Temporal contrast sensitivity with peripheral and central stimulation in glaucoma diagnosis

Correlation between Central Visual Field Defects and Stereopsis in Patients with Early-to-Moderate Visual Field Loss

PURPOSE

To investigate the association between stereoacuity and the presence of central visual field defects (CVFDs) due to glaucoma.

DESIGN

A prospective, cross-sectional cohort study.

PARTICIPANTS

Participants with early-to-moderate glaucoma with a visual acuity better than 20/40, less than a 2-line difference in visual acuity between eyes, and 2 reliable Humphrey visual fields (VFs) (24-2 SITA standard) with mean deviation (MD) in the worse eye better than - 12 dB.

METHODS

Stereoacuity was measured using the Titmus stereo test. Participants with a significant field defect (P < 0.005) in any 1 of the central 4 points in the 24-2 SITA standard total deviation map in either eye were classified as having a CVFD. Vision-related quality of life (VR-QOL) was measured using 25-item National Eye Institute Visual Function Questionnaire scores. Logistic regression was used to determine the associations between the level of stereoacuity and age, sex, race, glaucoma type, presence of CVFDs, visual acuity, contrast sensitivity, and VF MD.

MAIN OUTCOME MEASURES

Stereoacuity in the CVFD and non-CVFD groups.

RESULTS

Sixty-five participants met the inclusion criteria. The mean age of the participants was 64.3 ± 8.0 years, and 64.6% were women. The median stereoacuity was 60 arc seconds (interquartile range [IQR], 40-120 arc seconds). Forty-two (65%) patients had CVFDs, and 23 (35%) patients did not. The median stereoacuity of the CVFD group was worse than that of the non-CVFD group (60 arc seconds [IQR, 50-140 arc seconds] vs. 40 arc seconds [IQR, 40-80 arc seconds], respectively; P = 0.001). The non-CVFD group had a higher percentage of participants with normal stereopsis than the non-CVFD group (61% vs. 21%, respectively; P = 0.001). A multivariable analysis found that the presence of CVFDs was associated with worse stereopsis levels (odds ratio, 4.49; P = 0.021). The CVFD group had a lower Visual Functioning Questionnaire-25 (VFQ-25) composite score (84.0 vs. 91.4; P = 0.004) and lower VFQ-25 subscale scores for general vision, near activities, and mental health (P < 0.05).

CONCLUSIONS

Central visual field defects were associated with increased odds of poor stereoacuity in patients with early-to-moderate glaucomatous VF loss. Specifically, patients without CVFDs are more likely to have normal stereopsis and higher VR-QOL than those with CVFDs. Patients with CVFDs should be counseled regarding how depth perception difficulties may affect daily living.

FINANCIAL DISCLOSURE(S)

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

Central contrast sensitivity perimetry discriminates between glaucomatous and non-glaucomatous eyes

Background

Glaucoma is an optic neuropathy which causes irreversible vision loss. Standard perimetry, which is essential for glaucoma diagnosis, can only detect glaucomatous visual filed loss when considerable structural damage has occurred. Contrast sensitivity is one of the visual function tests that is reduced in eyes with glaucoma. It is known to be affected in pre-perimetric stages of glaucoma.

Objective

The objective of this study was to investigate the discriminating ability of central contrast sensitivity perimetry in eyes with and without glaucoma.

Design

The study employed a cross-sectional study design.

Methods

The study participants were made of two groups; eyes diagnosed with glaucoma by an ophthalmologist based on visual field test and optical coherence tomography (OCT) and age- and sex-matched controls who were declared free from glaucoma. Static contrast sensitivity (CS) was measured in the central 10° of visual field using a custom psychophysical test.

Results

There were 45 eyes with glaucoma and 45 age- and sex-matched controls in this study. The static CS in the glaucoma group was significantly reduced in 9 out of the 13 tested locations in the central 10° of the visual field. The mean static CS at 5°, 10°, superior hemifield and inferior hemifield were all significantly reduced in the glaucoma patients compared to the controls.

