Development of smooth pursuit eye movements in very preterm infants: 1. General aspects

Brain MRI findings and their association with visual impairment in young adolescents born very preterm

PURPOSE

Very preterm birth increases risk for neonatal white matter injury, but there is limited data on to what extent this persists into adolescence and how this relates to ophthalmological outcomes. The aim of this study was to assess brain MRI findings in 12-year-old children born very preterm compared to controls and their association with concurrent ophthalmological outcomes.

METHODS

We included 47 children born very preterm and 22 full-term controls (gestational age <32 and >37 weeks, respectively). Brain MRI findings were studied in association with concurrent ophthalmological outcomes at 12-year follow-up.

RESULTS

Evans index (0.27 vs 0.25, p<0.001) and a proposed "posterior ventricle index" (0.47 vs 0.45, p=0.018) were increased in children born very preterm. Higher gestational age associated with larger corpus callosum area (β=10.7, 95%CI 0.59-20.8). Focal white matter lesions were observed in 15 (32%) of very preterm children and in 1 (5%) of full-term controls. Increased posterior ventricle index increased risk for visual acuity ≤1.0 (OR=1.07×1011, 95%CI=7.78-1.48×1021) and contrast sensitivity <0.5 (OR=2.6×1027, 95%CI=1.9×108-3.5×1046). Decreased peritrigonal white matter thickness associated with impaired visual acuity (β=0.04, 95%CI 0.002-0.07).

CONCLUSION

More white matter lesions and evidence of lower white matter volume were found in children born very preterm compared with full-term controls at 12-year follow-up. The association between larger posterior ventricle index and reduced visual acuity and contrast sensitivity suggests disturbances of the posterior visual pathway due to diffuse white matter lesions.

Clinimetric properties of visuo-perceptual and visuo-cognitive assessment tools used for children with cerebral visual impairment and cerebral palsy or developmental delay: a systematic review

PURPOSE

The aim of this systematic review is to evaluate the psychometrics and clinical utility of visuo-perceptual and visuo-cognitive assessment tools in children with cerebral visual impairment (CVI) and cerebral palsy (CP) or neurodevelopmental delay (DD).

MATERIALS AND METHODS

Five databases (PubMed, EMBASE, SCOPUS, CINAHL, and Cochrane Database) were comprehensively searched from 1970 till June 2021. The PRISMA checklist was utilised to report on the process of selecting eligible papers. The methodological quality of included studies was evaluated using COnsenus-based Standards for the selection of health Measurement INstrument (COSMIN) checklist.

RESULTS

Of the 26 assessment tools identified, only seven tools had psychometric evidence supporting their use. Based on COSMIN guidelines, 60% of included studies were rated as inadequate or doubtful for their methodological quality of measurement properties, with equal number being rated as indeterminate on the overall rating.

CONCLUSIONS

Cerebral visual impairment due to its varied clinical presentation is often missed in children with CP and DD. There is a paucity of studies reporting on the validity and reliability of functional vision tools. Further studies are needed to conduct high-quality psychometric reporting using the updated COSMIN guidelines to identify appropriate functional vision tools for children with CP or DD.Implications for rehabilitationThere are paucity of studies evaluating the validity and reliability of existing perceptual and cognitive assessment tools in children with cerebral visual impairment (CVI) and cerebral palsy (CP).Development of age-appropriate assessment tools evaluating all aspects of functional vision will assist in providing more holistic child-centric rehabilitation programs.A combination of detailed perinatal history, direct observation, and clinical assessments of functional vision are important to recognise CVI in children with CP.

Visual tracking at 4 months in preterm infants predicts 6.5-year cognition and attention

BACKGROUND

Visual tracking of moving objects requires sustained attention and prediction of the object's trajectory. We tested the hypothesis that measures of eye-head tracking of moving objects are associated to long-term neurodevelopment in very preterm infants.

METHODS

Visual tracking performance was assessed at 4 month's corrected age in 57 infants with gestational age <32 weeks. An object moved in front of the infant with sinusoidal or triangular (i.e. abrupt) turns of the direction. Gaze gain, smooth pursuit gain, and timing of gaze to object motion were analyzed. At 6.5 years the Wechsler Intelligence Scale for Children (WISC-IV), the Brown Attention Deficit Disorder (Brown ADD), and visual examination were performed.

