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People with amblyopia have been shown to have decreased fixational stability, particularly those with strabismic amblyopia. Fixational stability and visual acuity have been shown to be tightly correlated across multiple studies, suggesting a relationship between acuity and oculomotor stability. Reduced visual acuity is the sine qua non of amblyopia, and recovery is measured by the improvement in visual acuity. Here we ask whether fixational stability can be used as an objective marker for the recovery of visual function in amblyopia. We tracked children’s fixational stability during patching treatment over time and found fixational stability changes alongside improvements in visual acuity. This suggests fixational stability can be used as an objective measure for monitoring treatment in amblyopia and other disorders.

Background Previous studies have demonstrated that strabismus amblyopia can result in markedly brain function alterations. However, the differences in spontaneous brain activities of strabismus amblyopia (SA) patients still remain unclear. Therefore, the current study intended to employthe voxel-mirrored homotopic connectivity (VMHC) method to investigate the intrinsic brain activity changes in SA patients. Purpose To investigate the changes in cerebral hemispheric functional connections in patients with SA and their relationship with clinical manifestations using the VMHC method. Material and methods In the present study, a total of 17 patients with SA (eight males and nine females) and 17 age- and weight-matched healthy control (HC) groups were enrolled. Based on the VMHC method, all subjects were examined by functional magnetic resonance imaging. The functional interaction between cerebral hemispheres was directly evaluated. The Pearson’s correlation test was used to analyze the clinical features of patients with SA. In addition, their mean VMHC signal values and the receiver operating characteristic curve were used to distinguish patients with SA and HC groups. Results Compared with HC group, patients with SA had higher VMHC values in bilateral cingulum ant, caudate, hippocampus, and cerebellum crus 1. Moreover, the VMHC values of some regions were positively correlated with some clinical manifestations. In addition, receiver operating characteristic curves presented higher diagnostic value in these areas. Conclusion SA subjects showed abnormal brain interhemispheric functional connectivity in visual pathways, which might give some instructive information for understanding the neurological mechanisms of SA patients.

Funding Information: We thank Suvi Lehto for helping with the MEG recordings. This study was supported by the Sigrid Juselius foundation and the Academy of Finland to S.P. (SA 266402, SA 273807) and J.M.P. (SA 253130), and Oskar Öflund Foundation to H.J. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Amblyopia is a developmental disorder associated with abnormal visual experience during early childhood commonly arising from strabismus and/or anisometropia and leading to dysfunctions in visual cortex and to various visual deficits. The different forms of neuronal activity that are attenuated in amblyopia have been only partially characterized. In electrophysiological recordings of healthy human brain, the presentation of visual stimuli is associated with event-related activity and oscillatory responses. It has remained poorly understood whether these forms of activity are reduced in amblyopia and whether possible dysfunctions would arise from lower- or higher-order visual areas. We recorded neuronal activity with magnetoencephalography (MEG) from anisometropic amblyopic patients and control participants during two visual tasks presented separately for each eye and estimated neuronal activity from source-reconstructed MEG data. We investigated whether event-related and oscillatory responses would be reducedfor amblyopia and localized their cortical sources. Oscillation amplitudes and evoked responses were reduced for stimuli presented to the amblyopic eye in higher-order visual areas and in parietal and prefrontal cortices. Importantly, the reduction of oscillation amplitudes but not that of evoked responses was correlated with decreased visual acuity in amblyopia. These results show that attenuated oscillatory responses are correlated with visual deficits in anisometric amblyopia.

We aimed to examine visual acuity improvement effect and adherence in amblyopia training using tablet type vision training equipment (Occlu-pad). The subjects were 138 patients with amblyopia (average age of 5.5 ± 1.6 years old); their amblyopic visual acuity at the start of training was logMAR 0.15 to 1.3. Occlu-pad is a device that processes images such that amblyopic eyes can only view the image as it passes through polarized glasses; this is achieved by peeling off the polarizing film layer in the liquid crystal display of an iPad (Apple). Amblyopia training comprised either the instructional training with Occlu-pad or the eye patch (Patching) as a family training, after wearing perfectly corrected glasses. Visual acuity improvement following amblyopia training by Occlu-pad and Patching was significantly different after 6 months in patients with anisometropic amblyopia (p

Purpose To estimate the prevalence of amblyopia among medical students in Saudi Arabia, and investigate the impact of amblyopia on their Academic performance. Methods This is a cross-sectional study which targeted 478 of male medical students from the College of Medicine at King Khalid University. A questionnaire was used to investigate the demographics of participants. Distance visual acuity was assessed monocularly using tumbling “E” chart in all participants. Then detailed ophthalmic evaluation was performed for any student with two or more lines difference between the two eyes or visual acuity of ≤20/40 in either eye. Results A sample of 478 male medical students, of whom 12(2.5%) were found to have amblyopia. Anisometropic amblyopia was the most common type (10/12, 83.3%) followed by strabismic amblyopia (2/12, 16.7%). There is a significant relation between past ocular history and amblyopia (p-value = 0.008). Up to 25% of amblyopic students not diagnosed before and 25% of them agree that amblyopia affects their social & psychiatric status. There was no effect of amblyopia on the academic performance (P-value = 0.5). Conclusion Amblyopia was found in 2.5% of male medical students. Amblyopia had a moderate effect on the students' lives, but it did not affect their academic performance.