Conclusion

Static CS measurement is a sensitive approach that can be utilized to aid in the detection of glaucoma. The use of static CS can be adopted in the development of a cost-effective yet sensitive screening tool for the detection of glaucoma.

Visual function tests for glaucoma practice - What is relevant?

Glaucoma represents one of the most important ocular diseases causing irreversible ganglion cell death. It is one of the most common causes of visual impairment and morbidity in the elderly population. There are various tests for measuring visual function in glaucoma. While visual field remains the undisputed method for screening, diagnosis, and monitoring disease progression, other tests have been studied for their utility in glaucoma practice. This review discusses some of the commonly used tests of visual function that can be routinely used in clinics for glaucoma management. Among the various modalities of testing visual function in glaucoma, this review highlights the tests that are most clinically relevant.

Ocular Dominance and Functional Asymmetry in Visual Attention Networks

Purpose

The dorsal attention network (DAN) and the ventral attention network (VAN) are known to support visual attention, but the influences of ocular dominance on the attention networks are unclear. We aimed to explore how visual cortical asymmetry of the attention networks correlate with neurophysiological oscillation and connectivity markers of attentional processes.

Methods

An oddball task with concentric circle stimuli of three different sizes (i.e., spot size of 5°, 20°, or 30° of visual angle) was used to vary task difficulty. Event-related oscillations and interareal communication were tested with an electroencephalogram-based visual evoked components as a function of ocular dominance in 30 healthy subjects.

Results

Accuracy rates were higher in the dominant eyes compared with the nondominant eyes. Compared with the nondominant eyes, the dominant eyes had higher theta, low-alpha, and low-beta powers and lower high-alpha powers within the nodes of VAN and DAN. Furthermore, visual information processed by the dominant and nondominant eye had different fates, that is, the dominant eyes mainly relied on theta and low-alpha connectivity within both the VAN and the DAN, whereas the nondominant eyes mainly relied on theta connectivity within the VAN and high-alpha connectivity within the DAN. The difference in accuracy rate between the two eyes was correlated with the low-alpha oscillations in the anterior DAN area and low-alpha connectivity of the left DAN.

Conclusions

The ocular dominance processing and interareal communication reveal a cortical asymmetry underlying attention, and this reflects a two-way modulatory mechanism within attention networks in the human brain.

Cortical oscillations can differentiate the gradient of the simulated central visual field defect

PURPOSE

Covert spatial attention directs the attentional spotlight to a particular part of the visual field and modulates the retinotopic organized oscillatory brain activity. This study aimed to investigate the electrophysiological characteristics of oscillatory brain activity when simulating different defect degrees of the central visual field.

METHODS

The power of theta and alpha activity was extracted using time-frequency analysis in forty healthy participants enrolled in the three-stimulus oddball paradigm. Standard stimuli were black-and-white checkerboards. Target stimuli simulated different degrees of the central visual field defect by superimposing black discs with different radii (5, 10, 20, and 30 degrees of visual angle) on the center of the peripheral checkerboard stimulation, and distractor stimuli presented in the reverse form with a constant radius.

RESULTS

By simulating central visual field defects, the increased theta power and decreased alpha power was observed when detecting target stimuli. Besides, the magnitude of increased theta power and decreased alpha power peaked at the 10-degree defect conditions, and gradually decayed to the 5 and 30-degree defect conditions, which separately indicated two key points in the visual field through the spatial attentional modulations.

CONCLUSION

Using cortical oscillatory dynamics in the time-frequency platform, the defect category of the central visual field could be quantified by alpha and theta oscillations in power differences. These findings suggest that cortical oscillations are sensitive markers for the discrimination of gradient effects of the central visual field defects and further demonstrate the phenomenon of functional dissociation in the visual field in covert spatial attention status.

