Association of Psychosocial Factors with Activation Among Patients with Glaucoma

OBJECTIVE

To investigate the association of psychosocial factors with health self-management behaviors and beliefs among patients with primary open-angle glaucoma (POAG).

DESIGN

Prospective cross-sectional cohort study.

PARTICIPANTS

Patients (n = 202) with mild, moderate, or advanced bilateral POAG.

METHODS

Patients (N = 1164) were identified from electronic medical records at a single academic medical center. Letters soliciting participation were mailed to 591 randomly selected potential participants. Psychometric measures and a social determinants of health questionnaire were administered by phone to 202 study participants.

MAIN OUTCOME MEASURES

The National Eye Institute Visual Function Questionnaire-8 (NEI-VFQ), the Multidimensional Health Locus of Control (MHLC), the Perceived Medical Condition Self-Management Scale-4, the Patient Health Questionnaire-9 (PHQ), the Patient Activation Measure-13 (PAM), a health literacy question, and a social determinants of health questionnaire.

RESULTS

For each increase in level of POAG severity, there was a decrease in mean NEI-VFQ score (P < 0.001). For each unit increase in NEI-VFQ item 1, self-rated vision, mean PAM score increased (R2 = 5.3%; P = 0.001; 95% confidence interval [CI], 0.077-0.276). For each unit increase in "Internal" on the MHLC, mean PAM score increased (R2 = 19.3%; 95% CI, 0.649-1.166; P < 0.001). For each unit increase in "Doctors" on the MHLC, mean PAM score increased (R2 = 11.0%; 95% CI, 1.555-3.606; P < 0.001). For each unit increase in "Chance" on the MHLC, mean PAM score decreased (R2 = 2.6%; 95% CI, -0.664 to -0.051; P = 0.023). On multivariate analysis, adjusting for age, sex and race, for each unit increase in PHQ, mean PAM score decreased (95% CI, 0.061-1.35; P = 0.032); for each unit increase in MHLC "Doctors", mean PAM score increased (95% CI, -1.448 to 3.453; P < 0.001); for each unit increase in MHLC "Internal", mean PAM score increased (95% CI, 0.639-1.137; P < 0.001); for each unit increase in MHLC "Chance", mean PAM score decreased (95% CI, -0.685 to -0.098; P = 0.009).

CONCLUSIONS

We identified modifiable behavioral factors that could increase patients' self-perceived ability and confidence to manage their own eye care. Locus of control (MHLC), level of depression (PHQ), and self-rated functional vision (NEI-VFQ) were each associated with patient behaviors, attitudes, and beliefs needed for health self-management (activation, assessed by the PAM) and may be important determinants of adherence behaviors. Targeting change in patients' care beliefs and behaviors may improve activation and treatment outcomes.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Wearables for persons with blindness and low vision: form factor matters

Based on statistics from the WHO and the International Agency for the Prevention of Blindness, an estimated 43.3 million people have blindness and 295 million have moderate and severe vision impairment globally as of 2020, statistics expected to increase to 61 million and 474 million respectively by 2050, staggering numbers. Blindness and low vision (BLV) stultify many activities of daily living, as sight is beneficial to most functional tasks. Assistive technologies for persons with blindness and low vision (pBLV) consist of a wide range of aids that work in some way to enhance one's functioning and support independence. Although handheld and head-mounted approaches have been primary foci when building new platforms or devices to support function and mobility, this perspective reviews potential shortcomings of these form factors or embodiments and posits that a body-centered approach may overcome many of these limitations.

