Various Aspects Of Visual Function Research Articles

Visual function in Norwegian children aged 5-13 years with prenatal exposure to opioid maintenance therapy: A case-control study.

To assess various aspects of visual function in school children prenatally exposed to opioid maintenance therapy (OMT) and to explore possible outcome differences between prenatal methadone and buprenorphine exposure. In a cross-sectional case-control study, 63 children aged 5-13 years with prenatal OMT exposure were compared with 63 age- and gender-matched, non-exposed controls regarding important visual parameters, such as visual acuity, orthoptic status, refractive state, colour vision, and visual field. The OMT-exposed children had significantly poorer visual acuity, both for the best eye, the worst eye and binocularly. Two children had mild visual impairment. Manifest strabismus was more frequent in the OMT group, 30%, vs. 4.8% in the control group. The most frequent types of strabismus were accommodative esotropia and intermittent exotropia. Manifest nystagmus was present in 10 (16%) of the exposed children compared to one among the non-exposed children. The accommodative amplitude was decreased in the OMT group compared to the controls. After adjusting for polydrug exposure and SGA (small-for-gestational-age), the between-group differences in visual acuity, strabismus, and nystagmus remained. The methadone-exposed children had poorer visual acuity, increased frequency of strabismus and a higher percentage of nystagmus, hypermetropia and astigmatism compared to the buprenorphine-exposed children. School-age children exposed to methadone or buprenorphine in utero had a higher prevalence of strabismus and nystagmus, and a lower visual acuity and accommodation amplitude. Buprenorphine exposure was associated with more favourable results than methadone exposure on most visual outcome measures and should be the preferred substance in OMT.

Cortical Visual Impairment in CDKL5 Deficiency Disorder.

BackgroundCDKL5 deficiency disorder (CDD) is a developmental encephalopathy caused by pathogenic variants in the gene cyclin-dependent kinase-like 5. Cerebral visual impairment (CVI) is frequent in patients with CDD. In addition to being recognized as a specific feature of the pathology, it has been suggested that visual impairment may correlate with neurodevelopmental outcome and epilepsy severity, but no systematic behavioral visual assessment has been performed. The aim of our study was to evaluate clinical and electrophysiological profile of CVI in patients with CDD, to correlate various aspects of visual function to neurodevelopmental and epileptic features.MethodsThe study included all patients with CDD from the National Pathology Registry. All patients underwent neurological examination, a disease-specific functional assessment, structured clinical evaluation of visual functions, including pattern reversal visual evoked potential (VEP), and a detailed monitoring of epileptic features, including video-EEG.ResultsAll the 11 patients recorded in the CDKL5 national registry, 10 females and one male, age range of 1.5 to 24 years (mean 9, SD 7.7, median 6.5), were enrolled. Visual function is impaired in all patients; in particular, visual fields, visual acuity, contrast sensitivity, and stereopsis were consistently abnormal whereas other aspects, such as fixing and tracking, were relatively preserved. Pattern reversal VEP was abnormal in nearly 80% of our patients. No correlation was found among CVI severity, age, level of psychomotor development, EEG abnormalities, and pathology stages even if an overall less abnormal EEG pattern was more often associated with better visual results.ConclusionIn conclusion, CVI can be considered as a major feature of CDD with a diffuse involvement in several behavioral and electrophysiological aspects. Larger cohorts will help to better clarify the possible prognostic role of EEG severity in predicting both visual and developmental abnormalities.

Measuring the Contrast Sensitivity Function in Non-Neovascular and Neovascular Age-Related Macular Degeneration: The Quantitative Contrast Sensitivity Function Test.

Age-related macular degeneration (AMD) affects various aspects of visual function compromising patients’ functional vision and quality of life. Compared to visual acuity, contrast sensitivity correlates better with vision-related quality of life and subjectively perceived visual impairment. It may also be affected earlier in the course of AMD than visual acuity. However, lengthy testing times, coarse sampling and resolution, and poor test–retest reliability of the existing contrast testing methods have limited its widespread adoption into routine clinical practice. Using active learning principles, the qCSF can efficiently measure contrast sensitivity across multiple spatial frequencies with both high sensitivity in detecting subtle changes in visual function and robust test–retest reliability, emerging as a promising visual function endpoint in AMD both in clinical practice and future clinical trials.

