Perinatal cortical and subcortical visual loss: mechanisms of injury and associated ophthalmologic signs

Prevalence of strabismus and risk factors in adults born preterm with and without retinopathy of prematurity: results from the Gutenberg Prematurity Eye study

AIM

The purpose of this study was to assess the prevalence of strabismus and nystagmus and to analyse associated factors in preterm and full-term infants in adulthood.

METHODS

The Gutenberg Prematurity Eye Study is a retrospective cohort study with a prospective ophthalmological examination of participants born preterm and full-term (aged 18-52 years). Perinatal data were carefully assessed for risk factors and comprehensive ophthalmological examinations were conducted. The association between strabismus and nystagmus was assessed by analysing 16 different perinatal and actual risk factors in multivariable analysis. Participants were grouped into full-term controls (gestational age (GA) at birth ≥37 weeks), preterm participants without retinopathy of prematurity (ROP) and GA 33-36 weeks (group 2), GA 29-32 weeks (group 3), GA ≤28 weeks (group 4), non-treated ROP (group 5) and treated ROP (group 6).

RESULTS

In total, 892 eyes of 450 preterm and full-term individuals (mean age: 28.6 years, SD: ± 8.6 years, 251 females) were included. Strabismus was observed in 2.1% (3/140), 6.6% (9/137), 17.4% (16/92), 11.1% (2/18), 27.1% (13/48) and 60% (9/15) of participants and nystagmus in 0.7% (1/140), 1.5% (2/137), 4.3% (4/92), 5.6% (1/18), 10.4% (5/48) and 26.7% (4/15) of participants in the respective groups. In the multivariable regression model, strabismus was associated with GA (OR=0.90; p=0.046), anisometropia ≥1.5 diopter (OR=3.87; p=0.003), hypermetropia ≥2 diopter (OR=9.89; p<0.001) and astigmatism ≥1.5 diopter (OR=2.73; p=0.017). Esotropia was more frequent than exotropia and hypermetropia/hypometropia. Most strabismus cases occurred within the first 10 years of life. The strongest predictor associated with nystagmus was perinatal adverse events (OR=15.8; p=0.002).

CONCLUSION

Low GA and refraction of the eye are independent risk factors for strabismus, which typically occurs in the first 10 years of life. Perinatal adverse events are the most important factors for the presence of nystagmus in adulthood.

Overview of Neuro-Ophthalmic Findings in Leukodystrophies

Background: Leukodystrophies are a group of rare genetic diseases that primarily affect the white matter of the central nervous system. The broad spectrum of metabolic and pathological causes leads to manifestations at any age, most often in childhood and adolescence, and a variety of symptoms. Leukodystrophies are usually progressive, resulting in severe disabilities and premature death. Progressive visual impairment is a common symptom. Currently, no overview of the manifold neuro-ophthalmologic manifestations and visual impact of leukodystrophies exists. Methods: Data from 217 patients in the Hamburg leukodystrophy cohort were analyzed retrospectively for neuro-ophthalmologic manifestations, age of disease onset, and magnetic resonance imaging, visual evoked potential, and optical coherence tomography findings and were compared with data from the literature. Results: In total, 68% of the patients suffered from neuro-ophthalmologic symptoms, such as optic atrophy, visual neglect, strabismus, and nystagmus. Depending on the type of leukodystrophy, neuro-ophthalmologic symptoms occurred early or late during the course of the disease. Magnetic resonance imaging scans revealed pathologic alterations in the visual tract that were temporally correlated with symptoms. Conclusions: The first optical coherence tomography findings in Krabbe disease and metachromatic leukodystrophy allow retinal assessments. Comprehensive literature research supports the results of this first overview of neuro-ophthalmologic findings in leukodystrophies.

CAD-Related Disorder (EIEE-50) in an Infant With Cortical Visual Impairment

PURPOSE

To document the association of CAD-related disorder (EIEE-50) with cortical visual impairment.

OBSERVATIONS

An 8-month-old Caucasian boy with whole genome sequencing confirming 2 variants in the gene CAD, who presented with severe seizures, microcephaly, hyperreflexia, hypotonia, anemia, and severe cortical visual impairment. Magnetic resonance imaging (MRI) of the brain noted thickened cortical gray matter along the right calcarine fissure as well as changes suggesting malformation of cortical development. Empiric uridine monophosphate supplementation has significantly improved seizure activity, hypotonia, and development and has led to resolution of anemia.

CONCLUSIONS AND IMPORTANCE

CAD-related disorder is treatable and may affect visual cortical development causing severe secondary cortical visual impairment, a newly described clinical manifestation.

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.

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.

A multimodal MRI study of functional and structural changes in concomitant exotropia

The present prospective study aimed to investigate the structural and functional changes in patients with concomitant exotropia using multimodal MRI. A total of 11 adult patients with concomitant exotropia (5 males and 6 females) and 11 healthy adult individuals (5 males and 6 females) were recruited and examined using multimodal MRI techniques. Near and distance exotropia deviation angles were measured. The structrual changes were evaluated using the gray matter volume. Functional reorganization was assessed using the amplitude of low-frequency fluctuation, regional homogeneity and resting-state functional connectivity (FC) on MRI. No significant differences could be found in terms of sex, age or body mass index between the two groups. However, the near and distance exotropia angles were significantly higer in the concomitant exotropia group compared with those in the normal control group (P<0.001). Compared with those in normal individuals, the bilateral thalamus, right middle temporal gyrus (MTG) and right cuneus had significantly reduced gray matter volumes in the concomitant exotropia group (false discovery rate corrected, P<0.05). Reduced FC was found between the bilateral thalamus and the bilateral precuneus, between the right MTG and the right medial superior frontal gyrus in addition to the right precuneus, and between the right cuneus and the right primary sensorimotor cortex (P<0.05, Gaussian random-field corrected) in the concomitant exotropia group compared with that in the normal individuals. In conclusion, the present study indicated that structural and functional reorganization occurs in specific brain regions of patients with concomitant exotropia. These reorganized areas appeared to mainly involve the subcortical structures and related cortices that process visual information.

The impact of perinatal brain injury on retinal nerve fiber layer thickness and optic nerve head parameters of premature children

PURPOSE

This study aims to evaluate the impact of birth weight (BW), gestational age (GA), retinopathy of prematurity (ROP), and perinatal brain injury (PBI) on optic nerve head (ONH) parameters and nerve fiber layer thickness (RNFLT) in preterm children.

