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: Amblyopia and strabismus affect 2%-5% of the population and cause a broad range of visual deficits. The response to treatment is generally assessed using visual acuity, which is an insensitive measure of visual function and may, therefore, underestimate binocular vision gains in these patients. On the other hand, the contrast sensitivity function (CSF) generally takes longer to assess than visual acuity, but it is better correlated with improvement in a range of visual tasks and, notably, with improvements in binocular vision. The present study aims to assess monocular and binocular CSFs in amblyopia and strabismus patients. : Both monocular CSFs and the binocular CSF were assessed for subjects with amblyopia ( = 11), strabismus without amblyopia ( = 20), and normally sighted controls ( = 24) using a tablet-based implementation of the quick CSF, which can assess a full CSF in <3 min. Binocular summation was evaluated against a baseline model of simple probability summation. : The CSF of amblyopic eyes was impaired at mid-to-high spatial frequencies compared to fellow eyes, strabismic eyes without amblyopia, and control eyes. Binocular contrast summation exceeded probability summation in controls, but not in subjects with amblyopia (with or without strabismus) or strabismus without amblyopia who were able to fuse at the test distance. Binocular summation was less than probability summation in strabismic subjects who were unable to fuse. : We conclude that monocular and binocular contrast sensitivity deficits define important characteristics of amblyopia and strabismus that are not captured by visual acuity alone and can be measured efficiently using the quick CSF.

Sensorimotor coupling in healthy humans is demonstrated by the higher accuracy of visually tracking intrinsically—rather than extrinsically—generated hand movements in the fronto-parallel plane. It is unknown whether this coupling also facilitates vergence eye movements for tracking objects in depth, or can overcome symmetric or asymmetric binocular visual impairments. Human observers were therefore asked to track with their gaze a target moving horizontally or in depth. The movement of the target was either directly controlled by the observer’s hand or followed hand movements executed by the observer in a previous trial. Visual impairments were simulated by blurring stimuli independently in each eye. Accuracy was higher for self-generated movements in all conditions, demonstrating that motor signals are employed by the oculomotor system to improve the accuracy of vergence as well as horizontal eye movements. Asymmetric monocular blur affected horizontal tracking less than symmetric binocular blur, but impaired tracking in depth as much as binocular blur. There was a critical blur level up to which pursuit and vergence eye movements maintained tracking accuracy independent of blur level. Hand–eye coordination may therefore help compensate for functional deficits associated with eye disease and may be employed to augment visual impairment rehabilitation.

Stereopsis, the perception of depth based on the disparity of the images projected to the retinas of the two eyes, is an important process in our three-dimensional world; however, 3–5% of the population is stereoblind or has seriously impaired stereovision. Here we provide evidence for the recovery of stereopsis through perceptual learning, the repetitive practice of a demanding visual task, in human adults long deprived of normal binocular vision. We used a training paradigm that combines monocular cues that were correlated perfectly with the disparity cues. Following perceptual learning (thousands of trials) with stereoscopic gratings, five adults who initially were stereoblind or stereoanomalous showed substantial recovery of stereopsis, both on psychophysical tests with stimuli that contained no monocular cues and on clinical testing. They reported that depth \"popped out\" in daily life, and enjoyed 3D movies for the first time. After training, stereo tests with dynamic random-dot stereograms and band-pass noise revealed the properties of the recovered stereopsis: It has reduced resolution and precision, although it is based on perceiving depth by detecting binocular disparity. We conclude that some human adults deprived of normal binocular vision can recover stereopsis at least partially.