Afferent and Efferent Visual Markers of Alzheimer's Disease: A Review and Update in Early Stage Disease

Vision, which requires extensive neural involvement, is often impaired in Alzheimer's disease (AD). Over the last few decades, accumulating evidence has shown that various visual functions and structures are compromised in Alzheimer's dementia and when measured can detect those with dementia from those with normal aging. These visual changes involve both the afferent and efferent parts of the visual system, which correspond to the sensory and eye movement aspects of vision, respectively. There are fewer, but a growing number of studies, that focus on the detection of predementia stages. Visual biomarkers that detect these stages are paramount in the development of successful disease-modifying therapies by identifying appropriate research participants and in identifying those who would receive future therapies. This review provides a summary and update on common afferent and efferent visual markers of AD with a focus on mild cognitive impairment (MCI) and preclinical disease detection. We further propose future directions in this area. Given the ease of performing visual tests, the accessibility of the eye, and advances in ocular technology, visual measures have the potential to be effective, practical, and non-invasive biomarkers of AD.

Contrast Sensitivity and Glaucoma

Spatial contrast sensitivity decline occurs in different types and stages of glaucoma. In this short review we discuss methods of assessing contrast sensitivity, the role of contrast sensitivity in the pathogenesis of glaucoma and its practical application in clinical practice.

Evaluation of contrast sensitivity in patients with advanced glaucoma: comparison of two tests

AIMS

To evaluate contrast sensitivity (CS) in patients with advanced glaucomatous visual field damage, and to compare two clinical CS tests.

METHODS

This was a cross-sectional test-retest study. Twenty-eight patients with open-angle glaucoma, visual acuity (VA) better than 20/40 and visual field mean deviation (MD) worse than -15 dB were enrolled. Patients underwent VA, visual field and CS testing with the Pelli-Robson (PR) chart and the Freiburg Visual Acuity and Contrast Test (FrACT). Retest measurements were obtained within 1 week to 1 month.

RESULTS

Median (IQR) age and MD were 61.5 (55.5 to 69.2) years and -27.7 (-29.7 to -22.7) dB, respectively. Median (IQR) VA was 0.08 logarithm minimum angle of resolution (0.02 to 0.16), corresponding to 20/25 (20/20 to 20/30). Median (IQR) CS was 1.35 (1.11 to 1.51) log units with the PR chart and 1.39 (1.24 to 1.64) log units with FrACT. VA explained less than 40% of the variance in CS (adjusted R²=0.36). CS estimates of both tests were closely related (rho=0.88, p=0.001), but CS was 0.09 log units higher with FrACT compared with the PR chart, and the 95% repeatability intervals (Bland-Altman) were 46% tighter with the PR chart.

CONCLUSIONS

Despite near-normal VA, almost all patients showed moderate to profound deficits in CS. CS measurement provides additional information on central visual function in patients with advanced glaucoma.

Reduced contrast sensitivity among older women is associated with increased risk of cognitive impairment

OBJECTIVE

Several cross-sectional studies have reported an association between visual contrast sensitivity (a functional measure of low contrast vision) and poor cognitive performance or dementia, but no studies have investigated this association prospectively in a population-based cohort with final adjudication of mild cognitive impairment (MCI)/dementia.

METHODS

In a prospective, community-based study of aging women (Study of Osteoporotic Fractures), we analyzed whether visual contrast sensitivity was associated with increased risk of MCI or dementia and/or worse performance on various cognitive tests assessed 10 years later. Contrast sensitivity was assessed at baseline in each eye using a VISTECH VCTS 6500 wall chart. MCI/dementia was adjudicated by an expert panel. Multivariate logistic and linear regression models were analyzed.

RESULTS

Of 1,352 white (88.2%) and African American (11.8%) women with a mean age of 77.7 years (standard deviation = 3.3), 536 (39.6%) went on to develop MCI/dementia over 10 years. MCI/dementia risk was more than doubled (odds ratio = 2.16, 95% confidence interval = 1.58-2.96) in women with the lowest quartile of contrast sensitivity compared to the highest (p < 0.0001 for the linear trend). Reduced baseline contrast sensitivity was also associated with lower performance on several cognitive measures assessed 10 years later.

