Measuring the foveal avascular zone in diabetes: A study using optical coherence tomography angiography

Aims/Introduction

Diabetes is a global issue that currently affects 425 million people worldwide. One observable microvascular complication of this condition is a change in the foveal avascular zone (FAZ). In this study, we used optical coherence tomography angiography to investigate the effect of diabetes on the FAZ.

Materials and Methods

A total of 11 participants with diabetes and 11 participants without diabetes took part in this study. Participants in both groups were matched for age (P = 0.217) and sex (P = 0.338), and had no history of ocular disease. Macular optical coherence tomography angiography (OCT‐A) scans of participants’ right and left eyes were taken. Glycosylated hemoglobin (HbA_1c) and blood glucose levels were also measured. The FAZ area was manually segmented at the levels of the superficial capillary plexus (FAZ_SCP) and deep capillary plexus (FAZ_DCP).

Results

There was a strong relationship between the FAZ area of participants’ right and left eyes (P ≤ 0.001) in both diabetes and non‐diabetes groups. In the diabetes group, the FAZ_SCP (P = 0.047) and FAZ_DCP (P = 0.011) areas was significantly larger than in the non‐diabetes group. Moreover, multiple linear regression analysis predicted a 0.07‐mm² increase in the FAZ_SCP and FAZ_DCP areas of individuals with diabetes for every 1% increase in their HbA_1c level.

Conclusions

Our findings show that there is enlargement of the FAZ in individuals with diabetes compared with individuals without diabetes. In the diabetes group, this enlargement appears to be correlated with HbA_1c level. OCT‐A imaging could, therefore, be a useful tool to monitor the FAZ and identify potential early microvasculopathy in diabetes.

Sub-clinical thickening of the fovea in diabetes and its relationship to glycaemic control: a study using swept-source optical coherence tomography

Background

Accumulation of multiple pockets of fluid at the fovea, as a complication of poor blood glucose control in diabetes, causes impairment of central vision. A new ability to demonstrate a pre-clinical phase of this maculopathy could be valuable, enabling diabetic individuals to be alerted to the need to improve their glycaemic control. This study aimed to use swept-source optical coherence tomography (SS-OCT) to measure foveal thickness and macular volume in diabetic individuals without cystoid macular oedema, and in non-diabetic individuals, and relate these measures to participants’ glycaemic control.

Methods

Centre point thickness (CPT) and total macular volume (TMV) were measured using SS-OCT (DRI OCT Triton™, Topcon, Tokyo, Japan). Participants’ glycosylated haemoglobin (HbA_1c) level was also assessed (A_1cNow®+ System, PTS Diagnostics, Indianapolis, IN, USA). The diabetic (n = 27) and non-diabetic (n = 27) groups were matched for age (p = 0.100) and sex (p = 0.414), and HbA_1c level differed between diabetic and non-diabetic groups (p < 0.0005). The diabetic group comprised type 1 (n = 7) and type 2 (n = 20) diabetic individuals who were matched for duration of diabetes (p = 0.617) and whose glycaemic control was similar (p = 0.814).

Results

Diabetic individuals had significantly higher CPT (t(37) = 3.859, p < 0.0005) than non-diabetic individuals. In the diabetic group, multiple linear regression analysis revealed a conspicuous relationship between CPT and HbA_1c level (β = 0.501, t(21) = 3.139, p = 0.005): there was a 19-μm increase in CPT for each 1% increase in HbA_1c level. This relationship was not present in the non-diabetic group (β = − 0.068, t(23) = − 0.373, p = 0.712).

Conclusions

SS-OCT is the only way to measure macular thickness in vivo. Diabetic individuals en bloc had higher CPT compared with non-diabetic individuals. Moreover, in the diabetic group, HbA_1c level significantly predicted CPT. Our results suggest that, in diabetes, sub-clinical thickening may occur at the fovea before cystoid macular oedema becomes clinically evident. This could provide diabetic individuals with an early warning of disease progression and motivate them to improve control of their diabetes, with a view to avoiding the need of intra-vitreal injections with their attendant risks.