Previous studies have demonstrated that strabismus or amblyopia can result in marked brain function and anatomical alterations. However, differences in spontaneous brain activity in strabismus and amblyopia (SA) patients as compared with control individuals remain unclear. The present study aimed to analyze the potential brain activity changes in SA patients and their association with behavioral performance. In total, 16 patients with SA (10 women and 6 men) and 16 healthy controls (HCs; 6 men and 10 women) with matched age and sex were recruited. All subjects were examined with resting-state functional magnetic resonance imaging (rs-fMRI), and changes in the spontaneous brain activity of SA patients were evaluated by the regional homogeneity (ReHo) method. The diagnostic ability of the ReHo method was assessed using receiver operating characteristic (ROC) curve analysis. In addition, the association between the mean ReHo value in different brain regions and the behavioral performance was explored by correlation analysis. It was observed that the ReHo value was significantly increased in SA patients compared with HCs in the following brain regions: left lingual gyrus, right middle occipital gyrus/precuneus, bilateral anterior cingulate, left middle occipital gyrus and bilateral precentral gyrus. By contrast, the ReHo value of the left inferior frontal gyrus was significantly lower than that in HCs. ROC curve analysis indicated that the ReHo method has certain credibility for the diagnosis of SA patients. In addition, no similar changes were detected in other brain regions. These results revealed abnormal spontaneous brain activity in certain parts of the brain in adult patients with SA, which suggests the involvement of the neuropathological or compensatory mechanism in these patients, and may be beneficial for clinical treatment.

Background Strabismus and amblyopia are known to cause visual dysfunction, self-image disorders, difficulty in seeking employment and social and emotional barriers. These factors can have a serious and detrimental effect upon the patients’ health-related quality of life (HRQOL). Presently, a condition-specific questionnaire is not available for assessing the HRQOL in Chinese patients. This study developed a Chinese version of the Amblyopia and Strabismus Questionnaire (ASQE) and tested its reliability and validity in Chinese adult strabismus patients. Methods Chinese strabismus adults, adults with normal vision and patients with a variety of other eye diseases completed the Chinese version of the ASQE. Reliability was established by Cronbach’s alpha and test-retest. Validity was evaluated by content, construct, criterion-related, convergent and discriminative validities. Results A total of 202 adult strabismus patients with or without amblyopia, 100 visually normal adults, and 100 patients with other eye diseases (excluding strabismus and amblyopia) participated in this study. Using principal components analysis, six domains were extracted, with a content validity of 0.91. Four items were deleted giving final total of 22 items in the questionnaire. The total score of the ASQE was significantly correlated to the Adult Strabismus Questionnaire (AS-20) (r = 0.642, P < 0.01). The median scores for the adult strabismus patients were significantly lower (worse HRQOL) compared with visually normal adults (66.32 vs. 92.71; P  < 0.001) and patients with other eye diseases (66.32 vs. 79.50; P  < 0.001) thus demonstrating good discriminative validity for the questionnaire. The Cronbach’s alpha coefficient for internal consistent reliability was 0.887 and the test-retest reliability was 0.946. The mean total score of the ASQE was 65.85 (SD = 15.32) and the domain ‘social contact and appearance’ recorded the lowest mean score 43.78 (SD = 13.92) in strabismus patients. Conclusions The revised 22-item Chinese version of the ASQE showed good psychometric properties. It is suggested that this questionnaire provides a potentially useful measurement tool in clinical or research programs involving Chinese strabismus patients with or without associated amblyopia.

To determine the prevalence of amblyopia and refractive errors among 7 to 12-year-old primary school children in Tehran, Iran. This population-based cross-sectional study included 2,410 randomly selected students. Visual acuity was tested using an E-chart on Yang vision tester. Refractive errors were measured by photorefractometry and cycloautorefraction. Strabismus was checked using cover test. Direct ophthalmoscopy was used to assess the anterior segment, lens opacities, red reflex and fundus. Functional amblyopia was defined as best corrected visual acuity ≤20/40 in one or both eyes with no anatomical problems. Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9%) of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004). Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D) was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001), that of hyperopia decreased (P=0.007), but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9) and refractive errors, especially anisometropia (OR=12.87) and hyperopia (OR=11.87), were important amblyogenic risk factors. The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.

