Age-related psychophysical changes and low vision

The Differential Impact of Age on Vision-Related Quality of Life across the Visual Impairment Spectrum

PURPOSE

Visual impairment (VI) can have a detrimental impact on vision-related quality of life (VRQoL), but it is still unclear how this relationship varies with age across the VI spectrum. We determined the age-stratified, cross-sectional, and longitudinal associations between VI severity and VRQoL.

DESIGN

The baseline and follow-up Singapore Chinese Eye Studies (SCES-1/-2; 2009-2011 and 2015-2017).

PARTICIPANTS

A total of 3068 SCES-1 participants (mean age [standard deviation {SD}]: 59.5 [9.8] years; 50.2% female) and 1919 SCES-2 participants (mean age [SD]: 56.8 [8.3] years; 49.9% female).

METHODS

Visual impairment was defined as visual acuity (VA) of > 0.3 logarithm of the minimum angle of resolution (logMAR) units; VI severity as mild-moderate (logMAR scores less than the median of all individuals with VI) and severe (logMAR scores median or greater); and VI incidence as VI absence at baseline, but evident at follow-up. Age was stratified into 40 to 49 years, 50 to 64 years, and ≥65 years.

MAIN OUTCOME MEASURES

Rasch-transformed scores from the 32-item Impact of Visual Impairment (IVI) questionnaire were used to measure the "Reading," "Mobility," and "Emotional" domains of VRQoL. Multiple linear regression models determined the age-stratified associations of prevalent and incident VI with all 3 VRQoL outcomes, adjusted for potential confounders.

RESULTS

Of the 807 persons with prevalent VI, 55.9% had mild-moderate and 44.1% had severe VI. Compared with no VI, age-stratified analyses showed that VRQoL decrements were significant only in the older age groups (mild-moderate VI: 6.2% and 8.1% reduction in Mobility and Reading scores in those aged ≥ 65 years; severe VI: 8.5% to 13.4% reductions in the 3 VRQoL scores in those aged ≥ 50 years). This interaction with older age became more pronounced with incident VI (N = 168), where decrements in all 3 VRQoL domains were evident only in those aged ≥65 years compared with persons without incident VI.

CONCLUSIONS

Our results suggest that the VI-VRQoL associations are driven mainly by older individuals aged ≥65 years, highlighting the need for effective regular screening and early intervention modalities to prevent the presence and onset of VI, and subsequent VRQoL declines, in these individuals.

Perspectives: Hemianopia-Toward Novel Treatment Options Based on Oscillatory Activity?

Stroke has become one of the main causes of visual impairment, with more than 15 million incidences of first-time strokes, per year, worldwide. One-third of stroke survivors exhibit visual impairment, and most of them will not fully recover. Some recovery is possible, but this usually happens in the first few weeks after a stroke. Most of the rehabilitation options that are offered to patients are compensatory, such as optical aids or eye training. However, these techniques do not seem to provide a sufficient amount of improvement transferable to everyday life. Based on the relatively recent idea that the visual system can actually recover from a chronic lesion, visual retraining protocols have emerged, sometimes even in combination with noninvasive brain stimulation (NIBS), to further boost plastic changes in the residual visual tracts and network. The present article reviews the underlying mechanisms supporting visual retraining and describes the first clinical trials that applied NIBS combined with visual retraining. As a further perspective, it gathers the scientific evidence demonstrating the relevance of interregional functional synchronization of brain networks for visual field recovery, especially the causal role of α and γ oscillations in parieto-occipital regions. Because transcranial alternating current stimulation (tACS) can induce frequency-specific entrainment and modulate spike timing-dependent plasticity, we present a new promising interventional approach, consisting of applying physiologically motivated tACS protocols based on multifocal cross-frequency brain stimulation of the visuoattentional network for visual field recovery.