METHODS

ONH parameters and RNFLT were examined prospectively in 5-15-year-old preterm and full-term children with RTVue-100 OCT (Optovue, USA). The parameters of the two groups were compared and possible influences of BW, GA, ROP, and PBI analyzed in preterm children.

RESULTS

In total, 51 full-term and 55 preterm children were included. The mean age was 9.98 ± 3.4 years in full-term and 10.0 ± 2.5 years in preterm children. The mean GA in preterm children was 29.6 ± 3.8 weeks with a BW of 1523 ± 732 g. RNFLT was significantly lower in preterm than in full-term children in all but temporal quadrants. Cup area, volume, cup/disc area ratio, and horizontal cup/disc ratio (CDR) were significantly larger and rim area significantly thinner in preterm children. GA was positively correlated with superior, nasal, and overall RNFLT and negatively correlated with cup area, volume, and horizontal CDR. ROP stage correlated negatively with superior and nasal RNFLT. PBI was the only significant predicting factor for RNFL thinning in all but temporal quadrant in multiple regression analysis. Preterm children with PBI had a significantly larger optic cup (CDR 0.70 ± 0.33 vs. 0.37 ± 0.27) and thinner optic rim.

CONCLUSION

PBI correlated strongest with RNFL thinning, a thinner optic rim, and a larger optic cup in preterm children and should be evaluated in each patient to prevent incorrect diagnosis like glaucoma.

Neuropsychological Evidence Underlying Counterclockwise Bias in Running: Electroencephalography and Functional Magnetic Resonance Imaging Studies of Motor Imagery

We aimed to answer the question "why do people run the track counterclockwise (CCW)?" by investigating the neurophysiological differences in clockwise (CW) versus CCW direction using motor imagery. Three experiments were conducted with healthy adults. Electroencephalography (EEG) was used to examine hemispheric asymmetries in the prefrontal, frontal, and central regions during CW and CCW running imagery (n = 40). We also evaluated event-related potential (ERP) N200 and P300 amplitudes and latencies (n = 66) and conducted another experiment using functional magnetic resonance imaging (fMRI) (n = 30). EEG data indicated greater left frontal cortical activation during CCW imagery, whereas right frontal activation was more dominant during CW imagery. The prefrontal and central asymmetries demonstrated greater left prefrontal activation during both CW and CCW imagery, with CCW rotation exhibiting higher, though statistically insignificant, asymmetry scores than CW rotation. As a result of the fMRI experiment, greater activation was found during CW than during CCW running imagery in the brain regions of the left insula, Brodmann area 18, right caudate nucleus, left dorsolateral prefrontal cortex, left superior parietal cortex, and supplementary motor area. In the ERP experiment, no significant differences were found depending on direction. These findings suggest that CCW rotation might be associated with the motivational approach system, behavioral activation, or positive affect. However, CW rotation reflects withdrawal motivation, behavioral inhibition, or negative affect. Furthermore, CW rotation is understood to be associated with neural inefficiency, increased task difficulty, or unfamiliarity.

Prevalence of the Infantile Strabismus Complex in Premature Children With and Without Periventricular Leukomalacia

PURPOSE

To determine whether rates of strabismus and associated visuomotor deficits differed among children with different severities of periventricular leukomalacia (PVL).

DESIGN

Retrospective, case-control study.

METHODS

Brain magnetic resonance images (MRI) obtained from 98 children aged ≥2 years were analyzed using a standardized scoring system: 67 of 98 had PVL (mean GA 31 weeks) and 31 of 98 did not have PVL (mean GA 29 weeks). Severity of PVL was scored as degree of damage to the posterior optic radiations and the splenium of the corpus callosum on MRI. Ophthalmologic examination data were collated to assess the prevalence of visuomotor deficits and the relationship to PVL severity (grades 1-3, mild to severe).

RESULTS

Infantile strabismus was documented in 61% of children with mild, 74% with moderate, and 88% with severe PVL (esotropia: exotropia ratio 3.5:1). Associated ocular motor deficits also increased systematically with PVL severity: latent ("fusion maldevelopment") nystagmus (20%, 47%, and 40%, respectively), dissociated vertical deviation (13%, 28%, and 30%), and nasotemporal pursuit/optokinetic nystagmus asymmetry (23%, 38%, and 54%). Additionally, the prevalence of retrograde optic neuropathy increased with PVL severity (5%, 26%, and 38%). The prevalence of each of these signs was substantially lower in children who had no PVL.

CONCLUSIONS

Children who suffer PVL are likely to develop the deficits of the infantile strabismus complex. The deficits tend to increase systematically as a function of PVL severity. These findings provide evidence that infantile strabismus is linked to perinatal damage to cerebral vergence and gaze pathways.

Gray matter volume alterations in patients with strabismus and amblyopia: voxel-based morphometry study

This study proposes the use of the voxel-based morphometry (VBM) technique to investigate structural alterations of the cerebral cortex in patients with strabismus and amblyopia (SA). Sixteen patients with SA and sixteen healthy controls (HCs) underwent magnetic resonance imaging. Original whole brain images were analyzed using the VBM method. Pearson correlation analysis was performed to evaluate the relationship between mean gray matter volume (GMV) and clinical manifestations. Receiver operating characteristic (ROC) curve analysis was applied to classify the mean GMV values of the SA group and HCs. Compared with the HCs, GMV values in the SA group showed a significant difference in the right superior temporal gyrus, posterior and anterior lobes of the cerebellum, bilateral parahippocampal gyrus, and left anterior cingulate cortex. The mean GMV value in the right superior temporal gyrus, posterior and anterior lobes of the cerebellum, and bilateral parahippocampal gyrus were negatively correlated with the angle of strabismus. The ROC curve analysis of each cerebral region confirmed the accuracy of the area under the curve. Patients with SA have reduced GMV values in some brain regions. These findings might help to reveal the potential pathogenesis of SA and its relationship with the atrophy of specific regions of the brain.

Vision Abnormalities in Children and Young Adults With Cerebral Palsy; A Systematic Review

AIM

The current study was designed to provide detailed information on the prevalence of ocular abnormalities in patients with cerebral palsy (CP).

METHODS

Four international online scientific databases, including Web of Science, PubMed, Scopus, and Google Scholar were systemically searched. First, the titles of the articles were evaluated, and if relevant, their abstracts and full texts were reviewed. The quality of the studies was assessed using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist.

