Patterns of visual impairment associated with lesions of the preterm infant brain

Prevalence and Types of Strabismus in Cerebral Palsy: A Global and Historical Perspective Based on a Systematic Review and Meta-Analysis

PURPOSE

Strabismus is more frequent in cerebral palsy (CP) than in the normal population, but reports differ how much it is increased. We here examined the global prevalence and types of strabismus in CP, whether esotropia or exotropia is more frequent, and whether the prevalence differs between ethnicities and/or country income levels, and between generations.

METHODS

We compiled in a systematic review and meta-analysis the results of 147 CP studies that report the prevalence of strabismus or the ratio of esotropia to exotropia, and we conducted subgroup analyses for region (income level) and ethnicity. We performed a pooled analysis for the CP strabismus prevalence, and estimated the global number of CP cases with strabismus.

RESULTS

The pooled prevalence of strabismus in CP is 49.8% in high-income countries and 39.8% in lower-income countries. We estimate the global number of strabismus cases in CP as 12.2 million, with 7.6 million males and 4.6 million females, based on current estimates of 29.6 million global CP cases. Esotropia is more frequent than exotropia in Caucasians, while exotropia is more frequent than esotropia in Hispanic and in some Asian and African populations. The strabismus prevalence in CP increases with increasing country income levels.

CONCLUSION

Generational changes in strabismus prevalence appear to reflect a transition of CP types and an increase in prevalence as countries attain higher income and more effective maternal health care. The distribution of esotropia and exotropia in CP patients largely reflects the horizontal strabismus type that is predominant in the subject's ethnicity.

Morphine exposure and prematurity affect flash visual evoked potentials in preterm infants

Objective

The present study aimed to explore first the impact of perinatal risk factors on flash-VEP waves and morphology in a group of preterm infants studied at term equivalent age (TEA). Second, to correlate VEP morphology with neurological outcome at 2 years corrected age (CA).

Methods

Infants with a gestational age (GA) at birth <32 weeks, without major brain injury, were enrolled. Multivariate regression analyses were performed, and the models were run separately for each dependent variable N2, P2, N3 latencies and P2 amplitude. Logistic regression was applied to study N4 component (present/absent) and VEP morphology (regular/irregular). The predictors were GA, bronchopulmonary dysplasia (BPD), postmenstrual age at VEP registration, cumulative morphine and fentanyl dose, and painful procedures. Lastly, linear regression models were performed to assess the relation between the Bayley-III cognitive and motor scores at 2 years CA and VEP morphology, in relation to GA, BPD, painful procedures and cumulative morphine dose.

Results

Eighty infants were enrolled. Morphine was the predictor of N2 (R2 = 0.09, p = 0.006), P2 (R2 = 0.11, p = 0.002), and N3 (R2 = 0.13, p = 0.003) latencies. Younger GA was associated with lower amplitude (R2 = 0.05, p = 0.029). None of the independent variables predicted the presence of N4 component, nor VEP morphology in the logistic analysis. VEP morphology was not associated with cognitive and motor scores at 2 years.

Conclusions

Morphine treatment and prematurity were risk factors for altered VEPs parameters at TEA. In our cohort VEP morphology did not predict neurological outcome.

Significance

Morphine administration should be evaluated according to potential risks and benefits, and dosage individually accustomed, according to pain and comfort scores, considering the possible risk for neurodevelopmental impairment.

Prevalence and types of strabismus in cerebral palsy: A global and historical perspective based on a systematic review and meta-analysis

Purpose

Strabismus is more frequent in cerebral palsy (CP) than in the normal population, but reports differ how much it is increased. We here examined the global prevalence and types of strabismus in CP, whether esotropia or exotropia is more frequent, and whether the prevalence differs between ethnicities and/or country income levels, and between generations.

Methods

We compiled in a systematic review and meta-analysis the results of 147 CP studies that report the prevalence of strabismus or the ratio of esotropia to exotropia, and we conducted subgroup analyses for region (income level) and ethnicity. We performed a pooled analysis for the CP strabismus prevalence, and estimated the global number of CP cases with strabismus.

Results

The pooled prevalence of strabismus in CP is 49.8% in high-income countries and 39.8% in lower-income countries. We estimate the global number of strabismus cases in CP as 12.2 million, with 7.6 million males and 4.6 million females, based on current estimates of 29.6 million global CP cases. Esotropia is more frequent than exotropia in Caucasians, while exotropia is more frequent than esotropia in Hispanic and in some Asian and African populations. The strabismus prevalence in CP increases with increasing country income levels.

Conclusion

Generational changes in strabismus prevalence appear to reflect a transition of CP types and an increase in prevalence as countries attain higher income and more effective maternal health care. The distribution of esotropia and exotropia in CP patients largely reflects the horizontal strabismus type that is predominant in the subject's ethnicity.

The Multidisciplinary Guidelines for Diagnosis and Referral in Cerebral Visual Impairment

Introduction

Cerebral visual impairment (CVI) is an important cause of visual impairment in western countries. Perinatal hypoxic-ischemic damage is the most frequent cause of CVI but CVI can also be the result of a genetic disorder. The majority of children with CVI have cerebral palsy and/or developmental delay. Early diagnosis is crucial; however, there is a need for consensus on evidence based diagnostic tools and referral criteria. The aim of this study is to develop guidelines for diagnosis and referral in CVI according to the grade method.

Patients and Methods

We developed the guidelines according to the GRADE method 5 searches on CVI (children, developmental age ≤ 18 years) were performed in the databases Medline, Embase, and Psychinfo, each with a distinct topic.

Results

Based on evidence articles were selected on five topics: 1. Medical history and CVI-questionnaires 23 (out of 1,007). 2. Ophthalmological and orthoptic assessment 37 (out of 816). 3. Neuropsychological assessment 5 (out of 716). 4. Neuroradiological evaluation and magnetic resonance imaging (MRI) 9 (out of 723). 5. Genetic assessment 5 (out of 458).

Conclusion

In medical history taking, prematurity low birth weight and APGAR (Appearance, Pulse, Grimace, Activity, Respiration) Scores (<5) are important. Different questionnaires are advised for children under the age of 3 years, older children and for specific risk groups (extremely preterm). In ophthalmological examination, eye movements, specially saccades, accommodation, crowding, contrast sensitivity and visual fields should be evaluated. OCT can show objective signs of trans-synaptic degeneration and abnormalities in fixation and saccades can be measured with eye tracking. Screening of visual perceptive functioning is recommended and can be directive for further assessment. MRI findings in CVI in Cerebral Palsy can be structured in five groups: Brain maldevelopment, white and gray matter lesions, postnatal lesions and a normal MRI. In children with CVI and periventricular leukomalacia, brain lesion severity correlates with visual function impairment. A differentiation can be made between cortical and subcortical damage and related visual function impairment. Additional assessments (neurological or genetic) can be necessary to complete the diagnosis of CVI and/or to reveal the etiology.