Virtual reality as a means to explore assistive technologies for the visually impaired

Visual impairment represents a significant health and economic burden affecting 596 million globally. The incidence of visual impairment is expected to double by 2050 as our population ages. Independent navigation is challenging for persons with visual impairment, as they often rely on non-visual sensory signals to find the optimal route. In this context, electronic travel aids are promising solutions that can be used for obstacle detection and/or route guidance. However, electronic travel aids have limitations such as low uptake and limited training that restrict their widespread use. Here, we present a virtual reality platform for testing, refining, and training with electronic travel aids. We demonstrate the viability on an electronic travel aid developed in-house, consist of a wearable haptic feedback device. We designed an experiment in which participants donned the electronic travel aid and performed a virtual task while experiencing a simulation of three different visual impairments: age-related macular degeneration, diabetic retinopathy, and glaucoma. Our experiments indicate that our electronic travel aid significantly improves the completion time for all the three visual impairments and reduces the number of collisions for diabetic retinopathy and glaucoma. Overall, the combination of virtual reality and electronic travel aid may have a beneficial role on mobility rehabilitation of persons with visual impairment, by allowing early-phase testing of electronic travel aid prototypes in safe, realistic, and controllable settings.

<p>Decreasing Avoidable Vision Loss: Identifying Antecedents of Adherence</p>

Adherence to medication treatment protocols and active participation by individuals in their medical care are important for all patients, but especially for those with chronic conditions such as vision loss. Adherence is crucial for decreasing avoidable vision loss. Failure to take medications as prescribed and keep scheduled appointments reduces treatment effectiveness, increases complications and results in poorer outcomes. Reasons for nonadherence vary by diagnosis and include not understanding the importance of adherence, low health literacy, lack of adequate self-efficacy, low level of activation and behavioral issues including depression. Patients may lack information about their condition and its prognosis, available treatment alternatives, and other essential information such as how to monitor their eye condition, what to do if vision deteriorates and how to get needed community-based help. Each of these factors impedes patients’ ability to engage with their physician and participate in their own care. The ability of individuals with vision loss to actively and effectively manage their health care, ie, activation, has been understudied. When patients are involved with their own care, their care experience, and most importantly, their outcomes, are improved. Identifying antecedents of adherence may help provide disease- and patient-specific pathways to reduce avoidable vision loss.

ASSIST: Evaluating the usability and performance of an indoor navigation assistant for blind and visually impaired people

This paper describes the interface and testing of an indoor navigation app - ASSIST - that guides blind & visually impaired (BVI) individuals through an indoor environment with high accuracy while augmenting their understanding of the surrounding environment. ASSIST features personalized interfaces by considering the unique experiences that BVI individuals have in indoor wayfinding and offers multiple levels of multimodal feedback. After an overview of the technical approach and implementation of the first prototype of the ASSIST system, the results of two pilot studies performed with BVI individuals are presented - a performance study to collect data on mobility (walking speed, collisions, and navigation errors) while using the app, and a usability study to collect user evaluation data on the perceived helpfulness, safety, ease-of-use, and overall experience while using the app. Our studies show that ASSIST is useful in providing users with navigational guidance, improving their efficiency and (more significantly) their safety and accuracy in wayfinding indoors. Findings and user feedback from the studies confirm some of the previous results, while also providing some new insights into the creation of such an app, including the use of customized user interfaces and expanding the types of information provided.

Microperimetry: a review of fundus related perimetry

Visual field assessment is a key part of optometry and ophthalmology practice. However, in people with non-central or unstable fixation, it is not possible to relate defects on a visual field map to a specific retinal location. Microperimetry (or fundus related perimetry) is a technique that images the retina during visual field testing, enabling a correlation to be made between visual function and retinal structure. In this article, the history of fundus related perimetry is reviewed. Three modern microperimeters (MP-1, OCT/SLO and MAIA) are described and their relative merits identified. Finally, the uses of microperimetry in optometric practice are discussed.

Retinal dysfunction in carriers of bardet-biedl syndrome

PURPOSE

To determine whether retinal dysfunction in obligate carriers of the Bardet-Biedl syndrome (BBS) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG).

METHODS

Six obligate carriers of the BBS were examined for the study. Examination of each carrier included an ocular examination and mfERG testing of one eye. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 degrees in diameter. The amplitudes and implicit times in each location for the mfERG were compared with the corresponding values determined for a group of 34 normally sighted, age-similar control subjects.

RESULTS

Mapping of 103 local electroretinographic response amplitudes within a central 40 degrees area with the mfERG showed regions of reduced mfERG amplitudes in three of six carriers. Implicit time measurements in the 6 carriers were all normal except for those locations associated with abnormal amplitude reductions in 3 of the carriers. When present, retinal dysfunction was evident in the presence of a normal-appearing fundus.

