The features of diagnosis and treatmentof unilateral concomitant strabismus with visual fixation defect in preschool children

BACKGROUND:Particular difficulties in treatment of children with monolateral strabismus are associated with the presence of severe amblyopia in the squinting eye in combination with a visual fixation defect (acentral or intermittent). AIM:To assess the anatomical and functional status of children with visual fixation defects, to find out the causes of failures in treatment of this group of patients, to determine the tactics of their management. MATERIALS AND METHODS:The study included 92 children of preschool age (from 3 to 7 years) with monolateral concomitant strabismus. The follow-up period for the children ranged from 12 to 72 months. The average age of the examined children was 4.6 1.1 years. Three variants of visual fixation were identified in the squinting eye: central visual fixation (CVF) 68 eyes; intermittent visual fixation (IVF ) 7 eyes; and acentral visual fixation (AVF) 17 eyes. All patients underwent a comprehensive examination: visometry; strabometry; autorefractometry; determination of the critical frequency of light flashes; assessment of visual fixation; optical coherence tomography of the retina. All children underwent passive and active pleoptics. RESULTS:The visual acuity of children with CVF significantly increased due to pleoptics. At the same time in cases of IVF and even more in those of AVF, visual acuity remained significantly lower than that of the fixating eye, pleoptics were ineffective in this group of patients. In patients with CVF, the critical frequency of light flashes of the squinting eye increased in statistically significant figures, while in IVF and AVF, the difference between squinting and fixing eye remained. According to OCT data, changes in the macular area were detected in 18 (75%) eyes in patients with IVF and AVF, which allows us to distinguish organic pathology from amblyopia. CONCLUSIONS:In children with monolateral strabismus, it is necessary to determine visual fixation of the squinting eye. At IVF and AVF, it is mandatory to conduct optical coherence tomography of the macular area to exclude organic pathology. In patients with monolateral concomitant strabismus with IVF and AVF, surgery on oculomotor muscles is indicated.

Visual behavior and upper limb variability in coordination comparision between novices and experts performers in basketball free throws

The objective of the present research is to determine the differences in visual behavior and the upper limbs variability in coordination between expert performers and novice performers in basketball free throws. Methods: Nine right-handed men were tested. The skilled group consisted of four players who had an experience of 9.2 years (SD: 1.2) and play 9 hours per week (SD: 12). The novice group consisted of five players with no experience in Basketball. Visual behavior was evaluated using an eye-tracker head mounted and the upper limb kinematic behavior using a High-speed camera during 30 free throws. Results: There was a significant difference between the expert and novice performers in accuracy for the 30 trials (p<0.034). In Visual behavior were no significant differences the duration of the last visual fixation before the onset of elbow extension in execution phase (p>0,05) between expert and novice groups. There were statistically significant differences in the elbow-wrist variability in coordination in the throws duration time-windows of 100%, 90%, 80%, 30% (pvalue <0.05). 100% represent the last time-windows before ball release. The expert performers shows greater consistency in coordination, however novice subjects exhibit greater variability in the coordination in these intervals. Conclusion: The results suggest that the task of shooting free throws requires a long visual fixation to the site of interest, which temporarily is similar in subjects with different levels of skill. The higher reproducibility pattern suggests elbow-wrist coordination to be the key perceptuo-motor behavior in order to reach expert performance. El objetivo de la presente investigación es determinar las diferencias en el comportamiento visual y la variabilidad de los miembros superiores en la coordinación entre ejecutantes expertos y ejecutantes novatos en los tiros libres de baloncesto. Métodos: Se examinaron nueve hombres diestros. El grupo de expertos estaba formado por cuatro jugadores que tenían una experiencia de 9,2 años (SD: 1,2) y jugaban 9 horas a la semana (SD: 12). El grupo de novatos estaba formado por cinco jugadores sin experiencia en baloncesto. El comportamiento visual fue evaluado utilizando un eye-tracker montado en la cabeza y el comportamiento cinemático del miembro superior utilizando una cámara de alta velocidad durante 30 tiros libres. Resultados: Hubo una diferencia significativa entre los expertos y los novatos en la precisión de los 30 ensayos (p<0,034). En el comportamiento visual no hubo diferencias significativas en la duración de la última fijación visual antes del inicio de la extensión del codo en la fase de ejecución (p>0,05) entre los grupos de expertos y novatos. Hubo diferencias estadísticamente significativas en la variabilidad codo-muñeca en la coordinación en las ventanas de tiempo de duración de los lanzamientos del 100%, 90%, 80%, 30% (pvalor <0,05). El 100% representa las últimas ventanas de tiempo antes del lanzamiento del balón. Los ejecutantes expertos muestran una mayor consistencia en la coordinación, sin embargo los sujetos novatos exhiben una mayor variabilidad en la coordinación en estos intervalos. Conclusiones: Los resultados sugieren que la tarea de lanzar tiros libres requiere una larga fijación visual al sitio de interés, que temporalmente es similar en sujetos con diferentes niveles de habilidad. El patrón de mayor reproducibilidad sugiere que la coordinación codo-muñeca es la conducta perceptivo-motora clave para alcanzar un rendimiento experto.

