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Purpose: To investigate the demographics, eye surgeries, and social determinants of health in pediatric patients with low vision in one or both eyes., Methods: This is a cross-sectional study of children 3-18 years of age examined at an academic eye center from 2014 to 2019. Low vision was present if one eye had a distance best-corrected visual acuity (BCVA) of <20/70. ZIP code was used to estimate patient income via a public third-party database., Results: Of 47,571 children examined during the study period, 882 had at least one eye with low vision. Of the 882, 88 (10%) had BCVA of <20/400 in at least one eye, and 228 patients (26%) had bilateral low vision. The most common cause of low vision was refractive/strabismic amblyopia (n = 304). The severest forms of vision loss (BCVA<20/200) were predominantly due to retinal dystrophies or detachment (n = 91). Three hundred patients (34%) had undergone at least one ophthalmic surgery-predominantly extraocular muscle procedures in eyes with mild visual loss and vitreoretinal surgeries in those with more severe loss. The severity of vision loss was significantly associated with a higher likelihood and number of surgeries (P < 0.0001). Income and insurance coverage did not have a significant association with BCVA or the likelihood of surgery., Conclusions: Refractive and strabismic amblyopia are the predominant causes of reduced worse-eye vision in children, and retinal diseases commonly caused severe vision loss. The type and number of surgeries correlate with the severity of vision loss. We did not find any association of income and insurance type with studied outcomes., (Copyright © 2024 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.)

Purpose: Amblyopia damages visual sensory and ocular motor functions. One manifestation of the damage is abnormal fixational eye movements. Tiny fixation movements are normal; however, when these exceed a normal range, the behavior is labeled "fixation instability" (FI). Here we compare FI between normal and amblyopic subjects, and evaluate the relationship between FI and severity of amblyopia, strabismus angle, nystagmus, stereopsis, vergence, and subject age., Methods: Fixation eye movements were recorded using infrared video-oculography from 47 controls (15.3 ± 12.2 years of age) and 104 amblyopic subjects (13.3 ± 11.2 years of age) during binocular and monocular viewing. FI and vergence instability were quantified as the bivariate contour ellipse area (BCEA). We also calculated the ratio of FI between the 2 eyes: right eye/left eye for controls, amblyopic eye/fellow eye for amblyopes. Multiple regression analysis evaluated how FI related to a range of visuo-motor measures., Results: During binocular viewing, the FI of fellow and amblyopic eye, vergence instability, and inter-ocular FI ratios were least in anisometropic and most in mixed amblyopia (P < .05). Each correlated positively with the strabismus angle (P < .01). During monocular viewing, subjects with deeper amblyopia (P < .01) and larger strabismus angles (P < .05) had higher inter-ocular FI ratios. In all, 27% of anisometropic and >65% of strabismic/mixed amblyopes had nystagmus. Younger age and nystagmus increased FI and vergence instability (P < .05) but did not affect the inter-ocular FI ratios (P > .05)., Conclusions: Quantitative recording of perturbed eye movements in children reveal a major functional deficit linked to amblyopia. Imprecise fixation, measured as inter-ocular FI ratios, may be used as a robust marker for amblyopia and strabismus severity. NOTE: Publication of this article is sponsored by the American Ophthalmological Society., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Amblyopic and strabismus subjects experience inter-ocular suppression, impaired stereoacuity, and increased fixation instability. The purpose of the study was to investigate factors affecting suppression and stereoacuity and examine their relationship to fixation eye movement (FEM) abnormalities., Methods: We recruited 14 controls and 46 amblyopic subjects (anisometropic = 18, strabismic = 14, and mixed = 14) and 11 subjects with strabismus without amblyopia. We utilized the dichoptic motion coherence test to quantify suppression, and stereoacuity was assessed using the Titmus Fly test. We recorded FEMs using high-resolution video-oculography and classified subjects that did not have nystagmus (n = 27) versus those with nystagmus (n = 32; fusion maldevelopment nystagmus [FMN], n = 10) and nystagmus that did not meet the criteria of FMN (n = 20). We also recorded FEMs under dichoptic viewing (DcV) at varied fellow eye (FE) contrasts and computed the amplitude and velocity of the fast and slow FEMs and vergence instability., Results: Inter-ocular suppression and stereoacuity deficits were closely correlated with an amblyopic eye (AE), visual acuity, and strabismus angle. Subjects with nystagmus displayed more pronounced stereoacuity deficits than those without nystagmus. Strabismic subjects with and without amblyopia, who demonstrated a fixation switch at 100% FE contrast, had lower inter-ocular suppression than subjects lacking a fixation switch under DcV. Amplitude of fast FEMs and velocity of slow FEMs, and vergence instability were increased as the FE contrast was lowered in both amblyopic and strabismic subjects., Conclusions: The current study highlights the intricate relationships between AE visual acuity, eye deviation, and FEM abnormalities on suppression and stereoacuity deficits and underscores the need to evaluate FEM abnormalities while assessing dichoptic treatment outcomes.

