Treating amblyopia using altered reality enhances the fine-scale functional correlations in early visual areas.

Amblyopia is a developmental visual disorder that causes substantial visual deficits. Studies using resting-state functional magnetic resonance imaging have disclosed abnormal brain functional connectivity (FC) both across long-range cortical sites and within the visual cortex in amblyopes, which is considered to be related to impaired visual functions. However, little work has examined whether restoring the vision of amblyopes accompanies with an improvement of FC. Here in adult amblyopes and healthy participants, we compared their brain FC before and after an altered-reality adaptation training. Before the training, the voxel-wise FCs of amblyopia patients were substantially weaker than those of healthy control participants both within and across the early visual areas. After the training, visual acuities improved in amblyopes but not in the control participants. The effect kept strengthening in the subsequent month without further adaptation. Importantly, we observed enhanced voxel-wise FC both within and across the early visual areas of amblyopes. Moreover, the enhancement continued for at least 1 month. These results suggest that the effective treatment can improve both the amblyopes' vision and functional connections in the visual cortex.

Altered local spontaneous brain activity pattern in children with right-eye amblyopia of varying degrees: evidence from fMRI.

PURPOSE: To investigate the abnormal changes of local brain activity in children with right-eye amblyopia of varying degrees. METHODS: Data of resting-state functional magnetic resonance imaging were collected from 16 children with severe amblyopia, 17 children with mild to moderate amblyopia, and 15 children with normal binocular vision. Local brain activity was analyzed using the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo). RESULTS: There were extensive ALFF differences among the three groups in 10 brain regions. There were extensive differences in ReHo among the three groups in 11 brain regions. The ALFF and ReHo of the right orbital part of the middle frontal gyrus displayed a significantly positive correlation with the best-corrected visual acuity of the right eye, respectively. The ALFF value and ReHo value of the right orbital part of the middle frontal gyrus followed the pattern of normal control < mild to moderate amblyopia < severe amblyopia. CONCLUSION: This study demonstrated that there were changes in specific patterns of ALFF and ReHo in children with right-eye amblyopia of different degrees in brain regions performing visual sensorimotor and attentional control functions.

Macular superficial vascular density on optical coherence tomography angiography in children with unilateral anisometropic and bilateral hyperopic amblyopia.

We analyzed whether macular superficial vascular density (SVD) and foveal vascular zone (FAZ) on optical coherence tomography angiography (OCTA) can distinguish between bilateral ametropic and anisometropic amblyopia. We included 42, 33, and 50 eyes in the bilateral ametropic amblyopia, anisometropic amblyopia, and normal control groups, respectively. Using macular swept-source optical coherence tomography angiography, we measured and analyzed the superficial FAZ areas and five sectoral macular SVDs after magnification correction. The anisometropic amblyopic eye group showed significantly increased foveal SVDs (p < 0.001) and significantly decreased superficial FAZ areas (p < 0.001), compared with the remaining groups. Additionally, the bilateral ametropic amblyopia group had significantly decreased nasal SVDs. SVDs and superficial FAZ areas differed among hyperopic amblyopia subtypes. These findings may reflect vascular distribution differences and macular changes in hyperopic amblyopia subtypes compared with normal eyes.

Microvasculature evaluation of anisometropic amblyopia children by Angio-OCT.

To compare and assess the choroidal and retinal microstructural vascularity in amblyopic eyes with the fellow eyes in anisometropic amblyopic children using angiography optical coherence tomography (Angio-OCT). Twenty-seven children (54 eyes; 5.59 ± 1.08 years old; 59.3% girls) were enrolled in this study. Choroidal thickness (CT) was measured with the use of the enhanced depth imaging mode in Angio-OCT. Parafoveal/peripapillary vascular density indices and the foveal avascular zone (FAZ) size were analyzed by MATLAB code programming on Angio-OCT images. The mean FAZ size of the amblyopic eyes were larger both in superficial and deep capillary plexus layer (SCPL/DCPL). Compared with the contralateral eyes (BCVA were normal), all the vascular density indices of SCPL and DCPL in the parafoveal and peripapillary zones were lower in the amblyopic eyes, however, the difference was insignificant (p > 0.05). No significant decrease was observed in four quadrants analyses of the amblyopic eyes (p > 0.05). Except for the measurement at 2000 µm and 1500 µm from the fovea in temple, CT in amblyopic eyes were significantly thicken than the fellow eyes (p < 0.05). Compared with the fellow eyes, the CT of certain areas were thicker in the amblyopic eyes. Though the FAZ size of the amblyopic eyes was larger in SCPL/DCPL layers, the retinal vascular density indices in SCPL/DCPL were lower in amblyopia eyes without statistical difference. Angio-OCT may be an effective way to evaluate the status of the choroidal and retinal vascular system in amblyopic children.

