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To meet the ever increasing demand for computational speed and use of ever larger datasets, multi GPU instal- lations look very tempting. Lunarc and the Theoretical Astrophysics group at Lund Observatory collaborate on a pilot project to evaluate and utilize multi-GPU architectures for scientific calculations. Starting with a small workshop in 2009, continued investigations eventually lead to the procurement of the GPU-resource Timaeus, which is a four-node eight-GPU cluster with two Nvidia m2050 GPU-cards per node. The resource is housed within the larger cluster Platon and share disk-, network- and system resources with that cluster. The inaugu- ration of Timaeus coincided with the meeting "Computational Physics with GPUs" in November 2010, hosted by the Theoretical Astrophysics group at Lund Observatory. The meeting comprised of a two-day workshop on GPU-computing and a two-day science meeting on using GPUs as a tool for computational physics research, with a particular focus on astrophysics and computational biology. Today Timaeus is used by research groups from Lund, Stockholm and Lule in fields ranging from Astrophysics to Molecular Chemistry. We are investigating the use of GPUs with commercial software packages and user supplied MPI-enabled codes. Looking ahead, Lunarc will be installing a new cluster during the summer of 2011 which will have a small number of GPU-enabled nodes that will enable us to continue working with the combination of parallel codes and GPU-computing. It is clear that the combination of GPUs/CPUs is becoming an important part of high performance computing and here we will describe what has been done at Lunarc regarding GPU-computations and how we will continue to investigate the new and coming multi-GPU servers and how they can be utilized in our environment.

To estimate the age at diagnosis of retinitis pigmentosa and to determine visual acuity deterioration, visual field impairment and the frequency of cataracts in Usher syndrome types 1 and 2.

. Purpose:
To evaluate the effectiveness of the Lang II stereo card as a screening test for amblyopia and/or strabismus. Methods:
A total of 1046 children aged 12-13 years were examined in a field study in the Göteborg area, Sweden. In addition to the Lang II stereo card, the examination included visual acuity, cover testing, cycloplegic refraction, and inspection of the optical media and posterior pole. Results:
If every incorrect subject response was considered a reason for referral, the Lang II test would have correctly identified 82% (23 subjects) of the 28 children with manifest strabismus and 38% (11 subjects) of the 29 children with amblyopia. The test failed to refer 45% (21 subjects). Of all subjects referred, 44 (63%) were found to be ophthalmologically normal. Conclusions:
The Lang II stereo card is neither a reliable nor an efficient method of screening for amblyopia and/or strabismus.

The use of magnetic resonance imaging (MRI) in children with severe neurological impairment has defined a subgroup with increased T2-signals from cerebral white matter. The causes of white matter abnormalities are for the most part unknown, despite extensive investigation. Their clinical correlates and characteristics have still to be systematically analysed and described. We have compared clinical, ophthalmological and electro-ophthalmological findings in such children to delineate neurological and MRI patterns and have sought to correlate with the progression of disease. Clinical and electro-ophthalmological investigations were performed in 26 children with cerebral white matter abnormalities of unknown aetiology; 25 of the 26 children showed abnormalities, 23 clinical and 18 electro-ophthalmological. Optic nerve abnormalities, severe visual impairment and strabismus were the most common. Electro-ophthalmological abnormalities were increased latencies and abnormal waveform of the visual evoked potentials (VEP). Children with progressive disease all had abnormal VEP, whereas none of the ten children with a normal VEP deteriorated.We conclude that children with cerebral white matter abnormalities almost invariably had ophthalmological and often VEP abnormalities. Normal VEP was correlated with non-progressive disorder, as was hypoplasia or malformation of the papilla, whereas abnormal VEP were associated with progressive disease.

