Visual function in children with hemiplegia in the first years of life.

The aim of this study was to evaluate the incidence of visual function abnormalities in children with infantile hemiplegia, and the relation between visual abnormalities and type of lesion, as shown by brain MRI. Visual function was tested (grating acuity, visual field size, binocular optokinetic nystagmus [OKN], and ocular movements) in a group of 47 children with congenital or early acquired hemiplegic cerebral palsy (mean age 25 months, range 8 to 52 months). The cohort was subdivided into four groups according to MRI findings: brain malformations (n=5), abnormalities of the periventricular white matter (n=20), cortical-subcortical lesions (n=16), and non-progressive postnatal brain injuries (n=6). More than 80% of the children showed abnormal results in at least one visual test: acuity was the least impaired function, while visual field and OKN were abnormal in more than 50% of the cohort. No specific correlation could be identified between the type and timing of the lesions and visual function. Unlike adults with stroke, visual field defects were not always related to contralateral damage in the optic radiations or in the visual cortex. These results indicate that visual abnormalities are common in children with hemiplegia, and that they cannot always be predicted by MRI. All children with hemiplegia need a detailed assessment of visual function.

Screening for suppression in young children: the polaroid suppression test.

BACKGROUND: Assessment of monocular visual impairment during screening of young children is often hampered by lack of cooperation. Because strabismus, amblyopia, or anisometropia may lead to monocular suppression during binocular viewing conditions, a test was developed to screen for suppression in young children. METHODS: Children were invited to look through two polaroid filters of different polarization direction at two pictures covered with polaroid filters of opposite polarization direction. In this way, each eye could only see one of the two pictures. In cases of suppression, only one picture would be visible. Acuity measurements in 201 5-year-old children were compared with the Polaroid Suppresion test (PST) results. RESULTS: The PST had a high success rate (99.5%) and testing time was under 1 minute. Specificity of the PST for acuity impairments was 91%. The low sensitivity of 60% was caused mainly by the fact that some children with binocular acuity impairments were not detected with the PST. However, the PST was highly sensitive for significant interocular acuity differences. CONCLUSION: The PST has been found to be a useful screening method for amblyogenic factors in young children. The test can be carried out without occlusion of one eye. The apparatus is portable, the test duration is short, and the costs are low. The results indicate that the PST is a very promising tool to use in clinical conditions and for screening large numbers of young children.

Visual outcome at 5 years of newborn infants at risk of cerebral visual impairment.

Visual development at 5 years of age was tested in a group of 39 children who had shown severe neonatal encephalopathy or perinatal brain lesions, documented by medical history, cranial ultrasound, or MRI. In all children, grating acuity was tested during the first 2 years of life. The assessment protocol at 5 years included various visual functions (grating and resolution acuity, visual field size, depth perception, optokinetic nystagmus, and ocular motility), and neurological and cognitive development. The majority of the children showed visual disorders of different type and degree, which were not due to ophthalmological abnormalities. Visual defects correlated well with the results of early visual assessment and of neuroimaging. Visual outcome could be predicted by grating acuity at 1 to 2 years in 27 of the 39 children, by neonatal cranial ultrasound in 26 of the 32 cases examined by this technique, and by later MRI in 23 out of 27. Moreover, a significant correlation was found between visual, motor, and cognitive impairment.

Cerebral visual impairment in preterm infants with periventricular leukomalacia.

Neonatal brain lesions are the main cause of cerebral visual impairment in infancy, i.e., of a visual deficit caused by damage to posterior visual pathways. Visual outcome of preterm infants with periventricular leukomalacia (PVL) was investigated in 14 subjects affected by severe cystic PVL, another 34 with moderate PVL (prolonged periventricular echodensities), and 18 control preterm infants. All cases with significant ocular abnormalities (such as retinopathy of prematurity state III or upwards, optic nerve atrophy, or major refraction problems) were excluded. Visual acuity, visual field, eye alignment, fixation and following, optokinetic nystagmus, and visual threat were tested at 1 year of corrected age. A high incidence of cerebral visual impairment, consisting mainly of low visual acuity, severe oculomotor disorders, and reduced visual field, was found in infants with severe PVL. Visual defects were less frequent and less severe in the moderate PVL group, and very rare in the control group. The results of neuroimaging, and especially of magnetic resonance imaging, correlated with the visual outcome and indicate lesions at the level of optic radiations as the main anatomic substrate of the visual impairment. All infants with PVL need a visual follow-up, from the first months of life, the results of which are important both for visual and motor rehabilitation of these cases and for their daily care.