Purpose To compare the macular retinal thickness of moderately to severely amblyopic eyes with non-amblyopic eyes as controls. Methods This case control study was conducted on 56 children aged 4 to 10 years old (64.3% female subjects). Twenty-eight children had unilateral amblyopia (28 amblyopic eyes as cases and 28 normal fellow eyes as internal controls) and 28 children had normal visual acuity in both eyes and were considered as external controls (n = 56 eyes). Among our cases, 14 had strabismic amblyopia and 14 had anisometropic amblyopia. Macular retinal thickness was measured using optical coherence tomography at the center and in 1-, 3-, and 6-mm rings. Results Best-corrected visual acuity of the amblyopic eyes was less than that of the internal and external controls, and the best-corrected visual acuity of their fellow eyes was also less than that of the external controls. Thickness of the central macula and a 1-mm ring area in the amblyopic eyes was higher than that of both internal and external controls. Difference of central macular thickness ≥20 μm between two eyes of the amblyopic children was significantly more than non-amblyopic subjects. Conclusions Based on the results of this study, the macular retinal thickness was significantly higher in moderate to severe amblyopic eyes compared to their fellow eyes and external controls. This might be due to macular developmental disorders in amblyopic eyes. Therefore, optical coherence tomography imaging is recommended if subtle macular abnormalities are suspected in moderate to severe amblyopic eyes.

Masoud Khorrami-Nejad,1 Mohamad Reza Akbari,2 Bahram Khosravi1 1Department of Optometry, Faculty of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran Purpose: To determine the frequency of different types of strabismus and amblyopia in the patients of strabismus clinics from 2008 to 2014. Methods: This retrospective cross-sectional study was conducted using data from the archives of Farabi Hospital in Tehran, Iran, from 2008 to 2014. The study consisted of using records of strabismic patients. From these, strabismus types and associated abnormalities, types of amblyopia and other ocular pathological findings were recorded. Results: In this study, 1174 strabismic patients were studied. Accommodative esotropia (ET) was the most prevalent type of strabismus accounting for 25.04% of all strabismic patients while intermittent exotropia (XT), nonaccommodative ET and partially accommodative ET, with 12.09%, 11.24% and 10.39%, respectively, were relatively common. Also, 63.03% of all strabismic patients had esodeviation with XT coming second accounting for 24.53% of patients. Other ocular pathologic findings in addition to strabismus were found in 236 (20.1%) patients. The most common association with those types of strabismus was inferior oblique over action accounting for 11.07% of all cases, and 88 patients had nystagmus in addition to strabismus. Significantly 45% of patients had no amblyopia and 37% of patients had a combined type of amblyopia which was the most common type of amblyopia found in strabismic patients. Conclusion: The prevalence of ET was two and a half times more than XT and almost half of strabismic patients suffer from amblyopia. This study suggests that strabismus screening of children could be useful in the early detection of strabismus, appropriate management of it and prevention of strabismic amblyopia. Keywords: horizontal deviation, amblyopia, vertical deviation, inferior oblique over action

Amblyopia is a developmental disorder of vision associated with abnormal visual stimulation during early childhood. It is known that amblyopia may affect not only spatial vision parameters but also oculomotor behavior. Several previous studies showed that increased saccadic reaction time (latency) may be present in amblyopic subjects. In our recent work, we have demonstrated that not only amblyopic but also a dominant eye may show increased saccadic latency in strabismic individuals. Since saccadic latency can be considered as a decision time, we have applied LATER (Linear Approach to Threshold with Ergodic Rate) decision model to find out how developmental impairment of visual input affects visual decision-making processes, as well as to verify whether amblyopia affects also the cortical ability to inhibit more primitive, early saccadic responses during our modified delayed saccade task. Ten subjects with strabismic amblyopia and twelve control subjects were examined. As we expected, strabismic amblyopes showed decreased rate of rise of the neural decision signal for all viewing conditions as compared to controls. In addition, the comparison between the strabismic and anisometropic groups revealed that the amblyopic eye in strabismic subjects showed decreased rate of rise of the decision signal as compared to amblyopic eye in anisometropic subjects. Although we speculated that amblyopia may reduce the ability of cortical control and favor more reflexive, early saccadic actions to occur, our findings did not confirm this hypothesis. This study provide further evidence that amblyopia is associated with cortical deficits which affect the cortical decision about saccade initiation.