Age-related changes in local and global visual perception

Over the past 40 years, research has addressed the impact of the aging process on various aspects of visual function. Most studies have focused on age-related visual impairment in low-level local features of visual objects, such as orientation, contrast sensitivity and spatial frequency. However, whether there are lifespan changes in global visual perception is still unclear. To suitably frame this question, we defined global visual patterns by a topological approach, and local visual patterns were manipulated with different levels of geometrical invariants in descending order of structural stability from projective, affine, and then Euclidean features. Using the Configural Superiority Effect, we investigated the influence of aging on local and global visual perception through a comparison of young and old adults in Experiment 1; moreover, we provided continuous-aging data from 21 to 78 years of age to investigate age-related changes in visual perception in Experiment 2. We found a large perceptual decline across increasing age groups in local geometrical perception: for example, Euclidean (orientation), affine (parallelism), and projective (collinearity) discrimination. Moreover, the study provides a counterintuitive finding that global topological perception resists the aging process and remains constant throughout adult lifespan. These findings highlight the possibility that for humans, global topology may be a stable and fundamental component by which visual systems represent and characterize objects.

Early visual assessment in preterm infants with and without brain lesions: Correlation with visual and neurodevelopmental outcome at 12 months

Background Several studies have reported the development of various aspects of visual function in infancy and early childhood in both preterm and term-born infants, but only a few studies have focused on the predictive power of neonatal visual findings in infants with brain lesions. Aims To explore visual findings at term age, and at 3 and 12 months corrected age in preterm infants (gestational age < 33 weeks) with and without brain lesions; to compare the assessment at term age and at 12 months; and to assess the relationship between visual findings and neurodevelopmental outcome at 12 months. Study design Cranial ultrasound scans (US) were classified in normal, mild or major abnormalities. One-hundred and forty-five infants were assessed with age specific tests for visual function at term age, and at 3 and 12 months. Neurodevelopmental assessment (Griffiths' Scales) was performed at 12 months. Results A good correlation was found between early and late visual assessment and neurodevelopment outcome. Of the 121 infants with normal neonatal visual assessment, 119 were also normal at 12 months and 116 had normal developmental quotient. Of the 24 infants with abnormal neonatal visual assessment, 12 were also abnormal at 12 months. All the false positives had normalised by 3 months. Of the 35 infants with major US abnormalities, 20 had normal and 15 abnormal scores on the neonatal assessment. At 1 year 17 had normal and 18 abnormal scores. Conclusion A normal visual assessment at term age is a good predictor of normal visual and neurodevelopmental outcome at 12 months. An abnormal visual examination in the neonatal period was a less reliable prognostic indicator, infant should be reassessed at 3 months.

Visual performance and brain structures in the developing brain of pre-term infants

The presence of abnormal visual function has been related to overt lesions in the thalami, peritrigonal white matter (such as cavitational-necrotic periventricular leucomalacia) and optic radiations, and also to the extent of occipital cortex involvement. The normal development of visual function seems to depend on the integrity of a network that includes not only optic radiations and the primary visual cortex but also other cortical and subcortical areas, such as the frontal or temporal lobes or basal ganglia, which have been found to play a topical role in the development of vision. Therefore, the complex functions and functional connectivity of the developing brain of premature infants can be studied only with highly sophisticated techniques such as diffusion tensor tractography. The combined use of visual tests and neonatal structural and functional neuroimaging, which have become available for newborn infants, provides a better understanding of the correlation between structure and function from early life. This appears to be particularly relevant considering the essential role of early visual function in cognitive development. The identification of early visual impairment is also important, as it allows for early enrolment in intervention programmes. The association of clinical and functional studies to newer imaging techniques, which are being increasingly used also in neonates, are likely to provide further information on early aspects of vision and the mechanisms underlying brain plasticity, which are still not fully understood. Early exposure to a difficult postnatal environment together with early and unexpected removal from a protective milieu are exclusive and peculiar factors of prematurity that interfere with the normal development of the visual system in pre-term babies. The problem is further compounded by the influence of different perinatal brain lesions affecting the developing brain of premature babies. Nevertheless, in the last few decades, there have been considerable advances in our understanding of the development of vision in pre-term infants during early infancy. This has mainly been due to the development of age-specific tests assessing various aspects of visual function, from ophthalmological examination to more cortical aspects of vision, such as the ability to process orientation or different aspects of visual attention [1–7]. Improvements in understanding very early and specific neurological impairments in neurological functions have been reported in pre-term infants, known to be at risk of developing visual and visual-perceptual impairment. These impairments are due not only to retinopathy, a common finding in premature infants, but also to cerebral (central) visual impairment, secondary to brain lesions affecting the central visual pathway.