Measuring visual cortical oxygenation in diabetes using functional near-infrared spectroscopy

AIMS

Diabetes mellitus affects about 6% of the world's population, and the chronic complications of the disease may result in macro- and micro-vascular changes. The purpose of the current study was to shed light on visual cortical oxygenation in diabetic individuals. We then aimed to compare the haemodynamic response (HDR) to visual stimulation with glycaemic control, given the likelihood of diabetic individuals suffering from such macro- and micro-vascular insult.

METHODOLOGY

Thirty participants took part in this explorative study, fifteen of whom had diabetes and fifteen of whom were non-diabetic controls. The HDR, measured as concentrations of oxyhaemoglobin [HbO] and deoxyhaemoglobin [HbR], to visual stimulation was recorded over the primary visual cortex (V1) using a dual-channel oximeter. The stimulus comprised a pattern-reversal checkerboard presented in a block design. Participants' mean glycated haemoglobin (HbA1c) level (± SD) was 7.2 ± 0.6% in the diabetic group and 5.5 ± 0.4% in the non-diabetic group. Raw haemodynamic data were normalised to baseline, and the last 15 s of data from each 'stimulus on' and 'stimulus off' condition were averaged over seven duty cycles for each participant.

RESULTS

There were statistically significant differences in ∆[HbO] and ∆[HbR] to visual stimulation between diabetic and non-diabetic groups (p < 0.05). In the diabetic group, individuals with type 1 diabetes displayed an increased [HbO] (p < 0.01) and decreased [HbR] (p < 0.05) compared to their type 2 counterparts. There was also a linear relationship between both ∆[HbO] and ∆[HbR] as a function of HbA1c level (p < 0.0005).

CONCLUSIONS

Our findings suggest that fNIRS can be used as a quantitative measure of cortical oxygenation in diabetes. Diabetic individuals have a larger HDR to visual stimulation compared to non-diabetic individuals. This increase in ∆[HbO] and decrease in ∆[HbR] appears to be correlated with HbA1c level.

The chromatic selectivity of visual crowding

Precortical vision is mediated by three opponent mechanisms that combine receptoral outputs to form a luminance channel (L + M) and two chromatic channels, red-green (L/M) and blue-yellow (S/L + M). Here we ask the extent to which these basic color opponent mechanisms interact in the phenomenon of crowding, where nearby targets interfere with the processing of a central test target. The task was to identify the orientation of a Gabor patch while an annular plaid surrounded the patch. The radius of the annulus was varied in order to produce different separations of the test and flanker. The chromatic content of the Gabor and the annulus could be varied independently along the (L + M), (L/M), and (S/L + M) cardinal axes. For all targets, when the target and flanker shared the same chromaticity, performance decreased with decreasing separation of the target and annulus, i.e., a typical crowding effect was seen. When the test and flanker isolated different chromatic mechanisms, very little crowding was observed, even at the minimum separation of test target and annulus. In addition to this, intermediate chromaticities were found to produce intermediate levels of crowding. Finally, crowding effects using "half-wave rectified" stimuli suggest a locus for crowding effects beyond the level of color opponent mechanisms.

Early age-related decline in the effective number of trajectories tracked in adult human vision

Human performance in many visual and cognitive tasks declines with age, the rate of decline being task dependent. Here, we used a multiple-object tracking (MOT) task to provide a clear demonstration of a steep cognitive decline that begins relatively early in adult life. Stimuli consisted of 8 dots that moved along linear trajectories from left to right. At the midpoint of their trajectories, a certain number of dots, D (1, 2 or 3), deviated either clockwise or counter-clockwise by a certain magnitude (57 degrees, 38 degrees or 19 degrees); the task for observers was to identify the direction of deviation. Percent correct responses were measured for 22 observers aged 18-62 years and were converted to effective numbers of tracked trajectories (E) (S. P. Tripathy, S. Narasimhan, & B. T. Barrett, 2007). In 5 of the 7 conditions tested, there was a significant negative correlation between age and E, indicating an age-related decline in tracking ability. This decline was found to be equivalent to a mean performance drop of 16% per decade over the four decades of adulthood tested. Further analysis suggests that performance in this task starts to decline at around 30 years of age and falls off at the rate of approximately 20% every subsequent decade.

