Visual impairment and postural sway among older adults with glaucoma

The relationship between a simulated glaucoma impairment and postural threat on quiet stance

Peripheral visual field deficits developed through glaucoma have been shown to contribute to balance deficits and a fear of falling. Currently, there is no work that examines the relationship between fear of falling and quiet stance among glaucoma patients. Therefore, this study aimed to examine the impact of a virtual height-induced postural threat on balance control among healthy individuals exposed to a simulated glaucoma impairment. Participants stood on a force plate to measure kinetic responses while wearing a virtual reality (VR) head-mounted display (HMD) which also tracked head position. Surface electromyography (EMG) was also used to measure muscle activity from ankle stabilizing muscles. Trials were 60 s, with two at ground level and two at 7 virtual meters above ground, each exposing participants to normal vision and a VR-simulated glaucoma impairment. Electrodermal activity was collected, and questionnaires were completed following each trial to evaluate psychological aspects of the postural threat. Overall, while experiencing height-induced fear with normal vision, participants developed a tighter control of upright stance (decreased amplitude and increased frequency of balance-related movement); however, this was not observed for the simulated glaucoma conditions. Therefore, balance deficits among glaucoma patients may be mediated by fear of falling contributing to an unexpected postural strategy.

Effect of myopia-control lenses on central and peripheral visual performance in myopic children

PURPOSE

To evaluate the short-term effects of three myopia-control lenses, which impose peripheral myopic defocus while providing clear central vision, on central and peripheral visual performance in myopic children.

METHODS

Twenty-one myopic children were enrolled in the study. Central visual performance was assessed using the quick contrast sensitivity function. Peripheral visual performance was evaluated by measuring peripheral contrast threshold and global motion perception, while subjects maintained fixation through the central portion of the lens. Single-vision spectacle lenses (SVL), spectacle lenses with highly aspherical lenslets (HAL) and defocus-incorporated soft contact (DISC) lenses were evaluated in random order, followed by orthokeratology (OK) lenses. All tests were performed monocularly on the right eye.

RESULTS

The area under the log contrast sensitivity function (AULCSF) with DISC lenses was lower than that with SVL (1.14 vs. 1.40, p < 0.001) and HAL (1.14 vs. 1.33, p = 0.001). HAL increased the temporal visual field contrast threshold compared with OK lenses (p = 0.04), and OK lenses decreased the superior visual field contrast threshold compared with that of SVL (p = 0.04) and HAL (p = 0.005). HAL also increased the peripheral coherence threshold for identifying the contraction movement compared with OK lenses (p = 0.01).

CONCLUSIONS

The short-term use of these optical interventions for myopia control exhibited measurable differences in central and peripheral visual performance. Relevant attention could be paid to these differences, especially when children switch to different treatments. DISC lenses exhibited worse central contrast sensitivity than SVL and HAL. Imposing peripheral defocus signals did not affect children's peripheral visual performance compared with SVL. However, considering the poorer peripheral visual performance provided by HAL, OK lenses are recommended for children if there are specific demands for global scene recognition and motion perception.

The Association Between Frailty and Visual Field Loss in US Adults

PURPOSE

To describe the association between visual field loss and frailty in a nationally representative cohort of US adults.

DESIGN

Retrospective cross-sectional study.

METHODS

The cohort included adults 40 years or older with complete eye examination data from the 2005-2006 and 2007-2008 National Health and Nutrition Examination Surveys (NHANES). Visual field loss (VFL) was determined by frequency doubling technology and a 2-2-1 algorithm. A 36-item deficit accumulation-based frailty index was used to divide subjects into 4 categories of increasing frailty severity.

RESULTS

Of the 4897 participants, 4402 (93.2%) had no VFL, 301 (4.1%) had unilateral VFL, and 194 (2.73%) had bilateral VFL. Within the sample, 2 subjects197 (53.1%) were categorized as non-frail, 1659 (31.3%) as vulnerable, 732 (11.3%) as mildly frail, and 312 (4.3%) as most frail. In multivariable models adjusted for demographics, visual acuity, and history of cataract surgery, subjects with unilateral VFL had higher adjusted odds of being in a more frail category (adjusted odds ratio [aOR], 2.07; 95% CI, 1.42-3.02) than subjects without VFL. Subjects with bilateral VFL also had higher odds of a more frail category compared to subjects without VFL (aOR, 1.74; 95% CI, 1.20-2.52).

CONCLUSIONS

In the 2005-2008 NHANES adult population, VFL is associated with higher odds of frailty, independent of central visual acuity loss. Frail individuals may be more susceptible to diseases that can cause VFL, and/or VFL may predispose to frailty. Additional studies are needed to determine the directionality of this relationship and to assess potential interventions.

Physical Activity in Functionally Monocular Persons in the United States, 2003-2006

Purpose

Real-world physical activity patterns in monocular persons have not been previously characterized. This study uses a nationally representative sample to compare the physical activity levels of functionally monocular to binocularly sighted persons in the United States.

Methods

This cross-sectional study uses data from the 2003-2004 and 2005-2006 National Health and Nutrition Examination Survey (NHANES) to compare differences in physical activity between functionally monocular and binocular participants. The main outcome measures were accelerometer-measured mean steps per day and mean daily minutes of moderate or vigorous physical activity (MVPA). Statistical analysis was conducted using multivariable negative binomial regression models adjusted for age.

Results

In total, 7967 NHANES participants had complete visual acuity and accelerometer data. The mean age at baseline was 44.5 years, and a majority were Caucasian (73%) and female (51%). In models adjusted for age only, functionally monocular participants (n = 172) took fewer steps (9277 with 95% confidence interval [CI], 8800-9753 vs. 10,057 with 95% CI, 9832-10,281) and engaged in similar minutes of MVPA (26.75 with 95% CI, 22.0-31.5 vs. 26.70 with 95% CI, 25.6-27.7) per day compared to binocularly sighted participants (n = 7758). In our final model, functionally monocular participants took 16% fewer steps per day (P < 0.01) and engaged in 26% fewer minutes per day of MVPA (P = 0.01). Poorer visual acuity, older age, female gender, obesity, congestive heart failure, and arthritis were also associated with a statistically significant decrease in physical activity in both models.

Conclusions

Functionally monocular persons have lower physical activity levels compared to those with binocular eyesight in the United States, even after adjusting for better-eye visual acuity.

Translational Relevance

Our translational study provides insight into the epidemiology of physical activity and its impact on population health. We quantify real-world physical activity in two at-risk populations, monocular and blind individuals.

Peripheral visual field loss and activities of daily living

PURPOSE OF REVIEW

Peripheral visual field (VF) loss affects 13% of the population over 65. Its effect on activities of daily living and higher order visual processing is as important as it is inadequately understood. The purpose of this review is to summarize available literature on the impact of peripheral vision loss on driving, reading, face recognition, scene recognition and scene navigation.

RECENT FINDINGS

In this review, glaucoma and retrochiasmal cortical damage are utilized as examples of peripheral field loss which typically spare central vision and have patterns respecting the horizontal and vertical meridians, respectively. In both glaucoma and retrochiasmal damage, peripheral field loss causes driving difficulty - especially with lane maintenance - leading to driving cessation, loss of independence, and depression. Likewise, peripheral field loss can lead to slower reading speeds and decreased enjoyment from reading, and anxiety. In glaucoma and retrochiasmal field loss, face processing is impaired which impacts social functioning. Finally, scene recognition and navigation are also adversely affected, impacting wayfinding and hazard detection leading to decreased independence as well as more frequent injury.

SUMMARY

Peripheral VF loss is an under-recognized cause of patient distress and disability. All peripheral field loss is not the same, differential patterns of loss affect parameters of activities of daily living (ADL) and visual processing in particular ways. Future research should aim to further characterize patterns of deranged ADL and visual processing, their correlation with types of field loss, and associated mechanisms.