RESULTS

Gaze gain and smooth pursuit gain at 4 months were strongly related to all WISC-IV parameters at 6.5 years. Gaze gain for the triangular and sinusoidal motion patterns related similarly to the cognitive scores. For the sinusoidal motion pattern, timing related to most Brown ADD parameters. There were no statistically significant differences in associations dependent on motion pattern. Visual function did not influence the results.

CONCLUSION

The ability to attend to and smoothly track a moving object in infancy is an early marker of cognition and attention at 6.5 years.

IMPACT

Potential long-term implications of infant visual tracking of moving objects for school-age neurodevelopment has not been previously studied in very preterm infants. Early coordination of eye and head movements in gaze gain, smooth pursuit, and timing of gaze to object motion are closely associated with cognition and attention at 6.5 years. As related functions at 6.5 years include perceptual and verbal skills, working memory, processing speed and attention, predictive elements in gaze tracking of moving objects might be a suitable target for future intervention studies.

Immature brain structures were associated with poorer eye movement performance at 8 years of age in preterm born children

AIM

Eye movements have rarely been explored in preterm born children. The aim of this study was to compare horizontal eye movements in children born preterm and full term when they reached 8 years of age.

METHODS

Eye movements were recorded in 24 preterm born children (18 boys) and 26 matched controls (19 boys), recruited by a French hospital, using an eye tracker. This identified different types of visually guided saccades, namely step, gap, overlap and antisaccades and pursuit eye movements. The saccades task measured the latency and the percentage of anticipatory and express saccades and errors. The pursuit task measured the gain and percentage of intrusive saccades.

RESULTS

This study confirmed that children born at 24-28 weeks of gestation demonstrated a global deficit in inhibitory processes compared to children born full term. The saccades were less precise in the preterm group, anticipatory and express saccades were elevated and there was a high occurrence of intrusive saccades during pursuit movements.

CONCLUSION

These findings suggest that preterm born children have immature brain structures, particularly the parietal and frontal cortexes that are responsible for both saccade and pursuit performance. These could have been the cause of the abnormal inhibitory control measured in this study.

Home-based early stimulation program targeting visual and motor functions for preterm infants with delayed tracking: Feasibility of a Randomized Clinical Trial

AIMS

To verify the feasibility of a home-based early stimulation program targeting visual and motor functions in preterm infants with delayed visual tracking.

METHOD

We applied a randomized controlled trial. We included thirty low-risk preterm infants, from both genders, with delayed visual tracking, gestational between 28-37 weeks, and age at entrance between 1-2 months of corrected age, and absence of visual impairments. Infants were divided into two groups as follows: a) standard care group (SC) that received general orientation about sensory and motor development (16 infants); b) experimental group, that received a four-week home-based early stimulation program targeting visual and motor functions (ESPVM) applied by the caregivers (14 infants). The feasibility outcomes were retention and loss rates, adherence, adverse events, and stress signals. We obtained preliminary data by comparing visual tracking, motor development, and sensory behavior between groups at the end of the intervention.

RESULTS

Retention rate was high, 90 % of the caregivers provided ESPVM at least 22 days, and 70 % provided SC at least 17 days. No adverse events were reported. At the end of intervention, the ESPVM group presented higher frequencies of complete visual tracking for cards 7 (ESPVM = 57.3 %, SC = 6.3 %, p = 0.006) and 8 (ESPVM = 64.3 %, SC = 12.2 %, p = 0.013), and lower scores for total sensory profile (ESPVM: median = 58, range = 46-69; SC: median = 71, range = 54-90; p = 0.016). The groups were similar for motor development.

CONCLUSIONS

The protocol was feasible, and the results encourage a larger randomized controlled trial.

Average 2.5-year neurodevelopmental test results in children born very preterm did not rule out cognitive deficits at 6.5 years of age

Aim

The aim of the study was to investigate cognitive outcomes at 6.5 years in children born very preterm, in relation to neonatal characteristics and 2.5‐year neurodevelopment.

