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Visual acuity measurement is important for the detection and monitoring of eye disorders. Developing accurate and sensitive visual acuity tests suitable for young children is therefore desirable. Recognition or form visual acuity (VA), which is measured with matching in children aged 3 years and up, is more sensitive for detecting visual deficits compared to resolution VA. The Waterloo Differential Acuity Test (WatDAT) is a proposed recognition VA test using the concept of identifying the "odd one out" among distractors. The WatDAT is expected to be cognitively easier than matching tests and therefore may be used in younger children. The purpose of this study is to investigate the testability of the WatDAT paradigm in children aged 12–36 months, and to determine the optimum format and number of distractors. Fifty-one typically-developing children aged 12–36 months participated in the study. Data for Patti Pics (PP) and Face targets (FT) were collected for formats with 3, 4 and 5 distractors. The targets were presented binocularly on a computer touch screen at 30 cm. The task was to touch the face among identical non-faces or a house among circles. Following initial training, there were 5 presentations for each distractor format. Testability was defined as correctly identifying at least 4/5 presentations and was also determined for uncrowded PP symbols using matching. Of participants aged 18–36 months, 87% could perform the WatDAT PP targets with 3 distractors compared to 68% for the FT, while 48% could perform matching with PP. The testability for FT increased to 85% for children ≥22 months. Younger children showed lower testability. For the 3 distractor format, PP targets gave 9% testability in children 12 to <18 months, and FT gave a testability of 16% in children 12 to <22 months. WatDAT testability is higher than matching VA tests. This indicates that the newly developed WatDAT has potential for measuring recognition VA in children 18 months and older. [ABSTRACT FROM AUTHOR]

Purpose: To describe emerging applications of machine learning (ML) in pediatric ophthalmology with an emphasis on the diagnosis and treatment of disorders affecting visual development. Methods: Literature review of studies applying ML algorithms to problems in pediatric ophthalmology. Results: At present, the ML literature emphasizes applications in retinopathy of prematurity. However, there are increasing efforts to apply ML techniques in the diagnosis of amblyogenic conditions such as pediatric cataracts, strabismus, and high refractive error. Conclusions: A greater understanding of the principles governing ML will enable pediatric eye care providers to apply the methodology to unexplored challenges within the subspecialty. [ABSTRACT FROM AUTHOR]

Purpose: To report the newest ophthalmic manifestations of a mother-daughter pair diagnosed with toe syndactyly, telecanthus, anogenital and renal malformations (STAR) syndrome, a rare X-linked developmental disorder. Methods: The medical and ophthalmic records were reviewed for a mother-daughter pair diagnosed with FAM58A confirmed STAR syndrome on chromosome Xq28. Results: The m other at birth had left foot syndactyly, telecanthus, anal stenosis, and clitoromegaly and was told at 19 she had a hypoplastic left kidney. The daughter, born at 38 weeks after a complication of oligohydramnios, had a more severe presentation, demonstrating toe syndactyly, telecanthus, anal stenosis, clitoromegaly, bilateral renal hypoplasia, ureteral reflux, urogenital sinus, and congenital heart disease amongst others. The pair shared similar ophthalmic findings, though those of the daughter were more pronounced. They included bilateral, medial upper eyelid prominences with madarosis, mild peripapillary atrophy, and soft macular drusen with the daughter also displaying optic nerve hypoplasia and peripheral anterior synechia in the iridocorneal angle. Conclusion: These ophthalmic findings are the first reported to our knowledge in association with STAR syndrome. The literature frequently demonstrates that patients with developmental anomalies often have ocular manifestations, warranting a full ophthalmic examination when the diagnosis of STAR syndrome has been made or is being considered. [ABSTRACT FROM AUTHOR]

Normative visual field area, feasibility and repeatability using (Octopus) semi-automated kinetic perimetry are reported in 221 healthy volunteers aged 5-22 years. I4e and I2e stimuli assessed the visual field at 5°/second (°/s) or 3°/s. Blind spot was assessed with I2e at 2°/s. Reliable visual fields were plotted in 23% of participants <10 years, 64% of 10-12-year-olds, and 98% aged 13-22 years. Visual field areas were unchanged with age using 5°/s, but increased using 3°/s for I2e ( p = 0.028). Blind spot area was unchanged with age. Reaction times reduced with age ( p < 0.004). There was no learning effect. A test speed of 5°/s is recommended. [ABSTRACT FROM AUTHOR]