Eye Movement Abnormalities in Glaucoma Patients: A Review

Glaucoma is a common condition that relies on careful clinical assessment to diagnose and determine disease progression. There is growing evidence that glaucoma is associated not only with loss of retinal ganglion cells but also with degeneration of cortical and subcortical brain structures associated with vision and eye movements. The effect of glaucoma pathophysiology on eye movements is not well understood. In this review, we examine the evidence surrounding altered eye movements in glaucoma patients compared to healthy controls, with a focus on quantitative eye tracking studies measuring saccades, fixation, and optokinetic nystagmus in a range of visual tasks. The evidence suggests that glaucoma patients have alterations in several eye movement domains. Patients exhibit longer saccade latencies, which worsen with increasing glaucoma severity. Other saccadic abnormalities include lower saccade amplitude and velocity, and difficulty inhibiting reflexive saccades. Fixation is pathologically altered in glaucoma with reduced stability. Optokinetic nystagmus measures have also been shown to be abnormal. Complex visual tasks (eg reading, driving, and navigating obstacles), integrate these eye movements and result in behavioral adaptations. The review concludes with a summary of the evidence and recommendations for future research in this emerging field.

Visual Predictors of Postural Sway in Older Adults

Purpose

Accurate perception of body position relative to the environment through visual cues provides sensory input to the control of postural stability. This study explored which vision measures are most important for control of postural sway in older adults with a range of visual characteristics.

Methods

Participants included 421 older adults (mean age = 72.6 ± 6.1), 220 with vision impairment associated with a range of eye diseases and 201 with normal vision. Participants completed a series of vision, cognitive, and physical function tests. Postural sway was measured using an electronic forceplate (HUR Labs) on a foam surface with eyes open. Linear regression analysis identified the strongest visual predictors of postural sway, controlling for potential confounding factors, including cognitive and physical function.

Results

In univariate regression models, unadjusted and adjusted for age, all of the vision tests were significantly associated with postural sway (P < 0.05), with the strongest predictor being visual motion sensitivity (standardized regression coefficient, β = 0.340; age-adjusted β = 0.253). In multiple regression models, motion sensitivity (β = 0.187), integrated binocular visual fields (β = -0.109), and age (β = 0.234) were the only significant visual predictors of sway, adjusted for confounding factors, explaining 23% of the variance in postural sway.

Conclusions

Of the vision tests, visual motion perception and binocular visual fields were most strongly associated with postural stability in older adults with and without vision impairment.

Translational Relevance

Findings provide insight into the visual contributions to postural stability in older adults and have implications for falls risk assessment.

H. S, Joy A, Gopi A, Mathew J, Raja K. Decreased Postural Sway in Women Who Are Visually Impaired: Is it a Learned Protective Mechanism?

Introduction: Comparison of sway parameters of visually impaired participants to that of the sighted population may give insight into the intrinsic risk of falls relative to the surface. Sway is a natural mechanism to adjust the posture and maintain balance. But the sway characteristics on uneven surfaces are ill explored. There is a paucity of evidence on baseline values of sway amplitude in visually impaired women in comparison to sighted women, which underpins the importance of this study. Methods: Eighteen visually impaired young women and an equal number of age-matched sighted peers were recruited by convenience to this prospective observational study. Sway amplitude of the participants were measured using a sway meter on three different surfaces, with eyes opened and closed conditions, using videography and analyzed using Kinovea motion analyzing software. Demographics and participant characteristics were summarized using descriptive statistics. The comparison were performed using independent sample t-test. Results: Visually impaired women demonstrated lower amplitude of sway than sighted young women, irrespective of the surface. Discussion: There was a gradual increase in sway amplitude as the standing surfaces changed from even to sand and pebbles, respectively, for both groups. Implications for Practitioners: Contrary to the existing evidence, the results of this study indicate that visually impaired young individuals may not be not at higher intrinsic risk of falls on various terrains than their sighted peers. The authors hypothesize that the lower sway among visually impaired participants can be attributed to the learned strategy for safety from exposure to real-life pragmatic environments during everyday activities, which enabled them to adopt postural strategies as a safety measure. Hence, this strategy can potentially be used in dynamic situations to decrease the propensity for falls during ambulation in visually impaired individuals.

The Predictive Values of Changes in Local and Remote Brain Functional Connectivity in Primary Angle-Closure Glaucoma Patients According to Support Vector Machine Analysis

Purpose

The primary angle-closure glaucoma (PACG) is an irreversible blinding eye disease in the world. Previous neuroimaging studies demonstrated that PACG patients were associated with cerebral changes. However, the effect of optic atrophy on local and remote brain functional connectivity in PACG patients remains unknown.

Materials and Methods

In total, 23 patients with PACG and 23 well-matched Health Controls (HCs) were enrolled in our study and underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. The regional homogeneity (ReHo) method and functional connectivity (FC) method were used to evaluate the local and remote brain functional connectivity. Moreover, support vector machine (SVM) method was applied to constructing PACG classification model.

Results

Compared with the HC, PACG patients showed increased ReHo values in right cerebellum (CER)_8, left CER_4-5, and right CER_8. In contrast, PACG patients showed decreased ReHo values in the bilateral lingual gyrus (LING)/calcarine (CAL)/superior occipital gyrus (SOG) and right postcentral gyrus (PostCG). The ReHo value exhibited an accuracy of 91.30% and area under curve (AUC) of 0.95 for distinguishing the PACG patients from HC.

Conclusion

Our study demonstrated that the PACG patients showed abnormal ReHo value in the cerebellum, visual cortex, and supplementary motor area, which might be reflect the neurological mechanisms underlying vision loss and eye pain in PACG patients. Moreover, the ReHo values can be used as a useful biomarker for distinguishing the PACG patients from HCs.

Evaluation of away-from-home excursion patterns after falling among individuals with glaucoma: a longitudinal study

Background

Unintentional falls among older adults are associated with an ensuing decline in physical activity. Our objective is to evaluate the associations between fall status and changes in excursions after a fall.

Methods

Prospective cohort study of older adults with glaucoma or suspected glaucoma who reported falls for 1 year and wore a GPS device for 1-week at the baseline and 1 year later. GPS data were quantified into average: daily excursions, daily time away from home, and time per excursion. Fall status was categorized as fallers, injurious fallers, recurrent fallers, and recurrent injurious fallers. Multivariable negative binomial regression and generalized estimating equations models were employed to evaluate relationship between excursion parameters and fall status.

Results

A total of 192 eligible participants were included in the analyses. Approximately half were males (50.5%) with a mean age of 70.1 years and one-fourth were Black (28.1%). There were no significant associations between fall status and end-of-study excursion parameters (p > 0.06 for all), and visual field damage did not modify these relationships (p > 0.07 for all). For instance, patients with multiple falls during a one-year study period did not demonstrate more daily excursions (incident rate ratio [IRR] = 1.16, 95% confidence interval [CI] = 0.85 to 1.57), longer time per excursion (IRR = 0.79, 95% CI =0.59 to 1.06), or more average daily time away (IRR = 1.05, 95% CI = 0.84 to 1.30) conducted at the end-of-the study. Excursion parameters at the final assessment were not significantly different from those at baseline (p > 0.09 for all) and the changes did not vary by fall status (p > 0.23 for all).

Conclusions

Older adults with glaucoma did not modify their travel away from home after experiencing a fall. Additional research is necessary to understand how often maintenance of travel outside the home after a fall reflects proper compensation for greater fall risk or continued activity despite the risk of falling.

Visual Impairment and Objectively Measured Physical Activity in Middle-Aged and Older Adults

BACKGROUND

Vision loss is associated with increased risk of falls and restricted physical activity, yet the relationship between multiple vision measures and objectively measured physical activity, especially activity patterns, in mid-to-late life is not well understood.

METHOD

This study included 603 participants aged 50 years and older (mean age = 73.5) in the Baltimore Longitudinal Study of Aging who had the following assessments: presenting and best-corrected visual acuity, contrast sensitivity, visual fields, stereo acuity, and free-living physical activity using a wrist-worn ActiGraph accelerometer for 7 days. Linear regression models were used to examine the association between vision measures and daily activity counts, active minutes, and activity fragmentation (defined as an active-to-sedentary transition probability), adjusting for potential confounders. Mixed-effects models estimated differences in activity by time of day comparing those with and without each visual impairment.

RESULTS

In the fully adjusted model, worse presenting visual acuity, contrast sensitivity, and visual fields were associated with fewer activity counts, less active time, and more fragmented activity patterns (p < .05 for all). Participants with presenting or best-corrected visual acuity impairment had 19.2 and 29.3 fewer active minutes (p = .05 and p = .03, respectively) per day. Visual field impairment was associated with 268 636 fewer activity counts (p = .02), 46.2 fewer active minutes (p = .02) per day, and 3% greater activity fragmentation (p = .009). Differences in activity levels tended to be greatest from 6 am to 6 pm (p < .05).