The Assessment of Visual Function and Functional Vision

The complete assessment of vision-related abilities should consider visual function (the performance of components of the visual system) and functional vision (visual task-related ability). Assessment methods are highly dependent upon individual characteristics (eg, the presence and type of visual impairment). Typical visual function tests assess factors such as visual acuity, contrast sensitivity, color, depth, and motion perception. These properties each represent an aspect of visual function and may impact an individual's level of functional vision. The goal of any functional vision assessment should be to measure the visual task-related ability under real-world scenarios. Recent technological advancements such as virtual reality can provide new opportunities to improve traditional vision assessments by providing novel objective and ecologically valid measurements of performance, and allowing for the investigation of their neural basis. In this review, visual function and functional vision evaluation approaches are discussed in the context of traditional and novel acquisition methods.

Establishing the Feasibility of a Tablet-Based Consent Process with Older Adults: A Mixed-Methods Study

Purpose of the Study

This mixed-methods study explored the feasibility and acceptability of using a tablet-based research consent process with adults aged ≥65 years.

Design and Methods

In the first phase, focus group participants reported on their perceptions of a tablet-based consent process. In the second phase, older adults were randomized to view either a tablet-based or paper-based consent for a mock clinical trial. Measurements included: time to complete, adverse/unexpected events, user-friendliness, immediate comprehension, and retention at a 1-week delay.

Results

Focus group participants (N = 15) expressed interest in the novel format, cautioning that peers would need comprehensive orientation to use the technology. In the randomized pilot (N = 20), retention was 100% and all participants completed the protocol without the occurrence of adverse/unexpected events. Although the participants took longer to complete the tablet-based consent than the paper-based version, user-friendliness, immediate comprehension, and retention of the tablet-based consent were similar to the paper-based consent.

Discussion and Implications

The findings suggest that a tablet-based consent process is feasible to implement with older adults and acceptable to this population, but we would underscore that efforts to optimize design of tablet-based consent forms for older adults are warranted.

Residual vision activation and the brain-eye-vascular triad: Dysregulation, plasticity and restoration in low vision and blindness - a review

Vision loss due to ocular diseases such as glaucoma, optic neuropathy, macular degeneration, or diabetic retinopathy, are generally considered an exclusive affair of the retina and/or optic nerve. However, the brain, through multiple indirect influences, has also a major impact on functional visual impairment. Such indirect influences include intracerebral pressure, eye movements, top-down modulation (attention, cognition), and emotionally triggered stress hormone release affecting blood vessel dysregulation. Therefore, vision loss should be viewed as the result of multiple interactions within a “brain-eye-vascular triad”, and several eye diseases may also be considered as brain diseases in disguise. While the brain is part of the problem, it can also be part of the solution. Neuronal networks of the brain can “amplify” residual vision through neuroplasticity changes of local and global functional connectivity by activating, modulating and strengthening residual visual signals. The activation of residual vision can be achieved by different means such as vision restoration training, non-invasive brain stimulation, or blood flow enhancing medications. Modulating brain functional networks and improving vascular regulation may offer new opportunities to recover or restore low vision by increasing visual field size, visual acuity and overall functional vision. Hence, neuroscience offers new insights to better understand vision loss, and modulating brain and vascular function is a promising source for new opportunities to activate residual vision to achieve restoration and recovery to improve quality of live in patients suffering from low vision.

COGEVIS: A New Scale to Evaluate Cognition in Patients with Visual Deficiency

We evaluated the cognitive status of visually impaired patients referred to low vision rehabilitation (LVR) based on a standard cognitive battery and a new evaluation tool, named the COGEVIS, which can be used to assess patients with severe visual deficits. We studied patients aged 60 and above, referred to the LVR Hospital in Paris. Neurological and cognitive evaluations were performed in an expert memory center. Thirty-eight individuals, 17 women and 21 men with a mean age of 70.3 ± 1.3 years and a mean visual acuity of 0.12 ± 0.02, were recruited over a one-year period. Sixty-three percent of participants had normal cognitive status. Cognitive impairment was diagnosed in 37.5% of participants. The COGEVIS score cutoff point to screen for cognitive impairment was 24 (maximum score of 30) with a sensitivity of 66.7% and a specificity of 95%. Evaluation following 4 months of visual rehabilitation showed an improvement of Instrumental Activities of Daily Living (p = 0.004), National Eye Institute Visual Functioning Questionnaire (p = 0.035), and Montgomery–Åsberg Depression Rating Scale (p = 0.037). This study introduces a new short test to screen for cognitive impairment in visually impaired patients.

