Amblyopia Research Articles

The Clinical Characteristics of Amblyopia in Children Under 17 Years of Age in Qassim Region, Saudi Arabia.

PurposeTo provide the clinical characteristics of amblyopia in children under 17 years of age in Qassim Region, Saudi Arabia.Patients and MethodsThe study was a cross-sectional hospital-based, included 121 children with amblyopia aged between 3 and 17 years, referred from 6 hospitals in Qassim region to the paediatric optometry clinic at Qassim University medical city. Demographics and comprehensive ocular examination including visual acuity (VA), assessment of anterior and posterior segment, cycloplegic refraction (RE), angle of deviation, and cause of amblyopia were collected.ResultsThe mean age at diagnosis of amblyopia was 8.93 ± 3.67 years. The leading cause of amblyopia was strabismus and anisometropia shared the same percentage at 29.75%, and the combined-mechanism at 18.18%. Amblyopia was more common in males 57.85%, particularly strabismic amblyopia in 66.67% and anisometropic amblyopia in 61.11%, p = 0.408. Amblyopia was more predominant in the age group 6- to 9-year-old, particularly, strabismic amblyopia 44.44%, and amblyopia due to a combined mechanism of 36.36%, p = 0.066. The degree of hyperopia was not varied by the cause of amblyopia (P = 0.401), with slightly high hyperopia found in ametropic and strabismic amblyopia. Conversely, hyperopic astigmatism was significantly associated with amblyopia P = 0.020, with a high degree of hyperopic astigmatism found in meridional amblyopia and ametropic amblyopia.ConclusionThe commonest types of amblyopia in children were attributed to strabismus and anisometropia. Causes of amblyopia differed by age group with strabismus, anisometropia, and combined mechanism accounting for most children aged 6- to 9-years and strabismus for children aged less than 6 years. Hyperopic and myopic astigmatism were significantly associated with anisometropia and meridional amblyopia. Therefore, efforts should be made for early diagnosis and management of childhood amblyopia and uncorrected refractive errors to avoid their impact on quality of life.

Successful Treatment of Mixed Amblyopia with Optic Nerve Hypoplasia (ONH) in an Adult Indonesian Patient

Introduction: Amblyopia significantly contributes to low vision and blindness in adults in an Indonesian rural setting. The treatment of amblyopia, particularly anisometropic and/or strabismic amblyopia, has long been challenging for many clinicians. This study aims to report a promising result of refractive correction, occlusion therapy, and oral citicoline on mixed amblyopia with optic nerve hypoplasia in adult Indonesian patients. Case Presentation: A 20-year-old male with a chief complaint of blurry right eye since one year ago, becoming more severe lately. The patient had been strabismic since his childhood. History of using a -5 concave spherical lens on his RE, with the normal eye on his LE. Visual acuity (VA) of his RE was 3/60 and his LE was 6/30. The RE was deviated, with 30° of exotropia. Nystagmus was also found. Optical coherence tomography (OCT) examination found maculopathy and optic nerve hypoplasia in both eyes. We treated the patient with spectacles to correct the refractive error, occluded his fixing eye, and gave an oral citicoline. Conclusions: Refractive correction and occlusion therapy are still meaningful choices of therapy and have shown to be effective in treating amblyopia, combined with oral citicoline to prevent nerve cell damage. Our case of refractive correction, combined with occlusion therapy and oral citicoline on mixed amblyopia in an adult Indonesian patient, showed good results and a promising post-treatment prognosis with a decrease of exotropia degree and disappearance of nystagmus in just two months.

Retinal nerve fiber layer thickness in amblyopia.

To report retinal nerve fiber layer thickness (RNFLT) in eyes with amblyopia compared with contralateral healthy eyes. In this cross-sectional study, we included patients with anisometropic amblyopia, strabismic amblyopia, and mixed amblyopia. All subjects underwent complete ophthalmic examination, including RNFLT measurement with time-domain OCT (Stratus OCT) and scanning laser polarimeter (GDX VCC). A paired "t" test was used to compare average and quadrant-wise RNFL thickness between the amblyopic and contralateral normal eyes. In addition, an analysis of variance test was used to compare various RNFL thickness parameters between the three groups. A total of 33 eyes of 33 subjects with anisometropic amblyopia, 20 eyes of 20 subjects with strabismic amblyopia, and 38 eyes of 38 subjects with mixed amblyopia were included. In the anisometropic amblyopia group, the average RNFLT in the amblyopic eye was 98.2 μm and 99.8 μm in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 μm (26.78) in the anisometropic eye and 150.42 μm (23.84) in the fellow eye (P = 0.38). The difference between amblyopic and contralateral normal eye for RNFL and macular parameters was statistically insignificant in all three groups. The RNFL thickness in four quadrants was similar in the amblyopic and non-amblyopic eye between all three groups and statistically non-significant. Our study showed that RNFL thickness was similar in amblyopic and non-amblyopic eyes between all three amblyopia groups.