Introduction: Visual function deficits are seen in amblyopic subjects during fellow and binocular viewing. The purpose of the study was to examine the relationship between Fixation Eye Movement (FEM) abnormalities and binocular contrast sensitivity and optotype acuity deficits in amblyopia., Methods: We recruited 10 controls and 25 amblyopic subjects [Anisometropic = 6, Strabismic = 10, Mixed = 9]. We measured binocular contrast sensitivity at spatial frequencies 1,2, 4, 8, 12 and 16 and binocular and monocular optotype acuity using a staircase procedure. We recorded FEMs using high-resolution video-oculography and classified subjects as having no nystagmus(None = 9) or nystagmus without FMN(n = 7) and with Fusion Maldevelopment Nystagmus (FMN)(n = 9). We computed the fixation instability, amplitude and velocity of the fast and slow FEMs., Results: Amblyopic subjects with and without nystagmus had worse binocular contrast sensitivity at spatial frequencies 12 and 16 and binocular optotype acuity than controls. The abnormalities were most pronounced in amblyopic subjects with FMN. Fixation instability of the Fellow Eye and Amblyopic Eye and vergence instability, amplitude of fast FEMs and velocity of slow FEMs were increased with reduced binocular contrast sensitivity and reduced optotype acuity in amblyopic subjects., Conclusions: Fixation instability of Fellow Eye and Amblyopic Eye, optotype acuity and contrast sensitivity deficits are seen under binocular viewing in amblyopic subjects with and without nystagmus but are most pronounced in those with FMN. FEMs abnormalities correlate with both lower order (contrast sensitivity) and higher order (optotype acuity) visual function impairment in amblyopia., Competing Interests: Declaration of Competing Interest All authors have no actual or potential conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Amblyopia is a neurodevelopmental disorder caused by abnormal visual experience in early life that affects 3-5% of the population. Amblyopia results in a host of monocular and binocular visual afferent function deficits including reduced visual acuity, contrast sensitivity, depth perception, interocular suppression, and efferent function abnormalities such as unstable and inaccurate fixation. Conventional treatments such as patching therapy and newer dichoptic treatments are not always successful as 30-40% of patients experience recurrence/regression of amblyopia. There are numerous review articles focused on visual afferent function deficits and treatment modalities and outcomes in amblyopia. Recently, the advent of high spatial and temporal resolution eye trackers has spurred studies on fixation eye movements (FEMs) in healthy controls and neurologic and ophthalmic disorders. In this focused review, we will summarize studies evaluating FEM abnormalities in amblyopia. We will first describe the common devices and techniques used to quantify fixation abnormalities, and then highlight the importance of systematically evaluating the eye movements under different viewing conditions and describe the parameters crucial in assessing FEM abnormalities in amblyopia. We will summarize the evidence suggesting that FEM abnormalities are not limited to the amblyopic eye only but also affects the fellow eye and that FEM abnormalities can serve as biomarkers to predict the impact of amblyopia on visual functions. Beyond diagnosis, we will discuss the treatment and prognostic implications of the evaluation of FEM abnormalities in clinical practice., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Purpose: To determine whether rates of strabismus and associated visuomotor deficits differed among children with different severities of periventricular leukomalacia (PVL)., Design: Retrospective, case-control study., Methods: Brain magnetic resonance images (MRI) obtained from 98 children aged ≥2 years were analyzed using a standardized scoring system: 67 of 98 had PVL (mean GA 31 weeks) and 31 of 98 did not have PVL (mean GA 29 weeks). Severity of PVL was scored as degree of damage to the posterior optic radiations and the splenium of the corpus callosum on MRI. Ophthalmologic examination data were collated to assess the prevalence of visuomotor deficits and the relationship to PVL severity (grades 1-3, mild to severe)., Results: Infantile strabismus was documented in 61% of children with mild, 74% with moderate, and 88% with severe PVL (esotropia: exotropia ratio 3.5:1). Associated ocular motor deficits also increased systematically with PVL severity: latent ("fusion maldevelopment") nystagmus (20%, 47%, and 40%, respectively), dissociated vertical deviation (13%, 28%, and 30%), and nasotemporal pursuit/optokinetic nystagmus asymmetry (23%, 38%, and 54%). Additionally, the prevalence of retrograde optic neuropathy increased with PVL severity (5%, 26%, and 38%). The prevalence of each of these signs was substantially lower in children who had no PVL., Conclusions: Children who suffer PVL are likely to develop the deficits of the infantile strabismus complex. The deficits tend to increase systematically as a function of PVL severity. These findings provide evidence that infantile strabismus is linked to perinatal damage to cerebral vergence and gaze pathways., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: The aim of the study is to examine the association between amblyopia type and the presence of nystagmus on binocular and monocular functions of the fellow (FE) and amblyopic eye (AE)., Methods: We recruited 19 controls and 44 amblyopes (anisometropes=13, strabismic=10, mixed=21). We measured visual, grating, and vernier acuities and high/low spatial frequency (SF) contrast sensitivities in each eye using a staircase method. Stereoacuity was measured with the Titmus fly test. We recorded fixation eye movements (FEM) using high-resolution video-oculography. Subjects were classified as having either no nystagmus (n=18), fusion maldevelopment nystagmus syndrome (FMNS) (n=12), or nystagmus without any structural anomalies that does not meet the criteria for FMNS or infantile nystagmus (n=14)., Results: Analysis of visual function by clinical amblyopia type showed that patients with strabismus/mixed amblyopia (F (2,54)=9.5, p<0.001) were more likely to have poor stereopsis while controlling for AE grating acuity deficit. The FE of patients with anisometropia had greater contrast sensitivity deficits at low (F (2,43)=4.4, p=0.018) and high SF (F (2,42)=10.1, p<0.001). Analysis of visual function by FEM characteristics (low SF: (F (3,43)=4.3, p=0.010) and high SF: (F (3,42)=7.1, p=0.001) showed that the FE of patients with FMNS had worse low and high SF contrast sensitivities, whereas those without FMNS had greater contrast sensitivity deficits only at high SF compared to controls. Patients with FMNS (F (3,54) = 12.9, p<0.001) were more likely to have poor stereopsis while controlling for AE grating acuity deficit compared to patients without FMNS. All amblyopic patients had worse high SF contrast sensitivity of the AE irrespective of type or FEM characteristics (Type = F (2,43)=8.8, p=0.001; FEM characteristics= F (3,43)=5.1, p=0.004)., Conclusion: The presence of FMNS in patients with strabismic/mixed amblyopia is associated with poor/absent stereopsis. FE deficits vary across amblyopia type. Like FEM abnormalities, visual function deficits are seen in the FE of patients with and without nystagmus., Competing Interests: None of the authors have any conflicts of interest to report., (© 2021 Murray et al.)