Methods

A prospective cohort, with gestational age 22.3‐31.9 weeks, born 2004‐2007, were examined at 2.5 years with the Bayley Scales of Infant and Toddler Development (Bayley‐III) (n = 100) and at 6.5 years with the Wechsler Intelligence Scales (n = 91).

Results

Neonatal factors independently related to 6.5‐year outcome were gestational age, retinopathy of prematurity and treated persistent ductus arteriosus. The Bayley‐III cognitive scores explained only 44% of the Full‐Scale Intelligence Quotient result at 6.5 years, and 22% of the children had Wechsler index results below −1 SD, indicating cognitive impairment, after average test results at 2.5 years. The relative risk to score below −1 SD on the Full‐Scale IQ was 2.83 (95% CI 1.45‐5.53) in children with gestational age below 28 weeks and 2.22 (95% CI 1.18‐4.17) at gestational age 28‐31 weeks.

Conclusion

Very preterm infants born in the 2000s had increased risks for impaired cognition at 6.5 years, but individual predictions based on neonatal risks and 2.5‐year test results were not enough to identify all high‐risk children.

Using different definitions affected the reported prevalence of neurodevelopmental impairment in children born very preterm

AIM

We investigated the impact of varying definitions on the prevalence of neurodevelopmental impairment (NDI) in children born very preterm at 6.5 years of age.

METHODS

Cognitive development and neurosensory impairments were assessed in 91 children (40/51 girls/boys) born <32 gestational weeks, in 2004-2007 in Uppsala county, Sweden. The results were compared with data from a reference group of 67 children born full term. The prevalence of NDI in the present cohort was reported according to definitions used by seven contemporary studies of children born very or extremely preterm.

RESULTS

The prevalence of severe NDI varied from 2% to 23% depending on the definition used. The prevalence of cognitive impairment varied from 2% (-3 SD according to test norms) to 16% (-2 SD according to control group), the prevalence of cerebral palsy from 0% (severe) to 9% (any) and the prevalence of severe visual impairment from 0% (blindness) to 1% (visual acuity < 0.3). There were no children with severe hearing impairment.

CONCLUSION

A high variability in definitions affects the reporting of the prevalence of NDI in long-term follow-up studies of very or extremely preterm born children. There is a need for a better consensus to enable comparisons across studies.

Preterm Birth and the Development of Visual Attention During the First 2 Years of Life: A Systematic Review and Meta-analysis

Importance

Preterm birth is associated with an increased risk for long-lasting attention deficits. Early-life markers of attention abnormalities have not been established to date but could provide insights into the pathogenesis of attention abnormalities and could help identify susceptible individuals.

Objective

To examine whether preterm birth is associated with visual attention impairments in early life, and if so, in which attention functions and at which developmental period during the first 2 years of life.

Data Sources

PubMed and PsycINFO were searched on November 17, 2019, to identify studies involving visual attention outcomes in infants born preterm vs full term.

Study Selection

Peer-reviewed studies from the past 50 years met the eligibility criteria if they directly assessed visual attention outcomes until the age of 2 years in generally healthy infants born preterm or full term. The selection process was conducted by 2 independent reviewers.

Data Extraction and Synthesis

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline was followed. Random-effects models were used to determine standardized mean differences. The risk of bias was assessed both within and between studies.

Main Outcomes and Measures

Five nascent indices of visual attention were analyzed, including very basic functions-namely, the abilities to follow and fixate on visual targets-and more complex functions, such as visual processing (ie, habituation), recognition memory (ie, novelty preference), and the ability to effortfully focus attention for learning.

Results

A total of 53 studies were included, with 69 effect sizes and assessing a total of 3998 infants (2047 born preterm and 1951 born full term; of the 3376 for whom sex was reported, 1693 [50.1%] were girls). Preterm birth was associated with impairments in various attention indices, including visual-following in infancy (Cohen d, -0.77; 95% CI, -1.23 to -0.31), latency to fixate (Cohen d, -0.18; 95% CI, -0.33 to -0.02), novelty preference (Cohen d, -0.20; 95% CI, -0.32 to -0.08), and focused attention (Cohen d, -0.28; 95% CI, -0.45 to -0.11). In the neonatal period, preterm birth was associated with superior visual-following (Cohen d, 0.22; 95% CI, 0.03 to 0.40), possibly owing to the additional extrauterine exposure to sensory stimulation. However, this early association waned rapidly in infancy (Cohen d, -0.77; 95% CI, -1.23 to -0.31).