An ode to fetal, infant, and toddler neuroimaging: Chronicling early clinical to research applications with MRI, and an introduction to an academic society connecting the field

Fetal, infant, and toddler neuroimaging is commonly thought of as a development of modern times (last two decades). Yet, this field mobilized shortly after the discovery and implementation of MRI technology. Here, we provide a review of the parallel advancements in the fields of fetal, infant, and toddler neuroimaging, noting the shifts from clinical to research use, and the ongoing challenges in this fast-growing field. We chronicle the pioneering science of fetal, infant, and toddler neuroimaging, highlighting the early studies that set the stage for modern advances in imaging during this developmental period, and the large-scale multi-site efforts which ultimately led to the explosion of interest in the field today. Lastly, we consider the growing pains of the community and the need for an academic society that bridges expertise in developmental neuroscience, clinical science, as well as computational and biomedical engineering, to ensure special consideration of the vulnerable mother-offspring dyad (especially during pregnancy), data quality, and image processing tools that are created, rather than adapted, for the young brain.

Role of Structural, Metabolic, and Functional MRI in Monitoring Visual System Impairment and Recovery

The visual system, consisting of the eyes and the visual pathways of the brain, receives and interprets light from the environment so that we can perceive the world around us. A wide variety of disorders can affect human vision, ranging from ocular to neurologic to systemic in nature. While other noninvasive imaging techniques such as optical coherence tomography and ultrasound can image particular sections of the visual system, magnetic resonance imaging (MRI) offers high resolution without depth limitations. MRI also gives superior soft-tissue contrast throughout the entire pathway compared to computed tomography. By leveraging different imaging sequences, MRI is uniquely capable of unveiling the intricate processes of ocular anatomy, tissue physiology, and neurological function in the human visual system from the microscopic to macroscopic levels. In this review we discuss how structural, metabolic, and functional MRI can be used in the clinical assessment of normal and pathologic states in the anatomic structures of the visual system, including the eyes, optic nerves, optic chiasm, optic tracts, visual brain nuclei, optic radiations, and visual cortical areas. We detail a selection of recent clinical applications of MRI at each position along the visual pathways, including the evaluation of pathology, plasticity, and the potential for restoration, as well as its limitations and key areas of ongoing exploration. Our discussion of the current and future developments in MR ocular and neuroimaging highlights its potential impact on our ability to understand visual function in new detail and to improve our protection and treatment of anatomic structures that are integral to this fundamental sensory system. LEVEL OF EVIDENCE 3:   TECHNICAL EFFICACY STAGE 3:  .

In vivo MRI evaluation of early postnatal development in normal and impaired rat eyes

This study employed in vivo 7-T magnetic resonance imaging (MRI) to evaluate the postnatal ocular growth patterns under normal development or neonatal impairments in Sprague-Dawley rats. Using T2-weighted imaging on healthy rats from postnatal day (P) 1 (newborn) to P60 (adult), the volumes of the anterior chamber and posterior chamber (ACPC), lens, and vitreous humor increased logistically with ACPC expanding by 33-fold and the others by fivefold. Intravitreal potassium dichromate injection at P1, P7, and P14 led to T1-weighted signal enhancement in the developing retina by 188-289%. Upon unilateral hypoxic-ischemic encephalopathy at P7, monocular deprivation at P15, and monocular enucleation at P1, T2-weighted imaging of the adult rats showed decreased ocular volumes to different extents. In summary, in vivo high-field MRI allows for non-invasive evaluation of early postnatal development in the normal and impaired rat eyes. Chromium-enhanced MRI appeared effective in examining the developing retina before natural eyelid opening at P14 with relevance to lipid metabolism. The reduced ocular volumes upon neonatal visual impairments provided evidence to the emerging problems of why some impaired visual outcomes cannot be solely predicted by neurological assessments and suggested the need to look into both the eye and the brain under such conditions.

Amblyopia: prevalence, natural history, functional effects and treatment

Amblyopia, defined as poor vision due to abnormal visual experience early in life, affects approximately three per cent of the population and carries a projected lifetime risk of visual loss of at least 1.2 per cent. The presence of amblyopia or its risk factors, mainly strabismus or refractive error, have been primary conditions targeted in childhood vision screenings. Continued support for such screenings requires evidence-based understanding of the prevalence and natural history of amblyopia and its predisposing conditions, and proof that treatment is effective in the long term with minimal negative impact on the patient and family. This review summarises recent research relevant to the clinical understanding of amblyopia, including prevalence data, risk factors, the functional impact of amblyopia and optimum treatment regimes and their justification from a vision and life skills perspective. Collectively, these studies indicate that treatment for amblyopia is effective in reducing the overall prevalence and severity of visual loss from amblyopia. Correction of refractive error alone has been shown to significantly reduce amblyopia and less frequent occlusion can be just as effective as more extensive occlusion. Occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life, and these factors should be considered in prescribing treatment, particularly because of their influence on compliance. Ongoing treatment trials are being undertaken to determine both the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion. This review highlights the expansion of current knowledge regarding amblyopia and its treatment to help clinicians provide the best level of care for their amblyopic patients that current knowledge allows.

Lessons Learned from 23 Years of Experience in Testing Visual Fields of Neurologically Impaired Children

We sought to investigate the reliability of standard conventional perimetry (SCP) in neurologically impaired (NI) children using the examiner-based assessment of reliability scoring system and to determine the difference in time to diagnosis of a visual field defect between SCP and a behavioural visual field (BVF) test. Patient records of 115 NI children were retrospectively analysed. The full field peritest (FFP) had best reliability with 44% 'good' scores versus 22% for Goldmann perimetry (p < .001). The mean age of NI children able to perform SCP was 8.3 years versus 4.6 years for the BVF test (p < .001). Use of the BVF test may significantly reduce time to diagnosis.

Systemic 7,8-Dihydroxyflavone Treatment Protects Immature Retinas Against Hypoxic-Ischemic Injury via Müller Glia Regeneration and MAPK/ERK Activation

Purpose

Perinatal hypoxic-ischemic (HI) injury causes significant damages in the immature retina. The brain-derived neurotrophic factor is well known for its neuroprotective role but has limited clinical applications. A selective agonist of tyrosine kinase receptor B, 7,8-dihydroxyflavone (DHF), is a powerful therapeutic tool, when administered systemically. However, it remains unclear whether DHF treatment can protect the immature retinas against HI injury.

Methods

Postnatal (P) day 7 rat pups were intraperitoneally injected with DHF or vehicle 2 hours before and 18 hours after being subjected to HI injury. The outcomes were assessed at various timepoints after injury by electroretinography and histologic examinations. Neurogenesis was assessed by double-labeling of retinal sections with 5-bromo-2'-deoxyuridine and different neuronal markers.