Cortical Visual Function in Preterm Infants in the First Year

To assess visual function in low-risk preterm infants at 3, 5, and 12 months corrected age to determine whether the maturation of visual function in the first year is similar to that reported in term-born infants. Seventy-five low-risk infants (25.0-30.9 weeks gestation) underwent ophthalmological examinations and a battery of tests (fix and follow, visual fields, acuity, attention at distance, and fixation shift) designed to assess various aspects of visual function at 3, 5, and 12 months corrected age. The results were comparable with normative data from term-born infants in all tests but fixation shift, suggesting that maturation of most aspects of visual function is not significantly affected by preterm birth. In contrast, >25% of preterm infants failed the fixation shift test at 3 months, with a higher percentage of failing at 5 and 12 months. There is a specific profile of early visual behavior in low-risk preterm infants, with a high percentage of infants failing a test that specifically assesses visual attention and provides a measure of cortical processing.

Early assessment of visual function in preterm infants: How early is early?

Background Several studies reported on various aspects of visual function at term age and in the first months after birth but less has been reported in preterm infants before they reach termequivalent age. Aims To assess the suitability of a battery of tests of visual function for use in infants born at < 33 weeks gestation (GA) and assessed before 34 weeks post-menstrual age (PMA); to evaluate the distribution of the findings according to GA, and to compare the data with those previously published on preterm infants assessed at 35 weeks PMA. Study design Cross-sectional study. Subjects Sixty-four preterm infants with a GA < 33 weeks were studied. Outcome measures We used a battery of visual function tests previously validated at 35 and 40 weeks PMA in low-risk preterm infants. All the infants in this current study underwent the same assessment before 34 weeks PMA. Results Before 31 weeks PMA most infants could not be reliably assessed because of clinical instability, whilst after 31 weeks PMA most infants could be assessed and they showed progressive maturation in their responses with PMA. Some items (spontaneous ocular motility, horizontal tracking, tracking a coloured stimulus, and ocular fixation) showed similar results at 32–33 weeks PMA to those found in low-risk preterm at 35 weeks PMA. Ocular movements to a target and arc tracking were the items with the most immature responses. Conclusions Our results provide further evidence that a structured assessment of visual function can be used in clinical routine and for research purposes in infants as young as 31 weeks PMA.

Longitudinal assessment of visual development in non-syndromic craniosynostosis: a 1-year pre- and post-surgical study

Objective:to investigate visual function pre- and post surgery in children with single-suture non-syndromic craniosynostosisDesign:Twenty-nine infants (12 with sagittal synostosis, 10 with trigonocephaly and 7 with anterior plagiocephaly) were longitudinally evaluated...

Visual function in infants with non‐syndromic craniosynostosis

The aim of this study was to assess various aspects of visual function in children with single-suture, non-syndromic craniosynostosis. Thirty-eight infants (28 males, 10 females; age range 3.5-13mo, mean age 7mo, 11 with plagiocephaly, 12 with trigonocephaly, and 15 with scaphocephaly), were assessed with a battery of tests specifically designed to assess various aspects of visual function in infancy. Thirty-two of the 38 infants had at least one abnormality on one of the aspects of visual function assessed. Abnormal eye movements were found in eight infants of the whole cohort and were mainly found in infants with plagiocephaly (6/11), who also had frequent visual field abnormalities (5/11). In contrast, fixation shift, an aspect of visual function related to the integrity of parietal lobes, was more frequently abnormal in patients with scaphocephaly. Our results suggest that the presence and severity of visual impairment is related to the type of craniosynostosis. Follow-up studies after surgical correction are needed to evaluate the possible beneficial effects of reconstructive surgery on visual function.

Visual development in infants with prenatal post-haemorrhagic ventricular dilatation

Objective: The aim of this study was to assess visual function in 13 infants with evidence of prenatal post haemorrhagic ventricular dilatation. Design: Infants were assessed at 5, 12 and...

Thalamic atrophy in infants with PVL and cerebral visual impairment

The aim of this retrospective study was to establish the presence and severity of cerebral visual impairment in preterm infants with PVL. We also wished to establish whether abnormalities of visual function are related to brain MRI findings and more specifically not only to the involvement of optic radiations and occipital cortex but also to changes in the thalami, that are often affected in infants with PVL. Twelve infants with cystic PVL were assessed at 1 year (+ 2) corrected age with a battery of tests specifically designed to assess various aspects of visual function in infancy, such as ocular movements, visual acuity, visual fields and fixation shift. All infants also had a brain MRI. Eleven of the 12 had involvement of the optic radiations: all had some abnormalities of visual function and visual impairment was more severe in infants with more extensive involvement of the optic radiations. The child with normal optic radiations had normal visual function. Six of the 12 infants also had obvious signs of atrophy of the thalami and all had severe and wide-ranging abnormalities of visual function in all testing domains. Two children had equivocal atrophy of the thalami, both had some abnormalities of visual function. Four children had normal thalami and had normal visual function or only minor abnormalities on one of the visual tests. Our results suggest that the atrophy of the thalami may play an additional role in the abnormal development of visual function in infants with PVL and abnormal optic radiations.

