Astigmatism and maternal myopia as important factors affecting success rate of DIMS lens treatment

OBJECTIVE

To assess the efficacy of myopia control spectacle lenses (defocus incorporated multiple segments/DIMS) in slowing myopia progression among a diverse Central European paediatric population and investigate the contribution of baseline parameters on treatment outcomes.

METHODS AND ANALYSIS

This retrospective observational study included 62 individuals aged 4-17 years (mean±SD: 10.21±2.70) with progressing myopia but without ocular pathology with a range of -0.88 to -8.25 D spherical equivalent refraction (SER) (-3.73±1.56), coupled with astigmatism up to -3.25 D cylindrical. All participants were prescribed DIMS (Hoya MiyoSmart) spectacles. Key outcome variables were cycloplegic SER, measured for all participants and axial length (AL), assessed in a subset of patients, recorded at baseline, 6 months and 12 months. Quality of life assessments were conducted at baseline, at 2 weeks, and 3, 6, 9 and 12 months. Additionally, parental myopic dioptre was recorded when applicable.

RESULTS

At the 12-month mark, myopia progression in patients (mean±SE: -0.40±0.05) mirrored findings from prior European DIMS studies, but with 50% of patients showing no progression. A multivariate analysis of covariance model revealed that baseline astigmatism and younger age adversely affected therapy outcomes in both SER and AL, while severe maternal myopia led to greater SER progression. In contrast, only young age but not astigmatism was associated with AL increase in a comparable group of children with myopia, part of the LIFE Child Study, wearing single-vision spectacles. Patients reported consistent satisfaction with treatment, with minimal side effects, which diminished over the year.

CONCLUSION

In the European population, astigmatism, young age and severe maternal myopia are risk factors for suboptimal outcomes following DIMS therapy. Further research is necessary to elucidate the impact of astigmatism on myopic defocus therapy.

Study protocol of the Hungarian Longitudinal Study of Healthy Brain Aging (HuBA)

Background and purpose

Neuro­cog­nitive aging and the associated brain diseases impose a major social and economic burden. Therefore, substantial efforts have been put into revealing the lifestyle, the neurobiological and the genetic underpinnings of healthy neurocognitive aging. However, these studies take place almost exclusively in a limited number of highly-developed countries. Thus, it is an important open question to what extent their findings may generalize to neurocognitive aging in other, not yet investigated regions. The purpose of the Hungarian Longitudinal Study of Healthy Brain Aging (HuBA) is to collect multi-modal longitudinal data on healthy neurocognitive aging to address the data gap in this field in Central and Eastern Europe.

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Methods

We adapted the Australian Ima­ging, Biomarkers and Lifestyle (AIBL) study of aging study protocol to local circumstances and collected demographic, lifestyle, men­tal and physical health, medication and medical history related information as well as re­cor­ded a series of magnetic resonance imaging (MRI) data. In addition, participants were al­so offered to participate in the collection of blood samples to assess circulating in­flam­matory biomarkers as well as a sleep study aimed at evaluating the general sleep quality based on multi-day collection of subjective sleep questionnaires and whole-night elec­troencephalographic (EEG) data.

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Results

Baseline data collection has al­ready been accomplished for more than a hundred participants and data collection in the se­cond
session is on the way. The collected data might reveal specific local trends or could also indicate the generalizability of previous findings. Moreover, as the HuBA protocol al­so offers a sleep study designed for tho­rough characterization of participants’ sleep quality and related factors, our extended multi-modal dataset might provide a base for incorporating these measures into healthy and clinical aging research. 

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Conclusion

Besides its straightforward na­tional benefits in terms of health ex­pen­di­ture, we hope that this Hungarian initiative could provide results valid for the whole Cent­ral and Eastern European region and could also promote aging and Alzheimer’s disease research in these countries.

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Dichoptic Spatial Contrast Sensitivity Reflects Binocular Balance in Normal and Stereoanomalous Subjects

Purpose

To study binocular balance by comparing dichoptic and standard monocular contrast sensitivity function (CSF) in stereonormal and stereoanomalous/stereoblind amblyopic subjects.