Correlation between cerebral visual impairment and magnetic resonance imaging in children with neonatal encephalopathy.

To identify brain lesions most often associated with cerebral visual i mpairment (CVI) after neonatal encephalopathy and to evaluate the prognostic value of MRI for visual outcome, the authors reviewed visual assessments and brain MRI of 80 infants and young children with documented perinatal hypoxic-ischaemic and/or haemorrhagic insults. MRIs were classified according to the severity of lesions at the optic radiations and at the visual cortex; visual acuity was tested with the acuity card procedure. Among the 48 children found to have a CVI, 42 had moderate to severe lesions of the optic radiations and 19 had lesions of the visual cortex. In both cases visual acuity was statically correlated with MRI grading, but the damage at the optic radiations was the better predictor. Early detection of abnormal MR findings in the visual cortex and especially, at the optic radiations may indicate which infants with neonatal encephalopthy should receive longitudinal visual assessment and specific rehabilitation and educational management.

Strabismus in very low birth weight and/or very preterm children: discrepancy between age of onset and start of treatment.

Very low birth weight (VLBW; less than 1500 g) and/or very preterm children are at risk for strabismus. However, the age of onset of strabismus is still unknown. The present study reports on the frequency of strabismus in 450 5-year-old children born with a birth weight of less than 1500 g and/or with a gestational age below 32 weeks. The age at which strabismus was initially diagnosed was determined retrospectively. At 5 years of age 65 of the at-risk children (14.4%) presented with strabismus. Fifteen of them (3%) had at that age not been referred to or treated by an ophthalmologist. At 3 years of age only 28 strabismic children were being treated; 7 at-risk children (2%) had been treated for strabismus before the end of the 1st year. These results were compared to those from a second study in which eye alignment was longitudinally examined in 194 VLBW children from 6 weeks until 12 months of (corrected) age and additionally in 65 of these children at the age of 2.5 years. At a first glance, the frequency of strabismus in the longitudinal study seemed rather stable during the first 2.5 years of life, with values varying between 14% and 18%. However, only a small percentage of misalignments which were noted at 6 weeks of age persisted until 2.5 years. On the other hand, if children had a misalignment at 9 months, strabismus was still present when they were reexamined at 1 and at 2.5 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Acuity card testing in children with cerebral palsy related to magnetic resonance images, mental levels and motor abilities.

Visual acuity testing using Teller Acuity Cards was carried out on 78 infants and children affected by cerebral palsy (CP). Age of testing was between 3 and 109 months. The aim of the study was to investigate the usefulness of acuity cards in patients with CP, and to relate visual outcome with the type of CP, MRI findings, mental levels and motor disabilities. Visual acuity estimates were obtained for 60 children: acuity values were within normal values for age for 17 and below the 5th percentile for 43. Cerebral blindness was diagnosed in 10 patients. Eight infants were not testable, mainly because of behavioural problems. The overall success rate was 88%. Visual impairment in most infants with low acuity and in all blind children was not due to ophthalmological abnormalities. Visual outcome was significantly related to the type of CP, with hemiplegic children showing the best results and tetraplegics the worst. Cerebral blindness was significantly correlated with tetraplegia, the severity of lesions in the optic radiations, and visual cortex areas, as indicated by MRI, and the degree of mental, motor and oculomotor deficit. These correlations were mainly due to the blind subjects, who consistently showed major MRI abnormalities and severe motor, mental and oculomotor impairment. Longitudinal results obtained for 45 children showed visual outcome stable over time in 64.4% of cases, improvement in 6.6% and deterioration in 28.9%.

