Western Australia Atropine for the Treatment of Myopia (WA-ATOM) study: Rationale, methodology and participant baseline characteristics.

IMPORTANCE: Atropine eyedrops are a promising treatment for slowing myopia progression in East Asian children. However, its effects on children in Australia, including those of non-Asian background, have not been well-studied. BACKGROUND: The Western Australia Atropine for the Treatment of Myopia (WA-ATOM) study aims to determine the efficacy and long-term effects of low-dose atropine eyedrops in myopia control. This paper describes the study rationale, methodology and participant baseline characteristics. DESIGN: Single-centre, double-masked, randomized controlled trial. PARTICIPANTS: Children (6-16 years) with spherical equivalent ≤-1.50 D in each eye, astigmatism ≤1.50 D and myopia progression by ≥0.50 D/year. METHODS: Enrolled children were randomly assigned 2:1 to receive 0.01% atropine or placebo eyedrops. Participants are examined every 6 months during first 3 years of the study (2-year treatment phase followed by a 1-year washout phase), and then at a 5-year follow-up (2 years after the end of the washout phase). MAIN OUTCOME MEASURES: Annual progression rate of myopia and axial length, tolerability to eyedrops and incidence and severity of unwanted effects. RESULTS: Out of 311 children who were referred, 242 were suitable for study participation, and 153 were subsequently enrolled. The baseline characteristics of enrolled participants are presented. CONCLUSIONS AND RELEVANCE: Outcomes of the WA-ATOM study will inform on the efficacy, tolerability, safety and long-term effects of low-dose atropine eyedrops in myopia control in Australian children. The impact of ocular sun exposure, iris colour and parental myopia on the efficacy of low-dose atropine will also be assessed.

Audiovisual perception in amblyopia: A review and synthesis.

Amblyopia is a common developmental sensory disorder that has been extensively and systematically investigated as a unisensory visual impairment. However, its effects are increasingly recognized to extend beyond vision to the multisensory domain. Indeed, amblyopia is associated with altered cross-modal interactions in audiovisual temporal perception, audiovisual spatial perception, and audiovisual speech perception. Furthermore, although the visual impairment in amblyopia is typically unilateral, the multisensory abnormalities tend to persist even when viewing with both eyes. Knowledge of the extent and mechanisms of the audiovisual impairments in amblyopia, however, remains in its infancy. This work aims to review our current understanding of audiovisual processing and integration deficits in amblyopia, and considers the possible mechanisms underlying these abnormalities.

Bitot-like spots in children with normal vitamin A levels.

BACKGROUND/AIMS: A Bitot spot is a conjunctival lesion, classically associated with severe vitamin A deficiency. In this paediatric series, we describe conjunctival lesions indistinguishable from Bitot spots, seen in the presence of normal vitamin A levels. METHODS: This descriptive case series was performed by retrospective review of case notes, including all patients with Bitot-like spots found to have normal serum vitamin A levels, seen at the Hospital for Sick Children, Toronto, between 2006 and 2016. Data collected included age at presentation, ophthalmic and systemic diagnoses, and the presence of recognised genetic mutations. Histopathology was reviewed in one case. RESULTS: Ten patients with Bitot-like spots with laboratory-confirmed normal serum vitamin A levels were identified. The conjunctival lesions were indistinguishable clinically and histopathologically from classic Bitot spots and were noted to occur in a range of anterior segment pathologies, including aniridia, WAGR syndrome, Axenfeld-Rieger syndrome, and blepharokeratoconjunctivitis. CONCLUSIONS: Bitot-like spots are found in children with a number of anterior segment pathologies in the absence of vitamin A deficiency.

Impaired Spatial Hearing in Amblyopia: Evidence for Calibration of Auditory Maps by Retinocollicular Input in Humans.

