Development of an Age Band on the ManuVis for 3-Year-Old Children with Visual Impairments.

AIM: To compare fine motor performance of 3-year-old children with visual impairment with peers having normal vision, to provide reference scores for 3-year-old children with visual impairment on the ManuVis, and to assess inter-rater reliability. METHOD: 26 children with visual impairment (mean age: 3 years 7 months (SD 3 months); 17 boys) and 28 children with normal vision (mean age: 3 years 7 months (SD 4 months); 14 boys) participated in the study. The ManuVis age band for 3-year-old children comprised two one-handed tasks, two two-handed tasks, and a pre-writing task. RESULTS: Children with visual impairment needed more time on all tasks (p < .01) and performed the pre-writing task less accurately than children with normal vision (p < .001). Children aged 42-47 months performed significantly faster on two tasks and had better total scores than children aged 36-41 months (p < .05). Inter-rater reliability was excellent (Intra-class Correlation Coefficient = 0.96-0.99). CONCLUSIONS: The ManuVis age band for 3-year-old children is appropriate to assess fine motor skills, and is sensitive to differences between children with visual impairment and normal vision and between half-year age groups. Reference scores are provided for 3-year-old children with visual impairment to identify delayed fine motor development.

Optics of the human cornea influence the accuracy of stereo eye-tracking methods: a simulation study.

Current stereo eye-tracking methods model the cornea as a sphere with one refractive surface. However, the human cornea is slightly aspheric and has two refractive surfaces. Here we used ray-tracing and the Navarro eye-model to study how these optical properties affect the accuracy of different stereo eye-tracking methods. We found that pupil size, gaze direction and head position all influence the reconstruction of gaze. Resulting errors range between ± 1.0 degrees at best. This shows that stereo eye-tracking may be an option if reliable calibration is not possible, but the applied eye-model should account for the actual optics of the cornea.

Low vision aids for visually impaired children: a perception-action perspective.

It is a widely accepted belief in clinical practice that children with a visual impairment can profit from the use of a low vision aid (LVA). However, we found a considerable gap in our scientific understanding of LVA use, particularly in young children. This is the reason for the analysis presented in this paper. A selected overview of LVA use in adults is given, from which valuable insights are taken. Additionally, an action perspective for analysing LVA use is discussed as well as the results of tool-use studies in children. Mainly based on these three ingredients, we developed a conceptual framework for LVA use. The framework consists of three interacting relations between LVA, child and task. Performance of a particular child on a specific task with a certain LVA is constrained by the following three reciprocal and dynamic relations: the Child-to-Task relation (related to goal-information), the Child-to-LVA relation (related to control-information), and the LVA-to-Task relation (related to topology information).

The incidence of visual impairment due to retinopathy of prematurity (ROP) and concomitant disabilities in the Netherlands: a 30 year overview.

AIM: To determine the incidence of visual impairment (VI) caused by retinopathy of prematurity (ROP) and concomitant disabilities in preterm neonates born between 2000 and 2009 in the Netherlands. METHODS: Data were retrieved from the Dutch institutes for the visually impaired. They were compared with similar Dutch studies conducted in 1975-1987, 1986-1994 and 1994-2000. RESULTS: Records of 42 infants with VI due to ROP were included. A gradual decrease of gestational age and birthweight but an increase of duration of artificial ventilation, supplemental oxygen administration, bronchopulmonary dysplasia, developmental delay and behavioural abnormalities was found. Compared with the previous study (1994-2000), significantly fewer children were visually impaired due to ROP (1.84 per 100,000 live births/year vs 3.93 per 100,000 live births/year, p=0.000), the incidence of complete blindness decreased from 27.5% to 7.1% (p < 0.05) and more children were treated (66.7% vs 56.9%, NS). The incidence of concomitant disabilities was high and did not differ greatly from the previous study. CONCLUSION: This was a retrospective study showing a significant decrease in VI due to ROP in the Netherlands. Changes in neonatal care practices did not result in a decrease in the incidence of concomitant disabilities. More children were treated for ROP, but 33% were not treated.

Improvement of fine motor skills in children with visual impairment: an explorative study.

In this study we analysed the potential spin-off of magnifier training on the fine-motor skills of visually impaired children. The fine-motor skills of 4- and 5-year-old visually impaired children were assessed using the manual skills test for children (6-12 years) with a visual impairment (ManuVis) and movement assessment for children (Movement ABC), before and after receiving a 12-sessions training within a 6-weeks period. The training was designed to practice the use of a stand magnifier, as part of a larger research project on low-vision aids. In this study, fifteen children trained with a magnifier; seven without. Sixteen children had nystagmus. In this group head orientation (ocular torticollis) was monitored. Results showed an age-related progress in children's fine-motor skills after the training, irrespective of magnifier condition: performance speed of the ManuVis items went from 333.4s to 273.6s on average. Accuracy in the writing tasks also increased. Finally, for the children with nystagmus, an increase of ocular torticollis was found. These results suggest a careful reconsideration of which intervention is most effective for enhancing perceptuomotor performance in visually impaired children: specific 'fine-motor' training or 'non-specific' visual-attention training with a magnifier.

Fusional vergence in microstrabismus.

The fusional vergence velocity was studied in microstrabismus and in normal persons. In microstrabismus the system works less precisely in that small changes in disparity produce no response, while it is possible that the difference between the amplitude of the stimulus and the amplitude of the response is greater.