Results

At P8, 24-hours postinjury, brain-derived neurotrophic factor mRNA levels in the retina decreased significantly. DHF treatment partially protected immature retinas at both histologic and functional levels between P14 and P30 but did not prevent apoptosis, inflammation, or damage of the blood-retinal barrier (BRB) at P8. On the other hand, DHF treatment promoted the survival of proliferating inner retinal cells, including Müller glia, and enhanced their transdifferentiation to bipolar cells at P17. Moreover, DHF treatment rescued the levels of extracellular signal-regulated kinase (ERK) phosphorylation, which were significantly decreased after injury. The neuroprotective effects of DHF were markedly eliminated by inhibition of ERK phosphorylation.

Conclusions

Early systemic DHF treatment has neuroprotective effects against HI injury in immature retinas, possibly via promoting neurogenesis through the tyrosine kinase receptor B/ERK signaling pathway.

Chinese Abstract.

Perinatal risk factors for visuospatial attention and processing dysfunctions at 1 year of age in children born between 26 and 32 weeks

BACKGROUND

Children born preterm are at risk of visuospatial attention orienting and processing dysfunctions, which can be quantified early in life using visually-guided eye movement responses.

AIMS

To identify the prevalence and perinatal risk factors for visuospatial attention orienting and processing dysfunctions in children born preterm of 1 year of corrected age (CA).

STUDY DESIGN

123 children born between 26 and 33 weeks of gestation underwent a nonverbal visuospatial test at 1y CA, using an eye tracking-based paradigm. For the detected high-salient (cartoon and contrast), intermediate-salient (form and motion) and low-salient (color) stimuli, we quantified the reaction time to fixation (RTF). RTFs were compared to normative references from an age-matched control group (N = 38). The prevalence of perinatal risk factors (gestational age and weight, indices of neurological damage, overal sickness, respiratory failure, and retinopathy) was compared between the groups with normal and delayed RTFs.

RESULTS

At 1y CA, the preterm group had 7-20% less detected stimuli than the control group, particularly for intermediate and low-salient stimuli. Compared to normative RTFs, modest delays were found for high-salient cartoon (in 19% of preterm children) and contrast (8%), intermediate-salient motion (23%) and form (21%), and low-salient color stimuli (8%). These children had a significantly higher prevalence of perinatal risk factors for respiratory failure and intraventricular hemorrhages.

CONCLUSIONS

Children born between 26 and 32 weeks have a modest risk (8-23%) of visuospatial attention and processing dysfunction. This warrants early monitoring and support of general visual development in preterm children at risk of respiratory distress and disrupted cerebral blood flow.

Genome-Wide Association Study Identifies a Susceptibility Locus for Comitant Esotropia and Suggests a Parent-of-Origin Effect

Purpose

To identify genetic variants conferring susceptibility to esotropia. Esotropia is the most common form of comitant strabismus, has its highest incidence in European ancestry populations, and is believed to be inherited as a complex trait.

Methods

White European American discovery cohorts with nonaccommodative (826 cases and 2991 controls) or accommodative (224 cases and 749 controls) esotropia were investigated. White European Australian and United Kingdom cohorts with nonaccommodative (689 cases and 1448 controls) or accommodative (66 cases and 264 controls) esotropia were tested for replication. We performed a genome-wide case-control association study using a mixed linear additive model. Meta-analyses of discovery and replication cohorts were then conducted.

Results

A significant association with nonaccommodative esotropia was discovered (odds ratio [OR] = 1.41, P = 2.84 × 10-09) and replicated (OR = 1.23, P = 0.01) at rs2244352 [T] located within intron 1 of the WRB (tryptophan rich basic protein) gene on chromosome 21 (meta-analysis OR = 1.33, P = 9.58 × 10-11). This single nucleotide polymorphism (SNP) is differentially methylated, and there is a statistically significant skew toward paternal inheritance in the discovery cohort. Meta-analysis of the accommodative discovery and replication cohorts identified an association with rs912759 [T] (OR = 0.59, P = 1.89 × 10-08), an intergenic SNP on chromosome 1p31.1.

Conclusions

This is the first genome-wide association study (GWAS) to identify significant associations in esotropia and suggests a parent-of-origin effect. Additional cohorts will permit replication and extension of these findings. Future studies of rs2244352 and WRB should provide insight into pathophysiological mechanisms underlying comitant strabismus.

Comparative study of visual dysfunctions in 6-10-year-old very preterm- and full-term-born children

PURPOSE

To compare visual dysfunction between very preterm-born (VPB) children with no retinopathy of prematurity (no-ROP) at 6-10 years of age and age- and sex-matched full-term-born controls.

METHODS

This is an observational, prospective study that included 30 children, 6-10 years of age, born ≤ 32 weeks of gestation, with no-ROP, and 30 age- and sex-matched full-term-born controls, conducted from January 2015 until August 2015. All children underwent complete ophthalmic evaluation. Main outcome measures include visual functions (best corrected visual acuity (BCVA), color vision, and stereoacuity), ocular alignment, refractive errors, and the presence of amblyopia and nystagmus.

RESULTS

Mean BCVA of the right eyes was 0.04 ± 0.08 logMAR for VPB children and 0.02 ± 0.05 logMAR for the full-term children (P = 0.075). Mean BCVA for the left eyes was 0.07 ± 0.09 logMAR for VPB children and 0.02 ± 0.05 logMAR for the full-term children (P = 0.014). Refractive errors were slightly higher though not statistically significant in VPB children compared to full-term children (P = 0.125). The incidence of myopia and hypermetropia was 16.7 and 40%, respectively, in VPB children and 10 and 23.3%, respectively, in full-term children. Anisometropia found only in VPB children with an incidence of 16.7%. Amblyopia found in 10% of VPB children compared to 3.3% in full-term children. Strabismus was found equally in 10% of each group.

CONCLUSION

VPB children with no-ROP are at an increased risk of developing decreased BCVA at least in one eye and anisometropia compared to age-matched full-term controls.

Should we add visual acuity ratios to referral criteria for potential cerebral visual impairment?

PURPOSE

To determine whether the assessment of visual acuity ratios might improve the referral of children with (sub)normal visual acuity but at risk of cerebral visual impairment.

METHODS

In an exploratory study, we assessed visual acuity, crowding ratio and the ratios between grating acuity (Teller Acuity Cards-II) and optotype acuity (Cambridge Crowding Cards) in 60 typically developing school children (mean age 5y8m±1y1m), 21 children with ocular abnormalities only (5y7m±1y9m) and 26 children with (suspected) brain damage (5y7m±1y11m). Sensitivities and specificities were calculated for targets and controls from the perspective of different groups of diagnosticians: youth health care professionals (target: children with any visual abnormalities), ophthalmologists and low vision experts (target: children at risk of cerebral visual impairment).

RESULTS

For youth health care professionals subnormal visual acuity had the best sensitivity (76%) and specificity (70%). For ophthalmologists and low vision experts the crowding ratio had the best sensitivity (67%) and specificity (79 and 86%).