RESULTS

A total of 147 articles were found in the initial search. After applying the exclusion criteria, 65 articles were chosen for further review, from which 17 articles, comprising a total of 1734 patients with CP ranging in age from birth to 22 years, passed the STROBE quality check and were included in this review. The prevalence of ocular abnormalities in the CP patients reported in the evaluated studies ranged between 34% to 100%, with refractive error, strabismus, and nystagmus exhibiting the greatest overall prevalence at 52%, 48%, and 11%, respectively in this population.

CONCLUSION

Early ocular assessment of children with CP is essential for an accurate diagnosis, personalized rehabilitation and performing early interventions to improve their visual function.

Abnormal Vestibular-Ocular Reflexes in Children With Cortical Visual Impairment

BACKGROUND

To determine whether the vestibular-ocular reflexes (VORs) can be affected by central nervous system injury in children with cortical visual impairment (CVI).

METHODS

Retrospective case series. Twenty consecutive children with CVI who presented to a pediatric ophthalmology practice over an 18-month period were included in the study. Horizontal and vertical VORs were assessed by a pediatric neuro-ophthalmologist using the standard doll's head maneuver. MRI studies were independently reviewed by a pediatric neuroradiologist in a masked fashion. The main outcome measures were the integrity of the VORs and the presence of brainstem abnormalities on MRI.

RESULTS

VORs were found to be absent or severely impaired in 13/20 (65%) children with CVI. More surprisingly, the doll's head maneuver failed to substantially overcome the deviated eye position in 8/13 (62%) children with conjugate gaze deviations. Reduced brainstem size and signal abnormalities were found in 4/7 children with normal VORs and in 9/13 children with abnormal VORs (P = 0.6), showing noncorrelation with the integrity of the VOR.

CONCLUSION

VORs are commonly impaired in children with CVI. This ocular motor deficit reflects the diffuse cortical and subcortical injury that often accompanies perinatal injury to the developing brain. Consequently, these children may lack important visual compensatory mechanisms to stabilize gaze during head movements. This knowledge can help in planning visual rehabilitation.

Alternations of interhemispheric functional connectivity in children with strabismus and amblyopia: a resting-state fMRI study

Previous neuroimaging studies demonstrated that patients with strabismus or amblyopia can show significant functional and anatomical changes in the brain, but alterations of interhemispheric functional connectivity (FC) have not been well studied in this population. The current study analyzed whole-brain changes of interhemispheric FC in children with strabismus and amblyopia (CSA) using voxel-mirrored homotopic connectivity (VMHC).A total of 24 CSA (16 males and 8 females) and 24 normal controls (NCs) consisting of 16 and 8 age-, sex, and education-matched males and females, respectively, underwent functional magnetic resonance imaging (fMRI) scans in the resting state. According to Gaussian random field theory, changes in the resting state FC (rsFC) between hemispheres were evaluated using the VMHC method. The relationships between mean VMHC values in multiple brain regions and behavioral performance were evaluated by Pearson correlation analysis. In contrast to NCs, the CSA group showed significantly decreased VMHC values in the bilateral cerebellum, bilateral frontal superior orbital (frontal sup orb), bilateral temporal inferior(temporal inf),and bilateral frontal superior(frontal sup). CSA have abnormal interhemispheric FC in many brain regions, which may reflect dysfunction of eye movements and visual fusion. These findings might provide insight into the underlying pathogenetic mechanisms of CSA.

Clinical Spectrum of Ocular and Visual Dysfunction in Children with Periventricular Leukomalacia: A Need for an Interdisciplinary Approach

The study aimed to evaluate the ocular motility and visual and optic disc abnormalities in children diagnosed with periventricular leukomalacia (PVL). A retrospective analysis was performed on 51 consecutive children who had ophthalmic symptoms and were diagnosed with PVL by using magnetic resonance imaging. The patients were assessed for visual function, strabismus, cycloplegic refraction, fundus examination, and if appropriate, spectral-domain optical coherence tomography and visual field testing were applied. The primary outcome measures were the prevalence and visual and ocular motility dysfunctions. Mean age was 5.72 ± 2.6 years (range = 1–12), median birth weight was 2,740 g (range = 1,240–3,460), and median gestational age was 34 weeks (range = 28–38). In total, 21 patients (39.6%) had neurological deficit, 11 (21.5%) had intellectual disability, and 19 (37.2%) had no neurological symptom. In the spherical equivalent refractive error and cylinder power analysis, 10 patients had ≥3.0 D myopia, 15 had ≥3.0 D hyperopia, and eight had ≥2.50 D astigmatism. Thirteen (25.4%) children had a best-corrected visual acuity between 20/40 and 20/20 for Snellen card, while 9 (17.6%) had strabismic amblyopia and 6 (11.7%) had anisometropic amblyopia. Manifest strabismus was present in 35 patients (68.6%); of whom 12 had esotropia (23.5%), 16 had exotropia (31.3%) and 6 had vertical deviation (11.7%). Manifest or latent nystagmus was detected in 14 patients (27.4%). In 28 patients (54.9%), there was optic nerve abnormality. Two patients had hypoplastic disc, 14 had optic disc pallor, 7 had large cupping, and 5 had total optic atrophy. Six subjects underwent reliable visual field (VF) examinations, and all six had abnormal VFs, with inferior fields being most affected. Ocular motility disorders, optic nerve abnormalities, VF defects, and low visual acuity are common findings in this cohort of PVL patients and maybe the only presenting signs of the disease. The recognition of the visual disabilities and implementation of early rehabilitation may have a significant benefit in these children.

What assessments are currently used to investigate and diagnose cerebral visual impairment (CVI) in children? A systematic review

PURPOSE

Cerebral visual impairment (CVI) is the leading cause of childhood visual impairment in the developed world. Despite this, there are no agreed clinical guidelines for the investigation and diagnosis of the condition. Before development of such guidelines can commence, it is important to recognise which approaches are currently employed. This systematic review evaluated the literature to identify which methods of assessment are currently used to investigate and diagnose childhood CVI.

METHODS

Medline, Embase, CINAHL, Scopus and the Cochrane Library databases were systematically searched in January 2020 using defined search terms. Articles were included if they: (i) were research papers, conference abstracts or research protocols published in peer-reviewed scientific journals, or relevant textbooks; (ii) included a clinical investigation of CVI in children; (iii) provided an explanation or criteria to diagnose CVI and (iv) were specifically investigating cerebral/cortical visual impairment. Methods used to a) assess and b) diagnose CVI were extracted from included articles. 'Assessment scores' were assigned for each method employed by researchers to investigate and diagnose CVI to quantify and compare approaches between articles. A quality grading was also applied to each article.