INTERPRETATION

Among older women, reduced contrast sensitivity is associated with a greater risk of MCI/dementia. These findings suggest that visual system neurodegeneration or dysfunction may parallel or precede dementia-related cortical or subcortical degeneration, and that contrast sensitivity testing may be useful in identifying aging adults at high risk for dementia. Ann Neurol 2018;83:730-738.

Comparison of vision-related quality of life in primary open-angle glaucoma and dry-type age-related macular degeneration

PurposeTo compare quality of life (QoL) in patients with primary open-angle glaucoma (POAG) and dry-type age-related macular degeneration (AMD) with similar best-corrected visual acuity.MethodsAge-, sex-, and visual acuity-matched POAG and dry AMD patients were included in the study. Each patient performed 24-2 and 10-2 SITA standard visual field tests. Contrast sensitivity was evaluated with CSV-1000 HGT instrument. The 25 item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) was used to analyze QoL. Overall and subscale scores were converted to scores between 0 and 100, the higher scores indicating better vision-related QoL.ResultsOverall NEI-VFQ-25 scores were 86.44 and 84.66 in glaucoma and AMD groups, respectively (P=0.244). The highest scores were obtained in 'vision-related dependency' subgroup in glaucoma and 'color and peripheral vision' in AMD group, whereas the lowest scores were noted 'in peripheral vision' in both glaucoma and AMD patients. Glaucoma patients had significantly lower scores in ocular pain, color vision, and peripheral vision subgroups compared with the AMD group, whereas AMD patients had lower scores in near and distance vision activities, vision-related social activity, and dependency subgroups. Contrast sensitivity results and mean defect values showed correlation with NEI-VFQ-25 scores in both groups.ConclusionsGlaucoma and AMD patients with similar visual acuity experienced similar overall impairment in QoL. However, glaucoma patients described more difficulty with peripheral vision and ocular pain, whereas AMD patients complained more about near and distance vision and dependency items.

The Effect of Cataract on Early Stage Glaucoma Detection Using Spatial and Temporal Contrast Sensitivity Tests

BACKGROUND

To investigate the effect of cataract on the ability of spatial and temporal contrast sensitivity tests used to detect early glaucoma.

METHODS

Twenty-seven glaucoma subjects with early cataract (mean age 60 ± 10.2 years) which constituted the test group were recruited together with twenty-seven controls (cataract only) matched for age and cataract type from a primary eye care setting. Contrast sensitivity to flickering gratings at 20 Hz and stationary gratings with and without glare, were measured for 0.5, 1.5 and 3 cycles per degree (cpd) in central vision. Perimetry and structural measurements with the Heidelberg Retinal Tomograph (HRT) were also performed.

RESULTS

After considering the effect of cataract, contrast sensitivity to stationary gratings was reduced in the test group compared with controls with a statistically significant mean difference of 0.2 log units independent of spatial frequency. The flicker test showed a significant difference between test and control group at 1.5 and 3 cpd (p = 0.019 and p = 0.011 respectively). The percentage of glaucoma patients who could not see the temporal modulation was much higher compared with their cataract only counterparts. A significant correlation was found between the reduction of contrast sensitivity caused by glare and the Glaucoma Probability Score (GPS) as measured with the HRT (p<0.005).

CONCLUSIONS

These findings indicate that both spatial and temporal contrast sensitivity tests are suitable for distinguishing between vision loss as a consequence of glaucoma and vision loss caused by cataract only. The correlation between glare factor and GPS suggests that there may be an increase in intraocular stray light in glaucoma.

The Spaeth/Richman contrast sensitivity test (SPARCS): design, reproducibility and ability to identify patients with glaucoma

AIMS

(1) To determine the ability of a novel, internet-based contrast sensitivity test titled the Spaeth/Richman Contrast Sensitivity Test (SPARCS) to identify patients with glaucoma. (2) To determine the test-retest reliability of SPARCS.

