Infant Vision Research Articles

Vitreoretinal findings similar to retinopathy of prematurity in infants with compound heterozygous protein S deficiency

Objective To present previously undescribed vitreoretinal findings similar to severe retinopathy of prematurity (ROP) in two siblings (daughter and son) with a thrombophilic disorder, compound heterozygous protein S (PS) deficiency. Design Family genotype study and literature review. Participants Two unrelated heterozygous PS-deficient parents and their two children with compound heterozygous PS deficiency were studied. The gestational age and birth weight of the daughter were 40 weeks and 3200 g, respectively, and those of the son were 34 weeks and 2150 g, respectively. Three other neonates with homozygous or compound heterozygous PS deficiency and ophthalmologic findings were identified in the literature. Intervention The daughter underwent lensectomy-vitrectomy at 48 weeks adjusted age bilaterally. The son underwent therapy developed for severe ROP: laser therapy of the peripheral avascular retina at 39 weeks adjusted age, and bilateral lensectomy-vitrectomy with membrane peel of intravitreous proliferation from the optic disc at 42 weeks adjusted age. Main outcome measures The main clinical outcome measures were retinal appearance and functional vision. Genotypes of the family members were determined. Results One of the four eyes retained functional vision. A normal-appearing posterior retina, normal scotopic and photopic flash electroretinograms, and a normal flash visual-evoked response were documented from the left eye of the son at 62 weeks adjusted age. The other three eyes had inoperable retinal detachments and no functional vision. The mother had type I PS deficiency and the father had type II PS deficiency. Compound heterozygous PS deficiency was confirmed in both children. Conclusion In both children, normal vasculogenesis was interrupted. At 39 weeks adjusted age, the retinal examination of the son revealed extraretinal fibrovascular proliferation at the optic disc (reactivation of the hyaloid system) and in the peripheral retina (interruption of inner retinal vascularization). Patients with homozygous or compound heterozygous PS deficiency may present as infants with severe ROP. The authors’ experience suggests that appropriately timed surgical procedures, which are efficacious for ROP, can preserve vision in infants with thrombophilic disorders.

From the symptom to electroretinography diagnosis

Retinal function can be documented noninvasively and objectively by electroretinography, complementing clinical examinations. Symptoms of nightblindness and of dayblindness with photoaversion, nystagmus, poor vision in infants or unclear visual field defects are meaningful indications for ERG testing. We use standardized (ISCEV) full-field single flash ERGs to evaluate the function of the rod- and of the cone-system. In infants, general anesthesia is useful to combine an abbreviated ERG protocol with ophthalmoscopy and fundus photography. ERG testing facilitates to distinguish between functional deficits in the rod- and cone-system, between congenital-stationary retinal dysfunction and progressive retinal heredo-degenerations. Frequently a functional deficit of the retina without ophthalmoscopic changes can be assessed. These entities include achromatopsia, congenital stationary night blindness, early stages of retinitis pigmentosa (RP) or progressive cone dystrophy, as well as toxic retinal changes. Congenital amaurosis Leber (LCA), infantile RP, Usher's syndrome and retinal involvement in other neuropediatric or metabolic syndromes can be diagnosed or excluded by ERG recording early-on. Synoptic evaluation of the full-field ERG, pattern-ERG and VEP completes neuro-ophthalmological screening.

Polyunsaturated fatty acids and infant visual development: a critical appraisal of randomized clinical trials.

At the Consensus and Controversies Conference held in Barcelona in November 1996, one of the sessions focused on an evaluation of the effects of dietary polyunsaturated fatty acids (PUFA) on infant visual development. The intervention trials in preterm and term infants were reviewed and discussed in detail. Results of these trials, particularly those in term infants, were inconsistent; much discussion occurred concerning the causes of these diverse results. We attempt to reflect, rather than report exactly, the discussion relating to these issues and address the clinical trials according to recently published guidelines for conduct and reporting of randomized clinical trials (RCT). Compared with these recent guidelines, the published papers of RCT involving PUFA and visual function are often incomplete, making it difficult to assess if we can have a high degree of confidence in the reported effects (or lack of effects). Despite this, valuable data relating to the effect of diet on the visual development of infants were obtained. Our evaluation of the trials to date suggests that the definitive answer to the degree to which dietary long-chain PUFA is likely to influence visual development may only be resolved with impeccably conducted RCT.