CONCLUSIONS

Older adults with visual impairment have restricted and more fragmented patterns of daily activity. Longitudinal studies to quantify the long-term impacts of visual impairments on activity decline are warranted.

Sensory integration abilities for balance in glaucoma, a preliminary study

The goal of this study was to quantify the association between sensory integration abilities relevant for standing balance and disease stage in glaucoma. The disease stage was assessed using both functional (visual field deficit) and structural (retinal nerve fiber layer thickness) deficits in the better and worse eye. Balance was assessed using an adapted version of the well-established Sensory Organization Test (SOT). Eleven subjects diagnosed with mild to moderate glaucoma stood for 3 min in 6 sensory challenging postural conditions. Balance was assessed using sway magnitude and sway speed computed based on center-of-pressure data. Mixed linear regression analyses were used to investigate the associations between glaucoma severity and balance measures. Findings revealed that the visual field deficit severity in the better eye was associated with increased standing sway speed. This finding was confirmed in eyes open and closed conditions. Balance was not affected by the extent of the visual field deficit in the worse eye. Similarly, structural damage in either eye was not associated with the balance measures. In summary, this study found that postural control performance was associated with visual field deficit severity. The fact that this was found during eyes closed as well suggests that reduced postural control in glaucoma is not entirely attributed to impaired peripheral visual inputs. A larger study is needed to further investigate potential interactions between visual changes and central processing changes contributing to reduced balance function and increased incidence of falls in adults with glaucoma.

Gait characteristics during crossing over obstacle in patients with glaucoma using insole foot pressure

BACKGROUND

Glaucoma, is the most common cause of irreversible visual deficits, presents as an injury to the optic nerve and it is mainly associated with elevated intraocular pressure. The main symptom of glaucoma is a reduction of the visual field, which is usually a source of complaint at the advanced stage of disease. Because of visual deficit, gait dysfunctions, including low gait speed and increased bumping into objects, postural sway, and falling are occurred. Many studies have used stopwatch or motion-sensing devices to report on gait function following glaucoma. However, there are few reports on gait dysfunction assessed by examining foot pressure. This study investigated gait ability following glaucoma according to different gait conditions by assessing foot pressure.

METHODS

Thirty older adults (15 in the sex- and age-matched normal group and 15 in the glaucoma group) were recruited for this study. All participants were walked under 2 different gait conditions in an F-scan system and the subject' assessments were randomly assigned to rule out the order effect. Conditions included: gait over an obstacle in a straight 6 m path, gait in a straight path without an obstacle in the 6 m path. Gait variables included cadence, gait cycle, stance time, center of force (COF) deviation, and COF excursion. About 10 minutes were taken for gait evaluation.

RESULTS

When walking without an obstacle on a 6 m path, there were significant differences between the 2 groups in gait speed, cadence, gait cycle, and stance time (P < .05). There were significant differences when walking with an obstacle on a 6 m path (P < .05). Two-way analysis of variance showed significant effects associated with "glaucoma" not gait condition on all outcomes except for COF deviation and excursion. Also, there was no the interaction effect between "glaucoma" and "gait condition."

CONCLUSION

We demonstrated that glaucoma patients selected the gait strategy such as lower gait function in both gait conditions particularly, slower gait speed and cadence and longer gait cycle and stance time, as determined by examining foot pressure. We believe that our results could help to improve the quality of life of patients with glaucoma.

Do visual fields need to be considered in classification criteria within visually impaired shooting?

Classification within the sport of vision impairment (VI) shooting is based upon the athlete's visual function. This study aimed to determine whether more than one class of competition is needed within VI shooting on the basis of visual field loss. Qualification scores of 23 elite athletes were obtained at World Championship events in prone and standing shooting disciplines. Visual field data were obtained from classification data and from assessment at events. A standardized scoring protocol determined whether athletes had function (≥10 dB) or no function (<10 dB) at locations between 0-60 degrees eccentricity along 10 meridia. Visual field function was not associated with shooting performance in prone or standing disciplines (p > 0.05). Having measurable visual field function beyond 30 degrees made no difference to athletes' ability to shoot competitively in prone (p = 0.65) or standing disciplines (p = 0.47), although a potential impact on qualification was observed in the standing discipline. There was no evidence that loss of visual field function at any specific location adversely affected ability to shoot competitively. There is currently no evidence to consider visual fields in classification within prone or standing VI shooting, although further research is needed as the sport grows.

Topical Review: Assessment of Binocular Sensory Processes in Low Vision

SIGNIFICANCE

This article summarizes the evidence for a higher prevalence of binocular vision dysfunctions in individuals with vision impairment. Assessment for and identification of binocular vision dysfunctions can detect individuals experiencing difficulties in activities including reading, object placement tasks, and mobility.Comprehensive vision assessment in low vision populations is necessary to identify the extent of remaining vision and to enable directed rehabilitation efforts. In patients with vision impairment, little attention is typically paid to assessments of binocular vision, including ocular vergence, stereopsis, and binocular summation characteristics. In addition, binocular measurements of threshold automated visual fields are not routinely performed in clinical practice, leading to an incomplete understanding of individuals' binocular visual field and may affect rehabilitation outcomes.First, this review summarizes the prevalence of dysfunctions in ocular vergence, stereopsis, and binocular summation characteristics across a variety of ocular pathologies causing vision impairment. Second, this review examines the links between clinical measurements of binocular visual functions and outcome measures including quality of life and performance in functional tasks. There is an increased prevalence of dysfunctions in ocular alignment, stereopsis, and binocular summation across low vision cohorts compared with those with normal vision. The identification of binocular vision dysfunctions during routine low vision assessments is especially important in patients experiencing difficulties in activities of daily living, including but not limited to reading, object placement tasks, and mobility. However, further research is required to determine whether addressing the identified deficits in binocular vision in low vision rehabilitative efforts directly impacts patient outcomes.

Full-field electroretinography in age-related macular degeneration: an overall retinal response

PURPOSE

Age-related macular degeneration (AMD) is generally considered a disease of the macula. However, recent studies show peripheral retinal lesions are prevalent in patients with AMD, indicative of a disease process that is more widespread. Full-field electroretinography (ffERG) measures an electrical response, not only from the macula, but from the entire retina. We wanted to study the ffERG response in eyes with AMD.

METHODS

We performed full-field electroretinography (RETI-port/scan 21, Roland, Berlin) in 13 patients with early AMD, 25 patients with late AMD and 24 individuals without vitreoretinal disease as a control group. Dawson-Trick-Litzkow fibre electrodes were used. Statistical analysis was performed and a p-value <0.05 was considered significant.

RESULTS

After adjusting for multiple comparisons, both the light-adapted 3.0 a-wave implicit time (p < 0.001) and 30-Hertz flicker peak time (p = 0.012) showed significant difference between patients with late AMD and individuals without vitreoretinal disease. There was a significant difference in the light-adapted 3.0 a-wave implicit time (p = 0.011) between patients with early AMD and the control group, but the difference in 30 Hz flicker peak time was not significant (p = 0.256).

CONCLUSION

The difference in cone function measured by light-adapted 3.0 a-wave implicit time and 30-Hertz flicker peak time in early and late AMD when compared to healthy controls suggests a more diminished overall response when AMD has reached later stages.

Gait in Elderly Glaucoma: Impact of Lighting Conditions, Changes in Lighting, and Fear of Falling

Purpose

The purpose of this study was to characterize the impact of lighting changes on gait in elderly patients with glaucoma and evaluate whether associations are mediated by fear of falling (FOF).

Methods

Gait initiation and parameters measured with the GAITRite Electronic Walkway were captured in normal indoor light, then in dim light, and again in normal light (normal post dim [NPD]). Participants’ right and left eye visual fields (VFs) were merged into integrated VF (IVF) sensitivities. FOF was evaluated using a Rasch-analyzed questionnaire. Multivariable regression models evaluated whether IVF sensitivity was associated with lighting-dependent gait changes and if this relationship was mediated by FOF.