Single Center to Evaluate and Compare Anisometropic Amblyopia in Adults Using Blood Oxygenation Level-Dependent Functional Magnetic Resonance Imaging and Diffusion Kurtosis Imaging.

BACKGROUND Anisometropic amblyopia results from the unequal ability to focus between the right and left eyes. Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) measures the proportion of oxygenated hemoglobin in specific areas. Diffusion kurtosis imaging (DKI) is a method of diffusion tensor imaging that estimates the skewed distribution of water diffusion probability. We aimed to evaluate and compare 11 adult patients with anisometropic amblyopia (AA) with 13 normally sighted healthy controls (HC) using BOLD-fMRI and DKI. MATERIAL AND METHODS Eleven adults with AA (age range 20-49; mean age 29.18±8.089) and 13 HC adults (age range 22-50; mean age 28.00±5.79) were recruited. DKI scanning used a single excitation echo-planar imaging sequence and a region of interest to obtain DKI parameters for optic radiation; the corpus callosum was manually placed, including mean kurtosis (MK), fractional anisotropic (FA), and mean diffusivity (MD) values; and BOLD data used a gradient-echo echo-planar imaging sequence. RESULTS The AA group had lower MK and FA of bilateral optic radiation than the HC group (P=0.008 and P=0.006, respectively) and higher MD than the HC group (P=0.005). The MK of the corpus callosum in the AA group was lower than that of HC group (P=0.012).Compared with the non-dominant eyes of the HC group, the amblyopic eyes in the AA group had less activation range and intensity in Brodmann areas 17, 18, and 19. CONCLUSIONS The combined use of DKI and BOLD-fMRI detected microstructural changes associated with local visual pathways and identified damage to the visual cortex in patients with amblyopia.

[Abnormal spontaneous brain functional activity in adult patients with amblyopia: a resting-state functional magnetic resonance imaging study].

Amblyopia is a visual development deficit caused by abnormal visual experience in early life, mainly manifesting as defected visual acuity and binocular visual impairment, which is considered to reflect abnormal development of the brain rather than organic lesions of the eye. Previous studies have reported abnormal spontaneous brain activity in patients with amblyopia. However, the location of abnormal spontaneous activity in patients with amblyopia and the association between abnormal brain function activity and clinical deficits remain unclear. The purpose of this study is to analyze spontaneous brain functional activity abnormalities in patients with amblyopia and their associations with clinical defects using resting-state functional magnetic resonance imaging (fMRI) data. In this study, 31 patients with amblyopia and 31 healthy controls were enrolled for resting-state fMRI scanning. The results showed that spontaneous activity in the right angular gyrus, left posterior cerebellum, and left cingulate gyrus were significantly lower in patients with amblyopia than in controls, and spontaneous activity in the right middle temporal gyrus was significantly higher in patients with amblyopia. In addition, the spontaneous activity of the left cerebellum in patients with amblyopia was negatively associated with the best-corrected visual acuity of the amblyopic eye, and the spontaneous activity of the right middle temporal gyrus was positively associated with the stereoacuity. This study found that adult patients with amblyopia showed abnormal spontaneous activity in the angular gyrus, cerebellum, middle temporal gyrus, and cingulate gyrus. Furthermore, the functional abnormalities in the cerebellum and middle temporal gyrus may be associated with visual acuity defects and stereopsis deficiency in patients with amblyopia. These findings help explain the neural mechanism of amblyopia, thus promoting the improvement of the treatment strategy for amblyopia.

Optical Coherence Tomography Angiography in Patients with Amblyopia.