Visual outcome of low-birth-weight infants (1500-2500 g) at one year of corrected age.

Visual functions (grating acuity, visual field size, optokinetic nystagmus and eye alignment) were tested as part of a longitudinal study in 96 low-birth-weight infants (birth weight 1500-2500 g) at one year of corrected age. Except for optokinetic nystagmus, deficit rates of all visual functions were low, and the obtained values comparable with normal age values in full-term infants. Effects of gestational duration, birth weight and intrauterine growth retardation on visual functions could not be demonstrated. Some perinatal risk factors (mechanical ventilation, oxygen treatment for more than one day, the presence of maternal hypertensive disorders) and a less-optimal neurodevelopmental status at one year had a negligible effect on visual field size. The observed deficits are not likely to cause disability. Low-birth-weight infants appeared not to be at risk for developing visual deficits at one year of corrected age.

Visual functions in relation with neonatal cerebral ultrasound, neurology and cognitive development in very-low-birthweight children.

In order to determine the relationship between visual functions and neonatal cerebral ultrasound, neurological examinations and cognitive development, a prospective longitudinal study was conducted in 69 high-risk very-low-birthweight children. Visual development was studied at 1 and 2.6 years of corrected age by assessment of visual acuity, binocular visual fields, optokinetic nystagmus and strabismus. Visual impairments were found in 33% at age 1 and in 28% at age 2.6. Visual impairments were related to intraparenchymal damage, as detected by neonatal cerebral ultrasound, as well as to abnormal neurological examinations and lower mean developmental indices. A stepwise multiple regression analysis with neonatal cerebral ultrasound as the dependent variable and visual functions at ages 1 and 2.6 and neurological examinations at ages 1 and 2 as independent variables, however, demonstrated that standardized neurological examinations were better markers of neonatal cerebral damage than visual functions. In cognitive development at ages 1 and 2, the neurological examination at age 1 was the most important variable. In cognitive development at age 3.6, visual functions at age 2.6 were more important. Early visual impairments might thus influence later cognitive development. The effectiveness of appropriate early intervention strategies to stimulate visual and cognitive development in infants with less severe visual impairments should be subject to further study.

Visual field and grating acuity development in low-risk preterm infants during the first 2 1/2 years after term.

The effect of early visual experience on visual field size and grating acuity development was studied longitudinally in 36 appropriate for gestational age (AGA) and 26 small for gestational age (SGA) low-risk preterm infants. These were selected out of 194 very low birth weight (VLBW) infants (birthweight less than 1500 g) born in 1985 and 1986. Criteria for inclusion as low-risk were the absence of neurological, respiratory, circulatory and alimentary problems in the neonatal period; no retinopathy of prematurity and no evidence of abnormality on the neonatal cranial ultrasound scans. Binocular field sizes were assessed using kinetic arc perimetry. Binocular grating acuity was tested by means of the prototype version of the acuity card procedure. Results were compared with norms obtained in control fullterms in earlier studies. Infants were tested at 6 weeks, 6, 6, 9 and 12 months of age from the expected term date. Twenty-two of these infants were retested at 2 1/2 years of corrected age. Visual field size and visual acuity estimates of (both AGA and SGA) low-risk, VLBW preterms and control fullterms overlapped at all test ages, except for a slight but significantly faster development of the upper and the lower visual field at 6 weeks corrected age in the preterm group. These results indicate that for clinical purposes visual experience before the expected term date has not only no measurable effect on the normal development of behavioural acuity, but also no accelerating effect on the development of peripheral vision.

Visual acuity of low- and high-risk neonates and acuity development during the first year.