Aims: To document the expression of vasoactive intestinal polypeptide (VIP) in the visual cortex-17 of kittens with anisometropic amblyopia, and to investigate the relationship between VIP and the development of the visual system. Methods: Sixteen normal kittens (4-wk of age) were randomly divided into two groups: control and amblyopic. Amblyopia was produced by atropinization of one eye in eight kittens. Four (2 normal and 2 amblyopia) kittens were sacrificed at weeks 3, 6, 9, or 12 post-treatment respectively. Expression of VIP-mRNA in the visual cortex-17 was detected through in-situ hybridization. Neurons in the visual cortex were visualized by transmission electron microscopy (TEM). The number of neurons was analyzed via light microscopy (LM). Results: VIP-mRNA expression was increased with age in control kittens but remained nearly static in age-matched anisometropic amblyopic kittens ( p < 0.05). The number of VIP-positive cells of amblyopic kittens decreased dramatically when compared to normal age-matched kittens ( p < 0.05). The total comparison between different positive ranks suggested a significant difference. The degree of expression between these two groups was significantly different. Ultrastructurally, in the control group, the nuclear membrane of most neurons was discernable and chromatin was evenly distributed within the nucleus. Abundant cytoplasm and tubular-shaped mitochondria were observed. These cells were also rich in Golgi bodies, ribosomes, and endoplasmic reticulum. In amblyopic kittens, nuclei of most neurons were aggregated, the number of ribosomes and Golgi bodies was reduced, mitochondria were swollen, and mitochondrial cristae were shortened or even absent. The endoplasmic reticulum was distended and reduced in magnitude. Conclusions: VIP appears to play an important role in visual development, and its mRNA expression is affected by visual experiences. Visual dysfunction may down-regulate the expression of VIP-mRNA by impairing the structure and function of the neurons in the visual cortex, finally leading to amblyopia. [ABSTRACT FROM AUTHOR]

Aims: To document the expression of vasoactive intestinal polypeptide (VIP) in the visual cortex-17 of kittens with anisometropic amblyopia, and to investigate the relationship between VIP and the development of the visual system. Methods: Sixteen normal kittens (4-wk of age) were randomly divided into two groups: control and amblyopic. Amblyopia was produced by atropinization of one eye in eight kittens. Four (2 normal and 2 amblyopia) kittens were sacrificed at weeks 3, 6, 9, or 12 post-treatment respectively. Expression of VIP-mRNA in the visual cortex-17 was detected through in-situ hybridization. Neurons in the visual cortex were visualized by transmission electron microscopy (TEM). The number of neurons was analyzed via light microscopy (LM). Results: VIP-mRNA expression was increased with age in control kittens but remained nearly static in age-matched anisometropic amblyopic kittens ( p < 0.05). The number of VIP-positive cells of amblyopic kittens decreased dramatically when compared to normal age-matched kittens ( p < 0.05). The total comparison between different positive ranks suggested a significant difference. The degree of expression between these two groups was significantly different. Ultrastructurally, in the control group, the nuclear membrane of most neurons was discernable and chromatin was evenly distributed within the nucleus. Abundant cytoplasm and tubular-shaped mitochondria were observed. These cells were also rich in Golgi bodies, ribosomes, and endoplasmic reticulum. In amblyopic kittens, nuclei of most neurons were aggregated, the number of ribosomes and Golgi bodies was reduced, mitochondria were swollen, and mitochondrial cristae were shortened or even absent. The endoplasmic reticulum was distended and reduced in magnitude. Conclusions: VIP appears to play an important role in visual development, and its mRNA expression is affected by visual experiences. Visual dysfunction may down-regulate the expression of VIP-mRNA by impairing the structure and function of the neurons in the visual cortex, finally leading to amblyopia. [ABSTRACT FROM AUTHOR]