Revisiting Vision Rehabilitation

Low vision is a condition caused by eye or brain disease, in which visual acuity is 20/70 (3/10 or 6/18) or poorer in the better-seeing eye and cannot be corrected or improved with regular eyeglasses. It impacts personal ability to perform vision-dependent tasks as activities of daily living, walking, reading or using a computer. Rehabilitation is a multidisciplinary training dedicated to improve patients’ functional abilities and quality of life. It has to be personalized to every individual situation, whatever the underlying pathology.

Clinical Applications of Dexamethasone for Aged Eyes

The risk of severe eye problems has been found to increase significantly with age, particularly between the fifth and sixth decades of life. Cataracts, dry eye, neovascular age-related macular degeneration, diabetic retinopathy and retinal vein occlusion (RVO) are very common and very different age-related ocular diseases that reduce the patient's quality of life. The rationale for using corticosteroids to treat anterior and posterior ocular segment diseases is driven by inflammation. Dexamethasone, one of the most powerful corticosteroids available, is widely used for topical or intravitreal administration. Topical dexamethasone has proven efficacy for the management of postoperative inflammation in the anterior segment after cataract surgery and symptom relief in dry-eye disease. A new sustained-release 700 µg dexamethasone intravitreal implant (DEX) was recently approved for the treatment of macular edema following RVO, diabetic macular edema, or non-infectious uveitis, and its use is increasing, especially when other therapeutic agents have failed. The most common side effects are increased intraocular pressure and cataract formation. The potency of DEX, alone or in combination with other agents, makes DEX a promising option for treating several retinal diseases.

Systematic Review of the Clinical Application of Exposure Techniques to Community-Dwelling Older Adults with Anxiety

OBJECTIVES

Although exposure techniques are a first-line intervention for anxiety, clear evidence is lacking for their efficacy in treating the prevalent and debilitating condition of late life anxiety. This study sought to review the current literature on use of exposure with community-dwelling older patients.

METHODS

Searches of electronic databases were conducted to identify articles published through December 7, 2016. Inclusion criteria were: 1) sample age > 55, 2) therapy that included exposure, 3) anxiety as a target of the treatment. Exclusion criteria were: 1) not available in English, 2) no quantitative data, 3) inpatient setting. Methodological data and findings were extracted from the articles chosen for review.

RESULTS

The 54 eligible articles presented a total of 16 case studies, 9 uncontrolled trials, 24 controlled trials, and 6 secondary studies. A majority of the studies were conducted in the U.S.A with participants who received individual treatment. In vivo and imaginal exposure were the most frequently delivered techniques, and most treatments were multicomponent. Most studies found a reduction in anxiety symptoms.

CONCLUSIONS

Important research gaps need to be addressed.

CLINICAL IMPLICATIONS

The surveyed research provides a modest foundation of evidence for mental health practitioners who wish to incorporate exposure into treatment plans.

Functional Interplay Between the Putative Measures of Rostral and Caudal Efferent Regulation of Speech Perception in Noise

Efferent modulation has been demonstrated to be very important for speech perception, especially in the presence of noise. We examined the functional relationship between two efferent systems: the rostral and caudal efferent pathways and their individual influences on speech perception in noise. Earlier studies have shown that these two efferent mechanisms were correlated with speech perception in noise. However, previously, these mechanisms were studied in isolation, and their functional relationship with each other was not investigated. We used a correlational design to study the relationship if any, between these two mechanisms in young and old normal hearing individuals. We recorded context-dependent brainstem encoding as an index of rostral efferent function and contralateral suppression of otoacoustic emissions as an index of caudal efferent function in groups with good and poor speech perception in noise. These efferent mechanisms were analysed for their relationship with each other and with speech perception in noise. We found that the two efferent mechanisms did not show any functional relationship. Interestingly, both the efferent mechanisms correlated with speech perception in noise and they even emerged as significant predictors. Based on the data, we posit that the two efferent mechanisms function relatively independently but with a common goal of fine-tuning the afferent input and refining auditory perception in degraded listening conditions.