Purpose: To evaluate the peripapillary choroidal thickness (CT) in children with unilateral amblyopia using spectral-domain optical coherence tomography (SD-OCT). Methods: One hundred and six eyes of 53 children with unilateral amblyopia and 20 eyes of 20 children with normal vision were involved in this study. Of the 53 children with unilateral amblyopia, 29 (54.7%) had hyperopic anisometropic amblyopia and 24 (45.3%) had strabismic amblyopia. Peripapillary CT was measured from 6 mm length radial B-scans at the optic nerve head using the enhanced depth imaging program of an SD-OCT (Heidelberg Engineering, Germany). Age, sex, refractive error, and best-corrected visual acuity were also recorded. Results: The average peripapillary CT was greater in amblyopic eyes than in the fellow eyes of the children with amblyopia (P = 0.002), and control eyes (P < 0.001). There was no significant difference between the fellow eyes of children with amblyopia and the control eyes (P = 0.158). The average peripapillary CT was negatively correlated with axial length (AL) in amblyopic eyes (r = -0.381; P = 0.005) and fellow eyes (r = -0.392; P = 0.004) but not in control eyes (r = -0.232; P = 0.325). After adjustment for the possible effects of AL, the average peripapillary CT in amblyopic eyes was still greater than in fellow eyes (P = 0.014) and control eyes (P = 0.022). Conclusion: The peripapillary choroid of eyes with amblyopia was thicker than that of the fellow eyes and control eyes. No significant difference was observed between fellow eyes and control eyes.

BackgroundTraditional treatment of amblyopia involves either wearing a patch or atropine penalisation of the better eye. A new treatment is being developed on the basis of virtual reality technology allowing either DVD footage or computer games which present a common background to both eyes and the foreground, containing the imagery of interest, only to the amblyopic eye.MethodsA randomised control trial was performed on patients with amblyopia aged 4–8 years with three arms. All three arms had dichoptic stimulation using shutter glass technology. One arm had DVD footage shown to the amblyopic eye and common background to both, the second used a modified shooter game, Nux, with sprite and targets presented to the amblyopic eye (and background to both) while the third arm had both background and foreground presented to both eyes (non-interactive binocular treatment (non-I-BiT) games).ResultsSeventy-five patients were randomised; 67 were residual amblyopes and 70 had an associated strabismus. The visual acuity improved in all three arms by approximately 0.07 logMAR in the amblyopic eye at 6 weeks. There was no difference between I-BiT DVD and non-I-BiT games compared with I-BiT games (stated primary outcome) in terms of gain in vision.ConclusionsThere was a modest vision improvement in all three arms. Treatment was well tolerated and safe. There was no difference between the three treatments in terms of primary stated outcomes but treatment duration was short and the high proportion of previously treated amblyopia and strabismic amblyopia disadvantaged dichoptic stimulation treatment.Trial registration numberNCT01702727, results.

Purpose Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. Methods Children (4–12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. Results Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks ( P <0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. Conclusions Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

AimsTo examine the association between colour vision deficiency (CVD) and other ophthalmic disorders including amblyopia, strabismus and ametropia in a large population study.MethodsThe retrospective, cross-sectional study included 916 388 Israeli army male recruits who had their premilitary medical assessment at the age of 16–18 years from 2000 to 2020, analysing the prevalence of ophthalmic disorders including amblyopia, strabismus and ametropia in army recruits with CVD compared with all other recruits with normal colour vision. Demographic and socioeconomic data were also collected.ResultsThe prevalence of amblyopia (1.28% vs 0.71%, p<0.001), strabismus (1.09% vs 0.83%, p<0.001) and ametropia (moderate—less than 6.00 diopters, 35.05% vs 30.50%, p<0.001 and high—higher than 6.00 diopters, 3.18% vs 2.30%, p<0.001) were all higher among 28 001 (3.06%) army recruits with CVD compared with all other individuals with normal colour vision. CVD was more common in individuals with a higher socioeconomic status (high 3.15% vs low 2.93%, p<0.001) and varied according to recruits’ origin. It was most frequent in individuals whose mother was born in the former Soviet Union (4.98%) compared with other European countries (3.89%), North America (3.28%), Asia (2.78%) and Ethiopia (1.63%).ConclusionCVD is associated with an increased frequency of amblyopia, strabismus and ametropia, which can all impart vision difficulties besides colour vision impairment alone.