Results

In 213 participants (mean age = 71.4 years), gait initiation in dim light took longer with more VF damage (P = 0.02). Greater VF damage was associated with slower gait in dim (P < 0.001) and NPD (P = 0.003) lighting, as well as shorter strides (P = 0.02), broader stance (P = 0.003), and more variable stride velocity and length in all lighting (all P < 0.03). When moving from normal to dim lighting, those with more VF damage slowed gait and cadence, shortened stride length, and lengthened double support time (all P < 0.001). Velocity, cadence, and double support time did not return to baseline in NPD lighting (all P < 0.05). Fear of falling did not appear to mediate the relationship between IVF sensitivity and lighting-dependent gait changes.

Conclusions

Patients with more VF damage demonstrate gait degradation in extreme or changing lighting, which is not mediated by FOF.

Translational Relevance

Quantitative spatiotemporal gait evaluation reveals lighting-associated impairment, supporting patient-reported difficulty with nonideal lighting and equipping providers to advise patients about limitations.

Full-field Electroretinography in Age-related Macular Degeneration: can retinal electrophysiology predict the subjective visual outcome of cataract surgery?

PURPOSE

Predicting the visual gain from cataract surgery when the main cause of vision loss is age-related macular degeneration may be difficult and warrants the need for an objective predictor of subjective outcome. Full-field electroretinography is an objective measure of overall retinal function. We therefore wanted to study if full-field electroretinography can predict subjective visual outcome using visual function questionnaire.

METHODS

Thirty-one patients with age-related macular degeneration operated for bilateral cataract underwent full-field electroretinography preoperatively. Full-field electroretinography was performed according to International Society for the Clinical Electrophysiology of Vision standards using a Ganzfeld bowl (RETI-port/scan 21, Roland, Berlin) and Dawson-Trick-Litzkow fibre electrodes. Vision-related quality of life was measured using the National Eye Institute Visual Function Questionnaire-39 before first-eye surgery and 4.12 ± 2.11 months after second-eye surgery.

RESULTS

Mean change in composite visual function questionnaire score after cataract surgery was 9.2 ± 11.9. The patients were divided into three groups: visual function questionnaire composite score increase >10 (n = 17); no change (n = 8); and decrease (n = 6). In the dark-adapted full-field electroretinography responses, we found a significant difference between the three groups in the 0.01 b-wave amplitude (p = 0.05), the 10.0 b-wave amplitude (p = 0.04) and a near-significant difference in 3.0 a-wave amplitude (p = 0.09). Other dark-adapted responses (the 3.0 b-wave and 10.0 a-wave) did not show any significant differences between the three groups, and neither did the light-adapted responses.

CONCLUSION

Patients with low dark-adapted responses on full-field electroretinography preoperatively experience a decrease in subjective vision-related quality of life, suggesting that maintained rod function before cataract surgery may be important.

Prevalence and Consequences of Perceived Vision Difficulty in Aging Adults with HIV Infection

PURPOSE

Despite well-known ocular complications of HIV-related immune suppression, few studies have examined the prevalence and consequences of visual impairment among aging long-term survivors of HIV.

DESIGN

Retrospective cohort study.

METHODS

Aging HIV-infected (HIV+) men who have sex with men (MSM) and HIV-uninfected (HIV-) MSM controls reported their difficulty performing 6 vision-dependent tasks (difficulty defined as: no, a little, moderate, and extreme difficulty). Relationships were examined using logistic regression, regressing each outcome separately on categorical visual function responses, with missing data multiply imputed.

RESULTS

There were 634 age-matched pairs for a total sample of 1,268 MSM of 1,700 MSM with available data. The median age was 60 years old (interquartile range [IQR], 54, 66), and 23% were African American. Among HIV+ men, 95% were virally suppressed (viral load <400 copies/mL). HIV+ men were more likely to report moderate or extreme difficulty performing at least 1 task (21% for HIV+ compared to 13% for HIV-; P < .01). Participants reporting extreme vision-related difficulty performing at least 1 task had 11.2 times the odds of frailty (95% confidence interval [CI], 5.2-23.9), 2.6 times the odds of a slow gait speed (95% CI, 1.4-4.8), and 3.2 times the odds of impaired instrumental activities of daily living (95% CI: 1.6-6.3) compared to those reporting no vision-related difficulty on any task.

CONCLUSIONS

Perceived vision difficulty was more common among older HIV+ MSM than age-matched HIV- MSM controls and was associated with higher risk of depression and physical function loss among MSM.

Gait and Balance as Predictors and/or Mediators of Falls in Glaucoma

Purpose

To investigate the association between balance and gait measures with fall rates in glaucoma patients.

Methods

Balance and gait were measured for 239 participants with glaucoma or suspected glaucoma. Daily falls were evaluated over 24 months. Annual accelerometer trials captured average daily steps. Multivariable negative binomial models evaluated balance and gait associations with average daily steps and rates of falls per time or step, as well as whether balance and gait parameters mediated the association between integrated visual field (IVF) sensitivity and falls.

Results

Average age was 70.5 years (SD = 7.6), and 22% of the participants had moderate to severe visual field damage. Over the first 12 months of the follow-up, the cumulative probability of falling one or more times was 44.8%, and the cumulative probability of falling two or more times was 17.7%. Gait deficits were associated with fewer daily steps (P < 0.03), but no balance parameters were (P > 0.19). Worse balance was associated with a higher rate of falls per year and step (P < 0.03). No gait measures were associated with the rate of falls per year (P > 0.17). More time in double support and greater swing time variability were associated with higher falls per step, and higher velocity and faster cadence were associated with fewer falls per step (P < 0.05 for all). Neither gait nor balance measures mediated the relationship between visual field damage and fall rates. IVF remained an independent predictor of falls per step (rate ratio = 1.36 to 1.48; P < 0.001 to P < 0.005) in multivariable models including individual balance/gait parameters.

Conclusions

Although balance and gait measures are associated with fall rates, they do not explain why persons with greater visual field damage fall more frequently, suggesting the importance of other potential factors such as hazard perception.

Individual and combined effects of a cognitive task, light finger touch, and vision on standing balance in older adults with mild cognitive impairment

BACKGROUND

Postural instability and balance dysfunction have been identified in older adults with mild cognitive impairment (MCI). Performing a secondary task while standing can additionally jeopardize their balance.

AIMS

The purpose of the exploratory study was to investigate the individual and combined effects of a cognitive task, light finger touch and vision on postural sway in older adults with MCI as compared to healthy older adults.

METHODS

Five individuals with MCI and ten age-matched control subjects stood on the force platform with and without the performance of a cognitive task (counting backward from a randomly chosen three-digit number), with and without light finger touch contact applied to an external stable structure, and with eyes open or closed. The center of pressure (COP) excursion, range, velocity in antero-posterior and medial-lateral directions and sway area were calculated.

RESULTS

Participants demonstrated significantly larger postural sway when vision was not available (p < 0.05), smaller postural sway when using a finger touch contact (p < 0.05) and increased postural sway during the performance of the cognitive task (p < 0.05). When finger touch and a cognitive task were performed simultaneously, body sway decreased as compared to just standing in healthy older adults but not in individuals with MCI (p < 0.05).

CONCLUSIONS

The results help to better understand the individual and combined effects of vision, light touch and a cognitive task in postural control of individuals with MCI. The study outcome also provides a basis for future studies of balance control in patients with cognitive impairments.

Evaluation of Fear of Falling in Patients with Primary Open-Angle Glaucoma and the Importance of Inferior Visual Field Damage

Purpose

To evaluate fear of falling using the Fall Efficacy Scale-International (FES-I) in glaucoma patients and investigate its association with glaucomatous visual field loss.

Methods

This study included 273 patients (160 men and 113 women, average age 64.2 years) with primary open-angle glaucoma. Participants were requested to answer the FES-I questionnaire, translated into Japanese, in a face-to-face interview. The relationship between total FES-I score and the following variables was analyzed using multivariable linear regression: age, sex, better and worse best corrected visual acuity, total deviation (TD) in four visual field areas, body mass index (BMI), minutes walked per day, history of diabetes mellitus, history of systemic hypertension, number of previous falls.