The visual white matter: The application of diffusion MRI and fiber tractography to vision science

Visual neuroscience has traditionally focused much of its attention on understanding the response properties of single neurons or neuronal ensembles. The visual white matter and the long-range neuronal connections it supports are fundamental in establishing such neuronal response properties and visual function. This review article provides an introduction to measurements and methods to study the human visual white matter using diffusion MRI. These methods allow us to measure the microstructural and macrostructural properties of the white matter in living human individuals; they allow us to trace long-range connections between neurons in different parts of the visual system and to measure the biophysical properties of these connections. We also review a range of findings from recent studies on connections between different visual field maps, the effects of visual impairment on the white matter, and the properties underlying networks that process visual information supporting visual face recognition. Finally, we discuss a few promising directions for future studies. These include new methods for analysis of MRI data, open datasets that are becoming available to study brain connectivity and white matter properties, and open source software for the analysis of these data.

Cerebral versus Ocular Visual Impairment: The Impact on Developmental Neuroplasticity

Cortical/cerebral visual impairment (CVI) is clinically defined as significant visual dysfunction caused by injury to visual pathways and structures occurring during early perinatal development. Depending on the location and extent of damage, children with CVI often present with a myriad of visual deficits including decreased visual acuity and impaired visual field function. Most striking, however, are impairments in visual processing and attention which have a significant impact on learning, development, and independence. Within the educational arena, current evidence suggests that strategies designed for individuals with ocular visual impairment are not effective in the case of CVI. We propose that this variance may be related to differences in compensatory neuroplasticity related to the type of visual impairment, as well as underlying alterations in brain structural connectivity. We discuss the etiology and nature of visual impairments related to CVI, and how advanced neuroimaging techniques (i.e., diffusion-based imaging) may help uncover differences between ocular and cerebral causes of visual dysfunction. Revealing these differences may help in developing future strategies for the education and rehabilitation of individuals living with visual impairment.

Visual, Musculoskeletal, and Balance Complaints in AMD: A Follow-Up Study

Purpose. To investigate whether patients with age-related macular degeneration (AMD) run a potentially higher risk of developing visual, musculoskeletal, and balance complaints than age-matched controls with normal vision. Methods. Visual assessments, self-rated visual function, self-rated visual, musculoskeletal, and balance complaints, and perceived general health were obtained in 37 AMD patients and 18 controls, at baseline and after an average of 3.8 years later. Results. At follow-up both groups reported decreased visual acuity (VA) and visual function, but only AMD patients reported significantly increased visual, musculoskeletal, and balance complaints. Decreased VA, need for larger font size when reading, need for larger magnification, and decreased self-rated visual function were identified as risk markers for increased complaints in AMD patients. These complaints were also identified as risk markers for decreased health. For controls, decreased VA and self-reported visual function were associated with increased visual and balance complaints. Conclusions. Visual deterioration was a risk marker for increased visual, musculoskeletal, balance, and health complaints in AMD patients. Specifically, magnifying visual aids, such as CCTV, were a risk marker for increased complaints in AMD patients. This calls for early and coordinated actions to treat and prevent visual, musculoskeletal, balance, and health complaints in AMD patients.

Effects of aging on optical quality and visual function

BACKGROUND

We assessed the effects of aging on visual function and optical quality in a healthy adult population and provide reference values for different age ranges.

METHODS

We conducted a prospective study with 198 healthy volunteers from 31 to 70 years of age. The visual acuity (VA) and contrast sensitivity (CS) at 3, 6, 12 and 18 cycles per degree (cpd) frequencies were assessed, together with values of optical quality and intraocular scattering obtained with a double-pass system (Optical Quality Analysis System - OQAS), specifically the modulation transfer function cutoff frequency (MTF_cutoff ), the Strehl ratio, the OQAS values (OV) at contrasts of 100, 20 and nine per cent and the objective scatter index (OSI). We studied the change of these variables with age and obtained standard values for optical quality and intraocular scattering parameters for four age groups: 31 to 40, 41 to 50, 51 to 60 and 61 to 70 years.