Development of grating acuity in infants with Retinopathy of Prematurity

To evaluate the visual development in infants with stage 1 approximately 3 ROP and compare their visual results with healthy preterm infants. One hundred forty-four premature infants were recruited and were divided into 3 groups according to the stage of ROP. Randomly selected preterm subjects with no ROP were taken as controls. Ophthalmic examinations started 4 to 7 weeks after birth and were repeated as needed until the retina was fully vascularized or until any ROP that developed had resolved. Grating acuity was measured by acuity cards between 35-45 weeks of corrected age and by PL method at 12, 18 and 24 months of age. Infants with stage 3 ROP had slightly lower visual acuity scores compared to other infants at most of the testing points throughout the 35-45 week period, which did not show statistical significance at any week. Infants with stage 2 and 3 ROP had similar visual acuity values but slightly lower acuity scores than infants with stage I or no ROP at the 12 month follow-up. The differences were not statistically significant. Stage 3 ROP infants had significantly lower acuity scores compared to infants with stage 1-2 or no ROP at the 18 and 24 month follow-up visits (p<0.0001). We stress periodic monitoring of early visual acuity in infants with ROP because of the possibility of impaired visual development.

M- and L-cones in early infancy: III. Comparison of genotypic and phenotypic markers of color vision in infants and adults

Genetic analyses were performed on five male children (∼3 years), two suspect color-normals and three suspects for congenital color vision deficiencies. These classifications were based on visually-evoked potential (VEP) responses to M- and L-cone-isolating stimuli obtained in a previous study when each subject was either 4- or 8-weeks old. The present analyses were performed in a blind study to characterize the genotypes of these subjects. Four male adults with various color vision phenotypes were also tested as a control. DNA was isolated using a non-invasive technique followed by polymerase chain reaction (PCR) amplification and restriction enzyme analysis to examine the genomic DNA of each subject. The genetic analyses confirmed the VEP identification of two color defective infants, and were consistent with the diagnosis of two other infants as color normal. A third infant was predicted by VEP analysis to have a protan defect, but he did not have a gene array typically found in protan observers.

The infant patient

The infant patient presents a challenge to the optometrist who must structure an examination within the infant's limited capabilities and then manage a rapidly developing visual system. The present paper provides an overview of infant visual development and the visually guided behaviours expected during normal development. Techniques for assessing vision in infant are reviewed and a recommendation is given for the optometric examination of infants. Some important urgencies, emergencies and causes of visual impairment are highlighted.

The infant patient

The infant patient presents a challenge to the optometrist who must structure an examination within the infant’s limited capabilities and then manage a rapidly developing visual system. The present paper provides an overview of infant visual development and the visually guided behaviours expected during normal development. Techniques for assessing vision in infant are reviewed and a recommendation is given for the optometric examination of infants. Some important urgencies, emergencies and causes of visual impairment are highlighted.

Book Reviews

Books reviewd in this article Understanding Specific Learning Difficulties. By Margot Prior. Infant Vision. Edited by F. Vital‐Durand, J. Atkinson, &amp;. J. Braddick. Psychoses and Pervasive Developmental Disorders in Childhood and Adolescence. Edited by F. R. Volkmar. D. W. Winnicott. A Biographical Portrait. By B. Kahr. The Construction of Racial Identity in Children of Mixed Parentage: Mixed Metaphors. By I. Katz.

Feature Issues on Infant Vision

Feature Issues on Infant Vision

Two infant vision screening programmes: Prediction and prevention of strabismus and amblyopia from photo- and videorefractive screening

Two infant vision screening programmes: Prediction and prevention of strabismus and amblyopia from photo- and videorefractive screening

Vision and Hearing In ELBW Infants at 10 years: NL versus CH 44

Aim: To compare two regionally defined extremely low birth weight (ELBW) populations for visual and hearing problems at 10 years of age. Subjects: All lifeboms with birth weight 500-999 g born 1983 in NL (prevalence 1.69%.) and 1983-85 in CH (prev.1.64%).

Objective assessment of spatial vision using the visual evoked potential

Early assessment of the visual function is very important, as many congenital and acquired visual anomalies may lead to permanent visual loss, if not detected and effectively treated within the critical period of visual system development. Any tests employed to assess vision in infants should be objective and give a valid result quickly.The visual evoked potential (VEP) does not require active responses from the patient. It is recorded in relation to a time‐locked stimulus, typically a grating that reverses in phase (pattern reversal VEPs). Reversal VEPs have been used to estimate visual acuity. A more complete psychophysical description of the visual function is obtained with the contrast sensitivity function (CSF) which determines visibility not only of the finest detail, but also of a wide range of spatial frequencies. However, the VEP amplitude versus spatial frequency function does not accurately reflect the normal CSF when reversing gratings are employed. Reduced VEP responses are obtained in the middle spatial frequency range where stimulus visibility is highest.Here we show that 16 Hz on‐off modulation of a grating elicits a VEP versus spatial frequency plot which is similar to the CSF in a group of normal adults. When compared with reversal modulation, the test was more predictive of spatial vision defects in a group of amblyopes, thus demonstrating its clinical utility. We have shown that the same technique can be used to monitor age‐related changes in spatial vision in a group of infants whose ages ranged from 5 weeks to 14 months. The test promises to be a useful clinical tool in paediatric ophthalmology.Supported by a grant from the North Western Regional Health Authority.