Background: This study measured grating visual acuity in 173 children between 6-48 months of age who had different types of spastic cerebral palsy (CP). Method: Behavioural acuity was measured with the Teller Acuity Cards (TAC) using a staircase psychophysical procedure. Electrophysiological visual acuity was estimated using the sweep VEP (sVEP). Results: The percentage of children outside the superior tolerance limits was 44 of 63 (69%) and 50 of 55 (91%) of tetraplegic, 36 of 56 (64%) and 42 of 53 (79%) of diplegic, 10 of 48 (21%) and 12 of 40 (30%) of hemiplegic for sVEP and TAC, respectively. For the sVEP, the greater visual acuity deficit found in the tetraplegic group was significantly different from that of the hemiplegic group ( p < 0.001). In the TAC procedure the mean visual acuity deficits of the tetraplegic and diplegic groups were significantly different from that of hemiplegic group ( p < 0.001). The differences between sVEP and TAC means of visual acuity difference were statistically significant for the tetraplegic ( p < 0.001), diplegic ( p < 0.001), and hemiplegic group ( p = 0.004). Discussion: Better visual acuities were obtained in both procedures for hemiplegic children compared to diplegic or tetraplegic. Tetraplegic and diplegic children showed greater discrepancies between the TAC and sVEP results. Inter-ocular acuity difference was more frequent in sVEP measurements. Conclusions: Electrophysiologically measured visual acuity is better than behavioural visual acuity in children with CP. [ABSTRACT FROM AUTHOR]

Early in life, visual experience influences the refinement of the preferential response for specific stimulus features exhibited by neurons in the primary visual cortex. A striking example of this influence is the reduction in cortical direction selectivity observed in cats reared under high-frequency stroboscopic illumination. Although various mechanisms have been proposed to explain the maturation of individual properties of neuronal responses, a unified account of the joint development of the multiple response features of cortical neurons has remained elusive. In this study, we show that Hebbian synaptic plasticity accounts for the simultaneous refinement of orientation and direction selectivity under both normal and stroboscopic rearing, if one takes into account the spatiotemporal input to the retina during oculomotor activity. In a computational model of the LGN and V1, eye movements are sufficient to establish the patterns of thalamocortical activity required for a Hebbian refinement of both direction- and orientation-selective responses during exposure to natural stimuli. Furthermore, we show that consideration of fixational eye movements explains the simultaneous loss of direction selectivity and preservation of orientation selectivity observed as a consequence of stroboscopic rearing. These results further support a role for oculomotor activity in the refinement of the response properties of V1 neurons. [ABSTRACT FROM AUTHOR]

Cognitive scientists and developmental psychologists have suggested that development in perceptual, motor and memory functions of human infants as well as adaptive evaluation by caregivers facilitate learning for cognitive tasks by infants. This article presents a robotic approach to understanding the mechanism of how learning for joint attention can be helped by such functional development. A robot learns visuomotor mapping needed to achieve joint attention based on evaluations from a caregiver. The caregiver adjusts the criterion for evaluating the robot's performance from easy to difficult as the performance improves. At the same time, the robot also gradually develops its visual function by sharpening input images. Experiments reveal that the adaptive evaluation by the caregiver accelerates the robot's learning and that the visual development in the robot improves the accuracy of joint attention tasks due to its well-structured visuomotor mapping. These results constructively explain what roles synchronized functional development in infants and caregivers play in task learning by infants. [ABSTRACT FROM AUTHOR]

The possibility that infantile nystagmus (IN) may reflect a failure in early sensorimotor integration has been proposed for more than a century, but is only recently being borne out in animal studies. The underlying neural and genetic substrate for this plasticity is complex. We propose that, in most cases, IN develops as a developmental response to reduced contrast sensitivity to high-spatial frequencies in an early “critical period,” however caused, whether by structural malformations (e.g. foveal hypoplasia) or poor optics (e.g. cataract). As shown by psychophysics, contrast sensitivity to low spatial frequencies is enhanced by motion of the image across the retina. Based on our previous theoretical study (Harris & Berry, Nonlinear Dynamics, 2006), we argue that the best compromise between moving the image and maintaining the image near the fovea (or its remnant) is to oscillate the eyes with jerk nystagmus with increasing velocity waveforms, as seen empirically. The generation of jerk waveforms relies heavily on the saccadic system, which is immature in infancy. Pendular waveforms may therefore provide an alternative to jerk waveforms, and may explain why they are seen more often in young infants. We discuss the implications of this developmental model for the need to synchronize sensory and motor developments in normal development. Failure of this synchronization may also explain some idiopathic cases. In the congenital cases [of nystagmus] it is probable that the absence of the stimulus that accurate retinal impressions afford interferes with the functional development of the co-ordinating centers for the orbital muscles [Swanzy, 1895, p542]. [ABSTRACT FROM AUTHOR]