RESULTS

We found significant correlations between age and all variables analysed and significant differences among the age groups considered except for CS (3 cpd) (p = 0.067). Ageing particularly affected low-contrast parameters, such as the OV nine per cent and the OSI, which decreased to 37 and 50 per cent of their original values, respectively. The OSI was found to provide high sensitivity and specificity values, when healthy and caratactous eyes were considered. The results suggest that optical deficits are compensated until 50 years of age with sensory and perceptual factors, as smaller changes were found for visual function than for objective measurements of optical quality and intraocular scattering.

CONCLUSIONS

Measures of optical quality assessed by subjective psychophysical and objective techniques varied differently with age. Values obtained for each age group can be used to determine normal limits of optical quality and intraocular scattering for diagnosis of ocular conditions.

Effect of reduced visual acuity on precision of two-dimensional tracing movements

PURPOSE

We intended to assess consequences of reduced visual acuity for performance in a natural simple motor task (tracing) using objective kinematic performance measures. Specifically, we intended to elucidate the kind of relationship between the task performance and best corrected binocular visual acuity and to determine the threshold of visual acuity when task performance starts to deteriorate.

METHODS

Ninety-five individuals with different best corrected visual acuity participated in the study (age 49±12 years, mean±SD, 27 men and 68 women). The participants manually traced maze-like visual patterns of different spatial complexity presented on the screen of a portable notebook computer using Clinical Kinematic Assessment Tool software. Tracing error was computed as performance measure in each trial with a spatial pattern matching technique - rigid point set registration method.

RESULTS

The segmented linear regression analysis showed that the relation between visual acuity and tracing errors was best described with a regression function having a break point between two data segments. Tracing performance was unaffected by values of visual acuity below 0.2 on logMAR scale, but when logMAR values increased above this critical limit (i.e. when visual acuity is further reduced), tracing errors linearly increased. The rate of the increase of the tracing error correlated with the complexity of visual stimulus shape.

CONCLUSION

Testing of fine motor functions with objective kinematic measures during visuomotor tasks may help differentiating between actual effects of reduced visual acuity on eye-hand coordination in individuals with similar levels of impairment of visual acuity.

Visual Impairment Screening at the Geriatric Frailty Clinic for Assessment of Frailty and Prevention of Disability at the Gérontopôle

OBJECTIVES

To evaluate visual performance and factors associated with abnormal vision in patients screened for frailty at the Geriatric Frailty Clinic (GFC) for Assessment of Frailty and Prevention of Disability at Toulouse University Hospital.

DESIGN

Retrospective, observational cross-sectional, single-centre study.

SETTING

Institutional practice.

PARTICIPANTS

Patients were screened for frailty during a single-day hospital stay between October 2011 and October 2014 (n = 1648).

MEASUREMENTS

Collected medical records included sociodemographic data (including living environment and educational level), anthropometric data, and clinical data. The general evaluation included the patient's functional status using the Activities of Daily Living (ADL) scale and the Instrumental Activity of Daily Living (IADL) scale, the Mini-Mental State Examination (MMSE) for cognition testing, and the Short Physical Performance Battery (SPPB) for physical performance. We also examined Body Mass Index (BMI), the Mini-Nutritional Assessment (MNA), and the Hearing Handicap Inventory for the Elderly Screening (HHIE-S) tool. The ophthalmologic evaluation included assessing visual acuity using the Snellen decimal chart for distant vision, and the Parinaud chart for near vision. Patients were divided into groups based on normal distant/near vision (NDV and NNV groups) and abnormal distant/near vision (ADV and ANV groups). Abnormal distant or near vision was defined as visual acuity inferior to 20/40 or superior to a Parinaud score of 2, in at least one eye. Associations with frailty-associated factors were evaluated in both groups.