Binocular fusion disorders impair basic visual processing

In an era of increasing screen consumption, the requirement for binocular vision is demanding, leading to the emergence of syndromes such as the computer vision syndrome (CVS) or visual discomfort reported by virtual reality (VR) users. Heterophoria (phoria) is a latent eye misalignment (with a prevalence up to 35%) that appears in conditions that disrupt binocular vision and may affect the quality of binocular fusion. Collinear facilitation (CF), the mechanism for grouping contour elements, is a process that reveals lateral interactions by improving the visibility of a target by flankers placed collinearly. An abnormal pattern of CF has been observed in strabismic amblyopia. We hypothesize that phoria may affect CF in the horizontal meridian (HM) due to latent eye misalignment and its impact on binocular fusion. Fully corrected participants (phoria group and controls) completed a standard CF experiment for horizontal and vertical meridians during binocular and monocular viewing. Phoric observers exhibited (1) an asymmetry and an abnormal pattern of CF only for the HM, during both monocular and binocular viewing, (2) poor binocular summation between the monocular inputs, and (3) no binocular advantage of the CF. Phoria affects the CF in a way that is reminiscent of meridional amblyopia without being attributed to abnormal refraction. The abnormal pattern of CF in monocular viewing suggests that phoria could be a binocular developmental disorder that affects monocular spatial interactions. We suggest that the results could contribute to explain the visual discomfort experienced with VR users or symptoms when presenting CVS.

OPTICAL-REFLECTION METHOD OF ACCOMMODATIVE FACILITY TRAINING ON MERIDIONAL ACUITY IN TREATMENT OF ASTIGMATS WITH AMBLYOPIA

ackground: The efficacy of accommodative facility training as a method of treatment for meridional amblyopia (MA) in astigmatic children with amblyopia was studied. MA manifests itself as selective alterations in visual acuity (VA), with substantial differences in the ability to resolve contours of different orientations, and may cause impairments in mechanisms of integrated processing of visual stimulus, development of cognitive abilities in children and visual performance. Purpose: To assess the effect of optical-reflection method of accommodative facility training on vernier acuity in meridians (MVA) in the treatment of astigmatic children with amblyopia. Material and Methods: Twenty seven children aged 5 to 12 years, with both refractive amblyopia and with-the-rule hyperopic astigmatism were included in the study, and underwent an examination. The spherical component of refraction ranged from +0.5D to +5.5D, and the cylindical component, from 0.5D to 4.5D. Best-corrected visual acuity (Sivtsev Chart) was assessed. Accommodative facility training was performed monocularly by image defocusing with lenses of a variable power. A +0.5-D sphere was placed just in front of the best correction for the study eye in order to blur this line. The +0.5-D sphere was replaced by a -0.5-D sphere after the optotypes became clearly visible. Thereafter, the training cycle was repeated using a ±0.75-D sphere and, subsequently, a ±1.0-D sphere. Lens power was gradually increased until it could be compensated by accommodation. The treatment course consisted of one training session a day for 10 days. Special computer software was used to determine corrected MVA. Linear objects were presented on the computer screen, and the smallest lateral displacement of one line from another that can be detected by the examinee will characterize the level of MVA. Results: A new algorithm was proposed for assessing the efficacy of treatment of MA in astigmats, with refractive asymmetries and meridional asymmetries in vernier acuity considered as vector quantities. It was demonstrated that a group of amblyops with the same type of astigmatism was not homogeneous. It was found possible to split such a group of patients into three clusters that differ in the type of variation in meridional acuity in the orthogonal meridians compared to refractive asymmetries. One cluster had equal vernier acuities in the vertical and horizontal meridians, the second had vernier acuity in the horizontal meridian better than in the vertical meridian, and the third had vernier acuity in the horizontal meridian worse than in the vertical meridian. MVA was greater in magnitude in one of the orthogonal meridians than in another in the dominant eyes in 37% of study patients, and in the fellow eyes in 50% of study patients. MVA values in the orthogonal meridians were similar in 56.6% of study patients. There was a 15.1-percent increase, from 56.6% to 71.1% in the number of eyes with a similar vernier acuity in the orthogonal meridians after treatment. A positive effect was achieved through elimination of meridional asymmetry in vernier acuity in a portion of patients from clusters that differ in the direction of meridional asymmetry in vernier acuity. In addition, the number of eyes in the category of patients with a visual acuity of 0.75-0.8 (as assessed with complex optotypes) increased by 11.35%. Conclusion: The efficacy of treatment for MA should be assessed in homogeneous clusters with similar direction of meridional asymmetry in visual acuity. Preliminary data on the efficacy of treatment of amblyopia by accommodative facility training allows considering this training as a method of treatment for meridional amblyopia. The method of determination of meridional acuity should be included in the standard examination of patients with amblyopia.