CONCLUSIONS

Multifocal ERG testing can demonstrate areas of retinal dysfunction in carriers of the BBS. This test may therefore be useful for identifying some heterozygous carriers of this disease.

The effect of variably tinted spectacle lenses on visual performance in cataract subjects

PURPOSE

A body of clinical and laboratory evidence suggests that tinted spectacle lenses may have an effect on visual performance. The aim of this study was to quantify the effects of spectacle lens tint on the visual performance of 25 subjects with cataracts.

METHODS

Cataracts were scored based on best-corrected acuity and by comparison with the Lens Opacity Classification System (LOCS III) plates. Visual performance was assessed by measuring contrast sensitivity with and without glare (Morphonome software version 4.0). The effect of gray, brown, yellow, green and purple tinting was evaluated.

RESULTS

All subjects demonstrated an increase in contrast thresholds under glare conditions regardless of lens tint. However, brown and yellow lens tints resulted in the least amount of contrast threshold increase. Gray lens tint resulted in the largest contrast threshold increase.

CONCLUSIONS

Individuals with lenticular changes may benefit from brown or yellow spectacle lenses under glare conditions.

Effect of variable tinted spectacle lenses on visual performance in control subjects

PURPOSE

To evaluate quantitatively the effects of tinted spectacle lenses on visual performance in individuals without visual pathology.

METHODS

Twenty-five subjects were assessed by measuring contrast sensitivity with and without glare. Gray, brown, yellow, green, purple, and blue lens tints were evaluated. Measurements were repeated with each lens tint and with a clear lens, and the order was counterbalanced within and between subjects. Glare was induced with a modified brightness acuity tester.

RESULTS

All subjects demonstrated an increase in contrast thresholds under glare conditions for all lens tints. However, purple and blue lens tints resulted in the least amount of contrast threshold increase; the yellow lens tint resulted in the largest contrast threshold increase.

CONCLUSIONS

Purple and blue lens tints may improve contrast sensitivity in control subjects under glare conditions.

Rod phototransduction in transgenic mice expressing a mutant opsin gene

Rod-mediated electroretinograms (ERG's) were recorded from transgenic mice expressing a mouse opsin gene with three point mutations (V20G, P23H, and P27L; termed VPP mice) and from normal littermates. The leading edge of the alpha wave was analyzed in relation to a computational model of rod phototransduction [J. Physiol. 499, 719 (1992)], in which values for the maximum response (RmP3), transduction gain (S), and transduction delay (td) are derived from alpha-wave data. VPP mice exhibited an age-related decrease in RmP3. This decrease was consistent with reductions in the number of rod photoreceptors and in the length of rod outer segments observed in previous histological studies of the VPP retina. Values of S determined for the VPP mice were within the normal range, consistent with a normal amplification of the visual signal in VPP rods. At high stimulus intensities, both normal and VPP mice exhibited a decrease in S, which may reflect depletion of a phototransduction substrate at these stimulus levels. We examined the recovery of the alpha wave after a bright conditioning flash by measuring the rod alpha-wave response to a probe flash presented at varying times after the conditioning stimulus. In both normal and VPP mice a fourfold (0.6-log-unit) increase in conditioning stimulus intensity increased both T50%, the period required for half-maximal recovery, and tau, the exponential time constant describing recovery. However, the increases in T50% and tau were significantly greater in VPP mice, indicating an abnormally slow recovery of the flash response in VPP rods.

Sites of cone system sensitivity loss in retinitis pigmentosa

PURPOSE

To examine the sites of cone sensitivity loss in patients with retinitis pigmentosa by comparing focal electroretinographic and psychophysical modulation thresholds.

METHODS

Both psychophysical and electrophysiologic increment threshold curves were obtained in retinitis pigmentosa patients and a group of age-matched, normally-sighted adults.

RESULTS

The majority of the retinitis pigmentosa data could be accounted for by a vertical displacement of the normal curve. The retinitis pigmentosa patients showed similar patterns of cone sensitivity losses using both techniques.