Conclusions and Relevance

The findings suggest that preterm birth is associated with impingements to visual attention development in early life, as manifested in basic and then complex forms of attention. Advancements in neonatal care may underlie improvements found in the current era and accentuate several early protective factors.

Visual scanning preferences in low birth weight preterm infants

INTRODUCTION

Few studies have used eye tracking as a screening tool for autism spectrum disorder (ASD) in preterm infants.

OBJECTIVES

To evaluate fixation time on social and non-social figures and percentage of preterm babies who gazed at the images.

METHODS

This was a cross-sectional study of 31 preterm infants born weighing ≤ 2,000 g in which eye gaze was evaluated at 6 months of corrected age. Six boards with social and non-social figures were projected on a computer screen, successively, evaluating time and percentage of preterm babies who gazed at each board. The Modified Checklist for Autism in Toddlers (M-CHAT) was answered at 18 months of corrected age.

RESULTS

Preterm infants showed longer visual fixation time on social figures compared with non-social images, regardless of the position of the social figure on the board. Similar percentages of preterm infants gazed either at social or non-social figures, at social figures with a direct or an indirect look, and at the eyes or mouth of the social figures. No preterm infant screened positive on the M-CHAT.

CONCLUSION

At 6 months of corrected age, preterm infants show the ability to gaze in an eye-tracking test, with preference for social figures, suggesting that this tool could be useful as another screening instrument for ASD.

Impaired cognitive ability at 2.5 years predicts later visual and ophthalmological problems in children born very preterm

AIM

To identify possible predictive factors for visual problems at 6.5 years in children born very preterm.

METHODS

During 2004-2007, all very preterm infants (gestational age [GA] <32 weeks) in Uppsala County, Sweden were screened for retinopathy of prematurity (ROP) neonatally; at four months, visual tracking was tested; at 2.5 years, visuospatial and cognitive tests were carried out. At 6.5 years, 84 preterm children and a reference group of 64 full-term children underwent ophthalmological testing.

RESULTS

Mean visual acuity (VA) did not differ between the groups, but subnormal VA (≤0.8) was more common in the preterm group (31% vs 14%; p < 0.05). More often than full-term children, preterm children had impaired contrast sensitivity (<0.5) (36% vs 19%; p < 0.05) and strabismus (8% vs 0%; p < 0.05). Low GA, ROP, intraventricular haemorrhage 3-4/periventricular leukomalacia and cognitive disability at 2.5 years predicted ophthalmological and visual problems at 6.5 years. Visual tracking ability at four months was not predictive of ophthalmological outcome.

CONCLUSION

Children born preterm had more ophthalmological problems at 6.5 years of age, including subtle dysfunctions. ROP, early brain injury and impaired cognitive function around 2.5 years predicted later ophthalmological dysfunctions.

The Structured Observation of Motor Performance in Infants has convergent and discriminant validity in preterm and term infants

AIM

Methods are needed to evaluate the level of early motor development and quality of motor performance in infants. We examined the convergent and discriminant validity of the Structured Observation of Motor Performance in Infants (SOMP-I) for evaluating the level of motor development and quality of motor performance in preterm and term infants.

METHODS

A regional cohort of 111 preterm infants with a gestational age of <32 weeks and 72 healthy term born infants were assessed with the SOMP-I, at two, four, six and 10 months of corrected age. Convergent validity was analysed with a mixed model analysis of the motor performance over time. Discriminant validity was analysed with the Mann-Whitney U-test in groups with different neonatal characteristics.

RESULTS

Convergent validity was supported, as the level of motor development increased with age and the quality of motor performance improved over time. The method discriminated for both level and quality between the preterm and the term infants. The preterm infants demonstrated different quality deficits regardless of the level of motor development.

CONCLUSION

Convergent validity and discriminant validity of the SOMP-I were supported in preterm and term infants and facilitates early identification of infants with atypical motor development.