Pupillary reflex disorders in strabismic amblyopia with concomitant alternating squint

Purpose. To study pupillary reflexes (pupillary cycle time and pupillary reaction — V) in patients with strabismic amblyopia and concomitant alternating strabismus. Material and methods. 58 children (116 eyes) with concomitant alternating strabismus and strabismic amblyopia and 10 healthy children (20 eyes) with emmetropia (the control group) were examined, along with general testing, for pupillary reflexes according to S. Miller and H. Thompson’s method before and after color pulse stimulation, Sidorenko’s vacuum spectacles, and Focus and Relax programs. Results. All children with hyperopic astigmatism and high hyperopia showed a significant (p < 0.001) decrease in pupillary cycle time after treatment, on average, from 1317,0 ± 0.6 to 900,00 ± 2.08 m/s and an increase in the pupillary reaction rate, on average, from 1.7 ± 0.17 to 2.8 ± 0.1 mm/s. Сhildren with severe amblyopia showed more pronounced pupillary reflex disorders: pupillary cycle time was 1450,0 ± 1.0 m/s and V = 1.3 ± 0.17mm/s before treatment, whilst after treatment, significant improvements were achieved:pupillary cycle time fell to 1000,0 ± 1.3 mm/s, while V grew to 2.20 ± 0.15 mm/s (p < 0.01). Conclusion. The revealed disorders of pupillary reflexes in children with strabismic amblyopia indicate the pathology of the muscle part of the pupil-accommodative system and require specific treatment. Material and methods. 58 children (116 eyes) with concomitant alternating strabismus and strabismic amblyopia and 10 healthy children (20 eyes) with emmetropia (the control group) were examined, along with general testing, for pupillary reflexes according to S. Miller and H. Thompson’s method before and after color pulse stimulation, Sidorenko’s vacuum spectacles, and Focus and Relax programs. Results. All children with hyperopic astigmatism and high hyperopia showed a significant (p < 0.001) decrease in pupillary cycle time after treatment, on average, from 1317,0 ± 0.6 to 900,00 ± 2.08 m/s and an increase in the pupillary reaction rate, on average, from 1.7 ± 0.17 to 2.8 ± 0.1 mm/s. Сhildren with severe aamblyopia showed more pronounced pupillary reflex disorders: pupillary cycle time was 1450,0 ± 1.0 m/s and V = 1.3 ± 0.17mm/s before treatment, whilst after treatment, significant improvements were achieved:pupillary cycle time fell to 1000,0 ± 1.3 mm/s, while V grew to 2.20 ± 0.15 mm/s (p < 0.01). Conclusion. The revealed disorders of pupillary reflexes in children with strabismic amblyopia indicate the pathology of the muscle part of the pupil-accommodative system and require specific treatment.

Long-Term Efficacy of the Combination of Active Vision Therapy and Occlusion in Children with Strabismic and Anisometropic Amblyopia.

This retrospective study was conducted to evaluate the efficacy of the combined treatment of occlusion and active vision therapy in a total of 27 amblyopic children, including 14 strabismic and 13 anisometropic cases. For such purpose, changes in distance and near visual acuity as well as in the binocular function was evaluated during a two-year follow-up. In both amblyopia groups, significant improvements were found in distance and near visual acuity in the non-dominant eye (p < 0.001). In the strabismic amblyopia group, the percentage of patients with binocular function score (BF) > 3.3 decreased significantly from a baseline value of 64.3% to a two-year follow-up value of 7.1% (p < 0.001). In the anisometropic amblyopia group, this percentage also decreased significantly from a baseline value of 15.4% to a two-year follow-up value of 0.0% (p < 0.001). No recurrences were observed in the anisometropic amblyopia group, whereas recurrence occurred in two cases of the strabismic amblyopia group after finishing the vision rehabilitation process. In conclusion, the combined approach of the treatment evaluated is efficacious for providing an improvement in visual acuity and binocular function in both anisometropic and strabismic amblyopia, which was maintained over time.