Judging the shape of moving objects: discriminating dynamic angles

Studies of shape perception have typically focused on static shapes. Studies of motion perception have mainly investigated speed and direction. None have addressed performance for judging the shape of moving objects. We investigated this by determining the discrimination of geometric angles under various dynamic conditions (translation, rotation, and expansion). Angles were parts of imaginary triangles, defined by three vertex dots. Compared to static angles, results show no significant decline in the precision of angle judgments for any of the three motion types, up to speeds high enough to impair target visibility. Additional experiments provide evidence against a uniform mechanism underlying static and dynamic performance, which could rely on "snapshots" when processing moving angles. Rather, we find support for distinct mechanisms. Firstly, adding noise dots to the display affects rotating and expanding angles substantially more than those which are translating or static. Secondly, the ability to judge angles is unaffected when vertex dots are occluded for short periods. Given the dependence of dot trajectories on the overall triangle motion, the ability to precisely extrapolate the future position of a dot requires distinct computations for translating, expanding, and rotating shapes.

Integration across Time Determines Path Deviation Discrimination for Moving Objects

BACKGROUND

Human vision is vital in determining our interaction with the outside world. In this study we characterize our ability to judge changes in the direction of motion of objects-a common task which can allow us either to intercept moving objects, or else avoid them if they pose a threat.

METHODOLOGY/PRINCIPAL FINDINGS

Observers were presented with objects which moved across a computer monitor on a linear path until the midline, at which point they changed their direction of motion, and observers were required to judge the direction of change. In keeping with the variety of objects we encounter in the real world, we varied characteristics of the moving stimuli such as velocity, extent of motion path and the object size. Furthermore, we compared performance for moving objects with the ability of observers to detect a deviation in a line which formed the static trace of the motion path, since it has been suggested that a form of static memory trace may form the basis for these types of judgment. The static line judgments were well described by a 'scale invariant' model in which any two stimuli which possess the same two-dimensional geometry (length/width) result in the same level of performance. Performance for the moving objects was entirely different. Irrespective of the path length, object size or velocity of motion, path deviation thresholds depended simply upon the duration of the motion path in seconds.

CONCLUSIONS/SIGNIFICANCE

Human vision has long been known to integrate information across space in order to solve spatial tasks such as judgment of orientation or position. Here we demonstrate an intriguing mechanism which integrates direction information across time in order to optimize the judgment of path deviation for moving objects.

Effects of global shape on angle discrimination

Previous studies have been inconclusive as to whether angle discrimination performance can be predicted by the sensitivity of orientation discrimination mechanisms or by that of mechanisms specialised for angle coding. However, these studies have assumed that angle discrimination is independent of the shape of the object of which the angle is a part. This assumption was tested by measuring angle discrimination using angles that were parts of different triangular shapes. Angle discrimination thresholds were lowest when angles were presented in isosceles triangles (sides forming the angle were of identical length). Performance was significantly poorer when angles were presented in scalene triangles (sides of different lengths) and as much as three times worse when the sides forming the angle varied randomly in length between presentations. Comparing orientation discrimination for single lines with angle discrimination for different stimulus conditions (isosceles, scalene and random triangles) leads to conflicting conclusions as to the mechanisms underlying angle perception: line orientation sensitivity correctly predicts angle discrimination for random triangles, but underestimates angle acuity for isosceles triangles. The fact that performance in angle discrimination tasks is strongly dependant on the overall stimulus geometry implies that geometric angles are computed by mechanisms that are sensitive to global aspects of the stimulus.

Psychotherapy with older adults

The scope of need and possible benefit of psychosocial interventions in late life far exceeds the scientific evidence of efficacy. Most studies have been conducted in academic settings with self-selected, relatively independent older adults for whom measures of benefit were narrowly defined. In reviewing the existing literature concerning individual, group, and couples therapies in the geriatric population, we find that with appropriate adaptations for medical comorbidity, cognitive and sensory impairment, caregiver inclusion, and realistic modification of treatment goals, psychotherapeutic endeavors with the senior patient can prove to be highly successful.