RESULTS

Of 6454 identified articles, 45 met the inclusion criteria. From these, 10 categories of assessment utilised within included articles were identified: (1) Medical history, (2) Vision assessment/ophthalmologic examination, (3) Neuroimaging, (4) Visual behaviour and direct observation, (5) Structured history-taking, (6) Visual perception tests, (7) Ocular movement and posture assessment, (8) Intelligence/IQ assessment, (9) Clinical electrophysiology and (10) Neurodevelopmental tests. In terms of diagnostic criteria, the most commonly reported approach was one of exclusion, i.e., CVI was diagnosed when visual dysfunction could not be attributed to abnormalities detected in the anterior visual pathway.

CONCLUSION

There is a lack of common practice in the approaches used by clinicians to investigate and diagnose CVI in children. At present, a 'diagnosis of exclusion' remains the most common means to diagnose CVI. Development of clinical guidelines for assessment and diagnosis are necessary to ensure consistency in the diagnosis of CVI and the timely implementation of support to alleviate the impact of CVI on the child's daily living.

Neuro-ophthalmological manifestations of tuberous sclerosis: current perspectives

Tuberous sclerosis complex (TSC) is a complex, multi-system disorder with a well-described underlying genetic etiology. While retinal findings are common in TSC and important in establishing the diagnosis, TSC also has many potential neuro-ophthalmology manifestations. The neuro-ophthalmology manifestations of TSC can have a significant impact on visual function and are sometimes a sign of serious neurological disease. The purpose of this review is to describe the neuro-ophthalmological manifestations of TSC. These manifestations include optic nerve hamartomas, elevated intracranial pressure, cranial nerve palsies, cortical visual impairment, visual field deficits, and ocular toxicity from vigabatrin treatment of infantile spasms. It is important to be aware of potential neuro-ophthalmological manifestations in these patients in order to detect signs of vision- or life-threatening disease and to optimize visual function and quality-of-life.

The Reliability of the CVI Range: A Functional Vision Assessment for Children with Cortical Visual Impairment

Children who are identified as visually impaired frequently have a functional vision assessment as one way to determine how their visual impairment affects their educational performance. The CVI Range is a functional vision assessment for children with cortical visual impairment. The purpose of the study presented here was to examine the reliability of the CVI Range.

A comparison of surgical outcomes between pre-and full-term patients with exotropia

PURPOSE

To compare the surgical outcomes between pre- and full-term patients with exotropia and to examine the factors associated with surgical outcomes.

METHODS

This retrospective study included 48 pre- and 432 full-term patients with basic-type exotropia who underwent unilateral or bilateral lateral rectus muscle (ULR or BLR) recession. Preoperative characteristics and surgical outcomes were compared between the pre- and full-term infants. Additionally, factors affecting the surgical outcomes were evaluated in all patients.

RESULTS

The preoperative characteristics were significantly different between the pre- and full-term groups in terms of neurodevelopmental disabilities (p = 0.020). There were no significant differences between the pre- and full-term groups in terms of the success, overcorrection, and recurrence rates after the mean follow-up period of 34.6 ± 13.9 months (p = 0.697). The major cause of surgical failure was recurrence in both groups. Pre-term birth was not a risk factor for overcorrection and recurrence. However, regardless of the pre- or full-term birth status, the presence of neurodevelopmental disabilities significantly affected final overcorrection (p = 0.004).

CONCLUSIONS

Pre-term patients with exotropia showed similar surgical outcomes to full-term controls. The presence of neurodevelopmental disabilities was a risk factor for final overcorrection.

Infantile Exotropia and Developmental Delay

PURPOSE

To evaluate a group of infants with this disorder to determine the long-term outcome of surgery and to assess the need for neurologic evaluations.

METHODS

This interventional case series reviewed the records of infants who underwent surgery for the treatment of exotropia with onset during the first year of life. The preoperative ophthalmic and systemic findings, treatment, and developmental and ophthalmic outcomes were reviewed. Surgery was considered successful if the horizontal deviation was less than 10 prism diopters (PD). Developmental assessments were obtained at each visit.

RESULTS

Twenty-six patients presented between age 2 and 10 months with exotropia ranging from 20 to 95 PD. Ten (38%) patients had a developmental delay that was recognized at the first visit, 9 of whom had a systemic diagnosis at that time; the other patients remained developmentally normal during a mean follow-up of 7 years. Age at surgery ranged from 4 to 18 months. Surgery was successful in 10 (38%) of 26 patients after 1 surgery and in an additional 13 (50%) of 26 patients after a second surgery.

CONCLUSIONS

In this study, the need for more than 1 surgery was higher in infantile exotropia when compared to other forms of childhood strabismus, but most children achieved good alignment with one or two surgeries. Developmental delay is common in patients with infantile exotropia, but this was usually recognized at the time of the initial evaluation. In the current patients, routine neurologic screening or imaging of these otherwise developmentally normal infants was not required. [J Pediatr Ophthalmol Strabismus. 2018;55(4):225-228.].

Altered spontaneous brain activity patterns in strabismus with amblyopia patients using amplitude of low-frequency fluctuation: a resting-state fMRI study

OBJECTIVE

Previous studies have demonstrated that strabismus or amblyopia can result in markedly brain function and anatomical alterations. However, the differences in spontaneous brain activities of strabismus with amblyopia (SA) patients still remain unclear. This current study intended to use the amplitude of low-frequency fluctuation (ALFF) technique to investigate the intrinsic brain activity changes in SA subjects.

PATIENTS AND METHODS

A total of 16 patients with SA (6 males and 10 females) and 16 healthy controls (HCs; 6 males and 10 females) similarly matched in age, gender, and education status were recruited and examined with the resting-state functional MRI. The spontaneous brain activity changes were investigated using the ALFF technique. The receiver operating characteristic curve was performed to classify the mean ALFF signal values of the SA patients from HCs. The correlations between the ALFF values of distinct brain regions and the clinical manifestations in SA patients were evaluated in terms of the Pearson's correlation analysis.

RESULTS

Compared with HCs, SA patients had significantly decreased ALFF in the left cerebellum posterior lobe, left middle frontal gyrus, and bilateral thalamus. In contrast, SA patients showed increased ALFF values in the right superior frontal gyrus, right precuneus, left cuneus, and bilateral precentral gyrus. Nonetheless, there was no linear correlation between the mean ALFF values in brain regions and clinical features.

CONCLUSION

Diverse brain regions including vision-related and motion-related areas exhibited aberrant intrinsic brain activity patterns, which imply the neuropathologic mechanisms of oculomotor disorder and vision deficit in the SA patients.