The human ability for visualization extends far beyond the physical items that surround us. We are able to dismiss the constant influx of photons hitting our retinas, and instead picture the layout of our kindergarten classroom, envision the gently swaying palm trees of our dream vacation, or foresee the face of a yet-to-be-born child. As we inspect imaginary objects and people with our mind's eye, our corporeal eyeballs latch onto the fantasy. Research has found that our eyes can move as if seeing, even when there is nothing to look at. Thus, gaze explorations in the absence of actual vision have been reported in many contexts, including in visualization and memory tasks, and perhaps even during REM sleep. This symposium will present the manifold aspects of gaze dynamics in conditions when the visual input is impoverished or altogether absent. Presentations will address the characteristics of large and small eye movements during imagined and remembered scenes, the impact of visual field deficits on oculomotor control, and the role of eye movements in the future development of neural prosthetics for the blind. Video stream: https://vimeo.com/365522806.

Purpose: Optokinetic eye movements stabilize gaze by tracking motion of the visual scene during sustained movement of a creature's body. The purpose of this study was to describe vertical and horizontal optokinetic nystagmus (OKN) in nonhuman primates (NHPs) with normal binocular vision, and to compare their responses to NHPs with binocular maldevelopment induced by prism-rearing., Methods: Optical strabismus was created in infant macaques (n = 6) by fitting them with prism goggles. The goggles were removed after 3, 6, 9, or 12 weeks to determine the effects of increasing durations of binocular noncorrespondence. Infant NHPs (n = 2) reared wearing plano goggles served as controls. OKN was evoked by horizontal or vertical stripe motion. Eye movements were recorded by using binocular search coils., Results: NHPs reared in early infancy under conditions of binocular noncorrespondence for durations of 6 weeks or longer had horizontal OKN responses biased directionally in favor of nasalward motion. NHPs reared with prisms for any duration had vertical OKN responses more biased than normal NHPs in favor of upward motion. Diagonal "crosstalk" during horizontal or vertical OKN (vertical slow phases during horizontal stimulus motion, and vice versa) was present to some degree in all NHPs. However, crosstalk-upward during horizontal OKN and nasalward during vertical OKN-was most pronounced in NHPs reared with prism for durations long enough to induce a permanent esotropic strabismus (longer than 3 weeks)., Conclusions: With fusion maldevelopment, the OKN pathways retain a nasalward and upward bias. During forward locomotion, optic flow excites temporalward and downward visual motion in each eye. The OKN biases would act in counterbalance. The biases attenuate with emergence of fusion, but may persist and crosstalk when fusion is impeded.