Suicide and aging: international perspectives

From Durkheim to Kraepelin, suicide has been recognized as a social and psychiatric ill. Among clinical scientists in the United States, interest in suicide grew substantially in the 1980's as rates among older adults increased. However, major advances in the science of mental health seem unlikely to reduce the prevalence of suicide as long as case recognition at the community level continues to be problematic. Public policy promoted to reduce social risk factors coupled with greater attention to psychopathology is the logical outgrowth from the most recent data. Differences in suicide rates by nation add weight to the argument.

Psychiatric emergencies: rapid response and life-saving therapies

Mental status in older patients can be acutely affected by a range of factors, particularly polypharmacy, disorders of cognition, psychosis, and elder abuse. Patients so affected may be agitated, uncooperative, combative, suicidal, or incapable of participating in treatment decisions. In a life-threatening emergency, a patient may need to be restrained or a treatment administered against a patient's wishes. Key to successful management of psychiatric emergencies is an awareness of the potential scenarios, familiarity with appropriate interventions, and an understanding of patient rights. An increased alertness for life-threatening behaviors can help prevent an event from worsening and minimize the likelihood of a patient acting out on a threat of violence or suicide.

The relation of religious preference and practice to depressive symptoms among 1,855 older adults

Religious devotion is a complex phenomenon but a potentially important source of support and meaning in the lives of older adults. Nonetheless, attendance at religious services and religious preference (affiliation) have received relatively little prominence in epidemiological studies of late life mental illness despite their relative case of measurement. We examined differences in the prevalence and course of depressive symptoms and associated characteristics among 1,855 older community residents who expressed a Jewish, Catholic, or other religious preference. At baseline, Jewish religious preference was associated with a twofold elevation in the prevalence of depressive symptoms compared to Catholics. Lack of attendance at religious services was associated with greater prevalence of depression among all groups, significantly so among Catholics. The relationship of depression with Jewish religious preference and with failure to attend services could not be accounted for by measures of age, gender, health, disability, or social support. Twenty-four months following baseline, Jewish religious preference was associated with the emergence of depressive symptoms and remained significant when the effects of age, gender, health, disability, and social support were controlled. Failure to attend services was associated with both the emergence and persistence of depression but did not remain significant once the effects of other characteristics were controlled. For both religious and health care institutions, these findings have implications for the prevention, recognition, and treatment of late life mental illness.

Multifield magic-angle spinning and double-rotation nuclear magnetic resonance studies of a hydrated aluminophosphate molecular sieve: AlPO4-H2

AlPO4-H2 is a microporous hydrated aluminophosphate, structurally related to VPI-5, whose framework has highly elliptical 10-ring channels (2.9 x 7.6 A) parallel to the c crystallographic axis. To resolve a previously reported discrepancy between nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) data a highly crystalline AlPO4-H2 has been further characterized with 27Al and 31P magic-angle spinning (MAS) NMR at 11.7 T and 27Al double-rotation (DOR) NMR at 4.7 T. These present NMR data definitively show that the true space group symmetry of the AlPO4-H2 framework structure is triclinic rather than the higher orthorhombic symmetry proposed earlier from XRD studies.

The geriatric syndrome of late-life depression

Existing data on the treatment, course, and outcome of depression are not representative of the older depressed person who is most frequently encountered in clinical practice. If mental health services are to become more effectively applied, late-life depression should be conceptualized not as a categorical disorder but as a geriatric syndrome with multiple etiologies requiring a combination of treatments. To support this argument, the author reviews the prevalence of late-life depression across clinical and community settings and in association with somatic and central nervous system conditions. He recommends a comprehensive geriatric assessment and a tripartite treatment approach incorporating definitive, rehabilitative, and supportive interventions.

Cognitive impairment and mortality in older community residents

OBJECTIVE

Cognitive impairment among the elderly has been linked to mortality in studies of clinical populations. The purpose of this study was to examine the mortality risk associated with cognitive impairment among elderly populations in the community.