To evaluate the best-corrected visual acuity and stereoacuity gains in children7 years of age and adults with unilateral amblyopia treated with a prototype virtual reality-based binocular amblyopia therapy.In this randomized, double masked, cross-in clinical trial, patients at Boston Children's Hospital with unilateral anisometropic and/or strabismic amblyopia and history of prior amblyopia treatment failure were randomized to either a full-treatment group (8 weeks of binocular treatment using therapeutic software application in virtual reality headset) or a sham-crossover group (4 weeks of sham treatment followed by 4 weeks of binocular treatment). Amblyopic eye visual acuity and stereoacuity were evaluated at 4, 8, and 16 weeks' follow-up.The study cohort included 20 participants (10 females), with a median age of 9 years (range, 7-38 years). In the full-treatment group (11 patients), the mean amblyopic eye logMAR visual acuity at 16 weeks was 0.49 ± 0.26, compared with 0.47 ± 0.20 at baseline. In the sham-crossover group, it was 0.51 ± 0.18 at 16 weeks, compared with 0.53 ± 0.21 at baseline. Stereoacuity (log arcsec) was significantly improved, from 7.3 ± 2 at baseline to 6.6 ± 2.3 at 8 weeks (P 0.001) and 6.7 ± 2.6 at 16 weeks (P 0.001). No significant adverse events (diplopia, asthenopia, or worsening strabismus) were noted in either group.Although the virtual reality-based prototype for binocular amblyopia therapy did not significantly improve visual acuity in the amblyopic eyes of older children and adults, stereoacuity did significantly improve compared with baseline; improvements were clinically minute. However, larger studies are required to confirm the results.

Purpose To quantify vessel density of superficial capillary plexus (SCP), deep capillary plexus (DCP), and the foveal avascular zone (FAZ) of children's amblyopic eyes and to compare the measurements with those of companion eyes and age-matched controls. Methods Fifteen patients with strabismic amblyopia, and 15 age-matched controls were included in this cross-sectional study. SCP, DCP, and FAZ were measured via optical coherence tomographic angiography (OCTA). Results Mean subject age was 8.2 ± 2.3 years in the amblyopia group and 8.6 ± 2.2 years in the control group. The mean SCP at 1 mm, 2 mm, and 3 mm zones were (in the order amblyopic eye, companion eye, control) 1.399 ± 0.088, 5.854 ± 0.195, 12.866 ± 0.346; 1.467 ± 0.084, 5.979 ± 0.182, 12.965 ± 0.321; and 1.559 ± 0.052, 6.343 ± 0.190, 13.819 ± 0.423. SCP was significantly lower in amblyopic eyes than in companion eyes and controls ( P P P > 0.05). Conclusions Vessel density of SCP and DCP of eyes with amblyopia is lower than that of the companion eye and the age-matched controls.

Purpose: To evaluate the superficial retinal vascular plexus density using optical coherence tomography angiography (OCTA) in cases of strabismic amblyopia. Methods: Ten eyes of 10 patients with purely strabismic amblyopia underwent detailed ocular evaluation followed by the assessment of the superficial retinal plexus vascular density using OCTA (Topcon DRI OCT Triton, Swept Source OCT, Topcon, Japan). Ten contralateral normal eyes of the same patients were considered as control. All these 20 eyes underwent a 4.5 × 4.5 mm cube scan OCTA centered at the fovea. Using the Topcon propriety software all 20 eyes were assessed for the capillary plexus density of the superficial retinal vascular plexus along the superior, inferior, nasal, and temporal quadrants centered at the fovea. The numerical values were statistically assessed using a paired t-test with respect to each quadrant between the normal and the pathological eyes. Results: The average age of patients was 16 years and eight patients were males. The mean superficial retinal vascular plexus density along the superior, inferior, nasal, and temporal quadrants in normal and pathological eyes were 49.25 ± 30.34 and 48.93 ± 2.85, 47.22 ± 4.11 and 47.37 ± 4.8, 45.54 ± 1.55 and 43.81 ± 4.21, and 46.26 ± 4.63 and 46.38 ± 5.40, respectively. Similarly, the capillary densities along the central were 17.84 ± 3.49 and 17.24 ± 2.44 in normal and pathological eyes. The differences among all these four quadrants and central area were not statistically significant (P-values > 0.05 for all four quadrants and central area) as compared with the normal eyes. Conclusion: The superficial retinal vascular plexus density of a 4.5 × 4.5 mm cube centered at the fovea of eyes of cases of strabismic amblyopia is similar to that of normal eyes.