Prevalence and associated factors of strabismus in former preterm and full-term infants between 4 and 10 Years of age

Background

Limited data exist collating most of the associated factors for strabismus in one analysis. The aim of this study was to assess the prevalence of strabismus and to analyse associated factors in former preterm and full-term infants.

Methods

In this cross-sectional study, 239 former preterm infants with gestational age (GA) ≤ 32 weeks and 264 former full-term born infants with GA ≥ 37 weeks underwent detailed ophthalmologic examination in the age of 4–10 years and perinatal data assessment for risk factor analysis. Ophthalmologic examinations included cover testing, best corrected visual acuity, cycloplegic objective refraction, slit lamp as well as fundus examinations. For association analysis with strabismus, the following data was collected and included in multivariable analysis: sex, age at examination, anisometropia, myopic and hyperopic refractive error (≥ 3 dioptres), astigmatism, birth weight percentile, gestational age, retinopathy of prematurity occurrence, maternal age at childbirth, mother smoking, breastfeeding < 3 months, artificial ventilation, intraventricular bleeding, and other perinatal adverse events.

Results

Overall, 4/264 (2%) full-term infants, 15/125 (12%) preterm-infants with GA 29–32 weeks without ROP, 13/59 (22%) preterm infants with GA ≤ 28 weeks without ROP and 14/55 (26%) with GA ≤ 32 weeks with retinopathy of prematurity were affected by strabismus. In the multivariable regression model strabismus was associated with GA (OR = 0.84 per week; p = 0.001), hyperopic refractive error (OR = 4.22; p = 0.002) and astigmatism (OR = 1.68; p = 0.02).

Conclusion

This investigation highlights that low gestational age and refraction of the eye are independent risk factors for strabismus, while the other factors show less independent influence.

Is there consensus in defining childhood cerebral visual impairment? A systematic review of terminology and definitions

The childhood condition of visual difficulties caused by brain damage, commonly termed cortical or cerebral visual impairment (CVI), is well established but has no internationally accepted definition. Clarification of its core features is required to advance research and clinical practice. This systematic review aimed to identify the definitions of childhood CVI in the original scientific literature to describe and critically appraise a consensual definition of the condition. MEDLINE, EMBASE, PsychINFO, CINAHL and AMED databases were searched in January 2017. Studies were included if they (1) were published original research, (2) contained a childhood CVI sample, (3) contained a definition of CVI and (4) described their CVI identification/diagnostic method. Thematic analysis identified concepts within definitions and narrative synthesis was conducted. Of 1150 articles, 51 met inclusion criteria. Definitions were subdivided according to detail (descriptive definition, description not reaching definition status and diagnostic/operationalising criteria). Three themes concerning visual deficits, eye health and brain integrity were identified (each containing subthemes) and analysed individually across definitions. The most common themes were ‘visual impairment’ (n=20), ‘retrochiasmatic pathway damage’(n=13) and ‘normal/near normal eye health’ (n=15). The most consensual definition identified here may not be the best quality for advancing our understanding of CVI. We argue for the alternative definition: CVI is a verifiable visual dysfunction which cannot be attributed to disorders of the anterior visual pathways or any potentially co-occurring ocular impairment. We propose reporting guidelines to permit comparison across studies and increase the evidence base for more reliable clinical assessment and diagnosis.

Vision Assessments and Interventions for Infants 0-2 Years at High Risk for Cerebral Palsy: A Systematic Review

We performed a systematic review and evaluated the level of evidence of vision interventions and assessments for infants at high risk for or with a diagnosis of cerebral palsy from zero to two years of age. Articles were evaluated based on the level of methodologic quality, evidence, and clinical utilization. Thirty publications with vision assessments and five with vision interventions met criteria for inclusion. Assessments included standard care neuroimaging, electrophysiology, and neuro-ophthalmologic examination techniques that are utilized clinically with any preverbal or nonverbal pediatric patient. The overall level of evidence of interventions was strong for neuroprotective interventions such as caffeine and hypothermia but weak for surgery, visual training, or developmental programs. There are few evidence-based interventions and assessments that address cerebral/cortical visual impairment-related needs of infants and toddlers at high risk for or with cerebral palsy. Recommendation guidelines include the use of three types of standard care methodologies and two types of protective interventions.

Acquired pendular nystagmus

Acquired pendular nystagmus is comprised of quasi-sinusoidal oscillations of the eyes significantly affecting gaze holding and clarity of vision. The most common causes of acquired pendular nystagmus include demyelinating disorders such as multiple sclerosis and the syndrome of ocular palatal tremor. However, several other deficits, such as pharmacological intoxication, metabolic and genetic disorders, and granulomatous disorders can lead to syndromes mimicking acquired pendular nystagmus. Study of the kinematic features of acquired pendular nystagmus has suggested a putative pathophysiology of an otherwise mysterious neurological disorder. Here we review clinical features of neurological deficits that co-occur with acquired pendular nystagmus. Subsequent discussion of the pathophysiology of individual forms of pendular nystagmus speculates on mechanisms of the underlying disease while providing insights into pharmacotherapy of nystagmus.

Neuro-ophthalmic manifestations of prematurity

Increasing rates of preterm births coupled with better survival of these infants have resulted in higher prevalence of systemic and ocular complications associated with prematurity. In addition to retinopathy of prematurity, infants who are born preterm may suffer from severe visual impairment as a result of hypoxic ischemic encephalopathy, hypoglycemia, and other metabolic imbalances. The effect of these processes on the anterior visual pathway may result in optic atrophy, optic nerve hypoplasia or optic disc cupping and affection of the posterior visual pathway leads to cortical visual impairment (CVI). Other ocular associations include strabismus, nystagmus, and ocular motor abnormalities such as tonic down gaze and defective saccades and pursuits. Cortical and subcortical involvement also manifests as defects in functional vision and these have not yet been completely understood. Children with CVI may have visual field defects, photophobia, defective visual processing, and deficient color vision. Since most of these children also suffer from additional systemic disabilities, evaluation, and management remains a challenge. However, early diagnosis and initiation of rehabilitation therapy can prove to be of significant benefit in these children.

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.

The optic nerve and visual pathways

We review the clinical examination of the optic disc and assessment of the integrity of the visual pathways: assessment of vision in the infant and child, assessment of disc size and configuration, detection of abnormalities such as cupping or disc swelling and their significance, visual field examination in the child, and the various field defects which result from pathology affecting the visual pathway anywhere along its course. Congenital anomalies of the optic disc, their systemic associations and significance are discussed. We also review the presentation of the visually impaired child, the significance of nystagmus in this context, the differential diagnosis and investigation.