Binocular grating acuity of 65 neonates was measured using Teller acuity cards. At the time of testing, age corrected for prematurity ranged from -3 weeks to 2 weeks. On the basis of clinical data, serial ultrasound scans and EEG recording newborns were divided into 4 subgroups: fullterm low-risk (FLR, n = 22); preterm low-risk (PLR, n = 20); preterm medium-risk (PMR, n = 9) and preterm high-risk (PHR, n = 14). Mean visual acuity of PLR infants (0.86 cy/deg; S.D. 0.34 oct) was not significantly different from that of FLR newborns (0.80 cy/deg; S.D. 0.71 oct); the lower variability of the PLR infants might possibly be caused by their longer postnatal experience. Within the preterm groups, mean visual acuity of PLR newborns was found to be significantly higher than that of PMR (0.73 cy/deg; S.D. 0.26 oct) and PHR infants (0.73 cy/deg; S.D. 0.35 oct). This difference can not be explained by dissimilarities in postnatal or corrected age. Brain impairment, as documented by US scans and EEG recording could account for these findings. Longitudinal data are needed in order to substantiate these findings and correlate them with later neurological and neuro-imaging outcome. Preliminary results of an ongoing longitudinal study suggest acuity development of most, but not all, PHR infants, in whom a cystic-periventricular leukomalacia had been diagnosed, to be worse than that of low- and medium-risk infants.

The Rotterdam C-chart: norm values for visual acuity and interocular differences in 5-year-old children.

Common C-charts are often not suitable for developmental studies and assessment of visual acuity in young and visual impaired children, because of unequal steps between lines, uncomparable crowding, inadequate number of large optotypes on the first line and ceiling effects. Therefore a new C-chart (the Rotterdam C-chart) was developed on which optotypes on successive lines decreased in 1/3-octave steps (0.1-log steps) and on which crowding was comparable over the entire chart. Norm values for binocular and monocular visual acuity at test distances of 6 m and 40 cm and norm values for interocular acuity differences in 5-year-old children were determined by testing 201 5-year-olds with this chart. Results were compared to those obtained in 24 young adults. Although mean binocular and monocular acuity of the 5-year-olds were significantly lower than in adults, the distribution of acuity assessments were similar in the children and adults. Therefore, the Rotterdam C-chart seems suitable for developmental studies and for the assessment of visual acuity in young and visually impaired children.

Visual acuity in low birth weight (1500-2500 g) neonates.

Binocular grating acuity was tested in 138 low birth weight (LBW) neonates (birth weights ranging from 1500 to 2500 g) by means of the prototype version of the Acuity Card Procedure. No surrounding screen was used. Mean visual acuity of 107 neonates successfully assessed at mean corrected ages of -1.9 weeks (+/- 1.9 weeks) amounted to 0.58 cycles/degree (S.D. 0.71 octaves). Success rate was 77.5%. Mean postnatal age was 2.3 weeks (+/- 1.6 weeks). Acuity values of various subgroups ranged between 0.68 cycles/degree (S.D. 1.3 octaves) in low-risk, small for gestational age (SGA) preterms (n = 7), to 0.56 cycles/degree (S.D. 0.7 octaves) in SGA fullterms (n = 34), independent whether at low-or at high-risk. These differences were not significant, although with multiple regression analysis with adjustment for corrected age of testing, mean acuity of low-risk preterms was slightly better than of low-risk fullterms (P = 0.055). No significant change of acuity over corrected age could be demonstrated, except for a slight progress (r = 0.57; P less than 0.05) in the subgroup of 13 low-risk fullterms. The high variability of acuity values in neonates and the slow acuity development at term age hamper assessment of differences between various subgroups of neonates.

Visual acuity and visual field development after cryocoagulation in infants with retinopathy of prematurity.

Visual development was studied in 10 very-low-birth-weight infants (less than 1500 g) with retinopathy of prematurity (ROP) stage 3+ who had been treated with cryocoagulation in both eyes. Binocular visual acuity (acuity cards method) and binocular visual fields (kinetic perimetry) were assessed repeatedly in the first year of life. At 12 months corrected age, visual acuity was normal in seven and impaired in three infants, who appeared to be severely myopic. Normal visual fields were found in eight infants at this age. The results indicate that cryotherapy in cases of ROP stage 3+ does not interfere with visual acuity development. The effect on visual field development needs further investigation.