Objectives To evaluate the pupillary light reflex responses in patients with unilateral strabismic and anisometropic amblyopia using dynamic pupillometry. Materials and methods A total of 102 eyes of 51 patients with unilateral amblyopia were included in this cross-sectional study. Of the 51 patients, 37 (72.5%) had strabismic amblyopia and 14 (27.5%) had anisometropic amblyopia. All patients underwent complete ophthalmological examination, and pupillary light reflex responses were measured using a computerized dynamic pupillometry system (MonPack One; Metrovision, France). Initial pupil diameter; the amplitude, latency, duration, and velocity of pupil contraction; and the latency, duration, and velocity of pupil dilation were recorded. Results obtained from the patients’ amblyopic and normal fellow eyes were compared using paired-samples t-test and Wilcoxon signed rank test. Results The mean age of the patients was 11.9±6.0 years. Amblyopic eyes had longer contraction latency (p=0.009), shorter contraction duration (p=0.002), and higher dilation velocity (p=0.033) compared to fellow eyes, while other parameters did not show significant differences. In subgroup analysis, eyes with strabismic amblyopia had longer contraction latency (p=0.006) and shorter contraction duration (p=0.017), while eyes with anisometropic amblyopia had shorter contraction duration (p=0.030) when compared with fellow eyes. Conclusion In this study, the objective records obtained by dynamic pupillometry showed that pupillary light reflex responses are affected in amblyopic eyes. This finding may shed light on unclear aspects of the pathophysiology of amblyopia.

Purpose: Strabismus and anisometropia are the most common causes of amblyopia. It can be easily prevented or treated if detected early. With the changing socio-cultural-economic milieu of the society, the perspectives of strabismus in society are gradually changing but still adequate knowledge, awareness, and attitude of parents toward strabismus will help in preventing amblyopia and aid in the proper psychosocial adaptation of such children. This study aimed to assess knowledge and attitude of parents toward children suffering from strabismus. Methods: A prospective study was carried out from January 1 to February 29, 2016, through a structured questionnaire to assess the level of knowledge and attitude of parents of children suffering from strabismus. Results: One hundred and twenty parents of children with strabismus were interviewed through a questionnaire. Education level of 78 parents was less than graduation (60%) and of 42 parents (40%) was graduation or higher. The majority of the parents, i.e., 116 (96.67%) were bothered due to strabismus. One hundred and one (84.17%) parents felt that their child's strabismus was noticed by others during interaction. Seventy-four (61.67%) parents felt that their children will have difficulty in making friends. Ninety (75%) parents felt uncomfortable if someone asked something about their child's strabismus. One hundred and ten (91.67%) parents considered strabismus as cosmetic stigma. Conclusion: Some parents, especially from the lower educated segment, had poor understanding of strabismus, thus resulting in late presentation and ineffective countermeasures. The key to prevent strabismic amblyopia and its psychosocial impacts is to provide health education regarding strabismus.

Purpose While using their amblyopic eye, individuals with strabismic amblyopia count inaccurately and underestimate the number of features. These deficits are attributed to limitations in high-level cortical functions and attention. In the current study, we examined whether feature counting is affected in strabismic and anisometropic amblyopia during dichoptic viewing, a setup that can better capture binocular function disruptions. Methods Through a mirror stereoscope, Gabor patches were presented for 200 msec (Experiment 1) or 350 msec (Experiment 2) in both the left eye and the right eye of observers, who were required to combine the percepts and report the total number of patches. Counting performance and errors were compared across amblyopic groups and normal-sighted observers. The contribution and relation of each eye to performance was also evaluated. Results Anisometropic and strabismic amblyopia groups counted inaccurately and underestimated the number of features compared to the normal-sighted group. In both amblyopic groups, the amblyopic eye contributed less in comparison to the fellow eye. The strabismic group exhibited worse performance, and a more pronounced difference in eye contribution, in comparison to the anisometropic group. Conclusions Overall, our results support the view of higher-level cortical and binocular function deficits in amblyopia. Translational relevance The current study bridges the gap between research on high-cortical function deficits and clinical binocular function disruptions in amblyopia, which can help us better understand the neural mechanism of amblyopia and inform clinical therapeutic tasks and strategies.