METHODS

A prospective, cross-sectional study of patients with glaucoma and controls was performed. Subjects were assessed by SPARCS and the Pelli-Robson chart. Reliability of each test was assessed by the intraclass correlation coefficient and the coefficient of repeatability. Sensitivity and specificity for identifying glaucoma was also evaluated.

RESULTS

The intraclass correlation coefficient for SPARCS was 0.97 and 0.98 for Pelli-Robson. The coefficient of repeatability for SPARCS was ±6.7% and ±6.4% for Pelli-Robson. SPARCS identified patients with glaucoma with 79% sensitivity and 93% specificity.

CONCLUSIONS

SPARCS has high test-retest reliability. It is easily accessible via the internet and identifies patients with glaucoma well.

TRIAL REGISTRATION

NCT01300949.

National Eye Institute Visual Function Questionnaire: usefulness in glaucoma

The National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25) is the most commonly used patient-reported outcome measure to assess vision-related quality of life in patients with glaucoma. Glaucoma negatively affects the composite and several NEI-VFQ subscale scores; this effect is correlated with the severity of glaucomatous visual field loss. Contrast sensitivity, glare, and dark adaptation are potential items that could be added to the NEI-VFQ to make it more responsive to changes in vision-related quality of life in patients with glaucoma.

[Importance of flicker contrast tests in functional glaucoma diagnostics]

One of the many unsolved problems concerning glaucoma is early detection and many different methodologies have been developed. This article concentrates on methodologies belonging to the class of flicker contrast tests which present dynamic stimuli (with temporal frequencies generally above 10 Hz) and assess the perceptual thresholds for contrast, be it global or locally resolved. The tests include global flicker sensitivity, flicker perimetry (current embodiment: Pulsar), Rauschfeld campimetry, frequency doubling perimetry and flicker-defined edge perimetry. These different approaches are placed into historical perspective and are critically assessed.

Defining the nature of motion perception deficits in glaucoma using simple and complex motion stimuli

PURPOSE

The purpose of this study is to determine the nature of motion perception deficits in primary open-angle glaucoma by measuring the sensitivity of simple (luminance-defined) and complex (texture-defined) motion, the latter requiring supplementary neural processing to be resolved. These findings will help address the possible extent of the cortical damage in glaucoma that has been recently demonstrated by anatomic and physiological studies. They also serve the purpose of establishing which motion paradigms would be most appropriate for assessing glaucoma-related functional loss.

METHODS

Direction-identification thresholds for first-order and second-order motion were measured for 26 patients with primary open-angle glaucoma (for both phakic and pseudophakic) and 18 nonglaucomatous observers.

RESULTS

The glaucomatous observers showed significantly increased motion thresholds for both first- and second-order motion conditions when compared with nonglaucomatous observers. However, the relative increase in threshold for first-order motion did not differ significantly from that of second-order motion.

CONCLUSIONS

These findings imply that there is no measurable higher-level cortical function damage caused by the glaucomatous process because no greater loss in second-order motion was observed. Based on the results, we suggest that motion paradigms used to assess functional loss in primary open-angle glaucoma should consist of simple, first-order type stimuli to minimize potential confounds such as those introduced by both the normal and pathologic aging process on complex motion processing (i.e., perimetry using complex motion stimuli).

Beyond visual acuity: new and complementary tests of visual function

Visual acuity is an essential component of the routine ophthalmic examination and the most common measure of visual function. There is increasing recognition, however, of the need to evaluate visual function beyond the limited extent afforded by visual acuity. The primary objective of this article is to introduce a variety of new and lesser-used techniques for measuring visual function that complement visual acuity assessment, each of which has been shown to detect visual dysfunction in patients with normal visual acuity.

Psychophysical examination of paracentral defects in glaucoma

More than 50% of ganglion cells may be damaged before visual field loss is measurable by conventional methods in primary open angle glaucoma. There is general agreement on the need to improve early diagnosis of visual field loss in primary open angle glaucoma. In this article, new techniques that enlist measurement of paracentral regions are discussed, and the ability of each method to detect visual field loss prior to perimetric loss is described.