METHODS

Cognitive impairment and other social and health factors were assessed in 1855 elderly community residents. This sample was reinterviewed periodically to assess changes in health and survival.

RESULTS

At baseline 33% of the sample were mildly impaired and 8% were severely impaired. Across a 48-month observation period the survival probability was .85 for the cognitively unimpaired, .69 for the mildly impaired, and .51 for severely impaired respondents. When adjustments were made for the effects of other health and social covariates, severely impaired persons were twice as likely to die as unimpaired persons. Those who were mildly impaired were also at an increased risk.

CONCLUSIONS

Other investigators have found that cognitive impairment is a significant predictor of dementia. We found that it is a significant predictor of mortality as well. Early detection of impaired cognition and attention to associated health problems could improve the quality of life of these older adults and perhaps extend their survival.

Psychogeriatric emergencies

Through training and orientation, clinicians specializing in geriatric medicine are well-equipped to identify the various contributors to life-threatening mental states and associated conditions of older adults. The clinical drill to sort out factors contributing to a change in mental status is well-known and only the less frequently encountered causes and complications of treatment are considered in the previous paragraphs. In situations where a major mental disorder or suicidal or assaultive ideas are suspected, psychiatric consultation will be helpful. When treatment decisions (e.g., acceptance of hospital admission or diagnostic procedures) are difficult to resolve because of distress or conflict in the patient or family, a psychiatric consultation should also be considered. The more challenging task lies in the area of preventable emergencies, those that arise as a result of unsuspected suicidality, elder abuse or an unrecognized anxiety disorder. The pressures of ED practice and the complexity of pathology seen in the clinic work against keeping the physician alert to these possibilities. However, the present economic distress and demographic shifts in American society are unlikely to slow the increase in late life suicide and abuse. The extent to which more aggressive efforts at community outreach might offset the costs of emergency care as well as our seniors' quality of life remain to be demonstrated.

Depressive symptoms and mortality in elderly persons

Studies on the relationship between depression and mortality in elderly community populations have yielded contradictory findings, although an association frequently is found in studies of elderly psychiatric patients. These different results may be due to differences in the measures of depression, the populations under study, the covariates in the analysis, or to sample attrition. In this study of elderly residents of an urban neighborhood, depressive symptoms are measured at two time points. People are classified as consistently nonsymptomatic (N-N), with emergent symptoms (N-D), in remission (D-N), or persistently symptomatic (D-D). Symptoms of depression, sociodemographic characteristics, and measures of changes in health, functional status, number of chronic medical conditions, and social support are examined in relation to mortality in multivariate Cox regression models. Although symptoms of depression are not found to be related to time-to-death, older people, those with declines in health and functional status, and men have greater relative risks of mortality over a three-year follow-up.

Persistence and remission of depressive symptoms in late life

OBJECTIVE

The relation of poor health to the onset of depression symptoms in late life is well recognized, but little attention has been given to characteristics that might predict persistence or remission of depressive symptoms. In previous analyses the authors found that increasing disability and declining health preceded the emergence of depressive symptoms in older community residents and accounted for 70% of the variance explained by discriminant analyses. The aim of the present analysis was to examine the relevance of changes in health and disability to the persistence of depressive symptoms.

METHOD

A representative sample of 1,855 adults aged 65 or older were assessed with the Center for Epidemiologic Studies Depression Scale at baseline. Twenty-four months later, 1,577 individuals were available for a second assessment of depressive symptoms. The characteristics of the 97 community residents whose depressive symptoms persisted over 24 months were compared to those of the 114 whose symptoms remitted.

RESULTS

Changes in health, differences in age, sleep disturbance, and added formal support services accounted for more than 30% of the variance between the persistently depressed and remission groups. Advanced age and worsening health were associated with persistent symptoms, improved health with remission.

CONCLUSIONS

Previous studies have indicated that untoward changes in health and disability play a major role in the onset of depressive symptoms. These findings show a substantial contribution to chronicity as well.

