The other side of amblyopia

Comparative analysis of optic disc and macular microvasculature in children with anisometropic amblyopia before and after treatment

PURPOSE

To evaluate optic disc and macular microvasculature changes in children with anisometropic amblyopia before and after treatment.

METHODS

In all, 60 children with unilateral anisometropic amblyopia between the ages of 6 and 12 were randomly selected from the ophthalmology clinic of Fuyang People's Hospital, while 60 children with non-amblyopia in the same age range were randomly selected as a normal control group. The right eye was uniformly taken in the control group with at least 6 months of follow-up. Optical coherence tomography angiography (OCTA) was used to evaluate the macular vessel density of superficial capillary plexus (SCP) and deep capillary plexus (DCP), optic disc vascular density (VD), foveal avascular zone (FAZ) area, macular thickness, and retinal nerve fiber layer thickness (RNFLT).

RESULTS

Before treatment, the vessel density of the optic disc, macular SCP and DCP in the amblyopic group was significantly lower than those in the fellow eyes and the control group (P < 0.05), while there were no statistically significant differences in the vessel densities of the optic disc, macular SCP and DCP between the amblyopic eyes, the fellow eyes, and the control group after treatment (P>0.05). Statistically significant negative correlations were found between the alterations of BCVA in amblyopic eyes and the alterations of the vessel densities of the optic disc, macular SCP and DCP in amblyopia eyes (P<0.05) except for superior nasal (SN) and inferior nasal (IN) regions of the optic disc radial peripapillary capillary, temporal and nasal regions of macular parafoveal SCP, nasal regions of macular parafoveal DCP and inferior regions of macular perifoveal DCP(P>0.05).

CONCLUSION

Macular and optic disc vessel density in OCTA are lower in children with anisometropic amblyopia and tend to return to normal levels to a certain extent following treatment for amblyopia.

Differences Between Amblyopic and Fellow Eyes in Optical Coherence Tomography: A Cohort from Jordanian Population

Background and Objectives: Amblyopia is a condition where children undergo unilateral or bilateral vision loss due to a variety of disorders that impact the visual pathway. The assessment of retinal nerve fiber layer (RNFL) thickness in amblyopia has made optical coherence tomography (OCT) a useful technique for studying the pathophysiology of this condition. This study was conducted to assess OCT results for various forms of amblyopia, including macular thickness and peripapillary RNFL thickness. It is the first of its kind in Jordan. Materials and Methods: Sixty-one individuals, aged 14 to 67, who had been diagnosed with unilateral amblyopia participated in a prospective study. Both eyes underwent spectral-domain OCT imaging, and clinical and demographic information was gathered. Relationships between different types of amblyopia and OCT measurements were investigated. Results: Compared to the contralateral fellow eyes, the amblyopic eyes showed thicker fovea, and there were differences in foveal and macular thickness observed between the sexes. Individuals with anisometropic amblyopia exhibited a greater central macular thickness. While nasal optic nerve thickness was adversely correlated with age, inferior optic nerve thickness was considerably lower in amblyopia. Conclusions: This research indicates unique OCT traits in amblyopic eyes, which may have a role in amblyopia diagnosis and treatment. The prevention of long-term visual impairment depends heavily on early detection and care. More studies using larger cohorts and longitudinal designs are necessary to improve our knowledge of the pathogenesis of amblyopia and to provide the best possible clinical management approaches.

Deficits of the "Good" Eye in Amblyopia: Processing Geometric Properties

Purpose

Although fellow eyes of amblyopia are typically considered normal, recent studies have revealed impairments in certain aspects of vision. However, it remains unclear at which level of object processing these impairments occur. This study aims to investigate the functional level of visual perception impairment in the fellow eye of children and adults with amblyopia using the geometric functional hierarchy discrimination task based on Klein Mathematics methodology.

Methods

Seventy-six patients with amblyopia (40 children and 36 adults) and 77 age-matched healthy controls (40 children and 37 adults) were recruited for this study. The participants completed four sets of geometric hierarchies (in ascending order of stability: Euclidean, affine, projective, and topology) and one set of color discrimination tasks. They were instructed to rapidly and accurately select a distinct shape from the four quadrants.

Results

The participants' performance was evaluated using the inverse efficiency (IE) score (IE = response time (RT)/accuracy). The results of IEs show that the fellow eye of children with amblyopia exhibits normal topological processing, yet displays higher IEs in other geometric properties and color processing, suggesting impairments in these specific discrimination abilities. However, adults with amblyopia did not show deficits on any discrimination types compared with adult controls.

Conclusions

The lack of compromised topological processing suggests that amblyopia may not have inflicted any damage to the subcortical visual pathways. Furthermore, these deficits observed in the fellow eye tend to diminish significantly during adulthood, implying that amblyopia may potentially hinder the maturation process of the fellow eye.