To determine the optical coherence tomography angiography (OCTA) parameters including foveal avascular zone (FAZ) and vessel density (VD) in the amblyopic eyes compared with the fellow sound eyes and the eyes of the non-amblyopic subjects. In this case-control study, a total of 23 eyes from unilateral amblyopic children were included as cases. The sound eye of the amblyopic children was considered as the internal control and the right eyes of the non-amblyopic children were considered as the external control. All participants underwent image recording with OCTA. In the present study, an equal number of 23 unilateral amblyopic eyes and 23 right eyes of non-amblyopic age- and sex-matched children were included as the cases and controls, respectively. The average age of participants in the case and controls were 9.86 ± 3.12 and 8.5 ± 2.35 years, respectively. Twelve patients (52.2%) in the case group and 14 subjects (60.9%) in the control group were female. Whole vascular density of the macula in superficial capillary plexuses (SCP) was significantly lower in the external controls compared with the other studied groups (P = .026). However, the VD of the deep capillary plexuses (DCP) was significantly greater in the external controls than cases and internal controls (P= .029). The average FAZ area was 0.26 ± 0.06 mm2 in amblyopic eyes that was significantly higher compared with fellow eyes (0.21 ± 0.07 mm2; P= .022), but it was not different with non-amblyopic eyes (0.22 ± 0.118 mm2). Based on our findings, there were no significant difference in the cases of foveal, parafoveal, and perifoveal in both superficial and deep vascular densities among amblyopic and non-amblyopic eyes, whereas deep whole density of the amblyopic eyes showed lower percent compared to non-amblyopic ones that indicates decrease blood supply of the amblyopic eyes in this region. Additionally, FAZ was larger in amblyopic eyes than internal controls.

Macular and Optic Disc Parameters in Children with Amblyopic and Nonamblyopic Eyes under Optical Coherence Tomography Fundus Images.

The aim of this study was to investigate the characteristics of macular and optic disc parameters in children with amblyopic and nonamblyopic eyes, using fundus images under optical coherence tomography (OCT). 36 patients with anisometropic amblyopia were selected in the experimental group, and another 36 healthy volunteers were selected in the control group, OCT examinations were performed in all groups, and the mean diopter, mean corrected visual acuity (CVA), mean axial length, mean optic disc retinal nerve fiber layer (RNFL) thickness, and mean macular fovea thickness were recorded in the two groups. The results found that the average diopter of the patients in the control group and the experimental group was +2.30 ± 2.54 D and +5.51 ± 1.76 D, respectively. The average CVA was 0.86 ± 0.07 and 0.22 ± 0.16, respectively; the average eye axial length was 22.41 ± 1.20 mm and 21.11 ± 0.78 mm, respectively. As P < 0.05, the differences were statistically significant in the three indicators between the two groups. There was no significant difference between the two groups in the average thickness of the RNFL of the optic disc and the average thickness of the central fovea of macula (P > 0.05). There was some correlation among CVA, diopter, eye axial length, RNFL thickness, and average thickness of macular fovea, but the correlation was not significant. It was suggested that there were certain differences in the macular and optic disc parameters between amblyopic and nonamblyopic children, but the difference is little. Thereout, a certain objective basis was provided for the early detection and treatment of amblyopia.

Measurement Of Retinal Nerve Fiber Layer Thickness In Patients Of Unilateral Amblyopia Using Optical Coherence Tomography.

BACKGROUND: The retinal changes that develop in the eyes during amblyopia are still unclear. It has been proven that thickness of the nerve fiber layer of the retina is positively correlated with refractive error. The objective of the present study was to measure the Retinal Nerve Fiber Layer Thickness (RNFLT) using Ocular Coherence Tomography (OCT) in patients of amblyopia.. METHODS: A descriptive study was conducted in the Department of LRBT Free Eye Hospital, Lahore for 6 months. After meeting the inclusion criteria, 80 patients (40 amblyopic and 40 normal) were taken and grouped as A and B. Socio-demographic details of all the patients were recorded. They then underwent a complete ophthalmologic evaluation that included BCVA, slit lamp biomicroscopy, OCT examination was carried by TOPCON OCT. Each examination was done using the "fast retinal thickness" protocol for each test eye. Mean RNFLT was calculated for each eye. RESULTS: The mean age of patients was 12.58±4.44 years. There were 20 (50%) males and 20 (50%) females. In amblyopic eyes, the mean RNFLT was 125.82±13.06mm while in normal eyes, the mean RNFLT was 94.82±1.11mm. The overall mean RNFLT was significantly higher in amblyopic eyes as compared to normal eyes (p<0.01), as well as significant when data was stratified for age and gender. CONCLUSIONS: There was significant difference observed in RNFLT in amblyopic eyes as compared to normal eyes. So, these results can help us to enhance our knowledge and understand the causes of amblyopia hence improving diagnosis and management of disease.