CONCLUSION

Youth health care professionals best continue applying subnormal visual acuity for screening, whereas ophthalmologists and low vision experts best add the crowding ratio to their routine diagnostics, to distinguish children at risk of visual impairment in the context of brain damage from children with ocular pathology only.

[EFFECT OF HYPOXIA ON SYNAPTIC TRANSMISSION BETWEEN RETINAL GANGLION CELLS AND SUPERIOR COLLICULUS NEURONS IN COCULTURE]

In this study we conducted a series of experiments to characterize the effect and define the mechanisms of hypoxia on synaptic transmission between retinal ganglion cells and superior colliculus (SC) neurons. Application of hypoxic solution leads to a long lasting potentiation (LTP) NMDA-mediated synaptic transmission. Analysis of the oxygen deficiency effect on the spontaneous and miniature postsynaptic currents (sPSC and mPSC respectively) revealed an increase in the frequency of their occurrence and the appearance of the second peak in the mPSC histogram distribution. The assessment of quantum and binomial parameters reflects the complex pre- and postsynaptic changes during the potentiation, independent of the release probability. Most likely this LTP can be caused by an increase in the total number of active synapses. Glutamatergic synaptic transmission mediated by non-NMDA activation receptor-channel complexes, responded to application of deoxygenated solution by the brief depression, which is the result of presynaptic dysfunction and associates with decrease in release probability and number of active zones. GABAergic synaptic transmission mediated by activation GABA(A)-receptor-channel complexes, responded to hypoxic action by long term depression (LTD). Analysis of sPSC and mPSC showed a significant decrease in the frequency of their occurrence and significant (P = 0.05) decrease in the quantum over a period of oxygen deficiency. In general, the effect of hypoxia-induced LTD of GABAergic synaptic transmission is based on complex changes of presynaptic (independent on the release probability) and postsynaptic (reduction sensitivity of receptors in postsynaptic membrane) mechanisms.

Long-term effects of neonatal hypoxia-ischemia on structural and physiological integrity of the eye and visual pathway by multimodal MRI

PURPOSE

Neonatal hypoxia-ischemia is a major cause of brain damage in infants and may frequently present visual impairments. Although advancements in perinatal care have increased survival, the pathogenesis of hypoxic-ischemic injury and the long-term consequences to the visual system remain unclear. We hypothesized that neonatal hypoxia-ischemia can lead to chronic, MRI-detectable structural and physiological alterations in both the eye and the brain's visual pathways.

METHODS

Eight Sprague-Dawley rats underwent ligation of the left common carotid artery followed by hypoxia for 2 hours at postnatal day 7. One year later, T2-weighted MRI, gadolinium-enhanced MRI, chromium-enhanced MRI, manganese-enhanced MRI, and diffusion tensor MRI (DTI) of the visual system were evaluated and compared between opposite hemispheres using a 7-Tesla scanner.

RESULTS

Within the eyeball, systemic gadolinium administration revealed aqueous-vitreous or blood-ocular barrier leakage only in the ipsilesional left eye despite comparable aqueous humor dynamics in the anterior chamber of both eyes. Binocular intravitreal chromium injection showed compromised retinal integrity in the ipsilesional eye. Despite total loss of the ipsilesional visual cortex, both retinocollicular and retinogeniculate pathways projected from the contralesional eye toward ipsilesional visual cortex possessed stronger anterograde manganese transport and less disrupted structural integrity in DTI compared with the opposite hemispheres.

CONCLUSIONS

High-field, multimodal MRI demonstrated in vivo the long-term structural and physiological deficits in the eye and brain's visual pathways after unilateral neonatal hypoxic-ischemic injury. The remaining retinocollicular and retinogeniculate pathways appeared to be more vulnerable to anterograde degeneration from eye injury than retrograde, transsynaptic degeneration from visual cortex injury.

Low positive predictive value of referrals for infantile esotropia among children of Chinese descent

The prevalence of strabismus varies according to the population studied, ethnicity, and geographic region. Previous studies of Asian populations have found that, unlike Western populations, esotropia is 2.5 times less common than exotropia. Because of the homogeneous nature of the local populations studied, however, it is difficult to ascertain the real difference in the epidemiology among ethnic groups. The aim of this study was to determine the positive predictive value of referrals for infantile esotropia in otherwise healthy children referred to a tertiary eye care center in a large center in North America that serves a ethnically diverse population of over 8 million. We found a very low positive predictive value (5.9%) and a very high false referral rate (94.1%) among Chinese children referred for early-onset esotropia.

Low vision due to cerebral visual impairment: differentiating between acquired and genetic causes

Background

To gain more insight into genetic causes of cerebral visual impairment (CVI) in children and to compare ophthalmological findings between genetic and acquired forms of CVI.

Methods

The clinical data of 309 individuals (mainly children) with CVI, and a visual acuity ≤0.3 were analyzed for etiology and ocular variables. A differentiation was made between acquired and genetic causes. However, in persons with West syndrome or hydrocephalus, it might be impossible to unravel whether CVI is caused by the seizure disorder or increased intracranial pressure or by the underlying disorder (that in itself can be acquired or genetic). In two subgroups, individuals with ‘purely’ acquired CVI and with ‘purely’ genetic CVI, the ocular variables (such as strabismus, pale optic disc and visual field defects) were compared.

Results

It was possible to identify a putative cause for CVI in 60% (184/309) of the cohort. In the remaining 40% the etiology could not be determined. A ‘purely’ acquired cause was identified in 80 of the patients (26%). West syndrome and/or hydrocephalus was identified in 21 patients (7%), and in 17 patients (6%) both an acquired cause and West and/or hydrocephalus was present. In 66 patients (21%) a genetic diagnosis was obtained, of which 38 (12%) had other possible risk factor (acquired, preterm birth, West syndrome or hydrocephalus), making differentiation between acquired and genetic not possible. In the remaining 28 patients (9%) a ‘purely’ genetic cause was identified.

CVI was identified for the first time in several genetic syndromes, such as ATR-X, Mowat-Wilson, and Pitt Hopkins syndrome. In the subgroup with ‘purely’ acquired causes (N = 80) strabismus (88% versus 64%), pale optic discs (65% versus 27%) and visual field defects (72% versus 30%) could be observed more frequent than in the subgroup with ‘purely’ genetic disorders (N = 28).

Conclusions

We conclude that CVI can be part of a genetic syndrome and that abnormal ocular findings are present more frequently in acquired forms of CVI.

Decorrelation of cerebral visual inputs as the sufficient cause of infantile esotropia

BACKGROUND AND PURPOSE

Human infants at greatest risk for esotropia are those who suffer cerebral insults that could decorrelate signals from the two eyes during an early critical period of binocular, visuomotor development. The authors reared normal infant monkeys under conditions of binocular decorrelation to determine if this alone was sufficient to cause esotropia, and associated behavioral as well as neuroanatomic deficits.