139 Visual Findings in Infants with Periventricular Leukomalacia

Aims. The aim of the study was to assess cortical visual function in infants with cystic periventricular leukomalacia (PVL).Methods. Patients with type 3 PVL were assessed at 12 months corrected age using a battery of tests specifically designed to assess various aspects of visual function, including ocular movements, visual acuity (Keeler cards), visual fields and fixation shift. Infants with moderate or severe retinopathy (>stage 1) were excluded.Results. Thirteen infants (5 m, 8 f) with GA 30.6 + 3.7 weeks and BW 1573 + 583 grams were included in the study. All had some abnormalities of visual function but the spectrum of severity observed was very wide, ranging from isolated abnormal ocular movements to severe abnormalities on all the aspects of visual function assessed. Ocular movements abnormalities were frequent (11/13) often associated to inability to follow an object for a complete arc. Acuity was reduced in 9/13, fixation shift was abnormal in 11/13 and visual fields were reduced in 10/13. Brain MRI was available in 12 of the 13 infants and all had abnormal optic radiations. The infants who also had obvious signs of atrophy of the thalami had a higher risk of developing more severe visual abnormalities.Conclusions. Our results suggest that visual abnormalities are frequent in infants with cystic PVL and that a detailed assessment of various aspects of visual functions should be performed in order to identify the severity of cortical visual impairment.

Assessment of Visual Function in Children with Methylmalonic Aciduria and Homocystinuria

The aim of this study was to assess various aspects of visual function in 6 patients (age range: 9 months to 7 years and 8 months) with methylmalonic aciduria and homocystinuria. All patients had an ophthalmological examination and were tested with a battery of age-appropriate tests assessing various aspects of visual function such as acuity, visual fields and visual attention. None of the patients had significant retinal abnormalities but all 6 had nystagmus which was associated with strabismus in 3 of the 6. They all had some abnormalities on the behavioral tests assessing visual function which appeared to be related to the age of the patients. Visual impairment was more severe in the 3 patients below 3 years of age and milder in the older patients. The presence and the severity of abnormalities, in contrast, did not depend on the age at onset or the age when treatment was started and were only partly related to brain MRI findings. Severe hydrocephalus and basal ganglia involvement were associated with severe visual impairment, but abnormal visual findings were also present in the children with normal MRI and isolated mild periventricular changes. Our results suggest that age, brain lesions and other factors may be responsible for visual abnormalities in methylmalonic aciduria and homocystinuria. Further studies using early and sequential assessment of visual function are needed to establish whether the differences observed between younger and older children may be related to the duration of therapy.

DENDRITIC BRANCHING OF PYRAMIDAL CELLS IN THE VISUAL CORTEX OF THE NOCTURNAL OWL MONKEY: A FRACTAL ANALYSIS

The branching structure of neurones is thought to influence patterns of connectivity and how inputs are integrated within the arbor. Recent studies have revealed a remarkable degree of variation in the branching structure of pyramidal cells in the cerebral cortex of diurnal primates, suggesting regional specialization in neuronal function. Such specialization in pyramidal cell structure may be important for various aspects of visual function, such as object recognition and color processing. To better understand the functional role of regional variation in the pyramidal cell phenotype in visual processing, we determined the complexity of the dendritic branching pattern of pyramidal cells in visual cortex of the nocturnal New World owl monkey. We used the fractal dilation method to quantify the branching structure of pyramidal cells in the primary visual area (V1), the second visual area (V2) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively), which are often associated with color processing. We found that, as in diurnal monkeys, there was a trend for cells of increasing fractal dimension with progression through these cortical areas. The increasing complexity paralleled a trend for increasing symmetry. That we found a similar trend in both diurnal and nocturnal monkeys suggests that it was a feature of a common anthropoid ancestor.

Neonatal cerebral infarction and visual function at school age

Objective: To assess various aspects of visual function at school age in children with neonatal cerebral infarction. Patients and methods: Sixteen children born at term, who had cerebral infarction of...