Abnormal effective connectivity in visual cortices underlies stereopsis defects in amblyopia.

The neural basis underlying stereopsis defects in patients with amblyopia remains unclear, which hinders the development of clinical therapy. This study aimed to investigate visual network abnormalities in patients with amblyopia and their associations with stereopsis function. Spectral dynamic causal modeling methods were employed for resting-state functional magnetic resonance imaging data to investigate the effective connectivity (EC) among 14 predefined regions of interest in the dorsal and ventral visual pathways. We adopted two independent datasets, including a cross-sectional and a longitudinal dataset. In the cross-sectional dataset, we compared group differences in EC between 31 patients with amblyopia (mean age: 26.39 years old) and 31 healthy controls (mean age: 25.71 years old) and investigated the association between EC and stereoacuity. In addition, we explored EC changes after perceptual learning in a novel longitudinal dataset including 9 patients with amblyopia (mean age: 15.78 years old). We found consistent evidence from the two datasets indicating that the aberrant EC from V2v to LO2 is crucial for the stereoscopic deficits in the patients with amblyopia: it was weaker in the patients than in the controls, showed a positive linear relationship with the stereoscopic function, and increased after perceptual learning in the patients. In addition, higher-level dorsal (V3d, V3A, and V3B) and ventral areas (LO1 and LO2) were important nodes in the network of abnormal ECs associated with stereoscopic deficits in the patients with amblyopia. Our research provides insights into the neural mechanism underlying stereopsis deficits in patients with amblyopia and provides candidate targets for focused stimulus interventions to enhance the efficacy of clinical treatment for the improvement of stereopsis deficiency.

Functional connectivity density alterations in children with strabismus and amblyopia based on resting-state functional magnetic resonance imaging (fMRI).

PURPOSE: To explore functional connectivity density (FCD) values of brain areas in children with strabismus and amblyopia (SA) based on blood oxygen level-dependent (BOLD) signals. METHODS: This study recruited 26 children (14 male, 12 females) with SA and 26 healthy children (14 male, 12 female) as healthy controls (HCs). Both groups matched in age, gender, educational level and socioeconomic background. While resting, all participants underwent fMRI scanning and global FCD (gFCD) and local FCD (lFCD) values were calculated. Receiver operating characteristic (ROC) curves were created to investigate whether there was a significant difference between children with SA and healthy controls. RESULTS: When compared with healthy controls, children with SA had significantly lower gFCD values in the right cerebellum, left putamen, and right superior frontal gyrus; however, the same metrics showed opposite changes in the right angular gyrus, left middle cingulate gyrus, left angular gyrus, right superior parietal gyrus, and right middle frontal gyrus. In children with SA, lFCD values were found to be remarkably decreased in regions of the middle right temporal pole, right cerebellum, left putamen, left hippocampus, right hippocampus, left thalamus, left cerebellum; values were increased in the right superior parietal gyrus as compared with healthy controls. CONCLUSION: We noted abnormal neural connectivity in some brain areas of children with SA; detailing such connectivity aberrations is useful in exploring the pathophysiology of SA and providing useful information for future clinical management.

Altered functional connectivity of primary visual cortex in adults with strabismus and amblyopia: a resting-state fMRI study.

Functional connectivity of the primary visual cortex was explored with resting functional magnetic resonance imaging among adults with strabismus and amblyopia and healthy controls. We used the two-sample test and receiver operating characteristic curves to investigate the differences in mean functional connectivity values between the groups with strabismus and amblyopia and healthy controls. Compared with healthy controls, functional connectivity values in the left Brodmann areas 17, including bilateral lingual/angular gyri, were reduced in groups with strabismus and amblyopia. Moreover, functional connectivity values in the right Brodmann area 17, including left cuneus, right inferior occipital gyrus, and left inferior parietal lobule, were reduced in adults with strabismus and amblyopia. Our findings indicate that functional connectivity abnormalities exist between the primary visual cortex and other regions. This may be the basis of the pathological mechanism of visual dysfunction and stereovision disorders in adults with strabismus and amblyopia.

Gray matter volume alterations in patients with strabismus and amblyopia: voxel-based morphometry study.