Purpose: Evidence from animals and blind humans suggests that early visual experience influences the developmental calibration of auditory localization. Hypothesizing that unilateral amblyopia may involve cross-modal deficits in spatial hearing, we measured the precision and accuracy of sound localization in humans with amblyopia. Methods: All participants passed a standard hearing test. Experiment 1 measured sound localization precision for click stimuli in 10 adults with amblyopia and 10 controls using a minimum audible angle (MAA) task. Experiment 2 measured sound localization error (i.e., accuracy) for click train stimuli in 14 adults with amblyopia and 16 controls using an absolute sound localization task. Results: In Experiment 1, the MAA (mean ± SEM) was significantly greater in the amblyopia group compared with controls (2.75 ± 0.30° vs. 1.69 ± 0.09°, P = 0.006). In Experiment 2, the overall sound localization error was significantly greater in the amblyopia group compared with controls (P = 0.047). The amblyopia group also showed significantly greater sound localization error in the auditory hemispace ipsilateral to the amblyopic eye (P = 0.036). At a location within this auditory hemispace, the magnitude of sound localization error correlated significantly with deficits in stereo acuity (P = 0.036). Conclusions: The precision and accuracy of sound localization are impaired in unilateral amblyopia. The asymmetric pattern of sound localization error suggests that amblyopic vision may interfere with the development of spatial hearing via the retinocollicular pathway.

A suspected case of anesthesia-induced rhabdomyolysis in a child undergoing strabismus surgery.

We report a case of acute rhabdomyolysis following general anesthesia for strabismus surgery in a previously healthy 11-year-old girl. The patient received a depolarizing muscle relaxant (succinylcholine) and halogenated volatile anesthetic agent (sevoflurane) during surgery. In rare cases, these classes of drugs can trigger malignant hyperthermia (MH) or anesthesia-induced rhabdomyolysis (AIR), which can cause significant morbidity and mortality if not recognized and treated promptly. Pathophysiology, early recognition, and special considerations in strabismus patients are discussed.

Traumatic hyphaema in children: a retrospective and prospective study of outcomes at an Australian paediatric centre.

OBJECTIVE: This study aims to evaluate the presenting characteristics, management, outcomes and complications for paediatric traumatic hyphaema in Western Australia. METHODS AND ANALYSIS: A retrospective review of medical records was conducted for consecutive patients ≤16 years of age admitted for traumatic hyphaema to Princess Margaret Hospital for Children (Perth, Australia) between January 2002 and December 2013 (n=82). From this sample, a cohort whose injury occurred ≥5 years prior attended a prospective ocular examination (n=16). Hospital records were reviewed for patient demographics, injury details, management, visual outcomes and complications. The prospective cohort underwent examination for visual and structural outcomes. RESULTS: Most injuries (72%) resulted from projectile objects. Angle recession was present in 53% and was associated with projectiles (p=0.002). Most eyes (81%) achieved a final visual acuity of 0.3 logarithm of the minimum angle of resolution (logMAR) (20/40) or better. Age ≤5 years and posterior segment injury were significant predictors of final visual acuity poorer than 0.3 logMAR. At ≥5 years post-trauma, injured eyes had greater intraocular pressure (IOP) (p=0.024) and anterior chamber depth (ACD) (p=0.022) compared with sound eyes. IOP asymmetry was associated with angle recession (p=0.008) and ACD asymmetry (p=0.012). CONCLUSION: Poorer visual outcomes are associated with younger age at injury and posterior segment injury. Angle recession and ACD asymmetry are associated with IOP asymmetry 5-12 years after injury.

Optimal Audiovisual Integration in the Ventriloquism Effect But Pervasive Deficits in Unisensory Spatial Localization in Amblyopia.

Purpose: Classically understood as a deficit in spatial vision, amblyopia is increasingly recognized to also impair audiovisual multisensory processing. Studies to date, however, have not determined whether the audiovisual abnormalities reflect a failure of multisensory integration, or an optimal strategy in the face of unisensory impairment. We use the ventriloquism effect and the maximum-likelihood estimation (MLE) model of optimal integration to investigate integration of audiovisual spatial information in amblyopia. Methods: Participants with unilateral amblyopia (n = 14; mean age 28.8 years; 7 anisometropic, 3 strabismic, 4 mixed mechanism) and visually normal controls (n = 16, mean age 29.2 years) localized brief unimodal auditory, unimodal visual, and bimodal (audiovisual) stimuli during binocular viewing using a location discrimination task. A subset of bimodal trials involved the ventriloquism effect, an illusion in which auditory and visual stimuli originating from different locations are perceived as originating from a single location. Localization precision and bias were determined by psychometric curve fitting, and the observed parameters were compared with predictions from the MLE model. Results: Spatial localization precision was significantly reduced in the amblyopia group compared with the control group for unimodal visual, unimodal auditory, and bimodal stimuli. Analyses of localization precision and bias for bimodal stimuli showed no significant deviations from the MLE model in either the amblyopia group or the control group. Conclusions: Despite pervasive deficits in localization precision for visual, auditory, and audiovisual stimuli, audiovisual integration remains intact and optimal in unilateral amblyopia.