Results

Univariate analysis suggested that total FES-I score increased with age and in woman, whereas other variables were not significantly associated with total FES-I score. However, age (coefficient, 0.23; standard error [SE], 0.04; P < 0.001), sex (coefficient, 1.79 for women; SE, 0.84; P = 0.034), mean TD in the inferior central area (coefficient, 0.92; SE, 0.22; P <0.001), and mean TD in the inferior peripheral area (coefficient, –0.86; SE, 0.21; P < 0.001) were included in the optimal model for total FES-I score.

Conclusions

Inferior peripheral visual field damage and preserved inferior central visual field sensitivity were associated with increased fear of falling assessed with FES-I in glaucoma.

Eye Movements of Drivers with Glaucoma on a Visual Recognition Slide Test

SIGNIFICANCE

Glaucoma has been shown to impair hazard detection ability and increase crash risk compared to controls. Differences in visual search behavior of the driving scene may explain these differences; however, there has been limited investigation of this issue with inconsistent findings.

PURPOSE

Through eye movement tracking of older drivers with glaucoma, we explored their visual search behavior in comparison with controls while performing the DriveSafe, a slide recognition test purported to predict fitness to drive.

METHODS

Thirty-one drivers with glaucoma (mean age, 71.7 ± 6.3 years; average better-eye mean defect,-3 dB; average worse-eye mean defect,-12 dB) and 25 age-matched controls underwent measurements of their visual acuity, contrast sensitivity, visual fields, and useful field of view (visual processing speeds). Participants' eye movements were recorded while they completed the DriveSafe test, which consists of brief presentations of static, real-world driving scenes containing various road users (pedestrians, bicycles, vehicles). Participants reported the types, positions, and direction of travel of road users in each image; the score was the total number of correctly reported items (maximum, 128).

RESULTS

Drivers with glaucoma had significantly worse DriveSafe scores (P = .03), fixated on road users for shorter durations (P < .001), and exhibited smaller saccades (P = .02) compared with controls. For all participants, longer fixation times on road users (P < .001) was the eye movement measure most strongly associated with better DriveSafe scores; this relationship was not significantly different between groups. Useful field-of-view divided attention was the strongest visual predictor of DriveSafe scores.

CONCLUSIONS

Eye movement changes in the glaucoma group may reflect increased difficulty in identifying relevant objects in the visual scene, which may be related to their lower DriveSafe scores. Given the DriveSafe's potential utility in assessing drivers with visual impairment before on-road testing, further investigations on how DriveSafe performance and eye movement patterns compare to those during on-road driving are warranted.

Advanced glaucoma at diagnosis: current perspectives

Presentation with advanced glaucoma is a significant risk factor for lifetime blindness. The asymptomatic nature of glaucoma, particularly in early disease, means that substantial vision loss in one eye does not always translate into a perceptible loss of visual function. This, along with the lack of an effective screening strategy, contributes to late presentation. Those most at risk of presenting with advanced glaucoma have asymptomatic high intraocular pressure (IOP), no family history of glaucoma, are socially disadvantaged, and do not attend sight testing. Patients with glaucoma may have impaired functionality for daily activities, such as reading, walking and driving. Quality of life measures have shown this to be significantly worse in patients with more severe visual field loss, particularly if bilateral. In addition, quality of life decreases faster with further bilateral visual field loss when advanced visual field damage is present. Management of these patients requires disproportionally more resources than those with earlier disease. Both medical and surgical options are used as the initial approach to treat patients presenting with advanced glaucoma. The most recently published National Institute for Health and Care Excellence (NICE) guidelines suggest that patients presenting with advanced disease should be offered trabeculectomy as a primary intervention. However, more evidence is required to determine the best initial management. The Treatment of Advanced Glaucoma Study (TAGS) is being conducted, comparing primary medical management with primary mitomycin C-augmented trabeculectomy for people presenting with advanced open-angle glaucoma. The results of TAGS will provide robust evidence for the most appropriate initial intervention.

Changes in physical activity predict changes in a comprehensive model of balance in older community-dwelling adults. A longitudinal analysis of the TILDA study

Objective:

Falls due to poor balance can cause injury, disability, and death in older adults. The relationship between free-living physical activity (PA) and balance over time is poorly understood. The aim of this study is to explore the association between PA and balance in older adults over time

Methods:

Using two waves of data from the TILDA study (n=8,504 participants) a structural equation model was used to identify a composite measure of balance that incorporated measures of Timed Up and Go; handgrip strength; Mini Mental State Exam; vision; hearing; and steadiness. The patterns of change in PA and balance were then compared over time (controlling for covariates)

Results:

The results showed that one extra metabolic equivalent of task (MET) minute of PA improves balance by 4% over one week (Est=-0.10, SE=0.12), and by 5% cumulatively over two years (Est=-0.13, SE=0.02). Medication, alcohol consumption, sex, age, fear of falling, education, pain, and problems performing activities of daily living (ADL) were risk factors for balance

Conclusion:

This study provides a novel and robust model that should guide comprehensive balance assessment. PA promotion should engage older adults in more free-living PA that may be more relevant to them.

Measuring Disability in Glaucoma

BACKGROUND

Glaucomatous visual field loss can have far-reaching and debilitating consequences on an individual, affecting one's ability to perform many important tasks. Although assessment of glaucoma-related disability constitutes an important part of clinical care, there remains a lack of organized, detailed information on the most suitable methods to capture disability in glaucoma.

PURPOSE

This review details the available methods to measure glaucoma-related disability and highlights important findings from studies utilizing these various methods.

METHODS

The literature was reviewed to identify papers evaluating disability in glaucoma and findings were summarized by research methodology used and area of impairment.

RESULTS

Identified methods for capturing glaucoma-related disability included qualitative descriptions, glaucoma-specific quality of life questionnaires, vision-specific questionnaires, general health questionnaires, functional domain-specific questionnaires, evaluation of task performance, event assessment (ie, falls and motor vehicle accidents), and real-world behavior (ie, daily physical activity). Findings using these methods show a strong relationship between glaucoma and/or glaucoma severity and difficulties with reading, driving, mobility, and other tasks such as prehension and facial recognition. In addition, glaucoma has financial and psychological implications on the patient, and can affect caregivers in some cases as well.

CONCLUSIONS

A wide variety of research tools have been used to characterize the disability resulting from glaucoma. Together, these tools show that glaucoma affects many abilities which are important for independent living. Strengths and limitations of the various research techniques are discussed so that future studies may use the method(s) most suitable for answering the research question posed.

Widespread brain reorganization perturbs visuomotor coordination in early glaucoma

Glaucoma is the world's leading cause of irreversible blindness, and falls are a major public health concern in glaucoma patients. Although recent evidence suggests the involvements of the brain toward advanced glaucoma stages, the early brain changes and their clinical and behavioral consequences remain poorly described. This study aims to determine how glaucoma may impair the brain structurally and functionally within and beyond the visual pathway in the early stages, and whether these changes can explain visuomotor impairments in glaucoma. Using multi-parametric magnetic resonance imaging, glaucoma patients presented compromised white matter integrity along the central visual pathway and around the supramarginal gyrus, as well as reduced functional connectivity between the supramarginal gyrus and the visual occipital and superior sensorimotor areas when compared to healthy controls. Furthermore, decreased functional connectivity between the supramarginal gyrus and the visual brain network may negatively impact postural control measured with dynamic posturography in glaucoma patients. Taken together, this study demonstrates that widespread structural and functional brain reorganization is taking place in areas associated with visuomotor coordination in early glaucoma. These results implicate an important central mechanism by which glaucoma patients may be susceptible to visual impairments and increased risk of falls.

Peripheral Retinal Lesions in Eyes with Age-Related Macular Degeneration Using Ultra-Widefield Imaging: A Systematic Review with Meta-analyses

TOPIC

Age-related macular degeneration (AMD) is highly prevalent among the elderly. We systematically reviewed the literature to provide an overview of ultra-widefield imaging (UWFI) of peripheral retinal lesions in AMD.

CLINICAL RELEVANCE

Information regarding retinal characteristics and prevalence of AMD is based mainly on studies using color photography of the central retina, where early and potentially severe manifestations of the disease are found. However, this approach has the effect of neglecting the periphery. Studies using UWFI provide new evidence to show that clinical features associated with AMD are not exclusive to the area of the macula.