This study proposes the use of the voxel-based morphometry (VBM) technique to investigate structural alterations of the cerebral cortex in patients with strabismus and amblyopia (SA). Sixteen patients with SA and sixteen healthy controls (HCs) underwent magnetic resonance imaging. Original whole brain images were analyzed using the VBM method. Pearson correlation analysis was performed to evaluate the relationship between mean gray matter volume (GMV) and clinical manifestations. Receiver operating characteristic (ROC) curve analysis was applied to classify the mean GMV values of the SA group and HCs. Compared with the HCs, GMV values in the SA group showed a significant difference in the right superior temporal gyrus, posterior and anterior lobes of the cerebellum, bilateral parahippocampal gyrus, and left anterior cingulate cortex. The mean GMV value in the right superior temporal gyrus, posterior and anterior lobes of the cerebellum, and bilateral parahippocampal gyrus were negatively correlated with the angle of strabismus. The ROC curve analysis of each cerebral region confirmed the accuracy of the area under the curve. Patients with SA have reduced GMV values in some brain regions. These findings might help to reveal the potential pathogenesis of SA and its relationship with the atrophy of specific regions of the brain.

Optical coherence tomography angiography in amblyopia: A critical update on current understandings and future perspectives.

Optical coherence tomography angiography (OCTA) is a non-invasive tool to assess the retino-choroidal vasculature in vivo. It tracks the red blood cell movement and maps the vasculature in quick succession. In routine, diabetic retinopathy, age related macular degeneration, central serous chorioretinopathy, and others are commonly being studied to unveil its clinic role. On the other hand, amblyopia is a condition where the visual acuity is subnormal due to non-organic causes in the eye. But the OCTA studies till now have shown variable changes along retino-choroidal vasculature. Hence, to comprehend the existing literature knowledge, a systematic literature search was carried out and the original works describing novel findings in amblyopic eyes on OCTA were included. Upon detailed assessment, firstly, the disturbed vasculature along superficial retinal plexus, deeper retinal plexus, and choroidal plexus were evident in most untreated amblyopic eyes. However, such changes were not uniform, which is due to noted heterogenic patient profile, small sample size, biometric biases, non-uniform algorithms, and other factors. And to note, even in presence of such diverse changes, almost all the authors stated a plausible explanation for their notable changes. Secondly, the utility of OCTA in identifying vascular changes with standard treatments and segregation of visual beneficiaries from non-beneficiaries were possible. Hence, to conclude, OCTA is a valuable tool which can provide valuable useful insights into the amblyopic eyes during pre and post treatment periods. However, to gather more concrete evidence for clinical benefits, systematic, homogenous, and better structured clinical studies are mandated.

Excitatory Contribution to Binocular Interactions in Human Visual Cortex Is Reduced in Strabismic Amblyopia.

Binocular summation in strabismic amblyopia is typically reported as being absent or greatly reduced in behavioral studies and is thought to be because of a preferential loss of excitatory interactions between the eyes. Here, we studied how excitatory and suppressive interactions contribute to binocular contrast interactions along the visual cortical hierarchy of humans with strabismic and anisometropic amblyopia in both sexes, using source-imaged steady-state visual evoked potentials (SSVEP) over a wide range of relative contrast between the two eyes. Dichoptic parallel grating stimuli modulated at unique temporal frequencies in each eye allowed us to quantify spectral response components associated with monocular inputs (self-terms) and the response components because of interaction of the inputs of the two eyes [intermodulation (IM) terms]. Although anisometropic amblyopes revealed a similar pattern of responses to normal-vision observers, strabismic amblyopes exhibited substantially reduced IM responses across cortical regions of interest (V1, V3a, hV4, hMT+ and lateral occipital cortex), indicating reduced interocular interactions in visual cortex. A contrast gain control model that simultaneously fits self- and IM-term responses within each cortical area revealed different patterns of binocular interactions between individuals with normal and disrupted binocularity. Our model fits show that in strabismic amblyopia, the excitatory contribution to binocular interactions is significantly reduced in both V1 and extra-striate cortex, whereas suppressive contributions remain intact. Our results provide robust electrophysiological evidence supporting the view that disruption of binocular interactions in strabismus or amblyopia is because of preferential loss of excitatory interactions between the eyes.SIGNIFICANCE STATEMENT We studied how excitatory and suppressive interactions contribute to binocular contrast interactions along the visual cortical hierarchy of humans with normal and amblyopic vision, using source-imaged SSVEP and frequency-domain analysis of dichoptic stimuli over a wide range of relative contrast between the two eyes. A dichoptic contrast gain control model was used to characterize these interactions in amblyopia and provided a quantitative comparison to normal vision. Our model fits revealed different patterns of binocular interactions between normal and amblyopic vision. Strabismic amblyopia significantly reduced excitatory contributions to binocular interactions, whereas suppressive contributions remained intact. Our results provide robust evidence supporting the view that the preferential loss of excitatory interactions disrupts binocular interactions in strabismic amblyopia.