CONCLUSIONS

The combined electrophysiologic and psychophysical results provide support for an outer retina locus for these cone sensitivity losses. The data suggest that these deficits may be caused by a spatially independent loss of cone photoreceptors with normal adaptation properties in the remaining photoreceptors.

Maculopathy caused by intra-arterially administered cisplatin and intravenously administered carmustine

Eight patients with malignant gliomas were monitored with clinical examinations to study the effects of the combination of intravenous administration of carmustine and infraophthalmic intra-arterial administration of cisplatin on retinal and optic nerve function. Three patients developed a severe macular retinal pigment abnormality in the eye ipsilateral to the intra-arterial infusion. Electrophysiologic studies disclosed no evidence of a generalized disturbance in the photoreceptors, middle retinal layers, or retinal pigment epithelium. In contrast to previous studies involving patients whose visual loss was caused by vaso-occlusive lesions in the retina and optic nerve, our study involved patients with clinically significant maculopathy, that was not vascular in origin and that developed after treatment with carmustine and cisplatin. We suggest that the deficit may result from a localized retinal pigment disturbance in the macula.

Human VEP contrast modulation sensitivity: separation of magno- and parvocellular components

Human cortical visual evoked potentials (VEPs) were retrieved in real time (without averaging). The stimuli were sinusoidal gratings whose contrast was temporally modulated about some mean value. Electrophysiologically determined contrast modulation thresholds were measured at standing contrast over the range from 2.5% to 50%, defining an increment threshold function. Increment threshold functions were obtained under two different spatio-temporal stimulus conditions identified as "sustained" (4 c/deg grating modulated at 1.5 Hz) and "transient" (1 c/deg grating modulated at 20 Hz). Under each of these conditions, threshold responses were retrieved at both the fundamental and second harmonic of the contrast modulation frequency. Under "sustained" conditions log increment threshold responses and the fundamental the second harmonic of the modulation frequency were similar to those at the fundamental except for a saturation effect (i.e., above a mean contrast of 25% there was little further reduction in modulation sensitivity). There was no contrast gain control under "transient" stimulus conditions. In other words, the same absolute amount of contrast change produced threshold responses for all mean levels up to 25%. This was true at both the fundamental and second harmonic of the modulation frequency. Stimulus differences produce striking differences in the electrophysiologically inferred increment threshold function for grating contrast, but fundamental and second harmonic evoked responses reflect processes with similar increment threshold behavior.

The clinical utility of visual-evoked potential acuity testing

We assessed the clinical utility of objectively measured acuity using visual-evoked potentials. The technique was first standardized in normal emmetropic subjects and then applied to uncorrected myopic subjects. We found that visual-evoked potential acuity could accurately indicate Snellen acuity in emmetropia and corrected myopia; however, the two measures were highly correlated only in those uncorrected myopic subjects with visual acuities of 20/100 or better. In subjects with poorer than 20/200 uncorrected visual acuity caused by myopia, estimates of visual-evoked potential acuity could not be obtained. The correlation between these two measures of visual acuity was also lower in patients with decreased Snellen acuity attributable to retinal or ocular disease. We found that patients with unexplainable claims of decreased visual acuity could be diagnosed as having functional visual loss based on objective visual-evoked potential acuities.

Pattern electroretinogram threshold does not show contrast adaptation

Pattern electroretinogram (PERG) thresholds were examined using a swept contrast stimulus method. Stimulus contrast was either continuously changed (swept) from high to low (descending sweep), or from low to high (ascending sweep). Visual evoked potential (VEP) contrast threshold was higher when measured using descending sweeps than when using ascending sweeps. This VEP threshold difference has been attributed to cortical adaptation. Although previous work has reported changes in the PERG amplitude as a function of pre-exposure, we have found no analogous effect on the PERG threshold.