METHODS

Eligible studies had to detect lesions of the peripheral retina (based on the original definition of a standard macular grid, with the addition of 2 zones classed as peripheral) using UWFI in eyes with AMD. Ultra-widefield imaging included pseudocolor photography, fundus autofluorescence, fluorescein angiography, and indocyanine green angiography. Eligibility was restricted to human participants and studies written in English. We searched the bibliographic databases PubMed, the Cochrane Library, EMBASE, and the Web of Science on March 27, 2018. We calculated the prevalence of peripheral findings in eyes with AMD and performed similar meta-analyses on the healthy control group. A random-effects model was used because of possible study heterogeneity.

RESULTS

Twelve studies were eligible for the review, which included 3261 or more eyes. Studies were clinic based, apart from 1 study that was a random population sample of individuals 62 years of age or older. Studies were cross-sectional in nature, apart from 1 case-control study. The peripheral lesions most commonly observed were drusen, atrophy, and changes to the retinal pigment epithelium. In eyes with AMD, peripheral lesions were found in 82.7% of eyes (confidence interval, 78.4%-86.7%) compared with 33.3% of healthy eyes (confidence interval, 28.3%-38.5%).

CONCLUSIONS

Peripheral changes were found to be highly prevalent in eyes with AMD, supporting the claim that the disease is panretinal and not macula only. The clinical significance of peripheral lesions in AMD remains incompletely understood, and therefore, further UWFI studies are recommended.

Community-dwelling adults with a history of falling report lower perceived postural stability during a foam eyes closed test than non-fallers

Perceived postural stability has been reported to decrease as sway area increases on firm surfaces. However, changes in perceived stability under increasingly challenging conditions (e.g., removal of sensory inputs) and the relationship with sway area are not well characterized. Moreover, whether perceived stability varies as a function of age or history of falls is unknown. Here we investigate how perceived postural stability is related to sway area and whether this relationship varies as a function of age and fall history while vision and proprioceptive information are manipulated. Sway area was measured in 427 participants from the Baltimore Longitudinal Study of Aging while standing with eyes open and eyes closed on the floor and a foam cushion. Participants rated their stability [0 (completely unstable) to 10 (completely stable)] after each condition, and reported whether they had fallen in the past year. Perceived stability was negatively associated with sway area (cm²) such that individuals who swayed more felt less stable across all conditions (β = - 0.53, p < 0.001). Perceived stability decreased with increasing age (β = - 0.019, p < 0.001), independent of sway area. Fallers had a greater decline in perceived stability across conditions (F = 2.76, p = 0.042) compared to non-fallers, independent of sway area. Perceived postural stability declined as sway area increased during a multisensory balance test. A history of falling negatively impacts perceived postural stability when vision and proprioception are simultaneously challenged. Perceived postural stability may provide additional information useful for identifying individuals at risk of falls.

PrevenTing Falls in a high-risk, vision-impaired population through specialist ORientation and Mobility services: protocol for the PlaTFORM randomised trial

BACKGROUND

Older people with vision impairment have significant ongoing morbidity, including risk of falls, but are neglected in fall prevention programmes. PlaTFORM is a pragmatic evaluation of the Lifestyle-integrated Functional Exercise fall prevention programme for older people with vision impairment or blindness (v-LiFE). Implementation and scalability issues will also be investigated.

METHODS

PlaTFORM is a single-blinded, randomised trial designed to evaluate the v-LiFE programme compared with usual care. Primary outcomes are fall rate over 12 months, measured using prospective monthly fall calendars, and function and participation assessed by the Late-Life Function and Disability Instrument (Late-Life FDI) Function component. The secondary outcome is rate of falls requiring medical care. Activity-normalised fall rate will be estimated using accelerometer-measured physical activity data. EuroQol 5-dimension 5-level questionnaire will measure quality of life and impact of falls. Health record linkage will estimate resource use associated with falls. v-LiFE cost-effectiveness will be determined compared with usual care. 500 participants (250 per group) can provide 90% power to detect a significant between-group difference in fall rates; 588 will be recruited to allow for drop-out. Falls per person-year and Late-Life FDI will be compared between groups.

DISCUSSION

PlaTFORM will determine if falls can be prevented among older people with vision loss through a home-based exercise programme. v-LiFE embeds balance and strength training within everyday activities with the aim of preventing falls. The study will also determine whether the programme can be effectively delivered by personnel who provide Orientation and Mobility training for people with vision impairment.

TRIAL REGISTRATION NUMBER

ACTRN12616001186448p.

The clinical relevance of visualising the peripheral retina

Recent developments in imaging technologies now allow the documentation, qualitative and quantitative evaluation of peripheral retinal lesions. As wide field retinal imaging, capturing both the central and peripheral retina up to 200° eccentricity, is becoming readily available the question is: what is it that we gain by imaging the periphery? Based on accumulating evidence it is clear that findings in the periphery do not always associate to those observed in the posterior pole. However, the newly acquired information may provide useful clues to previously unrecognised disease features and may facilitate more accurate disease prognostication. In this review, we explore the anatomy and physiology of the peripheral retina, focusing on how it differs from the posterior pole, recount the history of peripheral retinal imaging, describe various peripheral retinal lesions and evaluate the overall relevance of peripheral retinal findings to different diseases.

Locations, Circumstances, and Outcomes of Falls in Patients With Glaucoma

PURPOSE

To characterize the locations, circumstances, and outcomes of falls in patients with varying degrees of glaucoma.

DESIGN

Prospective cohort study.

METHODS

Patients with suspected or diagnosed glaucoma completed monthly calendars reporting falls. After each fall, a 30-item questionnaire was administered to determine fall location, circumstances, and injury. Mean deviation on visual field (VF) testing was used to categorize glaucoma severity. Main outcome measures were fall locations, circumstances, and outcomes.

RESULTS

One-hundred forty-two patients experienced 330 falls. Falls were most likely to occur in/around the home (71%), and this likelihood did not vary significantly with severity of VF damage (P > .2). The most commonly cited fall circumstances were tripping (43.6%), slipping (31.3%), uneven flooring (23.5%), and poor vision (15.9%). The circumstances related to falls did not vary by severity of VF damage (P > .2), except for poor vision, which was more frequently cited in individuals with more advanced VF damage (P = .001). Forty-three percent of falls resulted in some injury; and the likelihood of injury did not vary by severity of VF loss (P = .60) or any other factor except floor type and number of comorbidities (P < .05 for all). Falls in persons with more severe glaucoma were more likely to result in a fracture (9.4%) or an emergency room visit (18.8%), though these associations did not persist in multivariable models (P > .5 for all).

CONCLUSIONS

Glaucoma patients fall mostly in/around the home and demonstrate similar fall circumstances across the spectrum of disease severity, suggesting that current fall prevention interventions, particularly those emphasizing home modification, may be an adequate starting point to prevent falls in this high-risk-group.

Low vision services: a practical guide for the clinician

Low vision has been defined by best-corrected visual acuity worse than 20/40 in the better eye, substantial visual field loss, or substantial loss of contrast sensitivity that cannot be corrected by refraction, medical treatment, or surgery. In the United States, low vision is most commonly caused by age-related macular degeneration, glaucoma, and diabetic retinopathy. Most patients with low vision are elderly, although patients of all ages – including pediatric patients – may be affected. Low vision may decrease a patient’s quality of life substantially, leading to emotional distress and possibly depression. Low vision specialists aim to maximize the remaining vision of a patient by providing optical aids, orientation and mobility training, psychosocial support, and other methods of rehabilitation. Innovations in technology and devices offer additional options in low vision rehabilitation. Clinicians should consider referral to low vision specialists when a patient has difficulty with reading, mobility, driving, recognizing faces, or suffers from emotional distress due to low vision. Early referral may lead to improved outcomes.

Ageing vision and falls: a review

Background

Falls are the leading cause of accidental injury and death among older adults. One of three adults over the age of 65 years falls annually. As the size of elderly population increases, falls become a major concern for public health and there is a pressing need to understand the causes of falls thoroughly.