Effectiveness of syntonic phototherapy in amblyopia in terms of improved visual acuity and contrast sensitivity

Purpose: To compare visual acuity and contrast sensitivity in different types of amblyopia and to see the effect of syntonic therapy on amblyopia in terms of visual acuity and contrast sensitivity. Study Design: A Quasi Experimental study Place and Duration of Study: A Qusai Experimental study was carried out from August 2021 to November 2021 at Madina Teaching Hospital Faisalabad. Methods: A total of 30 patients of either gender and age from 8 to 18 years were included. There were 15 patients with anisometropic amblyopia and 15 with strabismic amblyopia. The patients were recruited through non-probability purposive sampling technique. All the patients underwent assessment of visual acuity with Log MAR chart and contrast sensitivity with Pelli-Robsonchart. Syntonic phototherapy with red filter glasses was prescribed for 4 weeks. After 4 weeks, patients returned and underwent post-therapy assessment of visual acuity and contrast sensitivity. Paired sample t test and Independent sample t test was used with the help of IBM SPSS-23 to get a statistical result. Results: Syntonic phototherapy showed significant improvement in mean visual acuity of 0.223 (p=0.00) and contrast sensitivity of -0.200 (p=0.00) in amblyopia. Anisometropic amblyopia showed better improvement in visual acuity (p=0.016) and contrast sensitivity (p=0.035) by syntonic phototherapy as compared to patients with strabismic amblyopia. Conclusion: Significant improvement was seen in visual acuity and contrast sensitivity in patients with amblyopia after syntonic phototherapy. Anisometropic amblyopia showed better improvement as compared to strabismic amblyopia, in terms of visual acuity and contrast sensitivity.

Multi-modal Treatment Approach Incorporating Vision Therapy and Syntonics for Combined Organic and Functional Amblyopia

Background: Amblyopia is characterized by reduced visual acuity along with compromised binocular visual function. Form deprivation amblyopia is obstruction of light which prevents visual development. It is has traditionally been managed at an early stage of life through occlusion therapy. Case Summary: A 32-year-old male was diagnosed with acquired form deprivation strabismic amblyopia. Ocular trauma resulted in post pupilloplasty with membranectomy surgery of the right eye, and pseudophakia of the right eye, while the posterior segment was within normal limits. Stereopsis was absent. In-office and home vision therapy was implemented, which included syntonic phototherapy, space fixator, and monocular fixation in binocular field and Ambi-iNet. Conclusion: A multi-modality approach in treatment improved vision and stereopsis for an adult with acquired form deprivation strabismic amblyopia secondary to traumatic cataract, occlusio pupillae, and traumatic angle closure glaucoma.

Evaluation of Choroidal Vascular Index in Amblyopic Patients.

Objectives:To compare subfoveal choroidal thickness (SFCT) and choroidal vascular index (CVI) in patients with hyperopic refractive and strabismic amblyopia and healthy subjects.Materials and Methods:The study included 17 patients with strabismic amblyopia (Group 1), 29 patients with hyperopic refractive amblyopia (Group 2), and 16 eyes of 16 healthy volunteers (Group 3). Best corrected visual acuity was noted in all patients and volunteers. In addition to detailed anterior and posterior segment examinations, macular images were obtained by enhanced-depth imaging mode of optical coherence tomography (OCT). SFCT measurements were made from these images and CVI was calculated using the Image J program.Results:No significant difference was found between the groups in terms of age, gender, and intraocular pressure (p=0.27, 0.64, and 0.85, respectively). Mean BCVAs in Group 1 were 0.57±0.16 (0.3-0.8) in the amblyopic eyes, 0.94±0.08 (0.8-1.0) in the fellow eyes, and in Group 2 were 0.61±0.17 (0.2-0.8) in amblyopic eyes, 0.92±0.1 (0.8-1.0) in fellow eyes. BCVA in Group 3 was 1.0±0 (1.0-1.0). Mean SFCT of the amblyopic eyes in Groups 1 and 2 was 341.50±60.4 (277-481) and 370.06±65.3 (247-462), respectively, and in the healthy eyes of Groups 1 and 2 and Group 3 was 321.92±68.26 (251-440), 330.35±74.00 (194-502), and 327.62±40.79 (238-385), respectively. SFCT was significantly greater in the amblyopic eyes of Group 2 compared to Group 3 (p=0.01). Mean CVI was 0.681±0.032 (0.642-0.736) in the amblyopic eyes and 0.685±0.054 (0.587-0.788) in the fellow eyes of Group 1 patients; 0.664±0.033 (0.592-0.719) in the amblyopic eye and 0.707±0.039 (0.625-0.779) in the fellow eye in Group 2 patients; and 0.689±0.031 (0.612-0.748) in Group 3 patients. CVI was significantly lower in the amblyopic eyes of Group 2 compared with fellow eyes (p=0.02) and Group 3 (p=0.025).Conclusion:Morphological changes may be seen in the choroid in amblyopic eyes. We observed that the choroidal stromal component is increased in hyperopic amblyopic patients especially.