Cone function in congenital nyctalopia

A patient with congenital stationary night blindness (CSNB) (Schubert-Bornschein type) transmitted as an autosomal recessive trait was studied with several tests of electrical function as well as a variety of psychophysical procedures. Comparison of the patient's present findings with those obtained 23 years earlier showed that while rod thresholds have remained the same, cone sensitivity has decreased. Subjective flicker thresholds obtained following a bleach were unchanged during the course of dark adaptation. The absence of rod-cone interaction, together with an absent scotopic b-wave, implies that the defect is in the mid-retinal layers. Further, the absence of oscillatory potentials in the photopic electroretinogram (ERG) suggests that the interplexiform cell may be implicated in some manner. The focal ERG of the CSNB patient showed normal amplitude and normal phase delays, supporting the idea that the focal ERG samples primarily cone photoreceptor activity.

Contrast sensitivity of the human pattern electroretinogram

Contrast thresholds for the pattern electroretinogram (PERG) were measured using lock-in amplifier retrieval of the retinal signal and a swept contrast display. Contrast sensitivity functions (CSF) developed from these PERG contrast thresholds were compared with those established psychophysically under identical stimulus conditions. Whereas the PERG CSF showed a band-pass characteristic across temporal frequency, the psychophysical CSF (and a temporal CSF developed from visual evoked potential contrast thresholds) had a low-pass pattern. Across spatial frequency, the PERG and psychophysical CSFs had similar shapes, although the PERG CSF peaked at a lower spatial frequency than the psychophysical CSF.

Evaluating macular function using the focal ERG

A stimulus consisting of 96 red LEDs mounted in the rear of a ganzfeld bowl was used to elicit focal electroretinograms (FERG) from the central 9 degrees of the retina in human subjects. The luminance of the stimulus was driven sinusoidally at frequencies from 10-60 Hz. The temporal responsiveness and response phase lags of normal subjects and patients with retinal disease were measured. Normal subjects produced maximum amplitude FERG responses to stimuli between 30-40 Hz. Patients with retinitis pigmentosa showed a low-pass pattern of amplitude loss, with an additional frequency independent loss in sensitivity in those with poorer visual acuity. Patients with macular degeneration showed general amplitude loss associated with a relative sparing of the mid-temporal frequencies. The response phase lags in both patient groups were not significantly different from the normals. These findings point to a loss in temporal responsiveness accompanied by a secondary loss of sensitivity in these heredoretinal degenerations.

Objective assessment of temporal modulation transfer functions using the focal ERG

Temporal modulation transfer functions (MTF's) were recorded from the macula of nine normal subjects using focal electroretinography (FERG). An array of light emitting diodes (LED's) was used to experimentally manipulate stimulus temporal frequency, modulation depth, and mean luminance values. Two techniques were used to derive FERG modulation thresholds at several temporal frequencies: conventional averaging with extrapolation to a criterion amplitude, and a swept stimulus lock-in retrieval method. These two methods produced comparable results. The electrophysiologically derived MTF's were similar in shape to those obtained psychophysically. Six patients with retinal disease were also examined; all patients showed sensitivity losses which were most marked at the higher frequencies. Such losses tended to be greater in patients with poorer visual acuity.

A rapid evoked potential index of cortical adaptation

Contrast thresholds and acuity limits were measured in 4 observers with the swept visual evoked potential (VEP) technique. In this technique, grating contrast or grating spatial frequency is electronically varied while the subject's evoked response is retrieved in real time (without averaging). Contrast or spatial frequency variation make the stimulus vary in intensity; zero VEP response amplitude indicates the threshold intensity. Large shifts occur in the indicated threshold when stimulus sweep direction is reversed. Thresholds are always relatively elevated when the run begins with the strongest stimulus value. These shifts do not have a technical origin in the delay of the instrument (Nelson et al. 1984b). Here, it is shown that the shifts are due to orientation and spatial frequency selective adaptation, probably of cortical origin. Measureable adaptation is produced by momentary exposure to contrasts as low as 1.25%; nearly maximum adaptation (0.6 log units) is reached with 20% contrast. These findings support the concept of a contrast gain control mechanism in visual cortex, and pose practical problems for visual assessment with the evoked potential.