Purpose:Previous works show a pronounced disagreement on the reliability of stereo tests as screening tools for amblyopia and strabismus. This study's aim was to compare the ability of the Lang II, Frisby, Randot, Titmus, and TNO stereo tests to detect amblyopia and strabismus with visual acuity testing and cover testing. Methods:A total of 1035 school children aged 12 to 13 years were examined in a field study in Monterrey, Mexico. In addition to the 5 stereo tests, the examination included visual acuity, cover testing, refraction (skiascopy), and inspection of the red reflex and posterior pole. Results:Sensitivity ranged from 17% to 47% (Frisby-Titmus-Lang II-Randot-TNO, in order of occurrence). Of the 60 subjects with strabismus and/or amblyopia, only 8 subjects were identified by all 5 stereo tests. A considerable number of subjects (25), the majority of whom were amblyopic (23 subjects), were not identified by any of the tests. All stereo tests showed higher sensitivities for strabismus than for amblyopia. Conclusion:None of the 5 stereo tests studied is suitable for screening for amblyopia or strabismus. The results of both ocularly normal subjects and subjects with strabismus and/or amblyopia are variable, and there is no way of separating normal response from abnormal response. (J AAPOS 2001;5:316-22)

Aims.To follow visual development longitudinally in the normal neonate using the flash visual evoked potential (VEP) and to find indications for a relationship between potential development and visual development. Methods.Twenty healthy infants, born at term, were included in the study. Flash and patterned flash VEPs were used. The first VEP was recorded the day of birth or just postnatally, and succeeding recordings were performed the following weeks and months. Results.The data revealed different types of VEP in the neonatal period suggesting great variablity in visual function on the day of birth. In the early development a potential of long latency and duration preceded the development of a more compound potential of shorter latency. The two types of responses seemed to coalesce during early development; the first late response was attenuated and was eventually integrated in the more mature VEP. At approximately five weeks of age changes in the VEP were simultaneous with the development of responsive smiling and another visual behaviour of the infants. Conclusions.The results showed many similarities between the VEP development in infants and in immature animals. In developing animals geniculo-cortical and extra-geniculate visual afferent pathways evoke two types of VEPs similar to those recorded in the present study. The early responses were also similar to previous recordings from children with lesions in the geniculo-striatal pathway or primary cortex. Our interpretation of the results was that the human VEP also consists of responses evoked by afferents running both in geniculo-cortical and extra-geniculate pathways and that the two types of responses could be separated in the VEP in the neonatal period. These findings are important for our understanding of conditions with a delay in visual maturation, for example intracranial haemorrhages, hydrocephalus, pre/dys-maturity and `idiopathic' delayed visual maturation.

The primary aim of this project was to study the effect of flip lens-training on the accommodative function in a group of children with accommodative dysfunction and subjective symptoms such as asthenopia, headache, blurred vision, and avoidance of near activity. We also wanted to measure the accommodative facility among the children in comparison with a control group. Another aim of the study was whether flip lens-training increased accommodative facility, and to find out if it also had a positive effect on their asthenopia and related problems also in long term. Following the training period the accommodative facility and accommodative function significantly increased and two years after finishing the training period no child had regained any subjective symptoms and the objective findings were almost the same as at the end of facility training period. These results suggest that accommodative facility training is an efficient method built on loss of symptoms among children with accommodative infacility.

Purpose: To investigate children with delayed visual maturation (DVM) and correlate the electrophysiological findings to visual development. Methods: Three children, one from each of the DVM-classification groups, were subjected to routine ophthalmological examinations and electrophysiological examinations: flash visual evoked potential (VEP) and skin electrode electroretinography (ERG). Results: All three children had normal ERGs but initially abnormal VEP-recordings with marked delay of latency or grossly altered VEPs. When visual interest developed with responsive smiling at 4, 4.5 and approximately 12 months of age, a maturation in the VEPs also appeared, with development of a short-latency complex (≈70 ms). In the normal neonatal development of the VEP, a negativity at approximately 60–70 ms (N1) emerged at four to six weeks of postnatal life when the child started responsive smiling and showing raised visual interest. According to animal experimental research and human studies, the development of the specific response (the short-latency complex) represents the gradual onset of cortical activity mediated via the specific retino-geniculo-striatal pathway. Thus, when the short-latency complex of the VEP cannot be identified, the visual function is mainly of subcortical origin. Since the VEP developed in the same way in the children with DVM as in normal subjects, the patophysiological dysfunction and origins of DVM can partly be understood. Conclusions: The results show that i) children with DVM has a period of visual inattentiveness at a time when normal children show visual interest, ii) the VEP is abnormal in children with DVM at the time of visual inattentiveness, iii) the improvement of vision in DVM can be measured with VEP and iiii) the extra-geniculate system(s) provides for the visual function early neonatally in the normal child and in a prolonged period in the DVM-child as long as the VEPs are abnormal.