The subclassification of schizencephaly and its clinical characterization

We subclassified schizencephaly based on the association with optic nerve hypoplasia (ONH) and the absence of the septum pellucidum (ASP), and then characterized their clinical presentation and prognosis. The subjects of our study consisted of 10 cases with a mean age at the final evaluation of 10 years 3 months (range, 7 months to 25 years). The subclassification of schizencephaly consisted of the septo-optic dysplasia (SOD) group (n=3), with ONH and ASP; the optic hypoplasia (OHP) group (n=2), with ONH and without ASP, and; the classical group (n=5), without ONH. The subjects with an open-lip cleft in the SOD and the classical group showed hydrocephalus, but those in the OHP group did not. The SOD and the OHP group displayed severe psychomotor retardation regardless of the cleft morphology, but in the classical group, the subjects with an open-lip cleft or with diffuse cortical dysplasia were severely retarded. The SOD and the OHP group displayed intractable epilepsy. In contrast, all subjects in the classical group showed good control of epilepsy. The results of our investigation show that the subclassification of schizencephaly based on the association with ONH and ASP is useful. The SOD group means early fetal brain injury which results in extended cortical dysplasia while the OHP group means severe destructive brain injury which results in cerebro-cerebellar disruption.

[Primary exotropia: importance of cerebral MRI]

INTRODUCTION

Primary exotropia is a divergent strabismus that appears from the first day of life to the second year. It can be isolated or associated with a pathological context requiring cerebral imaging to determine diagnosis and prognosis. The objective of this study was to report the sensorimotor state and the result of MRI in infantile exotropia.

PATIENTS AND METHOD

Forty-seven children with primary exotropia had a complete ophthalmologic assessment (visual acuity, binocular vision, refraction with cycloplegia, eye fundus) and cerebral MRI (average age, 16 months). Deviation was classified into four categories<4 degrees, > or =4<10 degrees, > or =10<20 degrees, > or =20 degrees. MRI results were classified into seven categories: white matter abnormalities (gliosis, delay of maturation, periventricular leukomalacia, aspecific hyperintense signal, and necroses); Virchow-Robin enlargement space and enlarged subarachnoid space; gray matter abnormalities (necroses, cerebral atrophy, occipital cortex, basal ganglia); ventriculomegaly; thin corpus callosum; cerebellar injury; and tumor.

RESULTS

There was a statistically significant increase in the rate of pathological MRI as the angle deviation increased: 76.6% of patients had a pathological ophthalmologic exam (amblyopia, ptosis, head posture, Duane's syndrome, cataract, albinism, or pigmentary retinopathy). We found 38% nystagmus and 38% optic nerve hypoplasia. There was a real pathological context in 61.7% of the exotropia cases: 27.7% prematurity, 31.9% fetal distress, 21.3% facial dysmorphy (plagiocephaly), 12.8% psychomotor delay, and 14.9% epilepsy. Only three children had isolated exotropia. Thirty-four cerebral MRI (72.3%) were not normal. In pathological MRI, there was 61.8% white matter injury, 41.2% gray matter injury, and 17.6% thin corpus callosum.

CONCLUSION

This study demonstrates the fundamental contribution of cerebral MRI in infantile exotropia. The greater the deviation, the more abnormal the MRI results are. The pathological context and ophthalmological abnormalities are important in infantile exotropia.

Eye movements and binocular function in low birthweight teenagers

PURPOSE

To assess eye movements and binocular function in 14-year-olds with very low birthweight (VLBW: birthweight </= 1500 g) and 14-year-olds born at term but small for gestational age (SGA: birthweight < 10th percentile) in a population-based study.

METHODS

Ophthalmological examinations including measurements of heterophoria/tropia, near point of convergence, accommodative amplitude, stereopsis, nystagmus, saccades and smooth pursuit were performed in 51 adolescents with VLBW, 58 adolescents born SGA and in a control group consisting of 75 subjects of the same age.

RESULTS

Latent or manifest strabismus, poor stereopsis, poor convergence and nystagmus were all more frequent in the VLBW group than in the control group. The VLBW group did not differ from the control group regarding accommodative amplitude or saccades and smooth pursuit. The SGA population did not differ from the control group in the measured variables.

CONCLUSIONS

Premature birth with VLBW affects binocular visual functions negatively in adolescence, whereas birth small for date at term does not appear to be a risk factor for impaired eye movements and binocular function.

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.

Severe visual impairment in children with mild or moderate retinal residua following regressed threshold retinopathy of prematurity

PURPOSE

To describe clinical features of patients from the Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) trial who, after developing severe ROP in infancy, had minimal or moderate retinal residua in at least one eye but a visual acuity of worse than 20/200 in both eyes at the 10 year examination.

METHODS

Data from the 10 year CRYO-ROP Trial follow-up exams were evaluated to identify all patients with retinal outcomes of no retinopathy of prematurity (ROP) residua, straightened temporal vessels, or macular heterotopia in at least one eye, but visual acuity less than 20/200 in both eyes. Presence of optic atrophy, nystagmus, and optic disk cupping and developmental survey results were examined.

RESULTS

Of 247 patients examined at 10 years, 16 met our inclusion criteria. At the last age at which the following data were recorded, seven had optic atrophy at the 10 year examination, one had optic disk cupping >0.5 at the 5(1/2) year examination, and eight had nystagmus under binocular conditions at the 24 month examination. Nine patients had a below-normal developmental test score on the Functional Independence Measure for Children (WeeFIM). After clinical data interpretation, we concluded that the predominant cause of visual impairment was postgeniculate disease in five patients, ROP in six patients, and combined anterior and posterior visual pathway disease in two patients; in three patients data were insufficient to make a determination.

CONCLUSIONS

Poor visual function with mild to moderate retinal residua of severe ROP in at least one eye is relatively rare. In such patients, anterior, posterior, or combined visual pathway disease can occur.