Lock-in techniques for the swept stimulus evoked potential

We discuss the use of synchronous-demodulation (lock-in) techniques for evoked potential retrieval. Application to electronically swept visual displays is emphasized. These techniques permit a visual threshold to be specified in 20 s, but their application to visual assessment requires careful consideration of several problems, notably alleged delay in the instrumentation, specification of the baseline response level, and the nature of EEG interference. In addition, since stimulus waveform information is lost in all lock-in methods, questions concerning what activity is contributing to the measured response must be answered. A technique addressing these issues and combining phase-sensitive detection and vector computation is presented.

The assessment of evoked potential contrast thresholds using real-time retrieval

Electrophysiologic contrast sensitivity functions (CSF) have been estimated using lock-in amplifier signal retrieval of the visually evoked response (VER). These CSFs were compared with CSFs obtained psychophysically using the same stimulus conditions. The two measures of contrast sensitivity behave similarly in response to variations of temporal and spatial frequency. The major advantage of using real-time retrieval is speed. Threshold for a single spatiotemporal condition can be estimated in as little as 20 sec, making the application of electrophysiologic contrast sensitivity testing feasible for clinical populations.

Contrast sensitivity loss in multiple sclerosis. Selectivity by eye, orientation, and spatial frequency measured with the evoked potential

Multiple sclerosis can produce highly selective losses in visual function. Psychophysical studies have demonstrated contrast sensitivity deficits for spatial frequencies or for stimulus orientations. Using real-time lock-in retrieval of the visual evoked potential, the authors measured contrast sensitivity in 15 cases with probable or definite multiple sclerosis and acuities of 20/40 or better. Sine-wave grating contrast threshold determinations for three spatial frequencies (1, 4, and 8 cycles/deg) and four orientations (0, 45, 90, and 135 deg) revealed contrast deficits in at least one spatial frequency and orientation in every case. In most cases the visual losses were spotty or multifocal, and not the same in both eyes. Some cases with highly selective patterns of orientation or spatial frequency losses were observed and are discussed in terms of involvement of cortical functional architecture in the disease.

Spatiotemporal conditions which elicit or abolish the oblique effect in man: direct measurement with swept evoked potential

Reversing sine wave gratings were electronically swept in spatial frequency and contrast. The acuity limits and contrast thresholds of 4 observers were inferred from evoked potential stimulus-response functions elicited by these stimuli and retrieved with a quadrature lock-in amplifier. The evoked potential functions, linearized in the case of contrast by increasing contrast logarithmically with time, were extrapolated to the point of zero response. This point provides an electrophysiologically defined threshold value for acuity and for contrast. An oblique effect (superior sensitivity for HV-oriented gratings) could reliably be demonstrated in both acuity and contrast threshold performance. This oblique effect could readily be abolished under low spatial/high temporal frequency conditions. The findings are discussed in terms of shifting relative strengths of X and Y contributions to the steady-state evoked potential.

The 20/20 eye in multiple sclerosis

Using clinical and electrophysiologic measures, we evaluated the visual pathway of patients who had multiple sclerosis, 20/20 Snellen acuity, and no history of optic neuritis. Delayed latencies were found in the transient visual evoked potentials (VEPs) of 38% of the patients, and interocular latency differences were abnormal in 67%. Contrast VEPs were abnormal in 46%. Psychophysical determinations of contrast sensitivity were abnormal in 78%. Only 17% of the patients had dyschromatopsia, 36% had afferent pupillary abnormalities, and 59% had optic nerve pallor or nerve fiber layer loss. Psychophysical contrast evaluations and VEP studies were superior to other clinical evaluations in demonstrating visual dysfunction in these patients.

Recording the pattern electroretinogram: a cautionary note

It is possible to record a pattern electroretinogram (PERG) of near normal amplitude in a situation when the eye containing the active electrode is occluded. Because PERG recording requires high amplification and sensitive signal retrieval techniques, the electrode in the occluded eye records a distant potential from the unoccluded eye. Referencing the active electrode to an ipsilateral ear diminishes, but does not eliminate the referred PERG potential. Such unlooked for interaction may provide misleading data in situations where binocular viewing is used because of poor vision in one eye; therefore, occlusion of the eye not being tested should be undertaken whenever possible.