The Relationship between Fixation Stability and Retinal Structural Parameters in Children with Anisometropic, Strabismic and Mixed Amblyopia

(1) Background: Amblyopia is an ocular condition leading to structural and functional changes. The relationship between these changes is complex and remains poorly understood. (2) Methods: Participants included 31 children aged 5 to 9 years with strabismic (n = 9), anisometropic (n = 16) and mixed (n = 6) unilateral amblyopia, and 14 age-matched non-amblyopic children. The 95% and 63% Bivariate Contour Ellipse Area (BCEA), axial length, Foveal Avascular Zone (FAZ) area, center macular thickness and volume were assessed. The relationship between these parameters was explored. (3) Results: Statistically significant differences were found among the four groups in best corrected distance visual acuity (BCVA) (p < 0.001), BCEA 95% (p = 0.002) and BCEA 63% (p = 0.002), but not in the FAZ area, central macular thickness, central macular volume and axial length. Eyes with amblyopia had poorer BCVA and larger fixation instability than controls. Inter-ocular differences were more significant in patients with strabismic amblyopia, particularly in BCVA (p = 0.003), central macular thickness (p < 0.001) and central macular volume (p = 0.002). In amblyopic eyes, BCEA 95% and 63% were correlated with BCVA, but not with the FAZ area. (4) Conclusion: Amblyopia is associated with a reduction in fixation stability and BCVA, although there is a general lack of correlation with structural changes, suggesting a complex interaction between anatomy and function in amblyopia.

Children with strabismus and amblyopia presented abnormal spontaneous brain activities measured through fractional amplitude of low-frequency fluctuation (fALFF)

Purpose

Based on fMRI technology, we explored whether children with strabismus and amblyopia (SA) showed significant change in fractional amplitude of low-frequency fluctuation (fALFF) values in specific brain regions compared with healthy controls and whether this change could point to the clinical manifestations and pathogenesis of children with strabismus to a certain extent.

Methods

We enrolled 23 children with SA and the same number matched healthy controls in the ophthalmology department of the First Affiliated Hospital of Nanchang University, and the whole brain was scanned by rs-fMRI. The fALFF value of each brain area was derived to examine whether there is a statistical difference between the two groups. Meanwhile, the ROC curve was made in a view to evaluate whether this difference proves useful as a diagnostic index. Finally, we analyzed whether changes in the fALFF value of some specific brain regions are related to clinical manifestations.

Results

Compared with HCs, children with SA presented decreased fALFF values in the left temporal pole: the superior temporal gyrus, right middle temporal gyrus, right superior frontal gyrus, and right supplementary motor area. Meanwhile, they also showed higher fALFF values in specific brain areas, which included the left precentral gyrus, left inferior parietal, and left precuneus.

Conclusion

Children with SA showed abnormal fALFF values in different brain regions. Most of these regions were allocated to the visual formation pathway, the eye movement-related pathway, or other visual-related pathways, suggesting the pathological mechanism of the patient.

Current Management of Amblyopia with New Technologies for Binocular Treatment

Amblyopia is the most common cause of monocular poor vision affecting up to 3.7% of the global population. Classically, the first step in treatment has been optical correction, followed by patching and/or pharmacological treatment. However, this is an evolving scenario, since researchers and clinicians are interested in new binocular treatments due to the increasing development of new technologies. In this article main, current binocular treatments as Dig Rush, falling blocks, I-BiT, Occlu-tab, Vivid Vision, and movies are reviewed for binocular amblyopia management.

The impact of strabismus on psychosocial heath and quality of life: a systematic review

Strabismus can hinder an individual's ability to perform daily functions and negatively affect their well-being. I examine the impact strabismus has on psychosocial health and quality of life in children and adults and evaluate the challenges confronted by parents of children with strabismus. Numerous misconceptions exist regarding the impact strabismus has on overall health. Negative attitudes persist toward those affected, resulting in difficulties with self-image. Individuals with strabismus are at increased risk for both visual system and psychiatric disorders. Misinformation regarding available treatment options for children and adults with strabismus continues to exist, resulting in decreased access to care. Improved education of health care providers can increase appropriate referrals and initiation of treatment. Treatment of strabismus is not merely cosmetic and has the potential to improve psychosocial health and quality of life for children and adults with and without diplopia.