Temporal Ventriloquism Reveals Intact Audiovisual Temporal Integration in Amblyopia.

Purpose: We have shown previously that amblyopia involves impaired detection of asynchrony between auditory and visual events. To distinguish whether this impairment represents a defect in temporal integration or nonintegrative multisensory processing (e.g., cross-modal matching), we used the temporal ventriloquism effect in which visual temporal order judgment (TOJ) is normally enhanced by a lagging auditory click. Methods: Participants with amblyopia (n = 9) and normally sighted controls (n = 9) performed a visual TOJ task. Pairs of clicks accompanied the two lights such that the first click preceded the first light, or second click lagged the second light by 100, 200, or 450 ms. Baseline audiovisual synchrony and visual-only conditions also were tested. Results: Within both groups, just noticeable differences for the visual TOJ task were significantly reduced compared with baseline in the 100- and 200-ms click lag conditions. Within the amblyopia group, poorer stereo acuity and poorer visual acuity in the amblyopic eye were significantly associated with greater enhancement in visual TOJ performance in the 200-ms click lag condition. Conclusions: Audiovisual temporal integration is intact in amblyopia, as indicated by perceptual enhancement in the temporal ventriloquism effect. Furthermore, poorer stereo acuity and poorer visual acuity in the amblyopic eye are associated with a widened temporal binding window for the effect. These findings suggest that previously reported abnormalities in audiovisual multisensory processing may result from impaired cross-modal matching rather than a diminished capacity for temporal audiovisual integration.

Alterations in audiovisual simultaneity perception in amblyopia.

Amblyopia is a developmental visual impairment that is increasingly recognized to affect higher-level perceptual and multisensory processes. To further investigate the audiovisual (AV) perceptual impairments associated with this condition, we characterized the temporal interval in which asynchronous auditory and visual stimuli are perceived as simultaneous 50% of the time (i.e., the AV simultaneity window). Adults with unilateral amblyopia (n = 17) and visually normal controls (n = 17) judged the simultaneity of a flash and a click presented with both eyes viewing. The signal onset asynchrony (SOA) varied from 0 ms to 450 ms for auditory-lead and visual-lead conditions. A subset of participants with amblyopia (n = 6) was tested monocularly. Compared to the control group, the auditory-lead side of the AV simultaneity window was widened by 48 ms (36%; p = 0.002), whereas that of the visual-lead side was widened by 86 ms (37%; p = 0.02). The overall mean window width was 500 ms, compared to 366 ms among controls (37% wider; p = 0.002). Among participants with amblyopia, the simultaneity window parameters were unchanged by viewing condition, but subgroup analysis revealed differential effects on the parameters by amblyopia severity, etiology, and foveal suppression status. Possible mechanisms to explain these findings include visual temporal uncertainty, interocular perceptual latency asymmetry, and disruption of normal developmental tuning of sensitivity to audiovisual asynchrony.

Infantile nystagmus syndrome: clinical characteristics, current theories of pathogenesis, diagnosis, and management.

Infantile nystagmus syndrome (INS) is an important clinical diagnosis because it is a common presenting sign of many ocular, neurologic, and systemic diseases. Although INS has been studied for more than a century, its diagnosis and treatment remains a challenge to clinicians because of its varied manifestations and multiple associations, and its pathogenesis continues to rouse considerable scientific debate. Fueled by these challenges, recent basic research and clinical investigations have provided new insights into INS. New genetic discoveries and technological advances in ocular imaging have refined our understanding of INS subtypes and offer new diagnostic possibilities. Unexpected surgical outcomes have led to new understanding of its pathogenesis based on novel hypothesized pathways of ocular motor control. Comparative studies on nonhuman visual systems have also informed models of the neural substrate of INS in humans. This review brings together the classic profile of this disorder with recent research to provide an update on the clinical features of INS, an overview of the current theories on how and why INS develops, and a practical approach to the diagnosis and management of INS.