Spectrum of visual disorders in children with cerebral visual impairment

Cerebral visual impairment is a visual function deficit caused by damage to the retrogeniculate visual pathways in the absence of any major ocular disease. It is the main visual deficit in children in the developed world. Preperinatal hypoxic-ischemic damage is the most frequent cause of cerebral visual impairment, but the etiology is variable. The authors set out to evaluate the presence of visual disorders not attributable to any major ocular pathology in a sample of children with central nervous system disease and to describe the clinical picture of cerebral visual impairment in this cohort. One hundred twenty-one patients with central nervous system damage and visual impairment underwent a protocol developed at the authors' center that included neurologic, neurophthalmologic, and neuroradiologic assessments (brain magnetic resonance imaging). Reduced visual acuity was found in 105 of 121 patients, reduced contrast sensitivity in 58, abnormal optokinetic nystagmus in 88, and visual field deficit in 7. Fixation was altered in 58 patients, smooth pursuit in 95, and saccadic movements in 41. Strabismus was present in 88 patients, and abnormal ocular movements were found in 43 patients. Of the 27 patients in whom they could be assessed, visual-perceptual abilities were found to be impaired in 24. Fundus oculi abnormalities and refractive errors were frequently associated findings. This study confirms that the clinical expression of cerebral visual impairment can be variable and that, in addition to already well-documented symptoms (such as reduced visual acuity, visual field deficits, reduced contrast sensitivity), the clinical picture can also be characterized by oculomotor or visual-cognitive disorders. Cerebral visual impairment is often associated with ophthalmologic abnormalities, and these should be carefully sought. Early and careful assessment, taking into account both the neurophthalmologic and the ophthalmologic aspects, is essential for a correct diagnosis and the development of personalized rehabilitation programs.

Cortical visual impairment in children

PURPOSE OF REVIEW

Cortical visual impairment is rapidly becoming a leading cause of visual loss in children in developed countries predominately because of the improved survival rates of premature infants over the past decade.

RECENT FINDINGS

Most cases of cortical visual impairment arise from hypoxic ischemic injury to watershed areas of the brain. In the preterm infant the watershed areas are in the subcortex around the ventricles, while in the term infant the watershed areas are between the major arteries with injury to the subcortex and cortex. Therefore, preterm and term injury will manifest different ocular and visual system abnormalities as a result of this damage. Cognitive visual dysfunction, a type of cortical visual impairment, may occur in cases of damage to the peristriate cortex (association areas of the brain). The anterior visual pathways may also be damaged in a retrograde, transsynaptic fashion in cases of cortical visual impairment.

SUMMARY

Cortical visual impairment is a prevalent cause of visual loss in children. It encompasses a wide range of visual disabilities from no light reception to normal visual acuity with cognitive visual dysfunction.

Hypomyelinating leukoencephalopathy with paroxysmal tonic upgaze and absence of psychomotor development

Hypomyelinating leukoencephalopathies are characterized by a substantial and permanent deficit in myelin deposition in the brain. Although our knowledge and understanding of the etiology of white matter diseases has progressively increased, many cases with this disorder remain undiagnosed, despite extensive evaluations. Recently, new disease entities have been defined by combining magnetic resonance imaging pattern recognition and clinical features. We describe a 1-year-old Ashkenazi Jewish girl with a hypomyelinating leukoencephalopathy, who presented in the neonatal period with episodes of sustained paroxysmal tonic upward gaze, roving eye movements, pendular nystagmus, and severe hypotonia, with the later appearance of pyramidal and extrapyramidal signs and no development. In addition, she has dysmorphic signs. This clinical picture is not consistent with any of the previously described hypomyelinating leukoencephalopathies and may represent a new entity.

Systemic and ocular findings in 100 patients with optic nerve hypoplasia

To describe associated ocular, neurologic, and systemic findings in a population of children with optic nerve hypoplasia, a retrospective chart review of 100 patients with optic nerve hypoplasia for the presence of neurologic, radiologic, and endocrine abnormalities was performed. Neuroimaging and endocrine studies were obtained in 65 cases. Visual acuity and associated ocular, neurologic, endocrine, systemic, and structural brain abnormalities were recorded. Seventy-five percent had bilateral optic nerve hypoplasia. Conditions previously associated with optic nerve hypoplasia and present in our patients include premature birth in 21%, fetal alcohol syndrome in 9%, maternal diabetes in 6%, and endocrine abnormalities in 6%. Developmental delay was present in 32%, cerebral palsy in 13%, and seizures in 12%. Of those imaged, 60% had an abnormal study. Neuroimaging showed abnormalities in ventricles or white- or gray-matter development in 29 patients, septo-optic dysplasia in 10, hydrocephalus in 10, and corpus callosum abnormalities in 8. There was an associated clinical neurologic abnormality in 57% of patients with bilateral optic nerve hypoplasia and in 32% of patients with unilateral optic nerve hypoplasia. Patients with unilateral and bilateral optic nerve hypoplasia frequently have a wide range and common occurrence of concomitant neurologic, endocrine, and systemic abnormalities.

MR imaging of the neonatal brain

The advent of modern neuroimaging tools and methods has revolutionized the evaluation of the brain in neonates. The development of magnetic resonance (MR)-compatible monitoring tools and incubators has alleviated concerns regarding transportation of these unstable infants. The development of dedicated neonatal imaging coils has increased signal-to-noise ratios dramatically in images of the neonatal brain; this has made high-quality anatomic imaging, diffusion tensor imaging, and proton MR spectroscopy feasible in a normal imaging time. In centers that are equipped properly for neonatal MR imaging, MR is now unquestionably the study of choice for neonates who have encephalopathy or suspected brain injury. This article discusses the application of modern MR techniques to some of the causes of encephalopathy in neonates.

Effects of first trimester binge alcohol exposure on developing white matter in fetal sheep

Heavy prenatal alcohol exposure is associated with neurodevelopmental abnormalities. Neuropathologic and neuroimaging studies have shown a wide range of structural problems, including abnormal neuronal migration and volume reduction in specific brain regions, including white matter. We identified foci of significant fetal white matter microglia-macrophage immunoreactivity in a "binge" model of early prenatal alcohol exposure in sheep. Ewes of alcohol-exposed fetuses received daily 90 min alcohol (1.5 gm/kg i.v.) infusions at 30-60 d gestation (term = 147 d). Ewes of control fetuses received same volume infusions of normal saline intravenously. Near-term (125 d gestation) fetal brains were labeled with microglia-macrophages using HAM56 antibody. We quantified dense immunoreactive cellular regions across sections and anatomical locations using computer-assisted microscopy and quantitative morphometry. The proportional HAM56-positive area in cortical white matter was greater in the alcohol-exposed fetuses (1.6%) compared with the saline controls (0.7%). The areas were localized to the frontal gyral white matter, temporal gyral white matter, optic radiation, and others (corpus callosum, septum pellucidum, fasciculus subcallosus, and external capsule), with a greater distribution in the gyral white matter. The greater area of macrophage-rich regions in near-term fetal sheep brain suggests a vulnerability of developing white matter that is enhanced by early alcohol exposure.