Predictors of traumatic eye injuries at high-risk for ophthalmic complications in children

Eye injuries are important cause of ocular morbidity in children. There is lack of data regarding predictors for high-risk injuries that will result in ophthalmic complications. Most cases are managed by the emergency department (ED) physicians without immediate ophthalmologist evaluation. Our aim was to identify predictors for ophthalmological complications and to imply indications for early ophthalmologic consultation in the ED. A retrospective chart review of 834 patients ages 0-18 years who presented to the emergency department at Tel Aviv Medical Center between 2015 and 2018 following traumatic eye injuries was performed. All cases which later needed ophthalmological care were considered as high-risk for ophthalmic complications. An increased rate of eye injury was revealed over the years, but high-risk injury rate was stable. High-velocity mechanism, sport injury, orbital, anterior chamber, and retinal involvement were all significantly more common in the high-risk group compared to the low risk group. Only 10 patients, which represent 1.2% of all the patients, had decreased visual acuity on the last follow up, with significantly more injuries of high-velocity mechanism and anterior chamber involvement, in comparison to patients with normal visual acuity on the last follow up.Conclusion: High-velocity mechanism by itself, even with normal visual acuity and eye examination by the ED physician, should prompt to consider an urgent ophthalmologist consult. What is Known: •Traumatic eye injuries are an important cause of ocular morbidity in children. • Most injuries can be handled by a trained ED physician, but there are indications for an urgent ophthalmologist consultation. • It is crucial to discriminate between low and high-risk ocular injuries. What is New: • High-velocity mechanisms stand out as the most likely risk factor for final impaired visual acuity. • Normal visual acuity on presentation is not reassuring. • We recommend urgent ophthalmologist consultation in cases of high-velocity injury, even if visual acuity is preserved at presentation.

Effect of Stimulus Orientation on Visual Function in Children with Refractive Amblyopia

Purpose

We investigated and characterized the patterns of meridional anisotropies in newly diagnosed refractive amblyopes using pattern onset–offset visual evoked potentials (POVEPs) and psychophysical grating acuity (GA).

Methods

Twenty-five refractive amblyopes were recruited and compared with non-amblyopic controls from our previous study. Monocular POVEPs were recorded in response to sinewave 4 cycles per degree (cpd) grating stimuli oriented along each individual participants' principal astigmatic meridians, which were approximately horizontal (meridian 1) and vertical (meridian 2). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed along the same meridians using a two-alternative non-forced-choice technique. The C3 amplitudes and peak latencies of the POVEPs and GAs were compared across meridians for both groups (refractive amblyopes and controls) using linear mixed models (monocular) and ANOVA (binocular), and post hoc analysis was conducted to determine if meridional anisotropies in this cohort of amblyopes were related to low (≤1.50 diopters [D]), moderate (1.75–2.75 D) and high (≥3.00 D) astigmatism.

Results

In the newly diagnosed refractive amblyopes, there were no significant meridional anisotropies across all outcome measures, but the post hoc analysis demonstrated that C3 amplitude was significantly higher in those with low (P = 0.02) and moderate (P = 0.004) astigmatism compared to those with high astigmatism. Refractive amblyopes had poorer GA and C3 amplitudes compared to controls by approximately two lines on the logMAR chart (monocular: P = 0.013; binocular: P = 0.014) and approximately 6 µV (monocular: P = 0.009; binocular: P = 0.027), respectively.

Conclusions

Deleterious effects of high astigmatism was evident in newly diagnosed refractive amblyopes, but the neural deficits do not seem to be orientation-specific for the stimulus parameters investigated.

Simplified updates on the pathophysiology and recent developments in the treatment of amblyopia: A review

Amblyopia is the most common cause of monocular visual impairment affecting 2-5% of the general population. Amblyopia is a developmental cortical disorder of the visual pathway essentially due to abnormal visual stimulus, reaching the binocular cortical cells, which may be multivariate. Ganglion cells are of two types: parvocellular (P cells) and magnocellular (M cells); they are the first step where the light energy is converted in to neural impulse. P cells are involved in fine visual acuity, fine stereopsis, and color vision and M cells are involved in gross stereopsis and movement recognition. Strabismus, refractive error, cataract, and ptosis, occurring during critical period are highly amblyogenic. The critical period extends from birth to 7--8 years. The earlier the clinically significant refractive error and strabismus are detected and treated, the greater the likelihood of preventing amblyopia. Treatment for amblyopia in children includes: optical correction of significant refractive errors, patching, pharmacological treatment, and alternative therapies which include: vision therapy, binocular therapy, and liquid crystal display eyeglasses are newer treatment modalities for amblyopia. Age of starting the treatment is not predictive of outcome, instituting treatment on detection and early detection plays a role in achieving better outcomes. This review aims to give a simplified update on amblyopia, which will be of use to a clinician, in understanding the pathophysiology of the complex condition. We also share the cortical aspects of amblyopia and give recent developments in the treatment of amblyopia.