Main body of the abstract

While it is well documented that visual functions such as visual acuity, contrast sensitivity, and stereo acuity are correlated with fall risks, little attention has been paid to the relationship between falls and the ability of the visual system to perceive motion in the environment. The omission of visual motion perception in the literature is a critical gap because it is an essential function in maintaining balance. In the present article, we first review existing studies regarding visual risk factors for falls and the effect of ageing vision on falls. We then present a group of phenomena such as vection and sensory reweighting that provide information on how visual motion signals are used to maintain balance.

Conclusion

We suggest that the current list of visual risk factors for falls should be elaborated by taking into account the relationship between visual motion perception and balance control.

Physical activity, visual impairment, and eye disease

Numerous studies have demonstrated physical activity is a strong factor in overall health and well-being, and a growing body of literature, reviewed herein, suggests that several eye conditions, including glaucoma, age-related macular degeneration, and diabetic retinopathy, are associated with lower activity levels. Likewise, physical activity levels are lower in persons with worse vision. Research in this area has utilized both self-reported physical activity measures as well as objective measures of activity (i.e., accelerometers), each of which have their own strengths and limitations. Putative mechanisms explaining the association of various eye conditions with physical activity are discussed. It is possible that activity restriction occurs as a downstream consequence of eye disease/visual impairment, that activity restriction causes eye disease/visual impairment, or that causality is bidirectional; evidence supporting each of these theories is put forth. An improved understanding of the relationship between physical activity and eye disease will highlight potential secondary health risks resulting from eye disease, and can help determine whether activity might serve as a readily available preventative measure to prevent specific eye conditions.

Gait parameters, functional mobility and fall risk in individuals with early to moderate primary open angle glaucoma: a cross-sectional study

OBJECTIVE

This study investigated the influence of early to moderate primary open angle glaucoma on gait, functional mobility and fall risk.

METHODS

Thirty-three participants in the early and moderate stages of primary open angle glaucoma and 34 asymptomatic controls participated in the study. Spatiotemporal gait data were obtained with the GAITRite system and included: velocity, cadence, step length, base of support, swing, stance and double support times. Functional measures included the Timed Up and Go test, the Five-Repetition Sit-To-Stand test and the Dynamic Gait Index. Fall risk was measured using the Physiological Profile Assessment.

RESULTS

The variables contrast sensitivity, proprioception and the Timed Up and Go and Dynamic Gait Index tests were significantly different between groups. In addition, the glaucoma group presented significantly higher risk of falling compared to the control group. Individuals in the early and moderate stages of primary open glaucoma presented mobility and sensory deficits that increase the risk of falling.

CONCLUSIONS

The results of this study suggest that adding the Timed Up and Go and Dynamic Gait Index tests to routine physical therapy assessment of individuals with early glaucoma could be useful. Rehabilitation programs should focus on maintaining and/or improving mobility and balance, and prevention of falls in this population.

Age-Related Eye Disease and Participation in Cognitive Activities

Studies have found a benefit to living a cognitively active life in older age. Our goal was to quantify participation in cognitively stimulating activities in adults with and without age-related eye disease. We conducted a cross-sectional hospital-based study in Montreal, Canada of older adults (n = 303) having either age-related macular degeneration (AMD) (n = 96), glaucoma (n = 93), or normal vision (n = 114). To be eligible, the AMD group had to have bilateral late stage AMD with a better eye visual acuity of 20/30 or worse. The glaucoma group had to have a diagnosis of bilateral primary open-angle glaucoma with visual field mean deviation <  = −4 dB in their better eye. Further inclusion criteria included age ≥ 65 and a Mini-Mental State Exam Blind score ≥ 10. Cognitive activities were measured using the Victoria Longitudinal Study Activity Questionnaire. Linear regression was used. Patients with AMD (β = −4.2, 95% confidence interval (CI) −6.0, −2.4) and glaucoma (β = −1.8, 95% CI −3.3, −0.3) participated in fewer cognitive activities per month compared to those with normal vision after adjusting for age, sex, education, diabetes, number of comorbidities, cognition, and cataract. People with AMD and glaucoma participated in fewer cognitive activities, which could put them at risk for future cognitive impairment.

Loss of Peripheral Sensory Function Explains Much of the Increase in Postural Sway in Healthy Older Adults

Postural sway increases with age and peripheral sensory disease. Whether, peripheral sensory function is related to postural sway independent of age in healthy adults is unclear. Here, we investigated the relationship between tests of visual function (VISFIELD), vestibular function (CANAL or OTOLITH), proprioceptive function (PROP), and age, with center of mass sway area (COM) measured with eyes open then closed on firm and then a foam surface. A cross-sectional sample of 366 community dwelling healthy adults from the Baltimore Longitudinal Study of Aging was tested. Multiple linear regressions examined the association between COM and VISFIELD, PROP, CANAL, and OTOLITH separately and in multi-sensory models controlling for age and gender. PROP dominated sensory prediction of sway across most balance conditions (β's = 0.09–0.19, p's < 0.001), except on foam eyes closed where CANAL function loss was the only significant sensory predictor of sway (β = 2.12, p < 0.016). Age was not a consistent predictor of sway. This suggests loss of peripheral sensory function explains much of the age-associated increase in sway.

Gait Implications of Visual Field Damage from Glaucoma

PURPOSE

To evaluate fall-relevant gait features in older glaucoma patients.

METHODS

The GAITRite Electronic Walkway was used to define fall-related gait parameters in 239 patients with suspected or manifest glaucoma under normal usual-pace walking conditions and while carrying a cup or tray. Multiple linear regression models assessed the association between gait parameters and integrated visual field (IVF) sensitivity after controlling for age, race, sex, medications, and comorbid illness.

RESULTS

Under normal walking conditions, worse IVF sensitivity was associated with a wider base of support (β = 0.60 cm/5 dB IVF sensitivity decrement, 95% confidence interval [CI] = 0.12-1.09, P = 0.016). Worse IVF sensitivity was not associated with slower gait speed, shorter step or stride length, or greater left-right drift under normal walking conditions (P > 0.05 for all), but was during cup and/or tray carrying conditions (P < 0.05 for all). Worse IVF sensitivity was positively associated with greater stride-to-stride variability in step length, stride length, and stride velocity (P < 0.005 for all). Inferior and superior IVF sensitivity demonstrated associations with each of the above gait parameters as well, though these associations were consistently similar to, or weaker than, the associations noted for overall IVF sensitivity.

CONCLUSION

Glaucoma severity was associated with several gait parameters predictive of higher fall risk in prior studies, particularly measures of stride-to-stride variability. Gait may be useful in identifying glaucoma patients at higher risk of falls, and in designing and testing interventions to prevent falls in this high-risk group.

TRANSLATIONAL RELEVANCE

These findings could serve to inform the development of the interventions for falls prevention in glaucoma patients.

Falls prevention interventions for older adults with low vision: A scoping review: Étude de portée sur les interventions visant à prévenir les chutes chez les aînés ayant une basse vision

BACKGROUND

Older adults with low vision are especially vulnerable to falls. There are no comprehensive reviews of fall prevention interventions for older adults with vision loss who live in the community.

PURPOSE

The aim of this study was to review the evidence regarding community-based falls prevention interventions that appear inclusive of and/or accessible to individuals with low vision.

METHOD

A scoping review was completed using the framework developed by Arksey and O'Malley, and the charted data were analyzed using sums and percentages and qualitative content analysis.

FINDINGS

Seventeen publications were selected for this review. The analysis allowed for a thorough description of the types of falls prevention interventions (multiple components, home safety/modification, tai chi, the Alexander Technique, improvement of vision through vision assessment and referral, vision/agility training, and yoga), how each intervention addresses vision impairment, and the relation of results to falls risk.

IMPLICATIONS

Falls prevention research targeting individuals with visual impairment is limited, and the intervention approaches available may not be effective for older adults with permanent vision loss.

The Association of Glaucomatous Visual Field Loss and Balance

Purpose

To relate balance measures to visual field (VF) damage from glaucoma.

Methods

The OPAL kinematic system measured balance, as root mean square (RMS) sway, on 236 patients with suspect/diagnosed glaucoma. Balance was measured with feet shoulder width apart while standing on a firm/foam surface with eyes opened/closed (Instrumental Clinical Test of Sensory Integration and Balance [ICTSIB] conditions), and eyes open on a firm surface under feet together, semi-tandem, or tandem positions (standing balance conditions). Integrated VF (IVF) sensitivities were calculated by merging right and left eye 24-2 VF data.