Morphological changes in amblyopic eyes in choriocapillaris and Sattler's layer in comparison to healthy eyes, and in retinal nerve fiber layer in comparison to fellow eyes through quantification of mean reflectivity: A pilot study.

PURPOSE: Establishing the reliability of a new method to check the mean retinal and choroidal reflectivity and using it to find retinal and choroid changes in amblyopia. METHODS: Design: Retrospective case-control. Population: 28 subjects of which 10 were healthy controls (20 eyes): 8 with refractive errors, 1 with strabismus, and 1 with both. 18 patients with unilateral amblyopia included: 7 anisometropic, 6 isoametropic, 1 strabismic, and 4 combined. Mean participants' age: 13.77 years ± 10.28. Observation procedures: SD-OCT and ImageJ. Main outcome measure: mean reflectivity of retinal and choroid layers. Amblyopic, fellow, and healthy eyes were compared. RESULTS: The method of measuring reflectivity is good to excellent reliability for all regions of interest except the fourth. The mean reflectivity of the choriocapillaris and Sattler's layer in amblyopic eyes were significantly lower than in healthy eyes (p = 0.003 and p = 0.008 respectively). The RNFL reflectivity was lower than that of fellow eyes (p = 0.025). Post-hoc pairwise comparisons showed statistically significant differences between amblyopic and healthy eyes for choriocapillaris (p = 0.018) and Sattler's (p = 0.035), and between amblyopic and fellow eyes for RNFL (p = 0.039). CONCLUSION: A decrease in reflectivity of the choriocapillaris and Sattler's in amblyopic compared to healthy eyes, and a decrease in reflectivity of the RNFL in the amblyopic compared to fellow eyes, indicate that the pathophysiology is partly peripheral and might be bilateral.

Alternations of interhemispheric functional connectivity in children with strabismus and amblyopia: a resting-state fMRI study.

Previous neuroimaging studies demonstrated that patients with strabismus or amblyopia can show significant functional and anatomical changes in the brain, but alterations of interhemispheric functional connectivity (FC) have not been well studied in this population. The current study analyzed whole-brain changes of interhemispheric FC in children with strabismus and amblyopia (CSA) using voxel-mirrored homotopic connectivity (VMHC).A total of 24 CSA (16 males and 8 females) and 24 normal controls (NCs) consisting of 16 and 8 age-, sex, and education-matched males and females, respectively, underwent functional magnetic resonance imaging (fMRI) scans in the resting state. According to Gaussian random field theory, changes in the resting state FC (rsFC) between hemispheres were evaluated using the VMHC method. The relationships between mean VMHC values in multiple brain regions and behavioral performance were evaluated by Pearson correlation analysis. In contrast to NCs, the CSA group showed significantly decreased VMHC values in the bilateral cerebellum, bilateral frontal superior orbital (frontal sup orb), bilateral temporal inferior(temporal inf),and bilateral frontal superior(frontal sup). CSA have abnormal interhemispheric FC in many brain regions, which may reflect dysfunction of eye movements and visual fusion. These findings might provide insight into the underlying pathogenetic mechanisms of CSA.

Evaluation of choroidal thickness and retinal nerve fiber layer thickness in patients with unilateral amblyopia: a prospective study / Avaliação da espessura da coroide e da camada de fibras nervosas da retina em pacientes com ambliopia unilateral: um estudo prospectivo