Partial visual recovery in two fullterm infants after perinatal hypoxia.

Behavioural methods were used to assess the visual development of two infants with a history of severe perinatal hypoxia. Both infants were born fullterm and showed hypoxic-ischaemic encephalopathy and subsequent cerebral palsy. Low visual acuity, small and asymmetrical visual fields, asymmetrical binocular and monocular OKN, and absent visual threat response were demonstrated initially. Ophthalmological examination revealed strabismus, but no further abnormalities. Longitudinal assessments up to the age of two years showed impressive (partial) improvements of visual functions. The mechanism for these improvements is unknown. The present study emphasizes the necessity of repeated testing of visual functions in infants with cerebral damage after perinatal hypoxia.

[Behavioral determination of visual acuity in 1-to-4-year-old children]. / Gedragsmatige bepaling van de gezichtsscherpte bij kinderen van 1 tot 4 jaar.

Visual acuity was assessed in 210 children aged 1 to 4 years using the Acuity card method. Visual acuity is expressed in minutes of arc, indicating the minimal angle for separate perception of two lines. Binocular visual acuity showed a gradual growth from 1.8 to 0.9 min, arc and monocular visual acuity from 1.7 to 1 min. arc during this age period. Adult values of 0.65 min. arc(binocular) and 0.70 (monocular) were not yet reached at 4 years of age. Age norms for visual acuity in children from 1 to 4 years of age were determined. The success rate for binocular visual acuity assessment was 99.5% at all ages and increased for monocular acuity assessment from 50% in the 1 to 2 year old to 100% in the 4 year olds. Acuity assessment was fast (test time 3.3 and 2.0 minutes for assessment of binocular and monocular acuity respectively). The inter-observer reliability of the binocular assessment in the same child was high.

Effects of very low birth weight (VLBW) on visual development during the first year after term.

Behavioural visual functions were assessed in 155 very low birth weight (VLBW) infants during the first 12 months after expected term. Visual development was examined (mainly cross-sectionally) at 6 weeks, 3, 6, 9, and 12 months of corrected age by assessment of visual acuity, visual fields, optokinetic nystagmus and visual threat response. Many VLBW infants showed visual impairments (54.2%). No single visual function appeared to be specifically susceptible to impairments, deficits were often apparent across a range of functions. Visual impairments were observed at all test ages, and could already be assessed at 6 weeks of corrected age. The highest incidence of visual impairments was scored at 6 months corrected age. Beyond 6 months, less deficits were observed, suggesting in many infants a delayed rather than a permanently impaired visual development. In some infants deficits became evident at a later stage, after an apparently normal initial development. The results suggest that VLBW infants are at risk for impaired visual development.

Effects of perinatal hypoxia on visual development during the first year of (corrected) age.

Visual development was assessed in 124 infants (112 preterms and 12 fullterms) who had suffered from perinatal hypoxia and in 55 control preterm infants during the first year of corrected age. Using behavioural techniques, visual functions were tested during follow-up visits in the Sophia Children's Hospital. Corrected ages at testing ranged from 3 months to 1 year. During this period, infants with perinatal hypoxia showed more abnormalities in visual functions than preterm control infants. Gestational age at birth did not influence the outcome of visual development after perinatal hypoxia. Most visual impairments were demonstrated at 3 and 6 months of age. All infants with severe neuro-developmental handicaps showed visual deficits, although neuro-developmental abnormalities and visual deficits could be present as isolated phenomena. Ultrasound abnormalities related well with visual dysfunctions. Prospective studies of infants with visual deficits and a history of perinatal hypoxia are indicated.

Brightness discrimination and reward strategy in the rabbit.

Two groups of rabbits were trained on a brightness discrimination task. A two-choice discrimination apparatus was used. By means of food reward one group of rabbits was trained to open the darkest gate, the other was trained to open the brightest gate. The second group learned significantly faster than the first one.