Assessing visual function in clinical practice

Examination of the afferent visual system involves a structural assessment of the eye, the associated neurological structures, and the ocular adnexa, in addition to an evaluation of afferent visual function. The most common measure of visual function is Snellen visual acuity, which provides a rapid and useful measure of some aspects of central visual function but is a subjective parameter that conveys limited information regarding the overall function of the visual system. A wide variety of psychophysical and electrophysiological tests have been developed to capture various aspects of visual function more thoroughly. The main goal of this issue of the Ophthalmology Clinics of North America is to provide a comprehensive overview of tests that are currently available to practicing clinicians and promising new technologies that may eventually provide useful clinical information. This issue begins with a summary of techniques for evaluating the afferent pupillary light response. This often-underemphasized aspect of the afferent visual examination provides the only objective information regarding visual function that is readily available to a clinician during a routine eye exam. The articles by Kniestedt and Stamper, Swanson and Cohen, and Anderson review the evaluation of visual acuity, color vision, and standard perimetry, which, along with pupillary assessment, form the backbone of the clinical evaluation of visual function in standard practice. Owsley reviews contrast sensitivity, which is not used as often as it should be in clinical practice but nevertheless provides a more comprehensive measure of central function. Specialized tests of peripheral function are summarized by Anderson and Johnson and Racette and Sample for both short-wavelength automated perimetry and frequency doubling technology perimetry, which are designed to emphasize specific ganglion cell subpopulations and improve the sensitivity of visual field testing. Finally, Holopigian and Hood provide a thorough overview of the broad topic of electrophysiology; this article reviews tests that are useful in elucidating causes of occult visual loss (eg, electroretinography, electro-oculography, and visual-evoked potentials) as well as more recent developments in this area, including multifocal electrophysiologic techniques. Robbins and colleagues and Schneck and Haegerstrom-Portnoy tackle the difficult problems associated with visual function assessment in pediatric and elderly populations. These articles provide readers with practical tips and guidelines for the examination of these more challenging patients. Finally, Ball brings the assessment of visual function out of the clinic and laboratory in her summary of visual function in the real world. This

Basal ganglia damage and impaired visual function in the newborn infant

AIMTo examine the effects of early lesions in the visual pathway on visual function; and to identify early prognostic indicators of visual abnormalities.METHODSThe visual function of 37 infants with perinatal...

Visual function in full-term infants with hypoxic-ischaemic encephalopathy.

Thirty-one full term infants with hypoxic-ischaemic encephalopathy (HIE) were studied with a battery of tests designed to evaluate visual function in infancy and with serial MRI. Their age ranged between 5 and 31 months. The aim of the study was to evaluate whether the degree of HIE or the site and size of lesions on MRI could predict visual outcome. Twenty of the 31 infants studied showed abnormal results on at least one of the visual tests used. While visual function was generally normal in grade I HIE and severely impaired in grade III, visual outcome was variable in grade II. MRI findings were better predictors of visual impairment than the degree of HIE. Normal scans tended to be associated with normal visual function, irrespective of the severity of HIE. All but one of the infants with diffuse hemispheric involvement also showed multiple visual abnormalities. The concomitant involvement of basal ganglia was always associated with more severe visual outcome. These results suggest that infants with generalised lesions secondary to global insults are at high risk of severe visual impairment even in presence of normal acuity and require early assessment of various aspects of visual function.

Visual function during acute hypoglycaemia.

Hypoglycaemia symptoms are of particular interest in view of the importance of hypoglycaemia unawareness. Visual symptoms arising during acute hypoglycaemia may be the result of metabolic disturbances in the visual pathways within the central nervous system or impairment of the refractive apparatus of the eye and binocular function. This study investigated the effect of hypoglycaemia upon visual acuity, binocular interaction and contrast sensitivity. Various aspects of visual function were examined in ten normal subjects before, during and after acute insulin-induced hypoglycaemia. A simultaneous study of hypoglycaemic symptoms enabled us to relate the objective findings to the symptoms as reported by the subjects. Snellen visual acuity, fusion and stereopsis were not affected by hypoglycaemia. Five subjects noted visual disturbance. Eight developed significant impairment of contrast sensitivity, which closely matched the lowered blood glucose concentration. These observations suggest that hypoglycaemic visual symptoms are due to neuroglycopenia of central visual pathways rather than changes within the refractive apparatus or abnormality of binocular function. Although these symptoms are not a constant feature of the hypoglycaemic state, subtle impairment of visual function occurs in most cases. Contrast sensitivity testing can be useful for assessment of fine changes in visual function.