A longitudinal study of psychotropic prescriptions in a teaching nursing home

This study clarifies the methodological pitfalls of using cross-sectional data to characterize episodic and continuous patterns of prescribing psychotropic medications in nursing homes. Although more than half of the residents in a teaching nursing home received a psychotropic drug during their 5 years of residence, less than one-quarter were continuously medicated. The authors conclude that although the rates of psychotropic prescriptions are an important entry point for concerns about quality and appropriateness of psychotropic administration to older nursing home residents, longitudinal studies including the prescribing pattern, indications, and efficacy are needed to determine more clinically meaningful indicators of quality care.

The emergence of depressive symptoms in late life: the importance of declining health and increasing disability

Despite considerable progress in the epidemiology of late life depressive disorders, the determinants and course of late life depressive symptoms remain unclear. The apparent reciprocal relationship between depression and disability, a consistent finding in cross-sectional studies further confounds efforts to estimate the importance of depressive symptoms in the elderly. In a longitudinal study of 1457 aged community residents who completed the Center for Epidemiologic Studies Depression scale at baseline and 24 months later, a significant level of depressive symptoms emerged in 163 respondents (11%), while 1080 (74%) remained symptom free. Unlike other studies, we found that the number of medical conditions, social support, life events, and demographic characteristics contributed little to distinguish those with emerging symptoms from those who remained symptom free. However, increasing disability and declining health preceded the emergence of depressive symptoms and accounted for seventy percent of the variance explained by discriminant analysis. These findings have etiologic implications for both the course and determinants of depression in late life.

Hierarchy of characteristics associated with depressive symptoms in an urban elderly sample

In contrast to the uncertainty about the prevalence and importance of late-life depressive disorders, a consistent pattern of risk factors for depressive symptoms has been shown by studies using the Center for Epidemiologic Studies Depression Scale (CES-D). The authors surveyed a representative sample of 2,137 elderly community residents with the CES-D and found a hierarchy of characteristics associated with substantial levels of depressive symptoms: illness, disability, isolation, bereavement, and poverty. If these findings are confirmed by prospective studies, addressing modifiable factors in the emergence, persistence, and remission of depressive symptoms might extend the independent survival of older adults.

Significance of depression and cognitive impairment in patients undergoing programed stimulation of cardiac arrhythmias

Although depression and cognitive impairment have been associated with excess mortality following heart surgery, the relationship of these factors to death following treatment for cardiac arrhythmias is unknown. We prospectively examined the associations between biobehavioral factors, mortality, and arrhythmia manageability in 88 patients undergoing programed electrical stimulation for the diagnosis and treatment of supraventricular and ventricular tachyarrhythmias or syncope of unknown origin. Statistically significant relationships were identified between depression and mortality, and between cognitive impairment and mortality. No relationships were observed between cognitive impairment or psychologic profile and arrhythmia severity or treatment efficacy. Our data suggest that arrhythmia morbidity and mortality may in part be a function of cognitive and emotional impairments that lessen the individual's capacity to comply with lifesaving therapy, maintain a stable physiologic milieu, and continue an adaptive emotional life. Failure to recognize the clinical significance of these impairments in patients at risk for sudden cardiac death will contribute to the current difficulty reducing the death and disability associated with cardiac arrhythmias.

Acute fatal pneumonia in calves due to respiratory syncytial virus

An acute pneumonia developed in 28 calves which had been housed together from one to two weeks of age. The clinical signs included pyrexia, tachypnoea, respiratory distress and coughing. Some of the calves died. The pneumonia was characterised by an alveolitis with multinucleated syncytia, alveolar epithelial hyperplasia and bronchiolitis. Interstitial emphysema was also present. Fifteen of 19 calves examined serologically had rising neutralising antibody titres to respiratory syncytial virus; in nine calves the rise was fourfold or greater. Respiratory syncytial virus was not isolated from the calves. There was no evidence of parainfluenza type 3 virus involvement. The adult cows being sucked by the calves remained clinically normal throughout the incident. Six calves examined six weeks after the outbreak started had a chronic cuffing pneumonia characterised by lymphocytic bronchiolitis; some of the calves also had bronchiolitis obliterans. Mycoplasma dispar was found in two of them.