The Role of Binocularity in Anisometropic Amblyopia

Anisometropic amblyopia is unilateral by definition and current treatment recommendations reflect that characteristic. However, recent research suggests a binocular component that deserves consideration. The aim of this review is to consider the levels of anisometropia deemed amblyogenic, and the cortical changes that occur in the presence of anisometropic amblyopia. Particular attention is given to cortical changes that impact the binocularity of these individuals. Knowledge of binocular deficits in anisometropic amblyopia has implications for current, accepted treatment regimens which are monocular in nature. Therefore, the integrity of binocular function in anisometropic amblyopia and its impact on the visual outcome will be evaluated. Given the rise in binocular treatments under clinical trial for amblyopia, this review also aims to evaluate the evidence of potentially enhanced benefits to anisometropic amblyopes from proposed new binocular therapies.

Evaluation of static and dynamic pupil characteristics in hyperopic anisometropic amblyopia

PURPOSE

The aim of this study is to perform a comparison of static and dynamic pupillometry measurements in patients with hyperopic anisometropic amblyopia and age-matched controls.

METHODS

This prospective cross-sectional study consisted of 38 patients with hyperopic anisometropic amblyopia and 80 control subjects. A quantitative pupillometry system was used to evaluate the pupil characteristics of higher hyperopic eyes (Group 1), the fellow eyes (Group 2), and healthy eyes (Group 3). Static pupillometry measurements were taken including scotopic pupil diameter, mesopic pupil diameter, low-photopic pupil diameter, and high-photopic pupil diameter. Subsequently, dynamic pupillometry measurements were taken including resting diameter, amplitude of pupil contraction, latency of pupil contraction, duration of pupil contraction, velocity of pupil contraction, latency of pupil dilation, duration of pupil dilation, and velocity of pupil dilation.

RESULTS

Groups 1 and 2 had statistically significantly lower scotopic and high-photopic pupil diameter values compared with Group 3 (p < 0.05). The amplitude of pupil contraction values were also statistically significantly lower in Groups 1 and 2 compared with Group 3 (p = 0.001 and p = 0.003). However, there were no significant differences between the study and the control eyes with respect to mesopic and high-photopic pupil diameter, resting diameter, latency of pupil contraction, duration of pupil contraction, velocity of pupil contraction, latency of pupil dilation, duration of pupil dilation, and velocity of pupil dilation values (p > 0.05, for all).

CONCLUSION

Static and dynamic pupil characteristics of higher hyperopic eyes and their fellow eyes are similar. This may support that amblyopia is not a monocular disorder, but can affect both eyes.

Maturation of Binocular, Monocular Grating Acuity and of the Visual Interocular Difference in the First 2 Years of Life

The sweep visual evoked potential method (sVEP) is a powerful tool for measurement of visual acuity in infants. Despite the applicability and reliability of the technique in measuring visual functions the understanding of sVEP acuity maturation and how interocular difference of acuity develops in early infancy, as well as the availability of normality ranges, are rare in the literature. We measured binocular and monocular sVEPS acuities in 481 healthy infants aged from birth to 24 months without ophthalmological diseases. Binocular sVEP acuity was significantly higher than monocular visual acuities for almost all ages. Maturation of monocular sVEP acuity showed 2 longer critical periods while binocular acuity showed three maturation periods in the same age range. We found a systematic variation of the mean interocular acuity difference (IAD) range according to age from 1.45 cpd at birth to 0.31 cpd at 24 months. An additional contribution was the determination of sVEP acuity norms for the entire age range. We conclude that binocular and monocular sVEP acuities have distinct growth curves reflecting different maturation profiles for each function. Differences in IAD range shorten according to age and they should be considered in using the sVEP acuity measurements for clinical diagnosis as amblyopia.

Classification and diversity of amblyopia

Amblyopia is a developmental disorder that affects the spatial vision of one or both eyes in the absence of an obvious organic cause; it is associated with a history of abnormal visual experience during childhood. Subtypes have been defined based on the purported etiology, namely, strabismus (misaligned eyes) and/or anisometropia (unequal refractive error). Here we consider the usefulness of these subclassifications.

Comparison of quantitative measurement of foveal avascular zone and macular vessel density in eyes of children with amblyopia and healthy controls: an optical coherence tomography angiography study

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 < 0.05). The mean DCP at 1 mm, 2 mm, and 3 mm zones were 1.425 ± 0.069, 6.038 ± 0.186, 13.522 ± 0.336; 1.525 ± 0.072, 6.427 ± 0.190, 14.286 ± 0.322; and 1.685 ± 0.074, 6.895 ± 0.198, 15.355 ± 0.356. DCP was significantly lower in amblyopic eyes than companion eyes and controls (P < 0.05). The mean superficial FAZ were 0.287 ± 0.091, 0.262 ± 0.092, and 0.280 ± 0.097. The mean deep FAZ were 0.382 ± 0.092, 0.335 ± 0.080, and 0.329 ± 0.085. There was no significant difference in FAZ among groups (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.

Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications

PURPOSE

The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application.

METHODS

VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs.

RESULTS

Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01).

CONCLUSIONS

A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed.