Aging and vision

Anti-aging based on stem cell therapy: A scoping review

Stem cells are present in the tissues and organs and remain in a quiescent and undifferentiated state until it is physiologically necessary to produce new descendant cells. Due to their multipotency property, mesenchymal stem cells have attracted considerable attention worldwide due to their immunomodulation and therapeutic function in tissue regeneration. Stem cells secrete components such as paracrine factors, extracellular vesicles, and exosomes which have been shown to have anti-inflammatory, anti-aging, reconstruction and wound healing potentials in many in vitro and in vivo models. The pluripotency and immunomodulatory features of stem cells could potentially be an effective tool in cell therapy and tissue repair. Aging affects the capacity for self-renewal and differentiation of stem cells, decreasing the potential for regeneration and the loss of optimal functions in organisms over time. Current progress in the field of cellular therapy and regenerative medicine has facilitated the evolution of particular guidelines and quality control approaches, which eventually lead to clinical trials. Cell therapy could potentially be one of the most promising therapies to control aging due to the fact that single stem cell transplantation can regenerate or substitute the injured tissue. To understand the involvement of stem cells not only in tissue maintenance and disease but also in the control of aging it is important to know and identify their properties, functions, and regulation in vivo, which are addressed in this review.

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

Kafka's beautiful eyes: Forensic intelligence utilisation of phenotypic information

Franz Kafka had beautiful eyes. So striking, that many of the famous author's friends and peers commented on them - but quite variously ('dark', 'brown', 'grey' & 'blue'). Eye colour as perceived by an observer is subjective, being influenced by physiological, environmental, and even sociocultural factors. In a policing context, this does not mean that trait information such as eye colour is not valuable (far from it), but that it must be managed carefully. The Australian Federal Police has recently implemented a forensic DNA phenotyping (FDP, aka. physical trait prediction or PTP) capability, utilising massively parallel sequencing DNA technology to predict an individual's eye colour, biogeographical ancestry and sex from a crime scene sample. This information alone is not itself 'intelligence', but can be used to generate intelligence through holistic analyses undertaken within a transdisciplinary, all-source forensic intelligence (FORINT) framework. FORINT outputs posit abductive propositions typically at the activity/offence level, to provide insight and influence decision making. However, the use of predicted traits requires that they are compared to something; all Australian police databases include fields for physical traits, but no uniform standard is applied across all agencies. Moreover, collection is inconsistent and no automated systems are in place to capture such data systematically. Consider the 'Kafka problem': his peers gave multiply divergent descriptions of his eyes. If a Biology unit had predicted the eye colour of an 'unidentified author' using DNA - how would Kafka be confidently nominated as the contributor? We posit three maxims for law enforcement: (1) To expand the operational utility of forensic science in line with police demands, forensic science should operationalise FDP (e.g. operationally to rank a list of persons of interest, focus lines of enquiry in serious & organised crime, or assist with human remains identification). (2) Such advanced biological techniques are best delivered through an all-source FORINT framework, to maximise opportunities and minimise risk. (3) One cannot pursue techno-scientific advancements in isolation; it is also necessary to influence the operational posture for their implementation. In this paper we explore these issues and provide recommendations relating to (a) police practices, (b) image capture systems, and (c) research opportunities. Phenotypic trait prediction has great potential and can be operationalised effectively through a rigorous FORINT framework. However, there is (continual) work to be done to enhance the operational capabilities that are complementary to - but necessary for - effective forensic science contribution to investigations.

Preliminary Characterization of Age and Chronic Low Back Pain Effects on Multimodal Pain Sensitivity: A Comparison Study in Older Adults with and Without Chronic Low Back Pain

Though pain sensitivity impairments contribute to chronic pain in younger adults, it is unclear if pain hypersensitivity manifests with aging and is heightened in the geriatric chronic low back pain population. The cross-sectional study preliminarily addressed this gap by measuring pain sensitivity in older adults with chronic low back pain (n = 25) as well as pain-free sex-matched older (n = 25) and younger adults (n = 25). Pain sensitivity was quantified by 8 distinct measures that were subdivided as static (ie, pressure pain thresholds, heat pain thresholds, fixed mechanical pain, and fixed cold pain) and dynamic pain sensitivity (ie, mechanical temporal summation, thermal ramp and hold, heat pain aftersensations, and conditioned pain modulation). Test-retest reliability values for pain sensitivity ranged from moderate to excellent (intraclass correlation coefficients ≥ .500; p's < .05). The main effect for the group was significant (partial η2 = .413, P < .001), revealing between-group differences in pain sensitivity on 5 out of 8 tests (p's ≤ .043). Predominantly, both older adult groups demonstrated increased pain facilitation and decreased pain inhibition during dynamic pain sensitivity testing compared to pain-free younger adults (p's ≤ .044). Despite qualitative differences, static and dynamic pain sensitivity responses were statistically similar between older adults with and without chronic LBP (p's > .05). Findings suggest pain sensitivity can be reliably measured in older adults and that pain hypersensitivity develops with chronological aging, providing partial support for the theory that pain hypersensitivity may impact geriatric chronic pain populations. Further study is needed to more definitively parse out whether pain hypersensitivity is comparatively heightened in older adults with chronic LBP beyond the influence of chronological aging. PERSPECTIVE: This article establishes that surrogate measures of centrally mediated pain sensitization are heightened with aging. Impaired endogenous pain modulation may influence chronic pain development, maintenance, treatment efficacy, and/or ensuing disability, necessitating research to comprehensively characterize how pain hypersensitivity contributes to geriatric chronic pain conditions.

Neuronal Stability, Volumetric Changes, and Decrease in GFAP Expression of Marmoset (Callithrix jacchus) Subcortical Visual Nuclei During Aging

The physiological aging process is well known for functional decline in visual abilities. Among the components of the visual system, the dorsal lateral geniculate nucleus (DLG) and superior colliculus (SC) provide a good model for aging investigations, as these structures constitute the main visual pathways for retinal inputs reaching the visual cortex. However, there are limited data available on quantitative morphological and neurochemical aspects in DLG and SC across lifespan. Here, we used optical density to determine immunoexpression of glial fibrillary acidic protein (GFAP) and design-based stereological probes to estimate the neuronal number, total volume, and layer volume of the DLG and SC in marmosets (Callithrix jacchus), ranging from 36 to 143 months of age. Our results revealed an age-related increase in total volume and layer volume of the DLG, with an overall stability in SC volume. Furthermore, a stable neuronal number was demonstrated in DLG and superficial layers of SC (SCv). A decrease in GFAP immunoexpression was observed in both visual centers. The results indicate region-specific variability in volumetric parameter, possibly attributed to structural plastic events in response to inflammation and compensatory mechanisms at the cellular and subcellular level. Additionally, the DLG and SCv seem to be less vulnerable to aging effects in terms of neuronal number. The neuropeptidergic data suggest that reduced GFAP expression may reflect morphological atrophy in the astroglial cells. This study contributes to updating the current understanding of aging effects in the visual system and stablishes a crucial foundation for future research on visual perception throughout the aging process.

Aging decreases the precision of visual working memory

OBJECTIVES

As individuals age, cognitive abilities such as working memory (WM), decline. In the current study, we investigated the effect of age on WM, and elucidated sources of errors.

METHOD

A total of 102 healthy individuals, aged 18 to 71, participated in this research. We designed and administered a face-based visual WM task, collecting responses via a graded scale in a delayed match-to-sample reproduction task.

RESULTS

The error of participants increased significantly as they aged. Our analysis revealed a significant age-related rise in the standard deviation of error distribution. However, there was no significant change in uniform probability with age.

CONCLUSION

We found that WM performance declines through the lifespan. Investigating the sources of error, we found that the precision of WM decreased monotonously with age. The results also indicated that the probability of guessing the response as a measure of random response is not affected by age.

Age-related changes in the susceptibility to visual illusions of size

As the global population ages, understanding of the effect of aging on visual perception is of growing importance. This study investigates age-related changes in adulthood along size perception through the lens of three visual illusions: the Ponzo, Ebbinghaus, and Height-width illusions. Utilizing the Bayesian conceptualization of the aging brain, which posits increased reliance on prior knowledge with age, we explored potential differences in the susceptibility to visual illusions across different age groups in adults (ages 20-85 years). To this end, we used the BTPI (Ben-Gurion University Test for Perceptual Illusions), an online validated battery of visual illusions developed in our lab. The findings revealed distinct patterns of age-related changes for each of the illusions, challenging the idea of a generalized increase in reliance on prior knowledge with age. Specifically, we observed a systematic reduction in susceptibility to the Ebbinghaus illusion with age, while susceptibility to the Height-width illusion increased with age. As for the Ponzo illusion, there were no significant changes with age. These results underscore the complexity of age-related changes in visual perception and converge with previous findings to support the idea that different visual illusions of size are mediated by distinct perceptual mechanisms.

Sex and aging signatures of proteomics in human cerebrospinal fluid identify distinct clusters linked to neurodegeneration

Sex and age are major risk factors for chronic diseases. Recent studies examining age-related molecular changes in plasma provided insights into age-related disease biology. Cerebrospinal fluid (CSF) proteomics can provide additional insights into brain aging and neurodegeneration. By comprehensively examining 7,006 aptamers targeting 6,139 proteins in CSF obtained from 660 healthy individuals aged from 43 to 91 years old, we subsequently identified significant sex and aging effects on 5,097 aptamers in CSF. Many of these effects on CSF proteins had different magnitude or even opposite direction as those on plasma proteins, indicating distinctive CSF-specific signatures. Network analysis of these CSF proteins revealed not only modules associated with healthy aging but also modules showing sex differences. Through subsequent analyses, several modules were highlighted for their proteins implicated in specific diseases. Module 2 and 6 were enriched for many aging diseases including those in the circulatory systems, immune mechanisms, and neurodegeneration. Together, our findings fill a gap of current aging research and provide mechanistic understanding of proteomic changes in CSF during a healthy lifespan and insights for brain aging and diseases.

Evaluating the impact of different hard hats on the peripheral vision of construction workers

Construction safety is always an issue for construction workers. Hence, personal protective equipment plays a critical role in avoiding potential hazards on construction sites. Among these, hard hats protect against head contact with falling objects on construction sites. This study aims to examine the effects of hard hats with different peak lengths on the field of view at different angles in the upward part and to examine the effects of possible field of view losses caused by the hard hat on the reaction times of the workers. A questionnaire was designed and administered to the construction workers. Experiments were then conducted with a group of subjects to assess their peripheral vision level as well as reaction times. The study found that peripheral vision is affected by the peak size of hard hats. The study further revealed that there is a significant relationship between reaction times and hard hat peak size.

Sensational Dreams: The Prevalence of Sensory Experiences in Dreaming

Dreaming, a widely researched aspect of sleep, often mirrors waking-life experiences. Despite the prevalence of sensory perception during wakefulness, sensory experiences in dreams remain relatively unexplored. Free recall dream reports, where individuals describe their dreams freely, may not fully capture sensory dream experiences. In this study, we developed a dream diary with direct questions about sensory dream experiences. Participants reported sensory experiences in their dreams upon awakening, over multiple days, in a home-based setting (n = 3476 diaries). Our findings show that vision was the most common sensory dream experience, followed by audition and touch. Olfaction and gustation were reported at equally low rates. Multisensory dreams were far more prevalent than unisensory dreams. Additionally, the prevalence of sensory dream experiences varied across emotionally positive and negative dreams. A positive relationship was found between on the one hand sensory richness and, on the other emotional intensity of dreams and clarity of dream recall, for both positive and negative dreams. These results underscore the variety of dream experiences and suggest a link between sensory richness, emotional content and dream recall clarity. Systematic registration of sensory dream experiences offers valuable insights into dream manifestation, aiding the understanding of sleep-related memory consolidation and other aspects of sleep-related information processing.

Visual surround suppression at the neural and perceptual levels

Surround suppression was initially identified as a phenomenon at the neural level in which stimuli outside the neuron's receptive field alone cannot activate responses but can modulate neural responses to stimuli covered inside the receptive field. Subsequent studies showed that surround suppression is not only a critical property of neurons across species and brain areas but also has been found in visual perceptions. More importantly, surround suppression varies across individuals and shows significant differences between normal controls and patients with certain mental disorders. Here, we combined results from related literature and summarized the findings derived from physiological and psychophysical evidence. We first outline the basic properties of surround suppression in the visual system and perceptions. Then, we mainly summarize the differences in perceptual surround suppression among different human subjects. Our review suggests that there is no consensus regarding whether the strength of perceptual surround suppression could be used as an effective index to distinguish particular populations. Then, we summarized the similar mechanisms for surround suppression and cognitive impairments to further explore the potential clinical applications of surround suppression. A clearer understanding of the mechanisms of surround suppression in neural responses and perceptions is necessary for facilitating its clinical applications.

Visual Outcomes According to Age After Bilateral Implantation of Trifocal Intraocular Lenses

PURPOSE

To investigate the effect of age on visual outcomes after the bilateral implantation of trifocal intraocular lenses (IOLs).

METHODS

A total of 290 patients (580 eyes) who underwent bilateral implantation of a trifocal IOL were enrolled in this retrospective case-control study. Patients were divided into five age groups: 45 to 49, 50 to 54, 55 to 59, 60 to 64, and 65 years and older. Postoperative monocular uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively), uncorrected near visual acuity (UNVA), binocular distance-corrected defocus curve, spectacle dependence for near and distance vision, and patient satisfaction scores were compared among the five groups.

RESULTS

The 45 to 49 years group had significantly better mean UDVA (0.02 ± 0.05 logMAR) and UNVA (0.02 ± 0.04 logMAR) than the 65 years and older group (0.06 ± 0.09 and 0.09 ± 0.09 logMAR; P = .029 and P < .001; respectively). However, no significant differences were observed in the mean CDVA among the groups. Binocular visual performance of the 45 to 49 years group was better than that of the 65 years and older age group at defocuses of +1.00, +0.50, -1.00, and -3.00 D. No significant differences were observed in spectacle dependence for near and distance vision or in patient satisfaction scores among the five groups.

CONCLUSIONS

Bilateral implantation of trifocal IOLs can provide excellent near and distance vision in both young and older patients. However, UDVA and UNVA revealed considerably worse results in the older group, although no significant difference was observed in CDVA and postoperative refractive errors by age. [J Refract Surg. 2024;40(4):e270-e277.].

The rules of mature sex: Sexual scripts and the global challenge of rising STIs

Sexual health continues to be a socially complex problem globally with rising rates of sexually transmitted infections (STIs) despite extensive government and health marketing initiatives. In particular, STIs are rising at a greater rate in mature consumers than any other age group with the main reason cited as lack of condom use. The rules around condom use are based on sexual scripts or internalised guidelines and thus a key step in developing social marketing initiatives to increase condom use and address this global challenge is identifying the sexual scripts that motivate and inhibit condom use by mature consumers. Using sexual script theory, this research involves interviews with 24 mature single heterosexual Australian consumers to identify the sexual scripts that can be leveraged in health marketing to address the grand challenge of increasing mature consumer participation in protective sexual health behaviours.

Quantification of mediation effects of white matter functional characteristics on cognitive decline in aging

Cognitive decline with aging involves multifactorial processes, including changes in brain structure and function. This study focuses on the role of white matter functional characteristics, as reflected in blood oxygenation level-dependent signals, in age-related cognitive deterioration. Building on previous research confirming the reproducibility and age-dependence of blood oxygenation level-dependent signals acquired via functional magnetic resonance imaging, we here employ mediation analysis to test if aging affects cognition through white matter blood oxygenation level-dependent signal changes, impacting various cognitive domains and specific white matter regions. We used independent component analysis of resting-state blood oxygenation level-dependent signals to segment white matter into coherent hubs, offering a data-driven view of white matter's functional architecture. Through correlation analysis, we constructed a graph network and derived metrics to quantitatively assess regional functional properties based on resting-state blood oxygenation level-dependent fluctuations. Our analysis identified significant mediators in the age-cognition relationship, indicating that aging differentially influences cognitive functions by altering the functional characteristics of distinct white matter regions. These findings enhance our understanding of the neurobiological basis of cognitive aging, highlighting the critical role of white matter in maintaining cognitive integrity and proposing new approaches to assess interventions targeting cognitive decline in older populations.

Understanding how ageing impacts ganglion cell susceptibility to injury in glaucoma

Glaucoma is a leading cause of blindness worldwide, with a marked increase in prevalence with advancing age. Due to the multifactorial nature of glaucoma pathogenesis, dissecting how ageing impacts upon glaucoma risk requires analysis and synthesis of evidence from a vast literature. While there is a wealth of human clinical studies examining glaucoma pathogenesis and why older patients have increased risk, many aspects of the disease such as adaptations of retinal ganglion cells to stress, autophagy and the role of glial cells in glaucoma, require the use of animal models to study the complex cellular processes and interactions. Additionally, the accelerated nature of ageing in rodents facilitates the longitudinal study of changes that would not be feasible in human clinical studies. This review article examines evidence derived predominantly from rodent models on how the ageing process impacts upon various aspects of glaucoma pathology from the retinal ganglion cells themselves, to supporting cells and tissues such as glial cells, connective tissue and vasculature, in addition to oxidative stress and autophagy. An improved understanding of how ageing modifies these factors may lead to the development of different therapeutic strategies that target specific risk factors or processes involved in glaucoma.

The oscillatory features of visual processing are altered in healthy aging

The temporal features of visual processing were compared between young and elderly healthy participants in visual object and word recognition tasks using the technique of random temporal sampling. The target stimuli were additively combined with a white noise field and were exposed very briefly (200 ms). Target visibility oscillated randomly throughout exposure duration by manipulating the signal-to-noise ratio (SNR). Classification images (CIs) based on response accuracy were calculated to reflect processing efficiency according to the time elapsed since target onset and the power of SNR oscillations in the 5-55 Hz range. CIs differed substantially across groups whereas individuals of the same group largely shared crucial features such that a machine learning algorithm reached 100% accuracy in classifying the data patterns of individual participants into their proper group. These findings demonstrate altered perceptual oscillations in healthy aging and are consistent with previous investigations showing brain oscillation anomalies in the elderly.

Contrast Adaptation in Pseudophakic Patients with Macular Disorders

PURPOSE

To learn whether contrast adaptation, induced by positive spherical defocus, is compromised by macular disorders such as age-related macular degeneration (AMD) or epiretinal membranes (ERM) and to gain further insight in the functionality of the pathological macula and the level of "functional reserve" often postulated for the indication of presbyopia correcting IOLs.

METHODS

In a pilot study, patients with macular disorders, AMD and ERM, (n = 10) and healthy volunteers (n = 10) were tested to quantify contrast adaption after +4 D defocus for 10 min, by performing an interocular contrast matching task. Subjects manually adjusted the perceived contrast of the test patch as seen by the test eye to match to the contrast of a target patch with a fixed Michelson contrast of 0.2 as seen by the contralateral untreated eye.

RESULTS

Patients with macular disorders subjectively matched the 0.2 target contrast with a contrast of 0.24 ± 0.06 (mean ± SD) before adaptation and with a contrast of 0.19 ± 0.04 after adaptation (p < 0.05). Accordingly, patients with macular disorders showed an induced contrast gain by adaptation of 0.05 (27%), which was not different from the control group, which showed an induced contrast gain by adaptation of 0.06 (35%).

CONCLUSION

Patients with mild and moderate macular disorders, such as AMD and ERM, show an induced contrast adaptation, i.e. a gain in contrast sensitivity, at 3.2 cpd, which is not different in level from the induced contrast adaptation in healthy subjects. Macular disorders do not prevent adaptation of the patient's visual system to low contrast or blurred retinal images. Therefore, the implantation of presbyopia correcting IOLs is not a strict exclusion criterion for these patients, but the progressive nature of the macular disorder must be taken into account.

The status of binocular visual functions among Taiwan high-tech industry engineers and its correlation with computer vision symptom

To analyze the status of binocular visual functions, the relationship between binocular visual function and computer vision-related symptoms in the high-tech industry group. The study sample was comprised of 33 participants aged between 20 and 40 years of age. After completing basic information and the Computer Vision Symptom Scale (CVSS-17) questionnaire, the participants underwent a comprehensive examination of binocular visual function. All data were statistically analyzed with SPSS V26.0 software. The value of the binocular vision function of the Taiwan high-tech industry group was significantly different compared with the Scheiman and Morgan standard value. Study subjects were generally found to exhibit larger exophoric at distance, which in turn might lead to a lower ability to maintain binocular fusion to a single image, or recover from fusional disruption at distance. Subjects also experienced accommodation and convergence problems at near at the same time. Age, gender, and refractive errors had no significant impact on CVSS-17 scores, only the duration of computer usage showed a significant effect, particularly for internal symptom factor (ISF) dimensions. In addition, the interaction between the ISF and external symptom factor resulted in more severe visual symptoms. Long-term use of electronic devices may lead to an imbalance in binocular vision function, thereby increasing or exacerbating visual symptoms. If the use of electronic devices is an unchangeable trend, interventions in prescription, visual training or the visual design of electronic products become worthwhile topics for development.

Visual Information Processing in Older Adults: Force Control and Motor Unit Pool Modulation

Increased visual information about a task impairs force control in older adults. To date, however, it remains unclear how increased visual information changes the activation of the motor unit pool differently for young and older adults. Therefore, this study aimed to determine how increased visual information alters the activation of the motor neuron pool and influences force control in older adults. Fifteen older adults (66-86 years, seven women) and fifteen young adults (18-30 years, eight women) conducted a submaximal constant force task (15% of maximum) with ankle dorsiflexion for 20 s. The visual information processing was manipulated by changing the amount of force visual feedback into a low-gain (0.05°) or high-gain (1.2°) condition. Older adults exhibited greater force variability, especially at high-gain visual feedback. This exacerbated force variability from low- to high-gain visual feedback was associated with modulations of multiple motor units, not single motor units. Specifically, increased modulation of multiple motor units from 10 to 35 Hz may contribute to the amplification in force variability. Therefore, our findings suggest evidence that high-gain visual feedback amplifies force variability of older adults which is related to increases in the activation of motor neuron pool from 10 to 35 Hz.

Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina

Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.

Types, functions and mechanisms of robot-assisted intervention for fall prevention: A systematic scoping review

BACKGROUND

Any individual may experience accidental falls, particularly older adults. Although robots can prevent falls, knowledge of their fall-preventive use is limited.

OBJECTIVE

To explore the types, functions, and mechanisms of robot-assisted intervention for fall prevention.

METHODS

A systematic scoping review of global literature published from inception to January 2022 was conducted according to Arksey and O'Malley's five-step framework. Nine electronic databases, namely, PubMed, Embase, CINAHL, IEEE Xplore, the Cochrane Library, Scopus, Web of Science, PsycINFO, and ProQuest, were searched.

RESULTS

Seventy-one articles were found with developmental (n = 63), pilot (n = 4), survey (n = 3), and proof-of-concept (n = 1) designs across 14 countries. Six types of robot-assisted intervention were found, namely cane robots, walkers, wearables, prosthetics, exoskeletons, rollators, and other miscellaneous. Five main functions were observed including (i) detection of user fall, (ii) estimation of user state, (iii) estimation of user motion, (iv) estimation of user intentional direction, and (v) detection of user balance loss. Two categories of mechanisms of robots were found. The first category was executing initiation of incipient fall prevention such as modeling, measurement of user-robot distance, estimation of center of gravity, estimation and detection of user state, estimation of user intentional direction, and measurement of angle. The second category was achieving actualization of incipient fall prevention such as adjust optimal posture, automated braking, physical support, provision of assistive force, reposition, and control of bending angle.

CONCLUSIONS

Existing literature regarding robot-assisted intervention for fall prevention is in its infancy. Therefore, future research is required to assess its feasibility and effectiveness.

Age-Related Changes in the Utilization of Visual Information for Collision Prediction: A Study Using an Affordance-Based Model

The ability to predict collisions with moving objects deteriorates with aging. We followed the affordance-based model to identify optical variables that older adults had difficulty using for collision prediction. We reproduced a modified version of the interception task used in Steinmetz (Steinmetz, Layton, Powell, & Fajen, 2020, "Affordance-based versus current - future accounts of choosing whether to pursue or abandon the chase of a moving target," Journal of Vision, 20(3), 8) in a virtual reality (VR) environment and newly introduced perturbation for each of three optical variables (vertical and horizontal expansions of a moving object and the bearing angle produced between participants and a moving object). We expected that perturbation would negatively affect the performance only for those who rely on the optical variable to perform the interception task effectively. We tested 18 older and 15 younger adults and showed that older participants were not negatively affected by the perturbation for the vertical and horizontal expansion of a moving object, while they showed decreased performance when the perturbation was introduced with a bearing angle. These findings suggest that predicting collisions with moving objects deteriorates with aging because the perception of object expansion is impaired with aging.

Zebrafish optomotor response to second-order motion illustrates that age-related changes in motion detection depend on the activated motion system

Various aspects of visual functioning, including motion perception, change with age. Yet, there is a lack of comprehensive understanding of age-related alterations at different stages of motion processing and in each motion system. To understand the effects of aging on second-order motion processing, we investigated optomotor responses (OMR) in younger and older wild-type (AB-strain) and acetylcholinesterase (achesb55/+) mutant zebrafish. The mutant fish with decreased levels of acetylcholinesterase have been shown to have delayed age-related cognitive decline. Compared to previous results on first-order motion, we found distinct changes in OMR to second-order motion. The polarity of OMR was dependent on age, such that second-order stimulation led to mainly negative OMR in the younger group while older zebrafish had positive responses. Hence, these findings revealed an overall aging effect on the detection of second-order motion. Moreover, neither the genotype of zebrafish nor the spatial frequency of motion significantly changed the response magnitude. Our findings support the view that age-related changes in motion detection depend on the activated motion system.

The Effects of Aging on Rod Bipolar Cell Ribbon Synapses

The global health concern posed by age-related visual impairment highlights the need for further research focused on the visual changes that occur during the process of aging. To date, multiple sensory alterations related to aging have been identified, including morphological and functional changes in inner hair cochlear cells, photoreceptors, and retinal ganglion cells. While some age-related morphological changes are known to occur in rod bipolar cells in the retina, their effects on these cells and on their connection to other cells via ribbon synapses remain elusive. To investigate the effects of aging on rod bipolar cells and their ribbon synapses, we compared synaptic calcium currents, calcium dynamics, and exocytosis in zebrafish (Danio rerio) that were middle-aged (MA,18 months) or old-aged (OA, 36 months). The bipolar cell terminal in OA zebrafish exhibited a two-fold reduction in number of synaptic ribbons, an increased ribbon length, and a decrease in local Ca2+ signals at the tested ribbon location, with little change in the overall magnitude of the calcium current or exocytosis in response to brief pulses. Staining of the synaptic ribbons with antibodies specific for PKCa revealed shortening of the inner nuclear and plexiform layers (INL and IPL). These findings shed light on age-related changes in the retina that are related to synaptic ribbons and calcium signals.

The burden of vision loss in the Middle East and North Africa region, 1990-2019

BACKGROUND

The loss of vision is a substantial public health concern that has important implications for an individual's quality of life. The primary objective of this research was to document the burden of vision loss in the Middle East and North Africa (MENA) region, spanning the years 1990-2019, by age group, sex, underlying cause and sociodemographic index (SDI).

METHODS

Publicly available data concerning the burden of vision loss were acquired from the Global Burden of Disease study 2019. The data encompassed all 21 countries within the MENA region for the period spanning 1990 to 2019. The estimates were reported as raw counts and age-standardised rates per 100,000, accompanied by their corresponding 95% uncertainty intervals (UIs).

RESULTS

In 2019, MENA had an age-standardised point prevalence of 7040.0 (95% UI: 6195.0, 8002.7) and an YLD rate of 314.5 (222.1, 427.6) per 100,000 for vision loss, which were 11.1% (-12.5, -9.7) and 24.3% (-27.6, -20.8) lower, respectively, than in 1990. In 2019, Afghanistan [469.6 (333.0, 632.8)] had the largest age-standardised YLD rate and Turkey [210.7 (145.3, 290.9)] had the lowest. All countries showed a decrease in the age-standardised point prevalence and YLD rate between 1990 and 2019, except for Oman, Afghanistan, and Yemen. Furthermore, in 2019 the largest number of prevalent cases and YLDs were found in the 65-69 age group. Also in 2019, the age-standardised YLD rates in MENA exceeded the global averages for most age groups, for both males and females. In 2019, refractive disorders were the most common types of vision loss among children, adolescents, and middle-age adults in MENA, while near vision loss and cataracts were the most common among older adults. Finally, the burden of vision loss had a slightly negatively association with SDI over the period 1990-2019.

CONCLUSION

Although the burden of vision loss has decreased over the last three decades, the prevalence remains high. These results underscore the importance of healthcare policymakers taking action to implement preventive measures, especially among the elderly and those living in low socioeconomic countries, to decrease the attributable burden in MENA.

Circadian regulation in aging: Implications for spaceflight and life on earth

Alterations in the circadian system are characteristic of aging on Earth. With the decline in physiological processes due to aging, several health concerns including vision loss, cardiovascular disorders, cognitive impairments, and muscle mass loss arise in elderly populations. Similar health risks are reported as "red flag" risks among astronauts during and after a long-term Space exploration journey. However, little is known about the common molecular alterations underlying terrestrial aging and space-related aging in astronauts, and controversial conclusions have been recently reported. In light of the regulatory role of the circadian clock in the maintenance of human health, we review here the overlapping role of the circadian clock both on aging on Earth and spaceflight with a focus on the four most affected systems: visual, cardiovascular, central nervous, and musculoskeletal systems. In this review, we briefly introduce the regulatory role of the circadian clock in specific cellular processes followed by alterations in those processes due to aging. We next summarize the known molecular alterations associated with spaceflight, highlighting involved clock-regulated genes in space flown Drosophila, nematodes, small mammals, and astronauts. Finally, we discuss common genes that are altered in terms of their expression due to aging on Earth and spaceflight. Altogether, the data elaborated in this review strengthen our hypothesis regarding the timely need to include circadian dysregulation as an emerging hallmark of aging on Earth and beyond.

Single-cell RNA sequencing in dissecting microenvironment of age-related macular degeneration: Challenges and perspectives

Age-related macular degeneration (AMD) is the leading cause of blindness in individuals over the age of 50 years, yet its etiology and pathogenesis largely remain uncovered. Single-cell RNA sequencing (scRNA-seq) technologies are recently developed and have a number of advantages over conventional bulk RNA sequencing techniques in uncovering the heterogeneity of complex microenvironments containing numerous cell types and cell communications during various biological processes. In this review, we summarize the latest discovered cellular components and regulatory mechanisms during AMD development revealed by scRNA-seq. In addition, we discuss the main challenges and future directions in exploring the pathophysiology of AMD equipped with single-cell technologies. Our review underscores the importance of multimodal single-cell platforms (such as single-cell spatiotemporal multi-omics and single-cell exosome omics) as new approaches for basic and clinical AMD research in identifying biomarker, characterizing cellular responses to drug treatment and environmental stimulation.

Age-related differences in temporal binding and the influence of action body parts

If voluntary action is followed by an effect with a short time delay, the time interval between action and effect is often perceived to be shorter than it actually is. This perceptual time compression is termed intentional binding or temporal binding. We investigated age-related changes in adulthood considering temporal binding and its dependence on action body parts (i.e., hand vs. foot). This experiment included 17 young adults (mean age: 21.71 ± 3.14 years) and 27 older adults (mean age: 74.41 ± 3.38 years). Participants performed a button press task using their index fingers (hand condition) or toes (foot condition). The results showed that older participants exhibited a strong time compression comparable to young participants in the voluntary condition. Older participants also showed a strong time compression in involuntary action, which was induced by a mechanical device, differently from young participants. In line with previous research, the present age-related differences in time compression considering involuntary action suggest that causal belief significantly influences event perception rather than the associated intention of action or sensory afferents. The present results also suggest that the nature of action body parts has no significant influence on temporal binding, independent of age group.

Susceptibility to the sound-induced flash illusion is associated with gait speed in a large sample of middle-aged and older adults

BACKGROUND

Multisensory integration is the ability to appropriately merge information from different senses for the purpose of perceiving and acting in the environment. During walking, information from multiple senses must be integrated appropriately to coordinate effective movements. We tested the association between a well characterised multisensory task, the Sound-Induced Flash Illusion (SIFI), and gait speed in 3255 participants from The Irish Longitudinal Study on Ageing. High susceptibility to this illusion at longer stimulus onset asynchronies characterises older adults, and has been associated with cognitive and functional impairments, therefore it should be associated with slower gait speed.

METHOD

Gait was measured under three conditions; usual pace, cognitive dual tasking, and maximal walking speed. A separate logistic mixed effects regression model was run for 1) gait at usual pace, 2) change in gait speed for the cognitive dual tasking relative to usual pace and 3) change in maximal walking speed relative to usual pace. In all cases a binary response indicating a correct/incorrect response to each SIFI trial was the dependent variable. The model controlled for covariates including age, sex, education, vision and hearing abilities, Body Mass Index, and cognitive function.

RESULTS

Slower gait was associated with more illusions, particularly at longer temporal intervals between the flash-beep pair and the second beep, indicating that those who integrated incongruent sensory inputs over longer intervals, also walked slower. The relative changes in gait speed for cognitive dual tasking and maximal walking speed were also significantly associated with SIFI at longer SOAs.

CONCLUSIONS

These findings support growing evidence that mobility, susceptibility to falling and balance control are associated with multisensory processing in ageing.

Accuracy-speed-stability trade-offs in a targeted stepping task are similar in young and older adults

Introduction

Stepping accuracy, speed, and stability are lower in older compared to young adults. Lower stepping performance in older adults may be due to larger accuracy-speed-stability trade-offs because of reduced ability to simultaneously fulfill these task-level goals. Our goal was to evaluate whether trade-offs are larger in older compared to young adults in a targeted stepping task. Since sensorimotor function declines with age, our secondary goal was to evaluate whether poorer sensorimotor function was associated with larger trade-offs.

Methods

Twenty-five young (median 22 years old) and 25 older (median 70 years old) adults stepped into projected targets in conditions with various levels of accuracy, speed, and stability requirements. We determined trade-offs as the change in performance, i.e., foot placement error, step duration, and mediolateral center of pressure path length, between each of these conditions and a control condition. To assess age-related differences in the magnitude of trade-offs, we compared the change in performance between age groups. Associations between trade-offs and measures of sensorimotor function were tested using correlations.

Results

We found an accuracy-speed and an accuracy-stability trade-off in both young and older adults, but trade-offs were not different between young and older adults. Inter-subject differences in sensorimotor function could not explain inter-subject differences in trade-offs.

Conclusion

Age-related differences in the ability to combine task-level goals do not explain why older adults stepped less accurate and less stable than young adults. However, lower stability combined with an age-independent accuracy-stability trade-off could explain lower accuracy in older adults.

Association of Dual Sensory Impairment with Declining Physical Function in Community-Dwelling Older Adults

Few studies have investigated whether dual sensory impairment (DSI) adversely affects the deterioration of physical function in older adults compared to single sensory impairment (SSI, visual or auditory). We studied the association between DSI and declining physical function by analyzing the data of 2780 Korean community-dwelling adults aged 70-84 years. Sensory impairment was assessed through pure tone audiometry and visual acuity testing. Muscle strength (handgrip strength) and physical performance (timed up and go test and short physical performance battery (SPPB)) were evaluated. In the cross-sectional analysis, DSI was associated with higher odds of having low muscle strength (odds ratio (OR), 1.78; 95% confidence interval (CI), 1.27-2.48) and poor physical performance (SPPB: OR, 2.04; 95% CI, 1.38-3.00) than SSI. Among all sensory impairment groups in the longitudinal analysis, DSI at baseline increased the risk of deteriorating physical performance during the follow-up period (OR, 1.94; 95% CI, 1.31-2.88; p < 0.01) the most. DSI showed a more severe adverse effect on the decline in physical function among community-dwelling older adults than SSI. More comprehensive care is needed to prevent the deterioration of physical function in older adults due to DSI.

Routine binocular examination of young Taiwanese adults as a predictor of visual behavior performance

BACKGROUND

Morgan and Scheiman's Optometric Extension Program (OEP) expected binocular vision findings have longstanding use in optometry. With technological advances, the demands and standards of binocular function have changed. This study aimed to investigate which binocular visual functions can effectively predict visual behavior performance.

METHODS

Participants aged 15-24 years were recruited from two colleges and two universities. After completing the CSMU-Visual Behavioral Performance questionnaire (CSMU-VBP, with four components: near work, visual perception, visual comfort, and whole-body balance), participants were divided into symptomatic and asymptomatic groups based on questionnaire findings (cutoff: < 12 vs. ≥ 12 symptoms). Then a 24-step binocular visual examination was undertaken. Data were analyzed with one-sample, Student's, and paired t-tests. Additionally, receiver operating characteristic analysis was used to determine the predictors of binocular visual function required for near work, visual perception, visual comfort, and body balance dimensions.

RESULTS

Among 308 participants, 43 (14%) and 265 (86%) were symptomatic and asymptomatic, respectively. Among the 46 participants with abnormal binocular vision, 36 (78%) reported that they had no obvious symptoms. The commonest dysfunctions were accommodative excess and convergence excess. Most of the binocular visual findings significantly diverged from traditional normal values: amplitude of accommodation, as well as base-in prism to break and recovery points at distance were higher than traditional normal values, whereas others were lower than traditional normal values. Total CSMU-VBP scores indicated that the asymptomatic and symptomatic groups had significant differences in DBO recovery (t = 2.334, p = 0.020) and BAF (t = 1.984, p = 0.048). Receiver operating characteristic curve analysis yielded the following binocular visual functional cutoff points: near work (DBO blur < 7, DBO recovery < 5.5), visual perception (MAF < 10.5, BAF < 10.25), visual comfort (DLP <  - 2.25, DBI break > 11.5, NBI blur > 15, NBI break > 17.5, NBI recovery > 13, NPC < 5.75), and body balance (NFD_H >  - 0.5, gradient AC/A [minus] > 2.25, NPC < 4.75).

CONCLUSIONS

The mean values of binocular visual function among young Taiwanese adults were statistically different from traditional normative values. Further research is required to confirm whether these findings reflect impaired binocular vision or stringent criteria. Assessments of binocular visual function, especially binocular accommodation sensitivity, are crucial in routine optometric examination.

A correlational study between microstructural, macrostructural and functional age-related changes in the human visual cortex

Age-related changes in the human brain can be investigated from either structural or functional perspectives. Analysis of structural and functional age-related changes throughout the lifespan may help to understand the normal brain development process and monitor the structural and functional pathology of the brain. This study, combining dedicated electroencephalography (EEG) and magnetic resonance imaging (MRI) approaches in adults (20-78 years), highlights the complex relationship between micro/macrostructural properties and the functional responses to visual stimuli. Here, we aimed to relate age-related changes of the latency of visual evoked potentials (VEPs) to micro/macrostructural indexes and find any correlation between micro/macrostructural features, as well. We studied age-related structural changes in the brain, by using the MRI and diffusion-weighted imaging (DWI) as preferred imaging methods for extracting brain macrostructural parameters such as the cortical thickness, surface area, folding and curvature index, gray matter volume, and microstructural parameters such as mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD). All the mentioned features were significantly correlated with age in V1 and V2 regions of the visual cortex. Furthermore, we highlighted, negative correlations between structural features extracted from T1-weighted images and DWI. The latency and amplitude of the three dominants peaks (C1, P1, N1) of the VEP were considered as the brain functional features to be examined for correlation with age and structural features of the corresponding age. We observed significant correlations between mean C1 latency and GM volume averaged in V1 and V2. In hierarchical regression analysis, the structural index did not contribute to significant variance in the C1 latency after regressing out the effect of age. However, the age explained significant variance in the model after regressing out the effect of structural feature.

Factors affecting drivers' off-road glance behavior while interacting with in-vehicle voice interfaces

In-vehicle voice-based interfaces have been massively embedded in modern vehicles as a countermeasure to visual-manual distractions. However, limited data are available regarding the actual visual demands imposed on the driver when interacting with such an interface. How those factors that are associated with the drivers themselves affect their visual behavior when interacting with an in-vehicle voice-based interface remains understudied. This study focused on investigating factors affecting drivers' off-road visual behavior while interacting with a voice-based interface. A secondary data analysis leveraging structural equation modeling was performed based on data collected from a large-scale field experiment wherein participants drove a vehicle on the highway and performed a series of tasks using an in-vehicle voice interface. The results indicate that while voice-based interfaces are designed to help reduce drivers' visual demands, drivers can still direct their eyes off the road for a prolonged period of time during the interaction and exhibit potentially risky visual behavior. In addition, individual-level factors can exert influence on drivers' off-road visual behavior in such a way that older drivers and drivers with higher trust in technologies are associated with more long eyes-off-road glances when interacting with a voice-based interface. To promote the general public's adoption of in-vehicle voice interfaces and support safe interactions, we recommend relevant research and system design consider drivers' trust in, perceptions, and previous usage of similar technologies, as well as their individual characteristics such as age.

Visual expertise is more than meets the eye: an examination of holistic visual processing in radiologists and architects

Purpose

One of the dominant behavioral markers of visual-expert search strategy, holistic visual processing (HVP), suggests that experts process information from a larger region of space in conjunction with a more focused gaze pattern to improve search speed and accuracy. To date, extant literature suggests that visual search expertise is domain specific, including HVP and its associated behaviors.

Approach

The current study is the first to use eye tracking to directly measure the HVP strategies of two expert groups, radiologists and architects, in comparison to one another and a novice control.

Results

In doing so, we replicated and extended this prior research: visual expertise is domain specific. However, our eye-tracking data indicate that contrary to this prior work, HVP strategies are transferable across domains. Yet, despite the transfer of HVP strategies, there is neither reduced search time nor greater accuracy in visual search outside of an expert's domain.

Conclusions

Therefore, our data suggest that HVP behaviors are a particular form of visual search mechanism that, outside of an expert's native search-ecology, are not necessarily conducive to more general visual search success. It is in addition to explicit knowledge of an expert's domain, how to search, and where to search, that HVP strategies are their most effective for visual search success.

Motion sickness susceptibility and visually induced motion sickness as diagnostic signs in Parkinson's disease

Postural instability and loss of vestibular and somatosensory acuity can be part of the signs encountered in Parkinson's Disease (PD). Visual dependency is described in PD. These modifications of sensory input hierarchy are predictors of motion sickness (MS). The aim of this study was to assess MS susceptibility and effects of real induced MS in posture. 63 PD patients, whose medication levels (levodopa) reflected the pathology were evaluated, and 27 healthy controls, filled a MS questionnaire; 9 PD patients and 43 healthy controls were assessed by posturography using virtual reality. Drug amount predicted visual MS (p=0.01), but not real induced MS susceptibility. PD patients did not experience postural instability in virtual reality, contrary to healthy controls. Since PD patients do not seem to feel vestibular stimulated MS, they may not rely on vestibular and somatosensory inputs during the stimulation. However, they feel visually induced MS more with increased levodopa drug effect. Levodopa amount can increase visual dependency. The strongest MS predictors must be studied in PD to better understand the effect of visual stimulation and its absence in vestibular stimulation.

Differential effects in young and aged rats' navigational accuracy following instantaneous rotation of environmental cues

Successful navigation depends critically upon two broad categories of spatial navigation strategies that include allocentric and egocentric reference frames, relying on external or internal spatial information, respectively. As with older adults, aged rats show robust impairments on a number of different spatial navigation tasks. There is some evidence that these navigation impairments are accompanied by a bias toward relying on egocentric over allocentric navigation strategies. To test the degree to which young and aged animals utilize these two navigation approaches, a novel behavioral arena was used in which rats are trained to traverse a circular track and to stop at a learned goal location that is fixed with respect to a panorama of visual cues projected onto the surrounding walls. By instantaneously rotating the cues, allocentric and egocentric reference frames were put in direct and immediate conflict and goal navigation performance was assessed with respect to how accurately young and aged animals were able to utilize the rotated cues. Behavioral data collected from nine young and eight aged animals revealed that both age groups were able to update their navigation performance following cue rotation. Contrary to what was expected, however, aged animals showed more accurate overall goal navigation performance, stronger allocentric strategy use, and more evident changes in behavior in response to cue rotation compared to younger animals. The young rats appeared to mix egocentric and allocentric strategies for ICR task solution. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Multidimensional Environmental Factors and Sleep Health for Aging Adults: A Focused Narrative Review

The timing, amount, and quality of sleep are critical for an individual's health and quality of life. This paper provides a focused narrative review of the existing literature around multidimensional environments and sleep health for aging adults. Five electronic databases, Scopus, Web of Science, PubMed/Medline; EBSCOhost, PsycINFO (ProQuest), and Google Scholar yielded 54,502 total records. After removing duplicates, non-peer reviewed academic articles, and nonrelevant articles, 70 were included for review. We were able to categorize environmental factors into housing security, home environment, and neighborhood environment, and, within each environmental category, specific elements/aspects are discussed. This paper provides a comprehensive map connecting identified levels of influence (individual, home/house, and neighborhood-level) in which subfactors are listed under each level of influence/category with the related literature list. Our review highlights that multidimensional environmental factors can affect aging adults' sleep health and eventually their physical, mental, and cognitive health and that sleep disparities exist in racial minorities in socioeconomically disadvantaged communities in which cumulative environmental stressors coexist. Based on this focused narrative review on the multidimensional sleep environments for aging adults, knowledge gaps are identified, and future research directions are suggested.

Age-related normal limits for spatial vision

PURPOSE

To establish age-related, normal limits of monocular and binocular spatial vision under photopic and mesopic conditions.

METHODS

Photopic and mesopic visual acuity (VA) and contrast thresholds (CTs) were measured with both positive and negative contrast optotypes under binocular and monocular viewing conditions using the Acuity-Plus (AP) test. The experiments were carried out on participants (age range from 10 to 86 years), who met pre-established, normal sight criteria. Mean and ± 2.5σ limits were calculated within each 5-year subgroup. A biologically meaningful model was then fitted to predict mean values and upper and lower threshold limits for VA and CT as a function of age. The best-fit model parameters describe normal aging of spatial vision for each of the 16 experimental conditions investigated.

RESULTS

Out of the 382 participants recruited for this study, 285 participants passed the selection criteria for normal aging. Log transforms were applied to ensure approximate normal distributions. Outliers were also removed for each of the 16 stimulus conditions investigated based on the ±2.5σ limit criterion. VA, CTs and the overall variability were found to be age-invariant up to ~50 years in the photopic condition. A lower, age-invariant limit of ~30 years was more appropriate for the mesopic range with a gradual, but accelerating increase in both mean thresholds and intersubject variability above this age. Binocular thresholds were smaller and much less variable when compared to the thresholds measured in either eye. Results with negative contrast optotypes were significantly better than the corresponding results measured with positive contrast (p < 0.004).

CONCLUSIONS

This project has established the expected age limits of spatial vision for monocular and binocular viewing under photopic and high mesopic lighting with both positive and negative contrast optotypes using a single test, which can be implemented either in the clinic or in an occupational setting.

Second-order texture gratings produce overestimation of height in depictions of rectangles and steps

The horizontal-vertical illusion (HVI) has been proposed as a method to increase the perceived height of steps, increase toe clearance and prevent falls. High contrast vertical stripes are placed on the step riser abutting a horizontal edge-highlighter creating 'T' junctions which are thought to promote the illusion. Various configurations of the HVI were tested including luminance gratings (L) and second-order modulations of contrast (CM), spatial frequency (FM) and orientation (OM). Observers were asked to compare the apparent height of gratings with that of either filled, unmodulated rectangles or unfilled rectangles. Rectangles were presented alone or as part of a step with a highlighter. In some conditions highlighters matched the properties of the grating; in others or not. In one critical experiment, the HVI was compared for steps with highlighters that were separated from the riser by a thin line and those where the risers and highlighters were continuous. All gratings except FM appeared taller when presented in the step configuration with a continuous, matching highlighter. This effect was greatly reduced when a thin line separated the grating from the highlighter and abolished for mis-matched highlighters and risers. In the rectangle conditions, all cues appeared taller than blank rectangles and L and CM appeared taller than filled-unmodulated rectangles. In conclusion, second-order cues may be useful for inducing the HVI onto steps. However, the ability of vertical stripes and edge-highlighters to accentuate perceived step height may be due to aggregation of the highlighter into the grating rather than the normal horizontal-vertical illusion.

The role of informational content of visual speech in an audiovisual cocktail party: Evidence from cortical oscillations in young and old participants

Age-related differences in the processing of audiovisual speech in a multi-talker environment were investigated analysing event-related spectral perturbations (ERSPs), focusing on theta, alpha and beta oscillations that are assumed to reflect conflict processing, multisensory integration and attentional mechanisms, respectively. Eighteen older and 21 younger healthy adults completed a two-alternative forced-choice word discrimination task, responding to audiovisual speech stimuli. In a cocktail-party scenario with two competing talkers (located at -15° and 15° azimuth), target words (/yes/or/no/) appeared at a pre-defined (attended) position, distractor words at the other position. In two audiovisual conditions, acoustic speech was combined either with informative or uninformative visual speech. While a behavioural benefit for informative visual speech occurred for both age groups, differences between audiovisual conditions in the theta and beta band were only present for older adults. A stronger increase in theta perturbations for stimuli containing uninformative visual speech could be associated with early conflict processing, while a stronger suppression in beta perturbations for informative visual speech could be associated to audiovisual integration. Compared to the younger group, the older group showed generally stronger beta perturbations. No condition differences in the alpha band were found. Overall, the findings suggest age-related differences in audiovisual speech integration in a multi-talker environment. While the behavioural benefit of informative visual speech was unaffected by age, older adults had a stronger need for cognitive control when processing conflicting audiovisual speech input. Furthermore, mechanisms of audiovisual integration are differently activated depending on the informational content of the visual information.

Tandem pore domain acid-sensitive K channel 3 (TASK-3) regulates visual sensitivity in healthy and aging retina

Retinal ganglion cells (RGCs) not only collect but also integrate visual signals and send them from the retina to the brain. The mechanisms underlying the RGC integration of synaptic activity within retinal circuits have not been fully explored. Here, we identified a pronounced expression of tandem pore domain acid-sensitive potassium channel 3 (TASK-3), a two-pore domain potassium channel (K2P), in RGCs. By using a specific antagonist and TASK-3 knockout mice, we found that TASK-3 regulates the intrinsic excitability and the light sensitivity of RGCs by sensing neuronal activity-dependent extracellular acidification. In vivo, the blockade or loss of TASK-3 dampened pupillary light reflex, visual acuity, and contrast sensitivity. Furthermore, overexpressing TASK-3 specifically in RGCs using an adeno-associated virus approach restored the visual function of TASK-3 knockout mice and aged mice where the expression and function of TASK-3 were reduced. Thus, our results provide evidence that implicates a critical role of K2P in visual processing in the retina.

The Parietal Lobe in Alzheimer’s Disease and Blindness

The progressive aging of the population will notably increase the burden of those diseases which leads to a disabling situation, such as Alzheimer’s disease (AD) and ophthalmological diseases that cause a visual impairment (VI). Eye diseases that cause a VI raise neuroplastic processes in the parietal lobe. Meanwhile, the aforementioned lobe suffers a severe decline throughout AD. From this perspective, diving deeper into the particularities of the parietal lobe is of paramount importance. In this article, we discuss the functions of the parietal lobe, review the parietal anatomical and pathophysiological peculiarities in AD, and also describe some of the changes in the parietal region that occur after VI. Although the alterations in the hippocampus and the temporal lobe have been well documented in AD, the alterations of the parietal lobe have been less thoroughly explored. Recent neuroimaging studies have revealed that some metabolic and perfusion impairments along with a reduction of the white and grey matter could take place in the parietal lobe during AD. Conversely, it has been speculated that blinding ocular diseases induce a remodeling of the parietal region which is observable through the improvement of the integration of multimodal stimuli and in the increase of the volume of this cortical region. Based on current findings concerning the parietal lobe in both pathologies, we hypothesize that the increased activity of the parietal lobe in people with VI may diminish the neurodegeneration of this brain region in those who are visually impaired by oculardiseases.

No evidence for age-related alterations in the marmoset retina

The physiological aging process of the retina is accompanied by various and sometimes extensive changes: Macular degeneration, retinopathies and glaucoma are the most common findings in the elderly and can potentially lead to irreversible visual disablements up to blindness. To study the aging process and to identify possible therapeutic targets to counteract these diseases, the use of appropriate animal models is mandatory. Besides the most commonly used rodent species, a non-human primate, the common marmoset (Callithrix jacchus) emerged as a promising animal model of human aging over the last years. However, the visual aging process in this species is only partially characterized, especially with regard to retinal aberrations. Therefore, we assessed here for the first time potential changes in retinal morphology of the common marmoset of different age groups. By cell type specific immunolabeling, we analyzed different cell types and distributions, potential photoreceptor and ganglion cell loss, and structural reorganization. We detected no signs of age-related differences in staining patterns or densities of various cell populations. For example, there were no signs of photoreceptor degeneration, and there was only minimal sprouting of rod bipolar cells in aged retinas. Altogether, we describe here the maintenance of a stable neuronal architecture, distribution and number of different cell populations with only mild aberrations during the aging process in the common marmoset retina. These findings are in stark contrast to previously reported findings in rodent species and humans and deserve further investigations to identify the underlying mechanisms and possible therapeutic targets.

Improvement of neural contrast sensitivity after long-term adaptation in pseudophakic eyes

An adaptive optics (AO) system was used to investigate the effect of long-term neural adaptation to the habitual optical profile on neural contrast sensitivity in pseudophakic eyes after the correction of all aberrations, defocus, and astigmatism. Pseudophakic eyes were assessed at 4 and 8 months postoperatively for changes in visual performance. Visual benefit was observed in all eyes at all spatial frequencies after AO correction. The average visual benefit across spatial frequencies was higher in the pseudophakic group (3.31) at 4 months postoperatively compared to the normal group (2.41). The average contrast sensitivity after AO correction in the pseudophakic group improved by a factor of 1.73 between 4 and 8 months postoperatively. Contrast sensitivity in pseudophakic eyes was poorer, which could be attributed to long-term adaptation to the habitual optical profiles before the cataract surgery, in conjunction with age-related vision loss. Improved visual performance in pseudophakic eyes suggests that the aged neural system can be re-adapted for altered ocular optics.

Choroid and choriocapillaris changes in early-stage Parkinson’s disease: a swept-source optical coherence tomography angiography-based cross-sectional study

Background

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases in the aging population. Previous literature has reported thinning of the retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, and photoreceptor layer in PD patients. However, very few studies have used swept-source optical coherence tomography (SS-OCT) to study the choroid and choriocapillaris vascular changes in PD and their correlations with altered contrast sensitivity.

Methods

PD patients and controls were enrolled in the current study. We used a CSV-1000E instrument to assess contrast sensitivity and performed SS-OCT and SS-OCTA to measure outer retinal thickness, choroidal thickness, choriocapillaris flow density, choroidal vascular volume (CVV), and choroidal vascular index (CVI).

Results

One hundred eyes of 52 PD patients and 200 eyes of 100 healthy controls were recruited in the present study. Our study found remarkably impaired contrast sensitivity in PD patients (all P < 0.05). Significant thinning of the outer retinal layer and the choroid was appreciated in the PD group compared with the healthy controls (all P < 0.05). Choriocapillaris flow density, CVI, and CVV were significantly decreased in PD patients compared with healthy controls (all P < 0.05). Contrast sensitivity was weakly associated with outer retina thickness in the 3 mm circular area, with 3 cycles per degree being the most relevant (r = 0.535, P < 0.001).

Conclusion

Our study indicates that there is a significant decrease in contrast sensitivity, outer retina thickness, choriocapillaris flow density, CVI, and CVV in PD patients. This research has also identified a positive correlation between outer retina thickness and contrast sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01054-z.

Multisensory visual-vestibular training improves visual heading estimation in younger and older adults

Self-motion perception (e.g., when walking/driving) relies on the integration of multiple sensory cues including visual, vestibular, and proprioceptive signals. Changes in the efficacy of multisensory integration have been observed in older adults (OA), which can sometimes lead to errors in perceptual judgments and have been associated with functional declines such as increased falls risk. The objectives of this study were to determine whether passive, visual-vestibular self-motion heading perception could be improved by providing feedback during multisensory training, and whether training-related effects might be more apparent in OAs vs. younger adults (YA). We also investigated the extent to which training might transfer to improved standing-balance. OAs and YAs were passively translated and asked to judge their direction of heading relative to straight-ahead (left/right). Each participant completed three conditions: (1) vestibular-only (passive physical motion in the dark), (2) visual-only (cloud-of-dots display), and (3) bimodal (congruent vestibular and visual stimulation). Measures of heading precision and bias were obtained for each condition. Over the course of 3 days, participants were asked to make bimodal heading judgments and were provided with feedback ("correct"/"incorrect") on 900 training trials. Post-training, participants' biases, and precision in all three sensory conditions (vestibular, visual, bimodal), and their standing-balance performance, were assessed. Results demonstrated improved overall precision (i.e., reduced JNDs) in heading perception after training. Pre- vs. post-training difference scores showed that improvements in JNDs were only found in the visual-only condition. Particularly notable is that 27% of OAs initially could not discriminate their heading at all in the visual-only condition pre-training, but subsequently obtained thresholds in the visual-only condition post-training that were similar to those of the other participants. While OAs seemed to show optimal integration pre- and post-training (i.e., did not show significant differences between predicted and observed JNDs), YAs only showed optimal integration post-training. There were no significant effects of training for bimodal or vestibular-only heading estimates, nor standing-balance performance. These results indicate that it may be possible to improve unimodal (visual) heading perception using a multisensory (visual-vestibular) training paradigm. The results may also help to inform interventions targeting tasks for which effective self-motion perception is important.

Age-differences in interpreting the valence of ambiguous facial expressions: evidence for multiple contributing processes

Surprised facial expressions, which are ambiguous in valence, are interpreted more positively by older adults than by younger adults. To evaluate the processes contributing to this age difference, we varied the spatial frequency of the surprised-face stimuli. When faces were presented in a low-spatial-frequency band, it biased participants to rate them negatively. Although this occurred for both younger and older adults, the older adults' ratings of the low-spatial-frequency faces were more positive than that of the younger adults. This suggests that there is an age-related reduction in the default negativity of interpretations. We also found that older adults, as a whole, rated the high-spatial-frequency faces more positively than did younger adults. However, this effect was eliminated for the subset of older adults with poor high-spatial-frequency perception abilities for whom these faces were difficult to perceive. Thus, older adults' more positive interpretations of surprised faces may also reflect cognitively-effortful regulatory processes.

Ophthalmological Manifestations of Oculocutaneous and Ocular Albinism: Current Perspectives

Albinism describes a heterogeneous group of genetically determined disorders characterized by disrupted synthesis of melanin and a range of developmental ocular abnormalities. The main ocular features common to both oculocutaneous albinism (OCA), and ocular albinism (OA) include reduced visual acuity, refractive errors, foveal hypoplasia, congenital nystagmus, iris and fundus hypopigmentation and visual pathway misrouting, but clinical signs vary and there is phenotypic overlap with other pathologies. This study reviews the prevalence, genetics and ocular manifestations of OCA and OA, including abnormal development of the optic chiasm. The role of visual electrophysiology in the detection of chiasmal dysfunction and visual pathway misrouting is emphasized, highlighting how age-associated changes in visual evoked potential (VEP) test results must be considered to enable accurate diagnosis, and illustrated further by the inclusion of novel VEP data in genetically confirmed cases. Differential diagnosis is considered in the context of suspected retinal and other disorders, including rare syndromes that may masquerade as albinism.