Visual development in infants and young children with Down's syndrome

Visual development in infants and young children with Down's syndrome

Visual development in infants and young children with Down's syndrome

Purpose: Ocular and refractive defects are common amongst people with Down's syndrome. We are conducting a long‐term study of the development of refraction, accommodation and acuity in infants with Down's syndrome, from 12 weeks of age, in order to identify age of onset and possible consequences of such defects.Methods: To date, 54 children have entered the study. All measurements are made during home visits, and comprise Mohindra and dynamic retinoscopy, and Preferential Looking.Results: Cross‐sectional data suggest that acuity lies within normal ranges in infancy, and falls behind the norms only from the age of 2 years. Refractive errors in the general population decrease in infancy (the process of emmetropisation). Our data show that the opposite happens in children with Down's syndrome. The prevalence of refractive errors is higher in the preschool and school‐age children, than amongst the infants. Accommodation is defective from the earliest age of testing. Infants and young children with Down's syndrome consistently under‐accommodate to near targets, even when visual acuity and refractive errors are normal.Conclusions: The implication of accommodative dysfunction on emmetropisation is considered, and the possible association between visual and cognitive development explored.

RANDOT STEREOACUITY NORMS IN CHILDREN

1Exceptional Child and Infant Vision Testing Lab, The Ohio State University College of Optometry, Columbus, OH; 2The Ohio State University College of Optometry, Columbus, OH.

COMPARISONS OF STEREOTHRESHOLD FOR CONTOUR AND RANDOM DOT TARGETS

1Exceptional Child and Infant Vision Testing Lab, The Ohio State University College of Optometry, Columbus, OH; 2United States Armed Services, Biloxi, MI.

Infant luminance and chromatic contrast sensitivity: Optokinetic nystagmus data on 3-month-olds

Infant color vision is poor, and most psychophysical experiments agree that infant color vision emerges between ages 3 weeks and 3 months. Presumably, the color vision of infants is poor during the months immediately after it has emerged. We have tested two alternative explanations for the poor color vision of infants: (1) there is a special critical immaturity within the color pathways of infants; (2) infants have poor infant color vision because they are insensitive to contrast. Luminance and chromatic contrast thresholds were measured on 3-month-olds using optokinetic nystagmus (OKN), and adult luminance and chromatic contrast thresholds were measured using OKN and two forced-choice methods: direction-of-motion discrimination and grating detection. The infant chromatic-to-luminance contrast threshold ratio shows that infants are as sensitive or even more sensitive than adults to color, depending on the testing method used on adults. This result suggests that the general contrast insensitivity hypothesis is correct. Conservative “worst-case” quantitative analysis strongly suggests that this result is not the consequence of a luminance artifact.

Visual function deficits in children.

In the past year, new work on sensory testing in preverbal infants has expanded our knowledge in three areas: 1) visual acuity testing in infants in varying levels of illumination; 2) visual evoked cortical potential-evidence for binocular function in infantile esotropia; and 3) a new time-efficient method to evaluate color vision in newborns and infants. A newly reported sequel to loss of binocularity is the development of A and V pattern strabismus. In another study, loss of fusion, as with acute concomitant esotropia, was shown to be a sign of serious intracranial disease. Regarding motor visual function deficits, new treatments of infantile esotropia syndrome and nystagmus with botulinum toxin type A are presented. Regarding social issues, visual function deficit of abused children and infants born to drug-abusing mothers are presented as a timely reminder that child abuse is still an enormous social problem, and that the visual system is far from exempt from damage.

Transient Cortical Blindness in an Infant Exposed to Methamphetamine

An 11-month-old boy was brought to the pediatric emergency department for evaluation of acute onset of irritability and involuntary side-to-side turning of the head. Neurologic examination revealed cortical blindness. Toxicologic studies of blood and urine were positive for methamphetamine. The infant's vision and activity returned to normal within 12 hours. The possible mechanisms of this unusual form of amphetamine toxicity are discussed.[Gospe SM: Transient cortical blindness in an infant exposed to methamphetamine. Ann Emerg Med September 1995;26:380-382.]

Research opportunities in the Hospital Eye Service

Summary An analysis was undertaken of higher degrees by research awarded to optometrists based in the Hospital Eye Service since 1968. When these were considered in conjunction with current registration for higher degrees, it was possible to analyse research areas. The most popular topics were glaucoma, detection and measurement of progression (5); cornea (4); ocular biometry (3); infant vision and development (3); keratoconus (3); and contact lenses (3). In recent years, the scope of research has increased considerably and now embraces epidemiology, health economics and interdisciplinary decision making with other healthcare professionals. Successful completion rates for British College of Optometrist's Scholars for higher degrees for the hospital and university sectors were analysed. The total completion rate was 16/26 (65.4%), university based: 11/20 (55%), and hospital based: 6/6 (100%).