Postnatal systemic inflammation and neuro-ophthalmologic dysfunctions in extremely low gestational age children

AIM

Compared to infants born at term, children born very preterm are at increased risk of visual dysfunctions and neonatal systemic inflammation. Here, we explore whether these two propensities are related.

METHODS

As part of the ELGAN study, the concentrations of 16 mediators of inflammation were measured in blood obtained on postnatal days 1, 7, 14, 21 and 28 from 1062 children born before the 28th week of gestation. Presence of visual field deficit, strabismus and/or impaired visual fixation was recorded at age two. The concentrations of each protein were divided into quartiles within gestational week categories. We calculated odds ratios with 99% confidence intervals for having each disorder comparing children with concentration in the top quartile of each protein to children whose concentration was in the lower quartiles on the corresponding day. Analyses were adjusted for gestational age and birth weight Z-score.

RESULTS

Only one of 80 assessments (16 proteins on five different days) was significant for visual field deficit, and one for impaired fixation. No association was found between strabismus and any inflammatory mediator.

CONCLUSION

None of the three neuro-ophthalmologic dysfunctions assessed at two years appears to be associated with systemic inflammation measured the first four postnatal weeks.

Visual tracking in very preterm infants at 4 mo predicts neurodevelopment at 3 y of age

BACKGROUND

Typically developing infants track moving objects with eye and head movements in a smooth and predictive way at 4 mo of age, but this ability is delayed in very preterm infants. We hypothesized that visual tracking ability in very preterm infants predicts later neurodevelopment.

METHOD

In 67 very preterm infants (gestational age<32 wk), eye and head movements were assessed at 4 mo corrected age while the infant tracked a moving object. Gaze gain, smooth pursuit, head movements, and timing of gaze relative the object were analyzed off line. Results of the five subscales included in the Bayley Scales of Infant Development (BSID-III) at 3 y of age were evaluated in relation to the visual tracking data and to perinatal risk factors.

RESULTS

Significant correlations were obtained between gaze gain and cognition, receptive and expressive language, and fine motor function, respectively, also after controlling for gestational age, severe brain damage, retinopathy of prematurity, and bronchopulmonary dysplasia.

CONCLUSION

This is the first study demonstrating that the basic ability to visually track a moving object at 4 mo robustly predicts neurodevelopment at 3 y of age in children born very preterm.

Thalamic alterations in preterm neonates and their relation to ventral striatum disturbances revealed by a combined shape and pose analysis

Finding the neuroanatomical correlates of prematurity is vital to understanding which structures are affected, and to designing efficient prevention and treatment strategies. Converging results reveal that thalamic abnormalities are important indicators of prematurity. However, little is known about the localization of the abnormalities within the subnuclei of the thalamus, or on the association of altered thalamic development with other deep gray matter disturbances. Here, we aim to investigate the effect of prematurity on the thalamus and the putamen in the neonatal brain, and further investigate the associated abnormalities between these two structures. Using brain structural magnetic resonance imaging, we perform a novel combined shape and pose analysis of the thalamus and putamen between 17 preterm (41.12 ± 5.08 weeks) and 19 term-born (45.51 ± 5.40 weeks) neonates at term equivalent age. We also perform a set of correlation analyses between the thalamus and the putamen, based on the surface and pose results. We locate significant alterations on specific surface regions such as the anterior and ventral anterior (VA) thalamic nuclei, and significant relative pose changes of the left thalamus and the right putamen. In addition, we detect significant association between the thalamus and the putamen for both surface and pose parameters. The regions that are significantly associated include the VA, and the anterior and inferior putamen. We detect statistically significant surface deformations and pose changes on the thalamus and putamen, and for the first time, demonstrate the feasibility of using relative pose parameters as indicators for prematurity in neonates. Our methods show that regional abnormalities of the thalamus are associated with alterations of the putamen, possibly due to disturbed development of shared pre-frontal connectivity. More specifically, the significantly correlated regions in these two structures point to frontal-subcortical pathways including the dorsolateral prefrontal-subcortical circuit, the lateral orbitofrontal-subcortical circuit, the motor circuit, and the oculomotor circuit. These findings reveal new insight into potential subcortical structural covariates for poor neurodevelopmental outcomes in the preterm population.