Results

Mean age was 71 years (range, 57–93) and mean IVF sensitivity was 27.1 dB (normal = 31 dB). Lower IVF sensitivity was associated with greater RMS sway during eyes-open foam-surface testing (β = 0.23 z-score units/5 dB IVF sensitivity decrement, P = 0.001), but not during other ICTSIB conditions. Lower IVF sensitivity also was associated with greater RMS sway during feet together standing balance testing (0.10 z-score units/5 dB IVF sensitivity decrement, P = 0.049), but not during other standing balance conditions. Visual dependence of balance was lower in patients with worse IVF sensitivity (β = −21%/5 dB IVF sensitivity decrement, P < 0.001). Neither superior nor inferior IVF sensitivity consistently predicted balance measures better than measures of overall VF sensitivity.

Conclusions

Balance was worse in glaucoma patients with greater VF damage under foam surface testing (designed to inhibit proprioceptive contributions to balance) as well as feet-together firm-surface conditions when somatosensory inputs were available.

Translational Relevance

Good balance is essential to avoid unnecessary falls and patients with VF loss from glaucoma may be at higher risk of falls because of poor balance.

Functional visual fields: relationship of visual field areas to self-reported function

PURPOSE

The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss.

METHODS

Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory.

RESULTS

Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R² = 0.50; p < 0.0001), and for mobility (R² = 0.64; p < 0.0001). Central (0-30°) and peripheral (30-60°) visual field areas were similarly related to mobility function (R² = 0.61, p < 0.0001 and R² = 0.63, p < 0.0001 respectively), although the peripheral (30-60°) visual field was the best predictor of mobility self-reported function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R² = 0.56, p < 0.0001 and R² = 0.67, p < 0.0001 respectively). The inferior field was found to be the best predictor of mobility function in multiple regression analysis.

CONCLUSION

Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field.

Eye-Tracking as a Tool to Evaluate Functional Ability in Everyday Tasks in Glaucoma

To date, few studies have investigated the eye movement patterns of individuals with glaucoma while they undertake everyday tasks in real-world settings. While some of these studies have reported possible compensatory gaze patterns in those with glaucoma who demonstrated good task performance despite their visual field loss, little is known about the complex interaction between field loss and visual scanning strategies and the impact on task performance and, consequently, on quality of life. We review existing approaches that have quantified the effect of glaucomatous visual field defects on the ability to undertake everyday activities through the use of eye movement analysis. Furthermore, we discuss current developments in eye-tracking technology and the potential for combining eye-tracking with virtual reality and advanced analytical approaches. Recent technological developments suggest that systems based on eye-tracking have the potential to assist individuals with glaucomatous loss to maintain or even improve their performance on everyday tasks and hence enhance their long-term quality of life. We discuss novel approaches for studying the visual search behavior of individuals with glaucoma that have the potential to assist individuals with glaucoma, through the use of personalized programs that take into consideration the individual characteristics of their remaining visual field and visual search behavior.

Role of vision in sighted and blind soccer players in adapting to an unstable balance task

This study tested whether a compensatory hypothesis exists on postural control during standing unstable balance tasks comparing blind soccer players (n = 7) to sighted soccer players (n = 15) and sighted sedentary individuals (n = 6). All subjects performed a pre-test, a training of ten practice trials on a single day, and a post-test balance test. All tests were performed on an unstable surface placed on a force platform and under closed-eyes conditions, and a final test was performed with open eyes. Balance performance was assessed by resultant distance (RD) and the magnitude of mean velocity (MV) of the centre of pressure (CoP) displacement, and EMG signals from the gastrocnemius lateralis, tibialis anterior, rectus femoris, and peroneus longus were measured with surface electromyography. Principal component analysis (PCA) on EMG muscular activation was used to assess EMG pattern differences during the balance tasks. All groups improved their performance, obtaining low scores for the closed-eyes condition balance task after the training period in RD, VM, and aids received to keep balance in the novel task, and no differences were found between groups or in interaction effects. Sighted individuals and the control group showed significantly lower RD and VM scores under open-eyes conditions than blind participants. As regards neuromuscular behaviour, three principal patterns explained 84.15% of the variability in the measured data. The theoretical improvement of the other senses caused by visual deprivation does not allow blind individuals to obtain better balance than sighted individuals under closed-eyes conditions, thereby reinforcing the prominent role of vision in integrating and processing the other sensory inputs. In addition, blind individuals seem to increase their muscular co-activation as a safety strategy, but this behaviour is not different to that shown by sighted people under closed-eyes conditions.

Glaucoma and Driving: On-Road Driving Characteristics

Purpose

To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment.

Methods

Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire.

Results

Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability.

Conclusions

Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness.

History of falling and visual ability among independently living elderly in Sweden

Purpose

The aim of this study was to assess the performance-based visual ability among independently living elderly subjects and to investigate whether there was any association between visual ability and falls.

Subjects and methods

A total of 298 randomly selected subjects aged 70–85 years were invited for an examination including monocular and binocular visual acuity (VA), contrast sensitivity (CS), stereoscopic vision, and monocular visual fields (VFs), which were integrated to estimate the binocular VFs. Type of lenses used in their habitual correction was noted.

Results

Out of the 212 subjects who were examined, 38% reported at least one fall and 48% of these reported at least two falls during the last 2 years. Most subjects had normal results; 90% had normal binocular VA, 85% had normal binocular CS, and ~80% had positive stereopsis. Twenty-nine subjects had VF defects in the lower quadrants of the binocular VF, and 14 of these reported at least one fall. A significant association was seen between one fall or more and VA better eye, the odds ratio (OR) was 2.26, P=0.013, and between recurrent falls and lack of stereoscopic vision, the OR was 3.23, P=0.002; no other functional test showed any significant association with recurrent falls. The ORs were 1.58 for worse binocular VA, 0.60 for worse binocular CS, and 0.71 for non-normal stereoscopic vision for at least one fall, but wide confidence intervals made it difficult to draw firm conclusions about any association. Bifocal or progressive spectacles were worn by 71% with no significant difference between fallers and nonfallers (P=0.078).

Conclusion

Even though ~40% of the total sample had experienced one or more falls, the only visual function test significantly associated with falls were VA better eye, lack of stereoscopic vision, and recurrent falls. Our results suggest that there may be more powerful predictors of falling than decreased visual ability.

Reliability and Validity of the Visual, Musculoskeletal, and Balance Complaints Questionnaire

Purpose

To evaluate the reliability and validity of the 15-item Visual, Musculoskeletal, and Balance Complaints Questionnaire (VMB) for people with visual impairments, using confirmatory factor analysis (CFA) and with Rasch analysis for use as an outcome measure.

Methods

Two studies evaluated the VMB. In Study 1, VMB data were collected from 1249 out of 3063 individuals between 18 and 104 years old who were registered at a low vision center. CFA evaluated VMB factor structure and Rasch analysis evaluated VMB scale properties. In Study 2, a subsample of 52 individuals between 27 and 67 years old with visual impairments underwent further measurements. Visual clinical assessments, neck/scapular pain, and balance assessments were collected to evaluate the convergent validity of the VMB (i.e. the domain relationship with other, theoretically predicted measures).

Results

CFA supported the a priori three-factor structure of the VMB. The factor loadings of the items on their respective domains were all statistically significant. Rasch analysis indicated disordered categories and the original 10-point scale was subsequently replaced with a 5-point scale. Each VMB domain fitted the Rasch model, showing good metric properties, including unidimensionality (explained variances ≥66% and eigenvalues <1.9), person separation (1.86 to 2.29), reliability (0.87 to 0.94), item fit (infit MnSq’s >0.72 and outfit MnSq’s <1.47), targeting (0.30 to 0.50 logits), and insignificant differential item functioning (all DIFs but one <0.50 logits) from gender, age, and visual status. The three VMB domains correlated significantly with relevant visual, musculoskeletal, and balance assessments, demonstrating adequate convergent validity of the VMB.

Conclusions

The VMB is a simple, inexpensive, and quick yet reliable and valid way to screen and evaluate concurrent visual, musculoskeletal, and balance complaints, with contribution to epidemiological and intervention research and potential clinical implications for the field of health services and low vision rehabilitation.