[Cerebral visual impairment in brain-damaged children - four case studies]

Cerebral visual impairment is one of the main causes of childhood visual impairment in developed countries. These disorders are often linked with pre- or perinatal hypoxic brain injuries. The patterns of brain injuries depend on the severity and duration of hypoxia and the child's age. In premature children, periventricular leukomalacia affects the optic radiations and the subcortical visual brain. In full-term newborn babies, chronic hypoxia leads to the damage of the visual cortex and acute hypoxia damages the basal ganglia. They recover from cortical blindness in variable ways. Visual dysfunction is characterized by fixation troubles, subnormal acuity (crowding), difficulty with perceiving visual fields, movements, depth, cognitive defects (agnosia of images, objects or faces, visuospatial disorders), ocular motility disorders (tonic gaze deviation, strabismus, nystagmus). Accompanying these cerebral injuries, there are accommodation defects and optic disk abnormalities that vary according to the gestational age at the time of hypoxia.

Voxel-based analysis of MRI detects abnormal visual cortex in children and adults with amblyopia

Amblyopia, sometimes called "lazy eye," is a relatively common developmental visual disorder well characterized behaviorally; however, the neural substrates associated with amblyopia in humans remain unclear. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, possibly as a result of experience-dependent neuronal plasticity. Anatomic magnetic resonance imaging (MRI) and psychophysical vision testing was carried out on 74 subjects divided into two age ranges, 7-12 years and 18-35 years, and three diagnoses, strabismic amblyopia, anisometropic amblyopia, and normal vision. We report a behavioral impairment in contrast sensitivity for subjects with amblyopia, consistent with previous reports. When the high-resolution MRI brain images were analyzed quantitatively with optimized voxel-based morphometry, results indicated that adults and children with amblyopia have decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. This finding was confirmed with a separate region-of-interest analysis. For the children with amblyopia, additional gray matter reductions in parietal-occipital areas and ventral temporal cortex were detected, consistent with recent reports that amblyopia can result in spatial location and object processing deficits. These data are the first to provide possible neuroanatomic bases for the loss of binocularity and visual sensitivity in children and adults with amblyopia.

Congenital disorders of the optic nerve: excavations and hypoplasia

The principal congenital abnormalities of the optic disc that can significantly impair visual function are excavation of the optic disc and optic nerve hypoplasia. The excavated optic disc abnormalities comprise optic disc coloboma, morning glory syndrome, and peripapillary staphyloma. Optic nerve hypoplasia manifests as a small optic nerve, which may or may not be accompanied by a peripapillary ring (the double ring sign). In addition, the optic disc cupping, which occurs as a sequel to some cases of periventricular leucomalacia, can arguably be classified as a type of optic nerve hypoplasia. All of these conditions can be unilateral or bilateral and can impair visual function mildly or severely. It is essential that children with poor vision due to any of these conditions are managed by treating refractive errors, giving occlusion therapy in selected cases, and optimising the conditions at home and at school in an attempt to ensure that impaired vision does not impede development or education.

Neuroanatomy of adult strabismus: a voxel-based morphometric analysis of magnetic resonance structural scans

Cerebral deficit has been implicated in the genesis of strabismus and in the mechanisms adopted to compensate for the visual disorder. Voxel-based morphometry (VBM) was applied to magnetic resonance images of strabismic adults to detect any abnormal brain anatomy, which could not be easily identified by simple inspection. The gray matter volume in strabismic adults was smaller than that in normal subjects at the areas consistent with the occipital eye field (OEF) and parietal eye field (PEF). However, greater gray matter volume was found in strabismic adults relative to normal controls at the areas consistent with the frontal eye field (FEF), the supplementary eye field (SEF), the prefrontal cortex (PFC), and subcortical regions such as the thalamus and the basal ganglia. These opposite gray matter changes in the visual and the oculomotor processing areas are compatible with a hypothesis of plasticity in the oculomotor regions to compensate for the cortical deficits in the visual processing areas.

Visual impairment in children born prematurely from 1972 through 1989

PURPOSE

To investigate the incidence and causes of visual impairment in children born prematurely in Finland from 1972 through 1989, and to determine what conditions and factors were associated with its occurrence.

DESIGN

Retrospective, cross-sectional study.

SUBJECTS

All visually impaired individuals from 0 to 17 years of age who had been born at fewer than 37 gestational weeks in Finland from 1972 through 1989 for whom records were available in the Finnish Register of Visual Impairment were eligible for this study.

METHODS

Data in the Finnish Register of Visual Impairment relating to 556 children were supplemented with data from hospital records, and from the Register of Births, the Register of Congenital Malformations, the Finnish Care Register, and the Finnish Cancer Register. Data relating to causes associated with visual impairment in particular were collected. Data relating to the children born prematurely were compared with data relating to children born at full term. The chi-square test (Mantel-Haenszel), the Mann-Whitney U test, Fisher exact test, and stepwise logistic regression analysis were used in statistical analysis of the data.

MAIN OUTCOME MEASURES

Visual acuity, ophthalmologic diagnoses, associated systemic disease, multiple handicap, gestational age, birth weight, 5-minute Apgar scores, and prenatal, perinatal, and infantile or juvenile disorders or disease and treatment.

RESULTS

One hundred twenty-five of the 556 visually impaired children (23%; 11/100000 children less than 18 years of age) had been born preterm. Retinopathy of prematurity, optic atrophy, and cerebral amblyopia were the main diagnoses associated with visual impairment (in 46%, 28%, and 12% of cases, respectively). Sixty-six percent of those born prematurely with visual impairment were also affected by other handicaps (mental, motor, auditory), 54% by cerebral palsy and 36% by epilepsy. Eighty-eight of the 125 children (70%) born preterm with visual impairment were blind. Very low birth weight (<1500 g), young gestational age (fewer than 30 weeks), prenatal infection, hyperbilirubinemia, respiratory disorders, asphyxia, and lengthy mechanical ventilation were associated with an increased risk of visual impairment.

CONCLUSIONS

Premature birth was a major risk factor of severe visual impairment and blindness in childhood. The visual impairment often was accompanied by cerebral palsy, epilepsy, and other motor and mental handicaps. Retinopathy of prematurity, optic atrophy, and cerebral amblyopia were the main diagnoses associated with visual impairment. During the 18 years covered by the study, the increasing incidence of survival of infants born weighing fewer than 1500 g was associated with increasing incidence of blindness.