RESULTS

The mean age of the population was 82.6 ± 6.2 years. The gender distribution was 1,061 females (64.4%) and 587 males (35.6%). According to the Fried criteria, 619 patients (41.1%) were pre-frail and 771 (51.1%) were frail. Distant and near vision data were available for 1425 and 1426 patients, respectively. Distant vision was abnormal for 437 patients (30.7%). Near vision was abnormal for 199 patients (14%). Multiple regression analysis showed that abnormal distant vision as well as abnormal near vision were independently associated with greater age (P < 0.01), lower educational level (P < 0.05), lower performance on the MMSE (P < 0.001), and lower autonomy (P < 0.02), after controlling for age, gender, educational level, Fried criteria, and MMSE score.

CONCLUSION

The high prevalence of visual disorders observed in the study population and their association with lower autonomy and cognitive impairment emphasises the need for systematic screening of visual impairments in the elderly. Frailty was not found to be independently associated with abnormal vision.

Ashtanga-Based Yoga Therapy Increases the Sensory Contribution to Postural Stability in Visually-Impaired Persons at Risk for Falls as Measured by the Wii Balance Board: A Pilot Randomized Controlled Trial

Objective

Persons with visual impairment (VI) are at greater risk for falls due to irreparable damage to visual sensory input contributing to balance. Targeted training may significantly improve postural stability by strengthening the remaining sensory systems. Here, we evaluate the Ashtanga-based Yoga Therapy (AYT) program as a multi-sensory behavioral intervention to develop postural stability in VI.

Design

A randomized, waitlist-controlled, single-blind clinical trial

Methods

The trial was conducted between October 2012 and December 2013. Twenty-one legally blind participants were randomized to an 8-week AYT program (n = 11, mean (SD) age = 55(17)) or waitlist control (n=10, mean (SD) age = 55(10)). AYT subjects convened for one group session at a local yoga studio with an instructor and two individual home-based practice sessions per week for a total of 8 weeks. Subjects completed outcome measures at baseline and post-8 weeks of AYT. The primary outcome, absolute Center of Pressure (COP), was derived from the Wii Balance Board (WBB), a standalone posturography device, in 4 sensory conditions: firm surface, eyes open (EO); firm surface, eyes closed (EC); foam surface, EO; and foam surface, EC. Stabilization Indices (SI) were computed from COP measures to determine the relative visual (SI_firm, SI_foam), somatosensory (SI_EO, SI_EC) and vestibular (SI_V, i.e., Foam_EC vs. Firm_EO) contributions to balance. This study was not powered to detect between group differences, so significance of pre-post changes was assessed by paired samples t-tests within each group.

Results

Groups were equivalent at baseline (all p > 0.05). In the AYT group, absolute COP significantly increased in the Foam_EO (t(8) = -3.66, p = 0.01) and Foam_EC (t(8) = -3.90, p = 0.01) conditions. Relative somatosensory SI_EO (t(8) = -2.42, p = 0.04) and SI_EC (t(8) = -3.96, p = 0.01), and vestibular SI_V (t(8) = -2.47, p = 0.04) contributions to balance increased significantly. As expected, no significant changes from EO to EC conditions were found indicating an absence of visual dependency in VI. No significant pre-post changes were observed in the control group (all p > 0.05).

Conclusions

These preliminary results establish the potential for AYT training to develop the remaining somatosensory and vestibular responses used to optimize postural stability in a VI population.

Trial Registration

www.ClinicalTrials.govNCT01366677

Role of microglia adenosine A(2A) receptors in retinal and brain neurodegenerative diseases

Neuroinflammation mediated by microglial cells in the brain has been commonly associated with neurodegenerative diseases. Whether this microglia-mediated neuroinflammation is cause or consequence of neurodegeneration is still a matter of controversy. However, it is unequivocal that chronic neuroinflammation plays a role in disease progression and halting that process represents a potential therapeutic strategy. The neuromodulator adenosine emerges as a promising targeting candidate based on its ability to regulate microglial proliferation, chemotaxis, and reactivity through the activation of its G protein coupled A2A receptor (A2AR). This is in striking agreement with the ability of A2AR blockade to control several brain diseases. Retinal degenerative diseases have been also associated with microglia-mediated neuroinflammation, but the role of A2AR has been scarcely explored. This review aims to compare inflammatory features of Parkinson's and Alzheimer's diseases with glaucoma and diabetic retinopathy, discussing the therapeutic potential of A2AR in these degenerative conditions.