Purpose: Children with cerebral palsy (CP) tend to be either excluded from studies of strabismus repair or pooled with children who have other neurologic disorders. The authors limited this study to children with defined CP to determine the success or failure of restoring eye alignment and fusion., Methods: An observational, cross-sectional, prospective study was conducted on a representative cohort of 50 children. CP severity ranged from Gross Motor Function Classification System (GMFCS) level 1 (least severe) to 5 (most severe). Mean age at entrance and surgery was 3.5 years, and mean follow-up was 4.1 years (minimum 1 year)., Results: The predominant form of strabismus was infantile-onset: esotropia in 54%, exotropia in 26%, and dyskinesia in 10%. Sixty-six percent of esotropic children and 61% of exotropic children achieved optimal (microtropic) alignment after an average of 2 and 1.8 surgical procedures, respectively. The likelihood of optimal alignment was similar in children with mild (GMFCS level 1-2) versus severe (GMFCS level 3-5) CP (P = 0.7; χ(2)). Irrespective of GMFCS severity, 46% of children gained binocular fusion/stereopsis, but the quality of fusion gained was greater in children with mild CP (P < 0.05). Earlier surgery was more likely to be successful (P < 0.05)., Conclusions: Restoration of binocular alignment and a degree of fusion is a realistic goal in the majority of strabismic CP children. Repair may be achieved in children at both the mild and the severe ends of the GMFCS spectrum, without undue concern about treatment futility or excessive reoperation.

Purpose: A subset of children with high ametropia and neurobehavioral disorders have chronic difficulties with spectacle or contact lens wear. We report the results of refractive surgery in a series of these children treated using bilateral or unilateral phakic intraocular lenses (IOLs) for ametropia >10 D., Methods: Clinical course and outcome data were collated prospectively in a group of 12 children (mean age, 10.1 years; range, 4-17 years) with neurobehavioral disorders exacerbated by poor compliance with spectacles. Myopia in 18 eyes ranged from -10.0 to -22.75 D (mean, -15.2 D) and in 2 hyperopic eyes from +10.25 to +10.75 (mean, +10.5 D). Goal refraction was approximately 0 to +1 D. Correction was achieved by implantation of an iris-enclaved phakic IOL under general anesthesia. Mean follow-up was 9.1 months (range, 3-15 months)., Results: Myopia correction averaged 14.5 D and hyperopia correction 9.4 D. Eighty-six percent of eyes (17/20 eyes) were corrected to within +/- 1 D of emmetropia and the remaining 14% (3 eyes) to within +/- 2 D. Uncorrected visual acuity improved substantially in all 20 eyes (60-fold; from a mean of 20/3400 to a mean of 20/57). Ocular comorbidities in each child accounted for residual postoperative, subnormal visual acuity (eg, amblyopia, nystagmus, albinism, regressed retinopathy of prematurity). Visual functions (measured using a 23-item validated survey) improved. One eye required IOL exchange; no other clinically significant complications have been encountered., Conclusions: Phakic IOL implantation improves visual function substantially in neurobehaviorally impaired children who have high ametropia and difficulties wearing glasses.

Purpose: Cerebral palsy (CP) is a permanent, nonprogressive disorder of movement and posture due to a lesion of the fetal or infant brain. The goal was to determine whether children with different severities of CP, as defined using the Gross Motor Function Classification System (GMFCS), had different degrees or types of visual dysfunction., Methods: An observational, cross-sectional-design study was conducted by using neurologic and masked ophthalmic measurements on a representative cohort of 50 children with CP. Mean age was 5.6 years (range, 2-19.5 years); mean gestational age was 31 weeks., Results: The likelihood of debilitating visual deficits was greater in children with higher GMFCS scores, independent of gestational age. Children with level 5 disease (most severe) were at greatest risk for high myopia, absence of binocular fusion, dyskinetic strabismus, severe gaze dysfunction, and optic neuropathy or cerebral visual impairment (CVI). These deficits were rare or absent in children with the mildest disease, level 1. When categorized by anatomic or physiologic CP subtype, diplegic and spastic children were more often hyperopic and esotropic, but had the highest prevalence of fusion and stereopsis. In contrast, children with quadriplegic and mixed CP (dyskinetic, athetoid, hypotonic, and ataxic) more often had high myopia, CVI, dyskinetic strabismus, and gaze dysfunction., Conclusions: Visual deficits differ in children who have mild versus severe CP. Children with GMFCS level 1 to 2 have sensorimotor deficits resembling those of neurologically normal children with strabismus and amblyopia; children at level 3 to 5 have more severe deficits, not observed in neurologically normal children.