Ophthalmological outcome and visuospatial ability in very preterm children measured at 2.5 years corrected age

AIM

To investigate the ophthalmological outcome of very preterm children at 2.5 years corrected age (CA) and perform a test of visuospatial and cognitive abilities.

METHODS

A population-based, prospective study (LOVIS study) in Uppsala County, Sweden, comprised 111 very preterm children (<32 w gestational age [GA]) born between 1 January 2004 and 31 December 2007. Ophthalmic evaluations were undertaken in 98/109 children (89.9%) alive at 2.5 years. Spatial cognition was investigated with a test of five alternative blocks in 48 preterm and 25 term-born children.

RESULTS

Visual impairment, strabismus or refractive errors, were found in 12% of the children. None of the children were blind in both eyes. Logistic regression analyses revealed significant associations between strabismus and periventricular leucomalacia/intraventricular haemorrhage (OR 9.6, p = 0.025) and between refractive errors and severe retinopathy of prematurity (OR 9.8, p = 0.011) and GA (OR 0.763, p = 0.034). Oval and rectangular blocks were significantly more difficult to insert into a box for preterm than full-term children (p = 0.048 and 0.013, respectively). There was a significant correlation between total scores for the five blocks and GA at birth (p = 0.035).

CONCLUSION

Eye and visual problems were found in 12% of the preterm children at 30 months CA. Preterm children had difficulties with blocks of complex shapes.

Development of smooth pursuit eye movements in very preterm born infants: 3. Association with perinatal risk factors

AIM

To investigate the association between perinatal risk factors and neonatal complications and early oculo-motor development in very preterm infants.

METHODS

Perinatal risk factors were identified, and the potential association with early oculo-motor development was evaluated by measuring smooth pursuit eye movements (SP) at 2 and 4 months' corrected age (CA) in a population of very preterm infants born in Uppsala County 2004-2007 (n = 113).

RESULTS

Among the 15 tested factors, eight showed significant association in univariate analysis with lower levels of SP at 4 months' CA, namely administration of prenatal corticosteroids, gestational age, birthweight, bronchopulmonary dysplasia, retinopathy of prematurity, periventricular leukomalacia, intraventricular haemorrhage >grade 2, and persistent ductus arteriosus. At 2 months' CA, only retinopathy of prematurity >stage 2 was associated with lower levels of SP. When all factors significant in the univariate tests were included in multiple regressions aimed to assess each factor's independent relation to SP, periventricular leukomalacia was the only significant independent factor. When adding 2-5 of the significant factors using multiple regression analysis, the levels of SP became lower.

CONCLUSION

Perinatal risk factors were associated with lower levels of SP. This could be interpreted as delayed or disturbed development of normal oculomotor ability.

Development of smooth pursuit eye movements in very prematurely born infants: 2. The low-risk subgroup

AIM

To investigate the impact of premature birth on visual tracking in a group of 37 infants, born before the 32nd gestational weeks (mean 29 + 6 weeks) and diagnosed as being without major neonatal complications. This paper is a part of the LOVIS study (Strand Brodd, Ewald, Grönqvist, Holmström, Strömberg, Von Hofsten, et al. Acta Pediatrica, 2011).

METHODS

At 2 and 4 months corrected age, eye and head movements were measured when the infant tracked a moving object. The eye movements were analysed in terms of smooth pursuit and saccades (Vision Res, 37, 1997, 1799; Exp Brain Res, 146, 2002, 257). Accuracy of gaze, proportion of smooth pursuit, head movements and saccades were calculated.

RESULTS

  Between 2 and 4 months of age, all infants improved their ability to smoothly pursue a moving object. However, at both occasions, the preterm infants had less proportion smooth pursuit than the full-term infants. The groups did not differ with respect to gaze and head movements, but the saccade frequency was higher for the very preterms in some of the conditions.

CONCLUSION

The development of smooth pursuit in the low-risk preterm infant group was strongly delayed compared to typically developed infants. Thus, the 2 months or more extra visual experience did not have a distinguishable positive effect on visuo-motor development as expressed in smooth pursuit.