Within the last five years, there have been a number of exciting new advances in our knowledge and understanding of amblyopia. This article reviews recent psychophysical studies of naturally occurring amblyopia in humans. These studies suggest that: 1) There are significant differences in the patterns of visual loss among the clinically defined categories of amblyopes. A key factor in determining the nature of the loss is the presence or absence of binocularity. 2) Dysfunction within the amblyopic visual system first occurs in area V1, and the effects of amblyopia may be amplified downstream. 3) There appears to be substantial neural plasticity in the amblyopic brain beyond the “critical period.” [ABSTRACT FROM AUTHOR]

Background: The optimal age for surgery for infantile esotropia is controversial. Proponents of early surgery believe that further loss of binocular vision can be prevented by early surgery, a minority believes that binocular vision can even be restored by early surgery. The ELISSS compared early with late surgery in a prospective, controlled, non-randomized, multicenter trial. Methods: Fifty-eight clinics recruited children aged 6-18 months for the study. Each clinic operated all eligible children either 'early', i.e. at age 6-24 months, or 'late', i.e. at age 32-60 months. At baseline the angle of strabismus, refraction, degree of amblyopia and limitation of abduction were assessed. Intermediate examinations took place every six months. Children were evaluated at age six in the presence of independent observers. Primary endpoints were (i) level of binocular vision, (ii) manifest angle of strabismus at distance and (iii) remaining amblyopia. Secondary endpoints were number of operations, vertical strabismus, angle at near and the influence of surgical technique. Results: A total of 231 children were recruited for early and 301 for late surgery. Age at entry examination was 11.1 months (SD 3.7 months) in the early group and 10.9 (SD 3.7) months in the late group. Refraction, amblyopia and limitation of abduction were distributed equally in the early and late groups, but the angle of strabismus was slightly larger in the early group. Dropout-rates were 26.0% in the early and 22.3% in the late group. At age six, 13.5% of the early vs. 3.9% of the late group recognized the Titmus Housefly; 3.0% of the early and 3.9% of the late group had stereopsis beyond Titmus Housefly. No significant difference was found for angle of strabismus. 35.1% of the early group and 34.8% of the late group did not have an angle between 0° and 10°, the thresholds set for re-operation. For ratio of the visual acuities (remaining amblyopia) there was a small but significant advantage for the early group. There was hardly any correlation between the baseline parameters and the primary endpoints. Children scheduled for early surgery had first been operated at 20 (SD 8.4) months, but 8.2% had not been operated at age six. Children scheduled for late surgery had been operated at 49.1 (SD 12.7) months, but 20.1% had not been operated at age six. The number of operations per child was 1.18 (SD 0.67) in the early and 0.99 (SD 0.64) in the late group. Age at recruitment, age that strabismus reportedly had started and refraction at entry examination were similar among operated and non-operated children. Only the angle of strabismus at entry predicted, to some extent, whether a child had been operated at age six. Discussion: Children operated early had better gross stereopsis at age six as compared to children operated late. They had been operated more frequently, however, and a substantial number of children in both groups had not been operated at all. [ABSTRACT FROM AUTHOR]