In this study, we aimed to explore an objective, sensitive and quantitative measurement of interocular suppression in strabismic amblyopia. We compared 11 strabismic subjects with 12 normal vision subjects to explore the different response characterizations in normal eyes, nondominant and dominant eyes of strabismic subjects by using steady-state motion visual evoked potentials (SSMVEPs). Stimulation at different temporal frequencies was presented to two eyes by using an interocular dichoptic technique. Furthermore, canonical correlation analysis (CCA), signal-to-noise ratio (SNR) and some statistical methods, such as the paired t-test, analysis of variance (ANOVA) and correlation analysis, were used to analyze electroencephalography (EEG) signals. We proposed two indices-divergence J and suppression imbalance (SI) to describe the deficits in interocular suppression-and one index - mask attenuation coefficient (MAC)- to describe the influence of a dichoptic mask from the dominant eyes to nondominant eyes of strabismic subjects. A significant difference was found between nondominant and dominant eyes of strabismic subjects in SSMVEP response and SNR value while no apparent difference was observed between the two eyes in subjects with normal vision. There was a strong linear correlation between divergence J, SI and visual acuity difference of two eyes both in strabismic amblyopia and normal vision. A linear correlation was also found between visual acuity difference and MAC in patients with strabismic amblyopia. Our findings suggest that SSMVEPs can be an objective and quantitative method for measuring the interocular suppression in strabismus and assessing the deficits of strabismic amblyopia.

Optical treatment is the primary treatment of all types of amblyopia that has a refractive component. However, it is unclear how optical treatment impacts cortical processing in amblyopic children as some of them may readily improve letter recognition visual acuity (treatment responders) but others may not (treatment non-responders). The main aim was to investigate the electrophysiological and psychophysical effects of optical treatment in children who have been newly-diagnosed with amblyopia in comparison with normal maturation in non-amblyopic children. The secondary aim was to explore whether pattern onset-offset visual evoked potentials (POVEPs) and psychophysical grating acuities (GA) may be predictive of clinically significant improvements in letter recognition visual acuity (VA) after four months of optical treatment. The primary outcome measures were POVEP C3 amplitude and C3 latency and GA which were assessed in response to orientation-specific stimuli. The testing protocol was designed to optimize the assessment of meridional anisotropies and was able to identify children with refractive amblyopia and to monitor treatment outcomes. The study presented evidence that four months of optical treatment improved POVEP C3 amplitude on average, although within the amblyopic group, a subset of refractive amblyopes were not found to significantly improve in letter visual acuity. A comparison control group, comprised of non-amblyopic children, were also monitored over two visits four months apart, which represented age-normal characteristics and maturation. Meridional anisotropies were found to be a potentially useful indicator of normality, as there was evidence that orientation-specific neural mechanisms differed for the responders and non-responders to optical treatment, with the responders showing anisotropies more consistent with the control data. An onset of horizontal effect may indicate that the amblyopic visual systems are improving. Consequently, lower POVEP C3 amplitude in response to horizontally oriented grating stimuli at baseline was found to be a potential predictor of responder status after four months of optical treatment. The findings added new knowledge into the understanding of the electrophysiological and psychophysical effects of optical treatment in refractive amblyopia.

The present study aimed to explore temporal frequency discrimination in amblyopia, and the influence of attentional load on amblyopic temporal cognition. Twenty anisometropic amblyopes, 20 strabismic amblyopes and 20 normal subjects were recruited. A flickering disk was used for visual stimuli. A two-alternative, forced-choice staircase paradigm was used to measure the temporal frequency discrimination thresholds of amblyopic eyes, fellow eyes and normal dominant eyes under reference temporal frequencies of 5, 10 and 20 Hz. The just-noticeable differences data were analyzed statistically. In addition, the temporal frequency discrimination thresholds of the subjects were measured under different conditions of attentional load. The changes in temporal frequency discrimination thresholds were compared between amblyopic and normal eyes when attention was loaded. At the reference temporal frequencies of 5 and 10 Hz, temporal thresholds of amblyopic eyes were significantly increased compared with fellow eyes (P

Background To evaluate the effectiveness of binocularity-stimulating treatment in children with residual amblyopia following occlusion therapy for more than 6 months. Methods Of patients with amblyopia caused by anisometropia and/or strabismus, patients with residual amblyopia following more than 6 months of occlusion therapy were included. Subjects underwent one of the following types of binocularity-stimulating therapy: Bangerter foil (BF), head-mounted display (HMD) game, or BF/HMD combination (BF + HMD). Factors including age, sex, types of amblyopia, visual acuity, and duration of treatment were investigated. Baseline and final (after at least 2 months of treatment) visual acuity were also compared. Results Twenty-two patients with a mean age of 8.7 ± 1.3 years were included. Seven patients had anisometropic amblyopia, 8 patients had strabismic amblyopia, and 7 patients had combined amblyopia. After 4.4 ± 1.8 months of treatment, logarithm of the minimum angle of resolution (logMAR) visual acuity in the amblyopic eye improved from 0.22 ± 0.20 to 0.18 ± 0.15. Five of 22 patients (22.7%) gained more than 0.2 logMAR, including 1 of 10 patients (10.0%) in the BF group, 2 of 7 patients (28.6%) in the HMD group, and 2 of 5 patients (40.0%) in the BF + HMD group. No significant differences in clinical characteristics were identified among the three groups. Conclusions Binocularity-stimulating therapy is somewhat beneficial in children with residual amblyopia and might be attempted when children no longer benefit from sufficient long-term period of occlusion therapy.