METHODS

Binocular decorrelation was imposed using prism-goggles for durations of 3-24 weeks (control monkeys wore plano goggles), emulating unrepaired strabismus of durations 3 months to 2 years in human infants. Behavioral recordings were obtained, followed by neuroanatomic analysis of ocular dominance columns and binocular, horizontal connections in the striate visual cortex (area V1).

RESULTS

Concomitant, constant esotropia developed in each monkey exposed to decorrelation for a duration of 6-24 weeks. The severity of ocular motor signs (esotropia angle; dissociated vertical deviation; latent nystagmus; pursuit / optokinetic tracking asymmetry; fusional vergence deficits), and the loss of V1 binocular connections increased as a function of decorrelation duration. Stereopsis was deficient and motion visually evoked potentials were asymmetric. Monkeys exposed to decorrelation for 3 weeks showed transient esotropia, but regained normal alignment, visuomotor behaviors, and binocular V1 connections.

CONCLUSIONS

Binocular decorrelation is a sufficient cause of infantile esotropia when imposed during a critical period of visuomotor development. The systematic relationship between severity of visuomotor signs and severity of V1 connectivity deficits provides a neuroanatomic mechanism for these signs. Restoration of binocular fusion and V1 connections after short durations of decorrelation helps explain the benefits of early strabismus repair in humans.

Hypoxic-ischemic retinal injury in rat pups

BACKGROUND

Visual loss associated with brain damage, especially hypoxic-ischemic (HI) encephalopathy, is the most common cause of visual impairment in children in developed countries. We hypothesized that HI insults can cause long-term damage in immature eyes.

METHODS

In postnatal day 7 rat pups, HI was induced by unilateral common carotid artery ligation followed by hypoxia. Retina damage was assessed by electroretinography (ERG) and cell counting. Neuronal injury and astrogliosis were evaluated by terminal deoxynucleotidyl transferase nick-end labeling, cleaved caspase 3, ED1, and glial fibrillary acidic protein immunostaining.

RESULTS

We observed rapid and persistently extensive injuries in the ganglia cell layer (GCL), inner plexiform layer, and inner nuclear layer (INL) in ipsilateral retinas after HI injury, corresponding to the marked alteration in ERG. HI insult caused prominent microglial and Műller cell activation in ipsilateral inner retinas. Neuronal death in the GCL and INL after HI injury was mainly apoptotic, involving caspase-dependent pathways.

CONCLUSION

Our study demonstrated the first evidence of HI retinal damage at both the pathological and functional level using the Vannucci model in neonatal rats. Because retinal damage is often associated with HI injury, it is important to demonstrate that a particular neuroprotective strategy effectively preserves the retina in addition to the brain.

A systematic review on 'Foveal Crowding' in visually impaired children and perceptual learning as a method to reduce Crowding

BACKGROUND

This systematic review gives an overview of foveal crowding (the inability to recognize objects due to surrounding nearby contours in foveal vision) and possible interventions. Foveal crowding can have a major effect on reading rate and deciphering small pieces of information from busy visual scenes. Three specific groups experience more foveal crowding than adults with normal vision (NV): 1) children with NV, 2) visually impaired (VI) children and adults and 3) children with cerebral visual impairment (CVI). The extent and magnitude of foveal crowding as well as interventions aimed at reducing crowding were investigated in this review. The twofold goal of this review is : [A] to compare foveal crowding in children with NV, VI children and adults and CVI children and [B] to compare interventions to reduce crowding.

METHODS

Three electronic databases were used to conduct the literature search: PubMed, PsycINFO (Ovid), and Cochrane. Additional studies were identified by contacting experts. Search terms included visual perception, contour interaction, crowding, crowded, and contour interactions.

RESULTS

Children with normal vision show an extent of contour interaction over an area 1.5-3× as large as that seen in adults NV. The magnitude of contour interaction normally ranges between 1-2 lines on an acuity chart and this magnitude is even larger when stimuli are arranged in a circular configuration. Adults with congenital nystagmus (CN) show interaction areas that are 2× larger than those seen adults with NV. The magnitude of the crowding effect is also 2× as large in individuals with CN as in individuals with NV. Finally, children with CVI experience a magnitude of the crowding effect that is 3× the size of that experienced by adults with NV.

CONCLUSIONS

The methodological heterogeneity, the diversity in paradigms used to measure crowding, made it impossible to conduct a meta-analysis. This is the first systematic review to compare crowding ratios and it shows that charts with 50% interoptotype spacing were most sensitive to capture crowding effects. The groups that showed the largest crowding effects were individuals with CN, VI adults with central scotomas and children with CVI. Perceptual Learning seems to be a promising technique to reduce excessive foveal crowding effects.

Visual cortical function in very low birth weight infants without retinal or cerebral pathology

PURPOSE

Preterm infants are at high risk of visual and neural developmental deficits. However, the development of visual cortical function in preterm infants with no retinal or neurologic morbidity has not been well defined. To determine whether premature birth itself alters visual cortical function, swept parameter visual evoked potential (sVEP) responses of healthy preterm infants were compared with those of term infants.

METHODS

Fifty-two term infants and 58 very low birth weight (VLBW) infants without significant retinopathy of prematurity or neurologic morbidities were enrolled. Recruited VLBW infants were between 26 and 33 weeks of gestational age, with birth weights of less than 1500 g. Spatial frequency, contrast, and vernier offset sweep VEP tuning functions were measured at 5 to 7 months' corrected age. Acuity and contrast thresholds were derived by extrapolating the tuning functions to 0 amplitude. These thresholds and suprathreshold response amplitudes were compared between groups.

RESULTS

Preterm infants showed increased thresholds (indicating decreased sensitivity to visual stimuli) and reductions in amplitudes for all three measures. These changes in cortical responsiveness were larger in the <30 weeks ' gestational age subgroup than in the ≥30 weeks' gestational age subgroup.

CONCLUSIONS

Preterm infants with VLBW had measurable and significant changes in cortical responsiveness that were correlated with gestational age. These results suggest that premature birth in the absence of identifiable retinal or neurologic abnormalities has a significant effect on visual cortical sensitivity at 5 to 7 months' of corrected age and that gestational age is an important factor in visual development.

Visual function and white matter microstructure in very-low-birth-weight (VLBW) adolescents--a DTI study

Premature birth is associated with visual impairments, due to both cerebral and ocular pathology. This study examined the relationship between cerebral white matter microstructure, evaluated by diffusion tensor imaging (DTI), and visual function, in 30 preterm born adolescents with very low birth weight (VLBW=birth weight⩽1500g) and an age-matched group of 45 term born controls. Visual acuity correlated positively with fractional anisotropy (FA) in corpus callosum and in frontal white matter areas in the VLBW participants, but not in the control participants. Callosal visual connections may play a more important role in the development of good visual acuity than previously acknowledged in preterm born children.