Perceptual learning with dichoptic attention tasks improves attentional modulation in V1 and IPS and reduces interocular suppression in human amblyopia

Long-term and chronic visual suppression to the non-preferred eye in early childhood is a key factor in developing amblyopia, as well as a critical barrier to treat amblyopia. To explore the relationship between selective visual attention and amblyopic suppression and its role in the success of amblyopic training, we used EEG source-imaging to show that training human adults with strabismic and anisometropic amblyopia with dichoptic attention tasks improved attentional modulation of neural populations in the primary visual cortex (V1) and intraparietal sulcus (IPS). We also used psychophysics to show that training reduced interocular suppression along with visual acuity and stereoacuity improvements. Importantly, our results revealed that the reduction of interocular suppression by training was significantly correlated with the improvement of selective visual attention in both training-related and -unrelated tasks in the amblyopic eye, relative to the fellow eye. These findings suggest a relation between interocular suppression and selective visual attention bias between eyes in amblyopic vision, and that dichoptic training with high-attention demand tasks in the amblyopic eye might be an effective way to treat amblyopia.

Fixation Pattern Analysis With Microperimetry In Strabismic Subjects: A Pilot Study

ABSTRACTObjectiveStrabismic amblyopia is a motor and sensory deficit produced by unilateral constant strabismus and binocular imbalance. The aim of this study was to analyse the retinal fixation pattern using microperimetry in subjects with strabismus with and without amblyopia associated, and to compare the results with those obtained in normal subjects.MethodsProspective comparative study conducted at the Optometric Clinic of the University of Valencia and Oftalvist Alicante (Spain) including 46 eyes with ages from 3 to 16 years. Three groups were differentiated: patients with persistent strabismic amblyopia after occlusion and active therapy (group 1, 7 patients, 30.4%), strabismic patients without amblyopia (group 2, 8 patients, 34.8%) and a control group (8 patients, 34.8%). Microperimetric analysis was performed with the Macular Integrity Assessment (MAIA) system (Centervue, Padova, Italy) and using the following parameters: P1% and P2% fixation indexes, and the ellipse areas (BCEA) for 95% and 63% of points for the first 10 seconds, 30 seconds, 60 seconds, and the total examination time.ResultsSignificant differences were found between groups for dominant eyes in P2 calculated at 30 (p = .04) and 60 seconds (p = .03). However, these differences between groups in non-dominant eyes were close to statistical significance (p = .07 and p = .08). Specifically, P2 was significantly lower in group 1 compared to control group (p = .01). Best corrected visual acuity was found to be significantly correlated (p ≤ .04) with total P1 (dominant eye, r = −0.51; non-dominant eye, r = −0.50), total P2 (dominant eye, r = −0.50; non-dominant eye, r = −0.50), and BCEA63 (dominant eye, r = 0.50; non-dominant eye, r = 0.40) and BCEA95 (dominant eye, r = 0.50; non-dominant eye, r = 0.40) measured at 10 seconds.ConclusionsThe preliminary results of this study seem to indicate that subjects with strabismus have fixation instability regardless of the presence or absence of amblyopia.

Altered Brain Activity in Strabismic Amblyopic Children as Determined by Regional Homogeneity: A Resting-State Functional Magnetic Resonance Imaging Study.