Amblyopia therapy options have traditionally been limited to penalisation of the non-amblyopic eye with either patching or pharmaceutical penalisation. Solid evidence, mostly from the Pediatric Eye Disease Investigator Group, has validated both number of hours a day of patching and days per week of atropine use. The use of glasses alone has also been established as a good first-line therapy for both anisometropic and strabismic amblyopia. Unfortunately, visual acuity equalisation or even improvement is not always attainable with these methods. Additionally, non-compliance with prescribed therapies contributes to treatment failures, with data supporting difficulty adhering to full treatment sessions. Interest in alternative therapies for amblyopia treatment has long been a topic of interest among researchers and clinicians alike. Incorporating new technology with an understanding of the biological basis of amblyopia has led to enthusiasm for binocular treatment of amblyopia. Early work on perceptual learning as well as more recent enthusiasm for iPad-based dichoptic training have each generated interesting and promising data for vision improvement in amblyopes. Use of pharmaceutical augmentation of traditional therapies has also been investigated. Several different drugs with unique mechanisms of action are thought to be able to neurosensitise the brain and enhance responsiveness to amblyopia therapy. No new treatment has emerged from currently available evidence as superior to the traditional therapies in common practice today. But ongoing investigation into the use of both new technology and the understanding of the neural basis of amblyopia promises alternate or perhaps better cures in the future.

Although the neural locus of strabismic amblyopia has been shown to lie at the first site of binocular integration, first in cat and then in primate, an adequate mechanism is still lacking. Here we hypothesise that increased temporal dispersion of LGN X-cell afferents driven by the deviating eye onto single cortical neurons may provide a neural mechanism for strabismic amblyopia. This idea was investigated via single cell extracellular recordings of 93 X and 50 Y type LGN neurons from strabismic and normal cats. Both X and Y neurons driven by the non-deviating eye showed shorter latencies than those driven by either the strabismic or normal eyes. Also the mean latency difference between X and Y neurons was much greater for the strabismic cells compared with the other two groups. The incidence of lagged X-cells driven by the deviating eye of the strabismic cats was higher than that of LGN X-cells from normal animals. Remarkably, none of the cells recorded from the laminae driven by the non-deviating eye were of the lagged class. A simple computational model was constructed in which a mixture of lagged and non-lagged afferents converge on to single cortical neurons. Model cut-off spatial frequencies to a moving grating stimulus were sensitive to the temporal dispersion of the geniculate afferents. Thus strabismic amblyopia could be viewed as a lack of developmental tuning of geniculate lags for neurons driven by the amblyopic eye. Monocular control of fixation by the non-deviating eye is associated with reduced incidence of lagged neurons, suggesting that in normal vision, lagged neurons might play a role in maintaining binocular connections for cortical neurons.

Purpose To compare the choroidal thickness of children's eyes with amblyopia due to strabismus or anisometropia to the fellow eye and age-matched controls. Methods Forty patients with anisometropic amblyopia, 40 patients with strabismic amblyopia, and 40 age-matched controls were included in this cross-sectional study. Choroidal thickness was measured via the enhanced-depth imaging technique of spectral domain optical coherence tomography in all patients and controls. Choroidal thickness was measured at subfoveal area and at 500 μm intervals to the nasal and temporal to the fovea up to 2000 μm. Measurements were compared between the three groups. Results The mean ages were 7.9 ± 2.6 years (range, 4-13 years) in the anisometropic group, 9.0 ± 3.7 (range 4-15 years) years in the strabismic group, and 8.4 ± 2.6 years (range 4-15 years) in the control group. The mean subfoveal choroidal thickness in the anisometropic group was 362 ± 82 μm in the amblyopic eyes and 301 ± 54 μm in the fellow eyes; in the strabismic group, 413 ± 82 μm in the amblyopic eyes and 316 ± 54 μm in the fellow eyes. The mean subfoveal choroidal thickness was 310 ± 78 μm in control eyes. The subfoveal choroids of both anisometropic and strabismic amblyopic eyes were significantly thicker than that of the fellow eyes of the corresponding groups and the control eyes (P Conclusions The subfoveal choroid of eyes with anisometropic and strabismic amblyopia is significantly thicker than that of the fellow eye and the age-matched controls.

Strabismic amblyopia “blunt vision” is a developmental anomaly that affects binocular vision and results in lowered visual acuity. Strabismus is a term for a misalignment of the visual axes and is usually characterized by impaired ability of the strabismic eye to take up fixation. Such impaired fixation is usually a function of the temporally and spatially impaired binocular eye movements that normally underlie binocular shifts in visual attention. In this review, we discuss how abnormal eye movement function in children with misaligned eyes influences the development of normal binocular visual attention and results in deficits in visual function such as depth perception. We also discuss how eye movement function deficits in adult amblyopia patients can also lead to other abnormalities in visual perception. Finally, we examine how the nonamblyopic eye of an amblyope is also affected in strabismic amblyopia.