Estrabismo y ambliopía, conceptos básicos para el médico de atención primaria

El estrabismo y la ambliopía son patologías relativamente frecuentes en la población general. La ambliopía constituye la causa principal de disminución de visión unilateral. Existen diferentes tipos de estrabismo mientras que la ambliopía se debe únicamente a tres mecanismos fisiopatológicos. El objetivo de este artículo es brindar al médico de atención primaria y al estudiante de medicina una revisión completa y actualizada sobre estos dos temas. Para esto revisamos libros de texto reconocidos y utilizando MEDLINE, artículos representativos relacionados con el tema y mostramos un panorama general que incluye aspectos básicos de anatomía de los músculos extraoculares, nomenclatura y terminología empleada en estrabismo, aspectos de fisiología motora, pruebas clínicas utilizadas para el diagnóstico, generalidades sobre los principales tipos de estrabismo y manejo.

Pattern visual evoked potential performance in preterm preschoolers with average intelligence quotients

BACKGROUND

Preterm infants are more likely to develop visual perceptual and visual-motor impairments. Visual perceptual deficiencies may contribute to significant difficulties in daily life, but few reports are available relating electrophysiological assessment of the visual system to spatial information problems in premature preschoolers with average intelligence quotients.

AIM

This study was designed to investigate preterm preschoolers' responses to various spatial frequencies of pattern reversal visual evoked potential (PRVEP) and compare them to normal children.

DESIGN

Participants were 20 very low birth weight (VLBW), 41 low birth weight (LBW) and 41 normal children who were 4 to 6 years old and were free from major disability and developmentally appropriate for gestational age at birth. They were evaluated using the Chinese population adaptation of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) and recorded PRVEP at five levels of spatial frequency (checkerboard pattern (check) sizes of 108', 54', 27', 13' and 7') using a VikingQuest-IV neuroelectrophysiological device (Nicolet, Madison, WI, USA).

RESULTS

Compared with normal children, the LBW and VLBW groups had significantly lower level in the tests of verbal, performance and overall intelligence quotients, particularly in performance, although the levels were within the average range. The PRVEP P100 wave latencies were significantly prolonged at all five degrees of spatial frequency in the VLBW group compared with the controls, while showing delay in the LBW with 13' and 7' check size. In the meanwhile, the amplitudes of P100 at all five spatial frequencies were significantly smaller in the VLBW and LBW groups than in the normal children. And VLBW group had even lower P100 amplitudes than the LBW group.

CONCLUSIONS

Preterm preschoolers with average cognition capability are at risk of defect in visual-spatial perception, especially when they are confronted with more complicated information. PRVEP may provide an objective and convenient measurement in detecting the problem of visual perception in children.

Cerebral Visual Impairment: which perceptive visual dysfunctions can be expected in children with brain damage? A systematic review

The current definition of Cerebral Visual Impairment (CVI) includes all visual dysfunctions caused by damage to, or malfunctioning of, the retrochiasmatic visual pathways in the absence of damage to the anterior visual pathways or any major ocular disease. CVI is diagnosed by exclusion and the existence of many different causes and symptoms make it an overall non-categorized group. To date, no discrimination is made within CVI based on types of perceptive visual dysfunctions. The aim of this review was to outline which perceptive visual dysfunctions are to be expected based on a number of etiologies of brain damage and brain development disorders with their onset in the pre-, peri- or postnatal period. For each period two etiologies were chosen as the main characteristic brain damage. For each etiology a main search was performed. The selection of the articles was based on the following criteria: age, etiology, imaging, central pathology and perceptive visual function test. The perceptive visual functions included for this review were object recognition, face recognition, visual memory, orientation, visual spatial perception, motion perception and simultaneous perception. Our search resulted in 11 key articles. A diversity of research history is performed for the selected etiologies and their relation to perceptive visual dysfunctions. Periventricular Leukomalacia (PVL) was most studied, whereas the main tested perceptive visual function was visual spatial perception. As a conclusion, the present status of research in the field of CVI does not allow to correlate between etiology, location and perceptive visual dysfunctions in children with brain damage or a brain development disorder. A limiting factor could be the small number of objective tests performed in children experiencing problems in visual processing. Based on recent insights in central visual information processing, we recommend an alternative approach for the definition of CVI that is based on functional visual processing, rather than anatomical landmarks. This could be of benefit in daily practice to diagnose CVI.

An analysis of neonatal risk factors associated with the development of ophthalmologic problems at infancy and early childhood: a study of premature infants born at or before 32 weeks of gestation

BACKGROUND

To determine the frequency of ophthalmologic problems and the risk factors that affect the occurrence of these problems in premature newborns with a gestational age of 32 weeks or less.

METHODS

Premature newborns observed at a neonatal intensive care unit between January 2002 and March 2006 were included. A control visit including an ophthalmologic examination was performed at 10 months of age or later. Primary ocular morbidities were studied, and the association between these parameters and prenatal, perinatal, and neonatal characteristics were evaluated.

RESULTS

A total of 169 premature newborns were included in the study, and they were examined at a mean age of 25.85 ± 11.79 months (range: 10 to 42 months). There was complete vision loss (blindness) in 1 (0.6%) case, strabismus in 15 (8.9%) cases, and refractive errors in 10 (5.9%) cases. Twenty (77%) cases with any abnormality and 50 (35%) cases with a normal examination at follow-up had a history of retinopathy of prematurity (ROP) at any stage during the neonatal period (P = .001). Short gestational age (P = .018), low birth weight (P = .002), and the presence of ROP requiring retinal surgery during the neonatal period (P = .007) were determined to be significant risk factors for the development of vision loss, strabismus, and refractive errors.

CONCLUSION

Neonates with a gestational age of 32 weeks or less, especially those younger than 30 weeks, should not only be screened for ROP in the neonatal period, but should also have regular follow-up examinations to check for the development of other ophthalmologic problems during infancy and early childhood.

Ocular growth and morbidity in preterm children without retinopathy of prematurity

PURPOSE

To investigate ocular growth and morbidity in both preschool and school-aged children born prematurely without retinopathy of prematurity (ROP).

METHODS

This population-based study was carried out in 26 children, 5-7 years of age, born prematurely without ROP. All children underwent a full ocular examination, including corrected visual acuity, cycloplegic refractive errors, color vision, ocular alignment, and anterior and posterior segment examinations. Anterior chamber depth, lens thickness, vitreous length, and total axial length were measured.

RESULTS

There was no correlation between the degree of prematurity and visual acuity or refractive state. Two (7.7%) subjects had strabismus, two (7.7%) had amblyopia, and four (15%) had anisometropia. Total axial length was significantly correlated with both gestational age at birth (r=0.822, P<0.001) and birth weight (r=0.569, P=0.003). Similarly, vitreous length was also significantly correlated with gestational age (r=0.744, P<0.001) and birth weight (r=0.553, P=0.004).