ObjectiveEarlier research has determined that amblyopia or strabismus may cause remarkable brain anatomical and functional variations. Nonetheless, thus far, the spontaneous changes in brain activity in children with strabismus amblyopia (SA) remain unclear. The purpose of this study was to determine the association between abnormal brain activity in children with SA and its behavioral manifestations.Patients and Methods?A total of 24 children with SA (10 male and 14 female children) as well as 24 healthy controls (HCs), including 10 male and 14 female children were closely matched in sex and age, and examined using resting-state functional magnetic resonance imaging (fMRI). The regional homogeneity (ReHo) technique was applied to evaluate spontaneous cerebral activity variations in children with SA and HCs. Moreover, associations between altered ReHo values in distinct cerebral areas and the degree of strabismus were assessed using Pearson correlation analysis.ResultsRemarkably increased ReHo values were observed in the right lingual, right superior frontal medial, bilateral superior parietal, and right inferior parietal gyri of children with SA compared with HCs. In contrast, mean ReHo values in children with SA were lower in the right cerebellum, left superior frontal gyrus, and left putamen nucleus. Furthermore, esotropia showed a positive correlation with ReHo values of the left putamen.ConclusionThe anomalous spontaneous activity changes in several brain areas that are caused by SA may indicate neuropathologic mechanisms of visual deficits and oculomotor disorders in children with SA.

Functional Deficits and Structural Changes Associated With the Visual Attention Network During Resting State in Adult Strabismic and Anisometropic Amblyopes.

Our previous study has shown impaired blood oxygen level-dependent (BOLD)/functional magnetic resonance imaging (fMRI) activation of the visual attention network in strabismic amblyopia (SA). However, there has been no comparison of resting state fMRI activation and functional connectivity (FC) in brain regions of interest (ROIs) along the visual attention network including visual cortex (V1), intraparietal sulcus (IPS), and frontal eye fields (FEFs) during closed eye resting across the SA (n = 20, 13LE), or anisometropic amblyopes (AA) (n = 20, 13LE) groups. Hence, we compared, gray matter volume (GMV), amplitude of low frequency fluctuations (ALFFs), regional homogeneity (ReHo), and FC in the left and right hemisphere ROIs of the visual attention network in SA, AA, and healthy controls (HCs) (n = 21). Correlation analyses of corrected visual acuity (cVA) of amblyopic eye and MRI results were also performed and showed that the LogMAR cVA of the amblyopic eye positively correlated with right zALFF and zReHo FEF of SA and right IPS of AA only. GMV of both left and right hemisphere V1 areas was significantly greater but ALFF was significantly lower for SA compared to AA and HC groups. zALFF and zReHo analyses in the AA and SA groups indicated significantly higher activation than that in the HC group in the right FEF and IPS but lower than that in the HC group in the left FEF, and only the SA group showed lower activation in both V1 areas than the HC group. FC values of the right FEF–left V1, right FEF–right V1, and right FEF–right IPS pathways in the SA and AA groups were also significantly higher than those in the HC group whereas all other FC values were non-significant. Thus, this study indicates that even during resting-state the visual attention network function is impaired in SA and AA participants with only right hemisphere FEF showing significant activation in SA and IPS in AA suggesting that the slower saccade activation times characteristic of amblyopic eyes lead to the dominant eye controlling activation of the visual attention network.

A randomized study of network-based perception learning in the treatment of amblyopia children.

To compare the effectiveness of network-based perception learning (NBPL) and traditional training in the treatment of amblyopia children. This randomized controlled clinical trial recruited 56 participants aged 4-12y with anisometropic and/or strabismic amblyopia. Participants were randomly divided into two groups: the NBPL group (n=28) who received patching and NBPL for 3mo, and the control group (n=28) who got 3mo of patching and traditional training. Best-corrected visual acuity (BCVA) in the amblyopic eye and stereoacuity were measured and compared at baseline, 1, 2, and 3mo post-randomization. There were no significant differences in age, gender ratio, and BCVA between the two groups at baseline. At 3mo, most patients gained lines (2 logMAR lines on average) of BCVA in both groups except one 11-year-old girl in the control group (P<0.05). But no significant difference in BCVA improvement of the amblyopic eye between the two groups was found (P=0.725), and amblyopia resolved (BCVA of 0.1 logMAR or better or within 1 logMAR line of the fellow eye) for 13 (46.4%) participants in both groups. The number of patients with improvement of stereoacuity was 25 and 13 in the NBPL group and control group (P=0.041), respectively, and a significant difference exists in the distribution of stereopsis at 3mo between the two groups (P=0.015). Besides, in patients with measurable stereopsis improvement degree and space for improvement in the two groups, the NBPL group also achieved better stereoscopic improvement than the control group (10/11 vs 4/11, P<0.05). The NBPL system has a significant effect on the improvement of BCVA and stereoacuity of amblyopia children and is better than traditional training in terms of stereoacuity improvement. Perceptual learning visual training may play a more important role in the treatment of amblyopia in the future.

Accommodative Lag Persistence in Treated Anisometropic, Strabismic, and Mixed Amblyopia.