Purpose. Whereas many previous studies have identified the association between sustained near work and myopia, few have assessed the influence of concomitant levels of cognitive effort. This study investigates the effect of cognitive effort on near-work induced transient myopia (NITM). Methods. Subjects comprised of six early onset myopes (EOM; mean age 23.7 yrs: mean onset l0.8 yrs), six late-onset myopes (LOM; mean age 23.2 yrs; mean onset 20.0 yrs) and six emmetropes (EMM; mean age 23.8 yrs). Dynamic, monocular, ocular accommodation was measured with the Shin-Nippon SRW-5000 autorefractor. Subjects engaged passively or actively in a 5 minute arithmetic sum checking task presented monocularly on an LCD monitor via a Badal optical system. In all conditions the task was initially located at near (4.50 D) and immediately following the task instantaneously changed to far (0.00 D) for a further 5 minutes. The combinations of active (A) and passive (P) cognition were randomly allocated as P:P; A:P; A:A; P:A. Results. For the initial near task, LOMs were shown to have a significantly less accurate accommodative response than either EOMs or EMMs (p < 0.001). For the far task, post hoc analyses for refraction identified EOMs as demonstrating significant NITM compared to LOMs (p < 0.05), who in turn showed greater NITM than EMMs (p < 0.001). The data show that for EOMs the level of cognitive activity operating during the near and far tasks determines the persistence of NITM: persistence being maximal when active cognition at near is followed by passive cognition at far. Conclusions. Compared with EMMs. EOMs and LOMs are particularly susceptible to NITM such that sustained near vision reduces subsequent accommodative accuracy for far vision. It is speculated that the marked NITM found in EOM may be a consequence of the crystalline lens thinning shown to be a developmental feature of EOM. Whereas the role of small amounts of retinal defocus in myopigenesis remains equivocal, the results show that account needs to be taken of cognitive demand in assessing phenomena such as NITM. [ABSTRACT FROM AUTHOR]

PURPOSE: To evaluate nystagmus and other ocular oscillation patterns of blind adults in relation to visual experience/chronic visual deprivation. MATERIALS & METHODS: Participants: blind (n=33, self-reported vision (≤light perception, OU, with no light projection) and sighted (n=14) adults. Responses to requests to `look straight ahead' were elicited in darkness and videotaped. Pupil tracking of videos yielded digitized eye position data from 25 participants whose self-reported age of blindness onset ranged from birth to 65 years and ten sighted participants. RESULTS: Inspection of the graphs showed that no nystagmus occurred in sighted participants. Three of the ten participants with no visual experience had nystagmus. Of the 15 blind participants with 3-65 years of visual experience, six had jerk nystagmus in various directions, one had seesaw nystagmus, and six had stable gaze. CONCLUSIONS: Total lack of visual experience can give rise in adulthood to jerk nystagmus or a combination of oscillations, or (as stated by others) slow, random, eye movements alone. Adventitious blindness can leave straight-ahead gaze intact or may precipitate a jerk nystagmus with a decreasing velocity waveform. [ABSTRACT FROM AUTHOR]

PURPOSE: To study the effects of Duane's retraction syndrome on sensory visual development. METHODS: Monocular and binocular visual function and ocular motility have been studied and pattern reversal visual evoked potentials recorded from 22 patients with Duane's syndrome aged from 4 to 55 years. RESULTS: Sixteen of the patients maintained binocular single vision using an abnormal head posture. All had normal visual acuities in both eyes. The 12 adults in this group had a mean stereoacuity of 78 seconds of arc with the mus stereotest and 101 seconds of arc with the TNO test. Both these values were significantly worse than for normal adults with a similar age range. The binocular VEPs from these patients showed enhancement of the binocular P100 VEP amplitude compared to the mean monocular P100 amplitude when they used their head posture but, unlike in normal subjects, this binocular enhancement was not reduced significantly after the age of 5. Six patients had lost binocular function and had a manifest convergent squint. Of these, 4 were anisometropic. VEPs in this group showed mildly delayed P100 latencies in the affected eye with asymmetric amplitudes even though their amblyopia had been successfully treated by patching and only one patient had a substantially reduced acuity. In neither group was there any relationship between the degree of restriction of ocular motility and the sensory changes. CONCLUSION: Patients with Duane's syndrome who retain binocular single vision show abnormal binocular visual maturation after the age of 5 years. This results in reduced stereoacuity in the absence of amblyopia. [ABSTRACT FROM AUTHOR]