Luiz Cláudio Santos de Souza Lima,1 Adalmir Morterá Dantas,2 Guilherme Herzog Neto,1 Eduardo França Damasceno,1 Helena Parente Solari,1 Marcelo Palis Ventura1 1Department of General Surgery, Federal Fluminense University, Niteroi, 2Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil Purpose: To compare anisometropic hypermetropic amblyopic and strabismic amblyopic responses to pattern electroretinogram (PERG) and pattern visual evocated potential (PVEP). Materials and methods: Fifty-six patients – 18 hypermetropic anisometropic amblyopic children (mean age 9.70±2.5 years), 19 strabismic amblyopic children (mean age 10.30±2.6 years) and 19 normal emetropic subjects (mean age 10.10±2.2 years) – were enrolled in this study. After routine ophthalmic examination, PERG and PVEP were recorded in response to checks reversed at the rate of two reversals/second stimulating macular area. Results: The difference between hypermetropic anisometropic amblyopia and strabismus amblyopia with respect to P100/P50/N95 wave latencies (P=0.055/0.855/0.132) and P100/P50/N95 amplitudes (P=0.980/0.095/0.045) was not statistically significant. However, there was a significant statistical difference between strabismic amblyopia group and controls for P100/P50/N95 latencies (P=0.000/0.006/0.004). Conclusion: Our findings indicated that despite clinical differences between anisometropic amblyopic and strabismic amblyopic patients, no differences were found in the responses of PVEP and PERG. The abnormal components of the PVEP and PERG in amblyopic subjects could reflect a retinal dysfunction in the visual pathway. Keywords: amblyopia, strabismus, pattern electroretinogram, pattern visual evocated potential, anisometropia

Previous studies show slow reading in strabismic amblyopia. We recently identified amblyopia, not strabismus, as the key factor in slow reading in children. No studies have focused on reading in amblyopic children without strabismus. We examined reading in anisometropic children and evaluated whether slow reading was associated with ocular motor dysfunction in children with amblyopia.Anisometropic children (7-12 years) with or without amblyopia were compared to age-similar normal controls. Children silently read a grade-appropriate paragraph during binocular viewing. Reading rate (words/min), number of forward and regressive saccades (per 100 words) and fixation duration were recorded with the ReadAlyzer. Binocular fixation instability was also evaluated (EyeLink 1000).Amblyopic anisometropic children read more slowly (n = 25; mean with standard deviation, 149 ± 42 words/min) than nonamblyopic anisometropic children (n = 15; 196 ± 80 words/min; P = 0.024) and controls (n = 25; 191 ± 65 words/min; P = 0.020). Nonamblyopic anisometropic children read at a comparable rate to controls (P = 0.81). Slow reading in amblyopic anisometropic children was correlated with increased forward saccades (r = -0.84, P 0.001), increased regressive saccades (r = -0.85, P 0.001), and fellow eye instability during binocular viewing (r = -0.52, P = 0.019).Slow reading in school-age children with anisometropic amblyopia is related to increased frequency of saccades and fixation instability of the fellow eye. Further research should consider the effects of slower reading on academic performance.

Background Children with deprivation amblyopia due to childhood cataract have been excluded from much of the emerging research into amblyopia treatment. An investigation was conducted to determine whether contrast-balanced binocular treatment - a strategy currently being explored for children with anisometropic and strabismic amblyopia - may be effective in children with deprivation amblyopia. Methods An unmasked, case-series design intended to assess proof of principle was employed. Eighteen children with deprivation amblyopia due to childhood cataracts (early bilateral n = 7, early unilateral n = 7, developmental n = 4), as well as 10 children with anisometropic (n = 8) or mixed anisometropic and strabismic amblyopia (n = 2) were prescribed one hour a day of treatment over a six-week period. Supervised treatment was available. Visual acuity, contrast sensitivity, global motion perception and interocular suppression were measured pre- and post-treatment. Results Visual acuity improvements occurred in the anisometropic/strabismic group (0.15 ± 0.05 logMAR, p = 0.014), but contrast sensitivity did not change. As a group, children with deprivation amblyopia had a smaller but statistically significant improvement in weaker eye visual acuity (0.09 ± 0.03 logMAR, p = 0.004), as well a significant improvement in weaker eye contrast sensitivity (p = 0.004). Subgroup analysis suggested that the children with early bilateral deprivation had the largest improvements, while children with early unilateral cataract did not improve. Interestingly, binocular contrast sensitivity also improved in children with early bilateral deprivation. Global motion perception improved for both subgroups with early visual deprivation, as well as children with anisometropic or mixed anisometropic/strabismic amblyopia. Interocular suppression improved for all subgroups except children with early unilateral deprivation. Conclusion These data suggest that supervised contrast-balanced binocular treatment should be further investigated as a treatment option for children with deprivation amblyopia. However, for children with more severe deprivation amblyopia due to early unilateral cataracts, supplementary or alternative options should also be explored.