Fixation stability after surgical treatment of strabismus and biofeedback fixation training in amblyopic eyes

Background Visual fixation may be affected in amblyopic patients and, moreover, its stability may be associated with the effects of amblyopic treatments on visual performance in patients with strabismus. Therefore, fixation stability is a relevant biomarker that might predict the recurrence of amblyopia after a therapeutic intervention. Microperimetric biofeedback fixation training (BFT) can stabilize visual fixation in adult patients with central vision loss. It was the purpose of the present study to evaluate the effects of BFT on fixation stability in adult amblyopic patients after surgical intervention to treat strabismus. Methods Participants were 12 patients with strabismus (mean age = 29.6 ± 8.5 years; 6 females) and 12 healthy volunteers (mean age = 23.8 ± 1.5 years; 9 females). The protocol included ophthalmological and microperimetric follow-ups to measure fixation stability and macular sensitivity. BFT was applied monocularly to four amblyopic eyes either on the spontaneous preferential retinal locus or to a fixation area closer to the anatomical fovea after surgical treatment of strabismus. Results Baseline measurements showed significantly altered microperimetric average threshold in amblyopic eyes compared to fellow eyes (p = 0.024) and compared to control eyes (p < 0.001). Fixation was unstable in amblyopic eyes compared to control eyes (p < 0.001). Fixation stability did not significantly change after surgical alignment of strabismus (p = 0.805). BFT applied to operated eyes resulted in a more stable fixation with improvements of about 50% after three months of training. Conclusions Fixation stability improvements following BFT highlight its potential use in adult amblyopic eyes after the surgical alignment of the strabismus. Future investigations may also consider applying this method in combination with standard treatments to improve vision in amblyopic patients.

On the Question of Amblyopia, Its Patterns and Treatment

Purpose. Description of various clinical forms of amblyopia and the effectiveness of their treatment in children. Material and methods. 242 children from 3 to 18 years old were examined: 110 boys (45.5%) and 132 girls (54.5%). The scope of visual examinations included the following: visometry (Tomey TCP-1000 LED), autorefractometry (Tomey TR-4000), keratometry (Pentacam), determination of the nature of visual fixation (HEINEBETA 200S manual ophthalmoscope). Results and conclusion. The approaches to treatment, depending on the underlying pathology, can be functional, surgical and combined. Functional treatment is indicated for amblyopia associated with concomitant strabismus (especially monolateral) and ametropia without improvement in correction. Surgery is very effective in relieving obscuration amblyopia (cataract extraction with IOL implantation, keratoconus with crosslinking). Key words: amblyopia, ametropia, pleoptics, orthoptics, obscuration.

Optimal policy for attention-modulated decisions explains human fixation behavior

Traditional accumulation-to-bound decision-making models assume that all choice options are processed with equal attention. In real life decisions, however, humans alternate their visual fixation between individual items to efficiently gather relevant information (Yang et al., 2016). These fixations also causally affect one's choices, biasing them toward the longer-fixated item (Krajbich et al., 2010). We derive a normative decision-making model in which attention enhances the reliability of information, consistent with neurophysiological findings (Cohen and Maunsell, 2009). Furthermore, our model actively controls fixation changes to optimize information gathering. We show that the optimal model reproduces fixation-related choice biases seen in humans and provides a Bayesian computational rationale for this phenomenon. This insight led to additional predictions that we could confirm in human data. Finally, by varying the relative cognitive advantage conferred by attention, we show that decision performance is benefited by a balanced spread of resources between the attended and unattended items.

Effects of visual attention modulation on dynamic effective connectivity and visual fixation during own-face viewing in body dysmorphic disorder

BackgroundIn individuals with body dysmorphic disorder (BDD), selective attention biases and aberrant visual scanning patterns may cause imbalances in global vs. detailed visual processing, contributing to perceptual distortions for appearance. The mechanistic effects of modifying visual attention on brain function in BDD, which may be critical to developing perceptual-based treatments, have not been explored. This study tested the effects of visual-attention modulation on dorsal and ventral visual stream activation and connectivity, and eye behaviors.MethodsWe acquired functional magnetic resonance imaging data in 37 unmedicated adults with BDD and 30 controls. Participants viewed their faces under two conditions: a) unconstrained (naturalistically), and b) holding their gaze on the center of the image (visual-attention modulation), monitored with an eye-tracking camera. We analyzed activation and dynamic effective connectivity in dorsal and ventral visual streams and visual fixation duration.ResultsVisual-attention modulation resulted in longer fixation duration and reduced activation in dorsal and ventral visual streams in both groups compared with naturalistic viewing. Longer fixation duration was associated with greater effective connectivity from V1 to early dorsal visual stream during the second naturalistic viewing, across groups. During naturalistic viewing, there was greater V1 to early dorsal visual stream connectivity after, compared with before, visual-attention modulation.ConclusionsWhen viewing one’s face, longer visual fixation may confer greater communication in dorsal visual system, facilitating global/holistic visual processing. The finding that reduction in visual scanning while viewing one’s face results in persistent effects during unconstrained viewing has implications for perceptual retraining treatment design for BDD.