Methods

Sixteen amblyopes and 17 controls participated. Using the capability of the passive three-dimensional display, we measured their CSF both monocularly and dichoptically at spatial frequencies 0.5, 1, 2, 4, and 8 cpds using achromatic Gabor patches on a luminance noise background. During monocular stimulation, the untested eye was covered, while for the dichoptic stimulation the untested eye viewed background noise. Dichoptic CSF of both eyes was acquired within one block.

Results

In patients with central fixation, dichoptic viewing had a large negative impact on the CSF of the amblyopic eye, although it hardly affected that of the dominant eye. In contrast, dichoptic viewing had a small but significant effect on both eyes for controls. In addition, all participants lay along a continuum in terms of how much their two eyes were affected by dichoptic stimulation: by using two predefined contrast sensitivity ratios, namely, amblyopic sensitivity decrement and dichoptic sensitivity decrement, not only did we find a significant correlation between these variables among all participants, but also the two groups were identified with minimum error using a cluster analysis.

Conclusions

Dichoptic CSF may be considered to measure visual performance in patients with altered binocular vision, because it better reflects the visual capacity of the amblyopic eye than the standard monocular examinations. It may also be a more reliable parameter to assess the efficacy of modern approaches to treat amblyopia.

ALTERED BOLD RESPONSE WITHIN THE CORE FACE-PROCESSING NETWORK IN CONGENITAL PROSOPAGNOSIA

BACKGROUND AND PURPOSE

Congenital prosopagnosia is a life-long disorder of face perception. To study the neural backgrounds of congenital prosopagnosia we measured the blood oxygen level-dependent response of congenital prosopagnosic participants, using functional magnetic resonance imaging.

METHODS

We tested three persons of the family (father, daughter and son), having symptoms of congenital prosopagnosia, as well as healthy controls, using combined neuropsychological and functional magnetic resonance imaging methods. To reveal the neural correlates of the impairments, blood oxygen level-dependent responses within the occipito-temporal cortex were measured to faces and nonsense object images in a block-design experiment.

RESULTS

Neuropsychological tests demonstrated significant impairments of face perception/recognition in each subject. We found that the activity of the fusiform and occipital face areas as well as of the lateral occipital cortex was significantly reduced in congenital prosopagnosic participants when compared to controls. Analysis of the hemodynamic response function revealed a lower peak response, but also a significantly faster and stronger decay of the blood oxygen level-dependent response in the occipito-temporal areas in congenital prosopagnosic participants when compared to controls.

CONCLUSION

Our results emphasize the dysfunction of the core face processing system, as well as the lateral occipital complex, in congenital prosopagnosia. Further, the functional impairment of these areas is signalled best by the altered hemodynamic response function, showing abnormally low initial peak and stronger and faster decay in the later parts of the blood oxygen level-dependent response.

Amblyopic deficit beyond the fovea: delayed and variable single-trial ERP response latencies, but unaltered amplitudes

PURPOSE

Amblyopia was first described as a deficit of central vision. However, it has long been debated whether this dysfunction is limited to the fovea or whether extrafoveal vision is also affected, as studies concerning the latter are equivocal. The purpose of the study was to resolve this issue.

METHODS

We investigated the amblyopic effect on event-related potentials (ERPs) with foveal and perifoveal stimuli, either matched in size based on cortical magnification or presented as large annular stimuli. In two separate experiments we measured ERPs on amblyopic patients and control subjects using face images. Latency and amplitude of averaged ERPs and their single-trial distributions were analyzed.

RESULTS

When the fovea was stimulated, latency and amplitude of the early averaged ERP components increased and were reduced, respectively, in the amblyopic compared with the fellow eye. Importantly, perifoveal stimulation also elicited similar amblyopic deficits, which were clearly significant in the case of using cortical magnification scaled stimuli. However, single-trial peak analysis revealed that foveal and perifoveal effects differed in nature: Peak amplitudes were reduced only in foveal stimulation, while latencies were delayed and jittered at both the fovea and perifovea. Event-related potentials obtained from fellow eyes were not significantly different from those of normal observers.