PURPOSE To examine the effects of strabismic amblyopia and strabismus only, without amblyopia, on the temporal patterns of eye-hand coordination during both the planning and execution stages of visually-guided reaching. METHODS Forty-six adults (16 with strabismic amblyopia, 14 with strabismus only, and 16 visually normal) executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation. Viewing conditions were binocular, monocular viewing with the amblyopic eye, and monocular viewing with the fellow eye (dominant and nondominant viewing for participants without amblyopia). Temporal coordination between eye and hand movements was examined during reach planning (interval between the initiation of saccade and reaching, i.e., saccade-to-reach planning interval) and reach execution (interval between the initiation of saccade and reach peak velocity [PV], i.e., saccade-to-reach PV interval). The frequency and dynamics of secondary reach-related saccades were also examined. RESULTS The temporal patterns of eye-hand coordination prior to reach initiation were comparable among participants with strabismic amblyopia, strabismus only, and visually normal adults. However, the reach acceleration phase of participants with strabismic amblyopia and those with strabismus only were longer following target fixation (saccade-to-reach PV interval) than that of visually normal participants (P < 0.05). This effect was evident under all viewing conditions. The saccade-to-reach planning interval and the saccade-to-reach PV interval were not significantly different among participants with amblyopia with different levels of acuity and stereo acuity loss. Participants with strabismic amblyopia and strabismus only initiated secondary reach-related saccades significantly more frequently than visually normal participants. The amplitude and peak velocity of these saccades were significantly greater during amblyopic eye viewing in participants with amblyopia who also had negative stereopsis. CONCLUSIONS Adults with strabismic amblyopia and strabismus only showed an altered pattern of temporal eye-hand coordination during the reach acceleration phase, which might affect their ability to modify reach trajectory using early online control. Secondary reach-related saccades may provide a compensatory mechanism with which to facilitate the late online control process in order to ensure relatively good reaching performance during binocular and fellow eye viewing.

Syunsuke Araki,1 Atsushi Miki,1,2 Tsutomu Yamashita,1,2 Katsutoshi Goto,1,2 Kazuko Haruishi,1 Yoshiaki Ieki,1 Junichi Kiryu1 1Department of Ophthalmology, Kawasaki Medical School, Kurashiki, Japan; 2Department of Sensory Science, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Kurashiki, Japan Purpose: To compare the macular retinal thickness and characteristics of optic nerve head (ONH) parameters in amblyopic and fellow eyes in patients with unilateral amblyopia.Patients and methods: A total of 21 patients with unilateral amblyopia (14 patients with anisometropic amblyopia, four patients with strabismic amblyopia, and three patients with both) were examined using spectral-domain optical coherence tomography. The mean age of the patients was 8.5±3.5 years. The examined parameters included the mean macular (full, inner, and outer), ganglion cell complex and circumpapillary retinal nerve fiber layer (cpRNFL) thicknesses, and ONH parameters (rim volume, nerve head volume, cup volume, rim area, optic disc area, cup area, and cup-to-disc area ratio).Results: The amblyopic eyes were significantly more hyperopic than the fellow eyes (P

PubMed ID: 23244242, Purpose: To evaluate the retinal nerve fiber layer (RNFL) thickness of eyes with amblyopia using optical coherence tomography (OCT). Methods: RNFL thickness measurements obtained by time-domain OCT of amblyopic eyes of patients with strabismus (35 patients) and patients with anisometropia (30 patients) were compared with their fellow eyes and age- and gender-matched healthy eyes (40 participants). RNFL thickness values of the groups were also compared and the correlation between RNFL thickness and refraction was evaluated. Results: In the strabismic and anisometropic groups, there were no statistically significant diff erences in average RNFL thickness between amblyopic eyes and their fellow eyes (P > .05). Temporal RNFL quadrant in the hypermetropic anisometropic group, and superior RNFL quadrant in the myopic anisometropic group were significantly thinner in amblyopic eyes compared to their fellow eyes (P < .05). RNFL thickness did not differ between strabismic amblyopic, anisometropic amblyopic, and control eyes (P > .05). In the anisometropic group, a significant correlation was found between mean RNFL thickness and refraction (P < .05). Conclusion: Amblyopia is not associated with a decrease in RNFL thickness in strabismic or anisometropic amblyopia. In the anisometropic group, the inter-eye diff erences in RNFL thickness parameters seemed to be related to the refraction diff erences between the amblyopic eyes and their fellow eyes.