ABSTRACT Purpose: to compare the Subfoveal choroidal thickness (SFCT) and Retinal Nerve Fiber Layer Thickness (RNFL) of amblyopic and normal fellow eyes. Design: Prospective, cross-sectional, observational case series. Methods: Forty patients age 12 to 41 years (mean 23.73 ± 6.42) with unilateral amblyopia were studied. Among them, 11(28.2%) patients had amblyopia secondary to strabismus and 29(71.8 %) had anisometropic amblyopia. Optical coherence tomography (OCT) of the peripapillary RNFL thickness of amblyopic and fellow eyes was performed. RNFL thickness measurements were taken from the superior, inferior, nasal and temporal quadrants in the peripapillary region. Also, subfoveal choroidal thickness (SFCT) was measured using spectral domain optical coherence tomography (SD-OCT). Results: Mean global RNFL thickness of the amblyopic and fellow eyes was 104.48 microns and 102.83 microns, respectively. The difference between the two groups was not statistically significant (p>0.05%). The thicknesses of the superior, inferior, nasal and temporal quadrants of the retinal nerve fiber layer between the amblyopic and normal fellow eyes showed no statistically significant difference (p>0.05%). However, the SFCT of amblyopic eye was 11 or more microns thicker than the fellow eye and this was statistically significant different (p<0.05%). Conclusions: This study demonstrated SFCT in amblyopic eyes was significantly thicker than the normal fellow eyes. The amblyopic process may involve the choroid, but not the prepapillary NFL.

RESUMO Objetivo: comparar a espessura da coroide subfoveal (CSF) e da camada de fibra nervosa retinal (CFNR) de olhos amblíopes e normais. Design: série de casos prospectivos, transversais e observacionais. Métodos: Quarenta pacientes com idade entre 12 e 41 anos (média 23,73 ± 6,42) com ambliopia unilateral foram estudados. Entre eles, 11 (28,2%) pacientes apresentavam ambliopia secundária a estrabismo e 29 (71,8%) apresentavam ambliopia anisometrópica. Foi realizada tomografia de coerência óptica (TCO) da espessura da CFNR peripapilar do olho amblíope e do outro olho. As medidas de espessura da CFNR foram realizadas nos quadrantes superior, inferior, nasal e temporal na região peripapilar. Além disso, a espessura da coroide subfoveal (CSF) foi medida através de tomografia de coerência óptica de domínio espectral (TCO-DE). Resultados: A espessura média global da CFNR do olho amblíope e do outro olho foi de 104,48 mícrons e 102,83 mícrons, respectivamente. A diferença entre os dois grupos não foi estatisticamente significativa (p > 0,05%). As espessuras dos quadrantes superior, inferior, nasal e temporal da camada de fibras nervosas da retina entre o olho amblíope e o normal não apresentaram diferença estatisticamente significativa (p > 0,05%). No entanto, a CSF do olho amblíope foi 11 mícrons mais espessa (ou mais) do que a do outro olho - essa diferença foi estatisticamente significativa (p < 0,05%). Conclusões: Este estudo demonstrou que a CSF dos olhos amblíopes foi significativamente mais espessa do que a dos olhos normais. O processo amblíope pode envolver a coroide, mas ele não envolve a CFNR peripapilar.

Repetitive visual cortex transcranial random noise stimulation in adults with amblyopia.

We tested the hypothesis that five daily sessions of visual cortex transcranial random noise stimulation would improve contrast sensitivity, crowded and uncrowded visual acuity in adults with amblyopia. Nineteen adults with amblyopia (44.2 ± 14.9 years, 10 female) were randomly allocated to active or sham tRNS of the visual cortex (active, n = 9; sham, n = 10). Sixteen participants completed the study (n = 8 per group). tRNS was delivered for 25 min across five consecutive days. Monocular contrast sensitivity, uncrowded and crowded visual acuity were measured before, during, 5 min and 30 min post stimulation on each day. Active tRNS significantly improved contrast sensitivity and uncrowded visual acuity for both amblyopic and fellow eyes whereas sham stimulation had no effect. An analysis of the day by day effects revealed large within session improvements on day 1 for the active group that waned across subsequent days. No long-lasting (multi-day) improvements were observed for contrast sensitivity, however a long-lasting improvement in amblyopic eye uncrowded visual acuity was observed for the active group. This improvement remained at 28 day follow up. However, between-group differences in baseline uncrowded visual acuity complicate the interpretation of this effect. No effect of tRNS was observed for amblyopic eye crowded visual acuity. In agreement with previous non-invasive brain stimulation studies using different techniques, tRNS induced short-term contrast sensitivity improvements in adult amblyopic eyes, however, repeated sessions of tRNS did not lead to enhanced or long-lasting effects for the majority of outcome measures.