Peripheral visual field loss and activities of daily living

Approach to Vision Loss

OBJECTIVE

Diagnosing and differentiating among the many possible localizations and causes of vision loss is an essential skill for neurologists. This article outlines the examination of the eye and visual pathways and the differential diagnosis of pathophysiologic processes that can affect visual function.

LATEST DEVELOPMENTS

The eyes, optic nerves, and intracranial pathways of vision account for more than one-third of the volume of the human brain, and patients with vision loss are commonly seen by both eye care specialists and neurologists. A basic examination of the eye and visual pathways allows the neurologist to localize the abnormality causing the vision impairment and generate a differential diagnosis of the potential pathophysiologic processes that can cause a vision problem at that particular location. Neurologists should be aware of the many ocular causes of vision loss and recognize when a visual problem is not the result of an optic neuropathy or brain parenchymal lesion. The standard bedside examination of the visual system can be augmented using specialized ancillary testing of visual pathway structure and function, which is most often the purview of eye care specialists, although portable instruments such as small visual field machines and nonmydriatic ocular fundus imaging can be easily used in hospitals and neurology clinics.

ESSENTIAL POINTS

The approach to vision loss should include a history and examination geared toward localization, followed by a differential diagnosis based on the likely location of the pathophysiologic process. Coordinated care between neurologists and eye care specialists is essential for patients with optic neuropathy or other lesions of the intracranial pathways.

Individualized functional magnetic resonance imaging neuromodulation enhances visuospatial perception: a proof-of-concept study

This proof-of-concept study uses individualized functional magnetic resonance imaging neuromodulation (iNM) to explore the mechanisms that enhance BOLD signals in visuospatial perception (VP) networks that are crucial for navigation. Healthy participants (n = 8) performed a VP up- and down-direction discrimination task at full and subthreshold coherence through peripheral vision, and superimposed direction through visual imagery (VI) at central space under iNM and control conditions. iNM targets individualized anatomical and functional middle- and medial-superior temporal (MST) networks that control VP. We found that iNM engaged selective exteroceptive and interoceptive attention (SEIA) and motor planning (MP) networks. Specifically, iNM increased overall: (i) area under the curve of the BOLD magnitude: 100% in VP (but decreased for weak coherences), 21-47% in VI, 26-59% in MP and 48-76% in SEIA through encoding; and (ii) classification performance for each direction, coherence and network through decoding, predicting stimuli from brain maps. Our findings, derived from encoding and decoding models, suggest that mechanisms induced by iNM are causally linked in enhancing visuospatial networks and demonstrate iNM as a feasibility treatment for low-vision patients with cortical blindness or visuospatial impairments that precede cognitive decline.This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'.

Joint daily functional trajectory and risk of new-onset Alzheimer's disease and related dementias in older adults with normal and abnormal weight

BACKGROUND

Associations between daily functional trajectories and new-onset all-cause dementia and Alzheimer's disease (AD) and the role of body weight are underexplored.

METHODS

Data were from the Health and Retirement Study (HRS) 1994-2020. Daily function was assessed using (instrumental) activities of daily living ([I]ADLs). All-cause dementia and AD were defined by self- or proxy-reported physician diagnoses. Body weight was assessed using body mass index (BMI) and categorized as normal (18.5 kg/m2 ≤ BMI < 30 kg/m2) and abnormal (BMI < 18.5 kg/m2 or ≥30 kg/m2). The group-based trajectory modeling and Cox proportional hazards regression were utilized.

RESULTS

Of 18,763 adults included, 1236 developed new-onset dementia during a 10-year follow-up. The associations of ADL and IADL limitations at baseline with all-cause dementia and AD were much more pronounced in those with abnormal weight (P for interaction < 0.005). Five joint trajectories of ADL and IADL limitations were identified: No (72.7 %), Recovery (4.0 %), Recent emerging (16.4 %), Early emerging (4.8 %), and Severe (2.1 %). Furthermore, the 'Severe' joint trajectory (vs. 'No') was associated with 3.57- and 3.59-times higher risks of new-onset all-cause dementia and AD in participants with abnormal weight (P for interaction = 0.002 and 0.005). Notably, the Recovery joint trajectory (vs. No) was not associated with increased risks of all-cause dementia or AD.

LIMITATIONS

Self-/proxy-reported all-cause dementia and AD may introduce misclassification bias. Lifestyle factors were not quantified. BMI at baseline, but not its trajectory, was utilized. Potential reverse causation deserved attention.

CONCLUSIONS

Body weight control can help reduce the risk of progression from functional limitations to all-cause dementia and AD.

Peripheral vision contributes to implicit attentional learning: Findings from the "mouse-eye" paradigm

The central visual field is essential for activities like reading and face recognition. However, the impact of peripheral vision loss on daily activities is profound. While the importance of central vision is well established, the contribution of peripheral vision to spatial attention is less clear. In this study, we introduced a "mouse-eye" method as an alternative to traditional gaze-contingent eye tracking. We found that even in tasks requiring central vision, peripheral vision contributes to implicit attentional learning. Participants searched for a T among Ls, with the T appearing more often in one visual quadrant. Earlier studies showed that participants' awareness of the T location probability was not essential for their ability to learn. When we limited the visible area around the mouse cursor, only participants aware of the target's location probability showed learning; those unaware did not. Adding placeholders in the periphery did not restore implicit attentional learning. A control experiment showed that when participants were allowed to see all items while searching and moving the mouse to reveal the target's color, both aware and unaware participants acquired location probability learning. Our results underscore the importance of peripheral vision in implicitly guided attention. Without peripheral vision, only explicit, but not implicit, attentional learning prevails.

Social determinants of health and health disparities in glaucoma: A review

Social determinants of health and barriers to care can significantly impact patients' access to glaucoma care and treatment, resulting in disparities within disease presentation, progression, management, and treatment outcomes. The widespread adoption of electronic health record systems has allowed researchers and clinicians to further explore these relationships, identifying factors such as race, ethnicity, and socioeconomic status to be risk factors for more severe disease and lower treatment adherence. These disparities highlight potential targets for interventions to combat these disparities and improve overall patient outcomes. This article provides a summary of the available data on health disparities within glaucoma disease presentation, progression, management, treatment, and outcomes and discusses interventions to improve care delivery and outcomes among patients with glaucoma.

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.