CONCLUSIONS

This study showed that although the globe gets longer as gestational age approaches term and as birth weight increases, this condition does not result in any significant refractive error. According to the literature, the prevalence of strabismus, amblyopia, and anisometropia may be higher in preterm children without ROP than in age-matched, normally delivered children.

Visuospatial skills, ocular alignment, and magnetic resonance imaging findings in very low birth weight adolescents

PURPOSE

To describe ocular alignment and stereoacuity in adolescents with very low birth weight (VLBW) in comparison with a matched control group and to investigate associations with white matter damage of immaturity (WMDI) and visuospatial skills in the VLBW group.

METHODS

Fifty-nine 15-year-old VLBW subjects and 55 age- and sex-matched controls with normal birth weight underwent examination, including measurement of ocular alignment using cover test and Maddox rod and cycloplegic refraction. Stereoacuity was assessed with the TNO test, best-corrected visual acuity with a Konstantin Moutakis letter chart, and visuospatial skills with the performance tests, defined as performance intelligence quotient (IQ), in the Wechsler Intelligence Scale for Children (WISC-III). All VLBW subjects underwent magnetic resonance imaging of the brain.

RESULTS

Ocular misalignment was significantly more common in the VLBW group than in the control group (22% compared with 4%; p = 0.004). Exophoria, subnormal stereoacuity, and subnormal performance IQ were significantly more common in the VLBW group than in the control group (p = 0.006, p = 0.011, and p = 0.015, respectively). Ocular misalignment was associated with WMDI (p = 0.035) and subnormal performance IQ (p = 0.020). Of the VLBW subjects with ocular misalignment, 69% had WMDI and/or subnormal performance IQ.

CONCLUSIONS

The VLBW adolescents had more visuospatial problems, lower stereoacuity, and more ocular misalignment than the control subjects. Ocular misalignment was associated with visuospatial deficiencies and/or WMDI in the VLBW group and was a better predictor for visuospatial deficits than WMDI.

Long-term visual outcomes of laser-treated threshold retinopathy of prematurity: a study of refractive status at 7 years

PURPOSE

To assess the long-term visual outcomes and refractive status in patients with diode laser-treated threshold retinopathy of prematurity (ROP), and to investigate the causes of impaired visual function.

METHOD

A total of 60 eyes of 30 consecutive patients with diode laser-treated threshold ROP were recalled for assessment at the age of 7 years or more.

RESULTS

There were 38 eyes (65.5%) achieving 6/12 or better vision, however, an unfavourable visual outcome (6/60 or worse) occurred in four eyes (6.9%). One eye (1.7%) had unfavourable structural outcome. Of these 60 laser-treated eyes, 46 eyes (77.0%) were myopic, the overall mean spherical equivalent was -3.87 D. Anisometropia (>or=1.5 D) was also noted in 14 patients (46.7%). Strabismus was present in nine patients (30.0%). Perinatal neurological events of intraventricular haemorrhage (IVH) were identified in eight children (26.7%), periventricular leucomalacia (PVL) in eight children (26.7%), and cerebral palsy (CP) in four children (13.3%). There was a statistically significant association of the presence of strabismus with PVL (P=0.002). The presence of anisometropia was a significant risk factor associated with poor visual outcome of 6/15 or worse in laser-treated ROP (P=0.002).

CONCLUSION

The majority of patients with diode laser-treated threshold ROP had favourable anatomical and visual outcomes. However, anisometropia, advanced refractive error, strabismus, and perinatal neurological events remain important causes of impaired visual function. Long-term follow-up is very important for early detection and timely treatment of these ocular morbidities.

Visual, motor and perceptual abilities at school age in children with isolated mild antenatal ventricular dilatation

BACKGROUND

The detection of prenatal ventriculomegaly raises anxiety about possible neurological sequelae. A few studies have investigated possible neurodevelopmental sequelae in the first years after birth but no systematic assessment has been performed at school age.

AIMS

The aim of this study was to assess minor neurological signs, perceptual and visual function in a cohort of children with isolated mild antenatal ventricular dilatation examined at school age.

STUDY DESIGN

Seventeen children with evidence of mild antenatal ventriculomegaly in the second and third trimester of pregnancy were included in the study.

OUTCOME MEASURES

Children were assessed at school age (range 5 years 3 months-11 years, 11 months) using a structured neurological examination for minor neurological signs and age specific tests assessing perceptual motor abilities (Developmental Test of Visual-Motor Integration; Movement Assessment Battery for Children).

RESULTS

Only one of the 17 children had abnormal results. The remaining 16 had normal results on all the tests, irrespective of the magnitude and the symmetry of the dilatation or of its evolution on neonatal scan.

CONCLUSIONS

Our results suggest that children who had mild isolated prenatal ventricular dilatation are unlikely to develop even minor motor or perceptual difficulties at school age.

Spectrum of infantile esotropia in primates: Behavior, brains, and orbits

INTRODUCTION

Recent studies of human infants have described a spectrum of early-onset esotropia, from small angle to large heterotropias. We report here a similar spectrum of early-onset esotropia in infant monkeys, with emphasis on the relationship between visuomotor deficits, central nervous system circuitry, and orbital anatomy.

METHODS

Eye movements were recorded in macaque monkeys with natural, infantile-onset esotropia (n = 7) and in control monkeys (n = 2) to assess alignment, latent nystagmus, dissociated vertical deviation (DVD), and pursuit/optokinetic nystagmus (OKN) asymmetries. Acuity was measured by preferential-looking technique or spatial sweep visual-evoked potentials. Geniculo-striate pathways were then analyzed with neuroanatomic tracers and ocular dominance column labels. Extraocular muscles were examined by high-resolution magnetic resonance imaging (MRI) and anatomic sectioning of whole orbits.

RESULTS

Esotropia ranged from 4 to 13.5 degrees (7-24(Delta)) with fixation preference (if any) varying idiosyncratically (as in human). Severity of ocular motor dysfunction (ie, nystagmus velocity, DVD amplitude, pursuit-OKN nasal bias index) increased as the magnitude of esotropia angle. Animals with greater ocular motor deficits tended to have greater visual area V1 (striate cortex) neuroanatomic deficits, evident as fewer binocular horizontal connections in V1. Orbital MRI/anatomic analysis showed no difference in horizontal rectus cross-sectional areas, muscle paths, innervation densities, or cytoarchitecture compared with normal animals.

CONCLUSIONS

The infantile esotropia spectrum in nonhuman primates is remarkably similar to that reported in human infants. Concomitant esotropia in these primates cannot be ascribed to abnormalities of the extraocular muscles or orbit. These findings, combined with epidemiologic studies of humans, suggest that perturbations of cerebral binocular pathways in early development are the primary cause of the infantile esotropia syndrome.