CONCLUSIONS

Our findings revealed the existence of amblyopic deficits at the perifovea when the stimulated cortical area was matched in size to that of foveal stimulation. These deficits manifested themselves only in the temporal structure of the responses, unlike foveal deficits, which affected both component amplitude and latency.

How the visual cortex handles stimulus noise: insights from amblyopia

Adding noise to a visual image makes object recognition more effortful and has a widespread effect on human electrophysiological responses. However, visual cortical processes directly involved in handling the stimulus noise have yet to be identified and dissociated from the modulation of the neural responses due to the deteriorated structural information and increased stimulus uncertainty in the case of noisy images. Here we show that the impairment of face gender categorization performance in the case of noisy images in amblyopic patients correlates with amblyopic deficits measured in the noise-induced modulation of the P1/P2 components of single-trial event-related potentials (ERP). On the other hand, the N170 ERP component is similarly affected by the presence of noise in the two eyes and its modulation does not predict the behavioral deficit. These results have revealed that the efficient processing of noisy images depends on the engagement of additional processing resources both at the early, feature-specific as well as later, object-level stages of visual cortical processing reflected in the P1 and P2 ERP components, respectively. Our findings also suggest that noise-induced modulation of the N170 component might reflect diminished face-selective neuronal responses to face images with deteriorated structural information.

Amblyopic deficits in the timing and strength of visual cortical responses to faces

Behavioral research revealed that object vision is impaired in amblyopia. Nevertheless, neurophysiological research in humans has focused on the amblyopic effects at the earliest stage of visual cortical processing, leaving the question of later, object-specific neural processing deficits unexplored. By measuring event-related potentials (ERPs) to foveal face stimuli we characterized the amblyopic effects on the N170 component, reflecting higher-level structural face processing. Single trial analysis revealed that latencies of the ERP components increased and were more variable in the amblyopic eye compared to the fellow eye both in strabismic and anisometropic patent groups. Moreover, there was an additional delay of N170 relative to the early P1 component over the right hemisphere, which was absent in the fellow eye, suggesting a slower evolution of face specific cortical responses in amblyopia. On the other hand, distribution of single trial N170 peak amplitudes differed between the amblyopic and fellow eye only in the strabismic but not in the anisometropic patients. Furthermore, the amblyopic N170 latency increment but not the amplitude reduction correlated with the interocular differences in visual acuity and fixation stability. We found no difference in the anticipatory neural oscillations between stimulation of the amblyopic and the fellow eye implying that impairment of the neural processes underlying generation of stimulus-driven visual cortical responses might be the primary reason behind the observed amblyopic effects. These findings provide evidence that amblyopic disruption of early visual experience leads to deficits in the strength and timing of higher-level, face specific visual cortical responses, reflected in the N170 component.

Retention Interval Affects Visual Short-Term Memory Encoding

Humans can efficiently store fine-detailed facial emotional information in visual short-term memory for several seconds. However, an unresolved question is whether the same neural mechanisms underlie high-fidelity short-term memory for emotional expressions at different retention intervals. Here we show that retention interval affects the neural processes of short-term memory encoding using a delayed facial emotion discrimination task. The early sensory P100 component of the event-related potentials (ERP) was larger in the 1-s interstimulus interval (ISI) condition than in the 6-s ISI condition, whereas the face-specific N170 component was larger in the longer ISI condition. Furthermore, the memory-related late P3b component of the ERP responses was also modulated by retention interval: it was reduced in the 1-s ISI as compared with the 6-s condition. The present findings cannot be explained based on differences in sensory processing demands or overall task difficulty because there was no difference in the stimulus information and subjects' performance between the two different ISI conditions. These results reveal that encoding processes underlying high-precision short-term memory for facial emotional expressions are modulated depending on whether information has to be stored for one or for several seconds.