Background Amblyopic eyes typically exhibit greater lag of accommodation. Whether this improves after amblyopia treatment is inconclusive. The aim of this study is to report post-treatment accommodative response in amblyopia and to investigate if the lag is associated with visual acuity, treatment duration, and amblyopia type. Methods Monocular and binocular accommodative responses were measured using Nott's method of dynamic retinoscopy in amblyopia of anisometropic, strabismic, and combined anisometropic-strabismic types and age-matched controls with normal vision. The results were compared using the nonparametric Wilcoxon signed ranks test. Linear regression analysis was used to examine association of the lag to refractive error, duration of therapy, and visual acuity. Results Mean ± SD age of 46 amblyopic and 20 control subjects were 6.9 ± 1.8 and 6.9 ± 2.2 years, respectively. At the time of the study, 30 amblyopic subjects were receiving patching therapy and ceased in the remainder. In amblyopic eyes, mean ± SD monocular and binocular lags were 1.2 ± 0.6D and 1.0 ± 0.5D (p < 0.001), respectively, compared to 0.6 ± 0.3D and 0.5 ± 0.2D (p < 0.005), respectively, in nonamblyopic eyes and 0.4 ± 0.2D and 0.3 ± 0.2D (p=0.093), respectively, in the controls. By types, the monocular lag was significantly higher than the binocular lag (p=0.001) in mixed amblyopia (p=0.004); they were similar in anisometropic (p=0.283) and strabismic (p=0.743) amblyopia. Monocular lag was significantly correlated to BCVA (r = 0.46; p=0.001) and refraction (r = 0.42; p=0.001) but not to patching duration (r = 0.1; p=0.280). Conclusion Inadequate accommodative response, a higher lag, persists in amblyopic eyes even after the treatment. Impaired accommodative response is partly determined by posttherapy visual acuity. Further studies investigating the effect of accommodative lag on visual recovery and whether optical correction of the deficiency may improve visual outcome of the treatment are recommended.

Crowding changes appearance systematically in peripheral, amblyopic, and developing vision.

Visual crowding is the disruptive effect of clutter on object recognition. Although most prominent in adult peripheral vision, crowding also disrupts foveal vision in typically developing children and those with strabismic amblyopia. Do these crowding effects share the same mechanism? Here we exploit observations that crowded errors in peripheral vision are not random: Target objects appear either averaged with the flankers (assimilation) or replaced by them (substitution). If amblyopic and developmental crowding share the same mechanism, then their errors should be similarly systematic. We tested foveal vision in children aged 3 to 8 years with typical vision or strabismic amblyopia and peripheral vision in typical adults. The perceptual effects of crowding were measured by requiring observers to adjust a reference stimulus to match the perceived orientation of a target “Vac-Man” element. When the target was surrounded by flankers that differed by ± 30°, all three groups (adults and children with typical or amblyopic vision) reported orientations between the target and flankers (assimilation). Errors were reduced with ± 90° differences but primarily matched the flanker orientation (substitution) when they did occur. A population pooling model of crowding successfully simulated this pattern of errors in all three groups. We conclude that the perceptual effects of amblyopic and developing crowding are systematic and resemble the near periphery in adults, suggesting a common underlying mechanism.

Disruption of Positional Encoding at Small Separations in the Amblyopic Periphery.

PurposePositional judgments in amblyopia are impaired more at the center of the visual field than in the periphery. However, the effects of visual field position frequently are confounded with stimulus separation. The purpose of this experiment was to parse the effects of stimulus separation and eccentricity on the positional deficit in amblyopia.MethodsSubjects adjusted the positions of stimuli of varying separations on isoeccentric arcs. The task was simultaneous bisection and alignment of broadband, high-contrast, uncrowded targets with reference to central fixation. Ten strabismic amblyopes and five normally sighted controls performed the task dichoptically; a subset of amblyopes performed the task monocularly with the amblyopic eye. Spread (inverse of precision) and bias were measured at multiple visual field locations comprising two to three separation four eccentricity conditions in each visual field quadrant.ResultsIn normal controls, both spread and bias increased with eccentricity, and spread (but not bias) increased linearly with separation until 7° eccentricity. Strabismic amblyopes showed a different profile: spread and bias were higher at small separations at all eccentricities, such that performance showed a quadratic trend against separation. Thus, at each eccentricity, the difference in performance between groups was largest at the smallest separation.ConclusionsThese results are consistent with disruptions in Weber mechanisms of positional encoding in strabismic amblyopia, and indicate that binocular stimulation by proximal targets produces a loss of spatial precision well beyond the fovea.