Brain injury and the eye

Visual loss associated with brain damage is the single greatest cause of visual impairment in children in developed countries. Damage may occur in any of five separate visual systems: primary visual cortex, visual associative cortex area, optic radiations, optic nerves, and visual attention pathways. Improving our understanding of the pathophysiology of these causes for visual loss may lead to better rehabilitation and educational strategies for these children.

Ophthalmological problems associated with preterm birth

As survival of preterm infants improves, the long-term care of consequent ophthalmic problems is an expanding field. Preterm birth can inflict a host of challenges on the developing ocular system, resulting in the visual manifestations of varied significance and pathological scope. The ophthalmic condition most commonly associated with preterm birth is retinopathy of prematurity, which has the potential to result in devastating vision loss. However, the visual compromise from increased incidence of refractive errors, strabismus, and cerebral vision impairment has significant impact on visual function, which also has influence on other developmental aspects including psychological and educational. In this review, the normal ocular development is discussed, aiming to exemplify the impact of early exteriorisation on one of the more naive organs of prematurity. This is then related to the incidence and visual consequences of many types of deficit, including refractive error, strabismus, and loss of visual function in preterm populations, with comparisons to term infant studies. Often these conditions are linked with causal and resultant factors being impossible to segregate, but the common factor of increased rates of all types of ophthalmic deficits demonstrates that children born prematurely are indeed premature for life.

Long-term follow-up of visual functions in prematurely born children--a prospective population-based study up to 10 years of age

INTRODUCTION

Prematurely born children have an increased risk of ophthalmologic problems. There is still no consensus on how they should be followed. The purpose of this study was to evaluate predictive factors for problems in premature children at ten years of age and to discuss follow-up recommendations.

MATERIALS AND METHODS

One hundred ninety-nine children with a birth weight of 1500 g or less were screened for retinopathy of prematurity (ROP) in the neonatal period and thereafter ophthalmologically examined at 6 months, 1.5, 2.5, 3.5, and 10 years of age. "Visual dysfunction" at ten years of age was defined as visual acuity > or =0.1 logMAR and/or strabismus and/or subnormal contrast sensitivity. Multiple regression analyses were used to evaluate risk factors at an early age, which could predict problems at ten years of age.

RESULTS

Twenty-five percent of the cohort had visual dysfunction at ten years of age. Neurological complications, cryotreated ROP, anisometropia, and astigmatism were risk factors. The sensitivity was 75.5%, and the specificity 80.7% for the detection of visual dysfunction at ten years of age when all children with neurological complications, cryotreated ROP, strabismus, anisometropia > or =1 diopters (D) at 2.5 years, and astigmatism > or =2 D at 2.5 years were included in further follow-up.

CONCLUSIONS

Repeated ophthalmologic follow-up of prematurely born children should be performed in those with treated ROP and/or neurological conditions. For a third group without such problems, at least one follow-up is recommended. Such an examination also provides a good opportunity to identify neurological problems that warrant further ophthalmologic follow-up.

White-matter injury is associated with impaired gaze in premature infants

Periventricular leukomalacia is a risk factor for visual impairment in children born prematurely. The impact of diffuse white-matter injury, as detected on magnetic resonance imaging, on early visual function is unknown. We developed two 5-point visual-gaze scores to analyze the association between this clinical assessment and white-matter injury in 93 premature neonates <34 weeks of gestational age at birth. Older postmenstrual age was associated with higher values of the two gaze scores. Infants with moderate or severe white-matter injury had lower scores than their peers without white-matter injury (0.41 points, 95% confidence interval of 0.13-0.69 for visual fixation score; and 0.70 points, 95% confidence interval of 0.30-1.10 for conjugate score, P < 0.005). Using the results from both scales, a score of >or=9 in an infant examined at >or=36 weeks postmenstrual age predicted normal white matter on magnetic resonance examination, with a sensitivity of 84% and a specificity of 100%. These preliminary findings suggest that white-matter injury affects visual function even before term equivalent postmenstrual age.

Children born weighing less than 1701 g: visual and cognitive outcomes at 11-14 years

BACKGROUND AND OBJECTIVE

Few studies of low birthweight children have explored the relationship between later visual morbidity and neuropsychological function. This study evaluated these outcomes using a geographically defined cohort.

METHODS

Prospective study of retinopathy of prematurity (ROP) in infants born weighing <1701 g, undertaken in 1985-7. 254 of the survivors consented to ophthalmic examination at 10-13 years. Four children were severely disabled and could not complete the tests. 198 of the remaining agreed to neuropsychological assessment at 11-14 years (British Ability Scales II (BAS), Movement Assessment Battery (ABC), Neale Analysis of Reading Ability).

RESULTS

At 10-13 years, 99/198 children had an adverse ophthalmic outcome (AOO) (reduced acuity n=48, myopia n=40, strabismus n=36, colour defect n=2, field defect n=1). There were no significant differences between children with AOO and those with a normal ophthalmic outcome with regard to sex, gestation, birth weight, neonatal cranial scan appearances and social class. 106/198 had ROP; 98 had mild ROP with no increased risk of AOO in later childhood. All eight children with severe ROP had an AOO in later childhood. Children with an AOO performed worse on the BAS, ABC and reading ability tests.

CONCLUSIONS

At age 10-13, 50% of children born <1701 g have an AOO. These children are not simply those with earlier gestations, lower birth weight or ROP. Children with AOO have a worse neuropsychological outcome. The next step is to determine whether there are visual interventions which can improve ophthalmic outcome and whether a better neuropsychological outcome follows.

Visual function at 11 years of age in preterm-born children with and without fetal brain sparing

OBJECTIVE

We have demonstrated earlier an accelerated maturation of the visual evoked potential in the first year of life in preterm infants with antenatal brain sparing. We have now assessed visual functioning at 11 years of age in the same cohort and compared the groups with and without brain sparing.

DESIGN/METHODS

One hundred sixteen survivors included in a study on the outcome of preterm infants born at <33 weeks' gestation with and without fetal brain sparing and admitted to the NICU were followed extensively. Ninety-eight infants (85%) were again assessed at 11 years of age. Data were available for fetal Doppler measurements indicating brain sparing, neonatal cerebral ultrasound scanning, and developmental outcome in the first 5 years. Mean birth weight was 1303 g; mean gestational age was 29.8 weeks. The infants were divided into 2 groups with and without brain sparing. Visual functioning was estimated by measuring visual acuity, visual fields, eye position, and binocular function and by visual motor tests.

RESULTS

Six percent of the children were found to have a visual acuity of <0.8, 12% had strabismus, and 14% to 46% showed abnormal results on the visual motor tests. No statistical differences were found between the 2 groups. However, children with severe cerebral ultrasound diagnoses in the neonatal period were found to have significantly more abnormalities on visual functioning and lower scores on visual motor tests than children without these morbidities.

CONCLUSIONS

Children with fetal brain sparing do not demonstrate a different development of their visual functioning at late school age. However, an abnormal cerebral ultrasound in the neonatal period is associated with impaired visual function in later life.