide individual rehabilitation. Proposed solution Erasmus MC and VISIO have developed a method to assess the quality of CVIP based on: 1) presentation of specific sources of visual information (contrast, motion, form and color) that are known to be processed via separate channels in the brain and 2) measurement of orienting eye and/or head movement responses (Pel et al., 2010a). According recent theories separate visual channels all contribute to a saliency map that represents the most conspicuous area in a visual scene (Walther and Koch, 2006). Orienting eye movements are semi-automatically triggered based on this saliency map. Thus, the presence or absence of orienting eye movements in response to a particular visual stimulus is a quantitative method to study visual information processing. It allows us to quantify the information content of the visual stimulus and response parameters and to create a visual profile (Erasmus Visual Profile (EVP)) of an individual child. With the EVP method, visual stimuli that activate specific combinations of visual processing (contrast, form, motion, color) are presented on a special monitor screen that also holds a remote eye tracker camera system. The EVP of each individual child is compared to data from a control group. So far, oculomotor reaction times, accuracy and duration of fixation to a target of interest have been measured in a control group of 213 children and in a group of 30 children between the age of 0-14 years with brain damage, ad in children with congenital nystagmus (Pel et al., 2010b). Development of orienting behaviour was age dependent. In the control group orienting behaviour towards cartoons matured at 3, form coherence at 6 and motion expansion at 8 years. Children with CVIP impairments due to brain damage or congenital nystagmus had prolonged reaction times, more inaccurate fixations or higher detection thresholds. Project goal In the present proposal, we aim to further validate the EVP method. The plan is to conduct a longitudinal study in 120 children suspected of cerebral visual information processing disorders. We will compare the EVP outcome with data from currently used visual function and perception tests. The primary goals are: 1 To validate the new method in a risk group of 120 children. 2 To test the reliability in 60 children by conducting a test-retest. 3 To monitor visual development in 60 children in a longitudinal setting. Given the pilot outcomes of the new method, we expect that the EVP is at least comparable with the outcomes of currently used tests. We expect that the EVP is a good basis (1) to define an individual visual rehabilitation program, (2) to test effectiveness of treatment and (3) to compare individual outcome to norm data. We request funding for one PhD student. He/she will operate in a multidisciplinary team consisting of staff members from the Neuroscience department, from VISIO and Bartimeus. The task of the PhD student is to coordinate and perform data collection and analyse the data. Erasmus MC staff will supervise the PhD. Dr. Lena Jacobson, Karolinska Institute, Stockholm will act as external consultant. Erasmus MC will also train personnel and help to implement the analysis methodology at different Visio locations. Tests will be conducted conform guidelines of the Medical Ethical Committee of Erasmus MC. Children’s legal representatives will be asked for permission. Measurements will be done at locations of VISIO

Onderwerpen

Kenmerken

Projectnummer:
94309002
Looptijd: 100%
Looptijd: 100 %
2012
2016
Onderdeel van programma:
Projectleider en penvoerder:
Prof. dr. J. Steen
Verantwoordelijke organisatie:
Erasmus MC