Altered Spontaneous Brain Activity Patterns in Children With Strabismic Amblyopia After Low-Frequency Repetitive Transcranial Magnetic Stimulation: A Resting-State Functional Magnetic Resonance Imaging Study

ObjectivePrevious studies have demonstrated altered brain activity in strabismic amblyopia (SA). In this study, low-frequency repetitive transcranial magnetic stimulation (rTMS) was applied in children with strabismic amblyopia after they had undergone strabismus surgery. The effect of rTMS was investigated by measuring the changes of brain features using the amplitude of low-frequency fluctuation (ALFF).Materials and MethodsIn this study, 21 SA patients (12 males and 9 females) were recruited based on their age (7–13 years old), weight, and sex. They all had SA in their left eyes and they received rTMS treatment one month after strabismus surgery. Their vision before and after surgery were categorized as pre-rTMS (PRT) and post-rTMS (POT). All participants received rTMS treatment, underwent magnetic resonance imaging (MRI), and their data were analyzed using the repeated measures t-test. The team used correlation analysis to explore the relationship between logMAR visual acuity and ALFF.ResultsPre- versus post-rTMS values of ALFF were significantly different within individuals. In the POT group, ALFF values were significantly decreased in the Angular_R (AR), Parietal_Inf_L (PIL), and Cingulum_Mid_R (CMR) while ALFF values were significantly increased in the Fusiform_R (FR) and Frontal_Inf_Orb_L(FIL) compared to the PRT stage.ConclusionOur data showed that ALFF recorded from some brain regions was changed significantly after rTMS in strabismic amblyopes. The results may infer the pathological basis of SA and demonstrate that visual function may be improved using rTMS in strabismic amblyopic patients.

Visual acuity increase in meridional amblyopia by exercises with moving gratings as compared to stationary gratings

ABSTRACT The aim of the present work was to investigate the effect of a novel therapy based on pleoptic exercises combined with standard occlusion in patients with meridional amblyopia. The exercising system itself, termed focal ambient visual acuity stimulation (FAVAS), consists of sinusoidally modulated circular gratings, which were implemented as a background pattern in computer games binding the children's attention. For the assessment of therapeutic effects, we tested for the development of best-corrected visual acuity (BCVA) in patients trained with a gaming field background of moving gratings (Moving) compared to patients treated with stationary gratings (Stationary). Patients with amblyopia (caused by strabismus, refraction, or both) and astigmatism were randomly allocated to two groups, all of whom received a standard occlusion regimen. In combination with occlusion, using a crossover design, the first group (Moving-Stationary group) was alternately exercised for 10 days with a series of Moving followed by 10 days with Stationary and the second group (Stationary-Moving group) vice versa. The treatment-dependent training effect on BCVA was measured with respect to the alignment of the least vs. the most ametropic meridian in both groups. BCVA was examined using a meridionally direction-sensitive visual test inventory, and we estimated the monocular BCVA in all patients along four meridians: 0°, 45°, 90°, and 135° before and after Moving as compared to Stationary treatments. The Moving-Stationary group consisted of 17 children (34 eyes) aged 10 to 13 (average 11.6 ± 0.3) years. The Stationary-Moving group consisted of 20 children (40 eyes) aged 9 to 14 (average 12.5 ± 0.4). In both groups, visual acuity increased significantly only with Moving combined with occlusion. Thereby, the visual acuity (logMAR) along different meridians showed a statistically significant improvement induced by Moving if testing was coincident with alignment of the directional optical characters close to the most ametropic meridian in the Moving-Stationary group (0.73 ± 0.32 to 0.41 ± 0.22, p < 0.01) and also in the Stationary-Moving group (0.48 ± 0.27 to 0.33 ± 0.18, p < 0.01). Significant improvement was also induced by Moving if tested in alignment with the perpendicular orientation close to the least ametropic meridian, although with a smaller amount, in the Moving-Stationary group (0.49 ± 0.23 to 0.37 ± 0.21, p < 0.01) as well as in the Stationary-Moving group (0.33 ± 0.18 to 0.28 ± 0.16, p < 0.01). After Stationary combined with occlusion, however, there was no statistically significant improvement, regardless of the meridian. Visual training of patients with meridional amblyopia by a series of online exercises using attention-binding computer games which contained moving gratings as a background stimulus (Moving) resulted in a statistically significant improvement in visual acuity in the most refractive meridian, and to a lesser extent, in the least refractive meridian. No statistically significant improvement was achieved after the respective exercising series in the sham condition with stationary gratings (Stationary).