Objective Perimetry in Sporting-Related Mild Traumatic Brain Injury

Rapid, non-contact multifocal visual assessment in multiple sclerosis

OBJECTIVE

Previous work on temporally sparse multifocal methods suggests that the results are correlated with disability and progression in people with multiple sclerosis (PwMS). Here, we assess the diagnostic power of three cortically mediated sparse multifocal pupillographic objective perimetry (mfPOP) methods that quantified response-delay and light-sensitivity at up to 44 regions of both visual fields concurrently.

METHODS

One high-spatial-resolution mfPOP method, P129, and two rapid medium-resolution methods, W12 and W20, were tested on 44 PwMS and controls. W12 and W20 took 82 s to test both visual fields concurrently, providing response delay and sensitivity at each field location, while P129 took 7 min. Diagnostic power was assessed using areas under the receiver operating characteristic (AUROC) curves and effect-size (Hedges' g). Linear models examined significance. Concurrent testing of both eyes permitted assessment of between-eye asymmetries.

RESULTS

Per-region response delays and asymmetries achieved AUROCs of 86.6% ± 4.72% (mean ± SE) in relapsing-remitting MS, and 96.5% ± 2.30% in progressive MS. Performance increased with increasing disability scores, with even moderate EDSS 2 to 4.5 PwMS producing AUROCs of 82.1 to 89.8%, Hedge's g values up to 2.06, and p = 4.0e - 13. All tests performed well regardless of any history of optic neuritis. W12 and W20 performed as well or better than P129.

CONCLUSION

Overall, the 82-s tests (W12 and W20) performed better than P129. The results suggest that mfPOP assesses a correlate of disease severity rather than a history of inflammation, and that it may be useful in the clinical management of PwMS.

Objective perimetry and progression of multiple sclerosis

Introduction

We re-examined the per-region response amplitudes and delays obtained from multifocal pupillographic objective perimetry (mfPOP) after 10 years in 44 persons living with multiple sclerosis (PwMS), both to examine which parts of the visual field had progressed in terms of response properties and to examine if the baseline data could predict the overall progression of disease.

Methods

Expanded Disability Status Scale (EDSS) scores were assessed in 2009 and 2019. Both eyes of each participant were concurrently tested at 44 locations/eye on both occasions. Several measures of clinical progression were examined, using logistic regression to determine the odds of progression.

Results

At the second examination the 44 PwMS (31 females) were aged 61.0 ± 12.2 y. Mean EDSS had not changed significantly (3.69 ± 1.23 in 2009, 3.81 ± 2.00 in 2019). mfPOP delay increased progressively from inferior to superior regions of the visual fields while amplitudes demonstrated a temporal to nasal gradient. The mean of the 3 most delayed visual field regions was correlated with progression of MS by 2019 (p = 0.023). Logistic regression indicated a significant association between delay and odds of progression (p = 0.045): an individual with 3 regions at least 1 SD (40 ms) slower than the mean in 2009 had 2.05× (±SE: 1.43× to 2.95×) the odds of progression by 2019. A 1 SD shorter delay was associated with 2.05× lower odds of progression. Amplitude changes were not predictive of progression.

Significance

mfPOP may provide a rapid, convenient method of monitoring and predicting MS progression.

Brain trauma impacts retinal processing: photoreceptor pathway interactions in traumatic light sensitivity

BACKGROUND

Concussion-induced light sensitivity, or traumatic photalgia, is a lifelong debilitating problem for upwards of 50% of mild traumatic brain injury (mTBI) cases, though of unknown etiology. We employed spectral analysis of electroretinographic (ERG) responses to assess retinal changes in mTBI as a function of the degree of photalgia.

METHODS

The design was a case-control study of the changes in the ERG waveform as a function of level of light sensitivity in individuals who had suffered incidents of mild traumatic brain injury. The mTBI participants were categorized into non-, mild-, and severe-photalgic groups based on their spectral nociophysical settings. Light-adapted ERG responses were recorded from each eye for 200 ms on-off stimulation of three spectral colors (R:red, G:green, and B:blue) and their sum (W:white) at the highest pain-free intensity level for each participant. The requirement of controls for testing hypersensitive individuals at lower light levels was addressed by recording a full light intensity series in the control group.

RESULTS

Both the b-wave and the photopic negative response (PhNR) were significantly reduced in the non-photalgic mTBI group relative to controls. In the photalgic groups, the main b-wave peak shifted to the timing of the rod b-wave, with reduced amplitude at the timing of the cone response.

CONCLUSION

These results suggest the interpretation that the primary etiology of the painful light sensitivity in mTBI is release of the rod pathway from cone-mediated inhibition at high light levels, causing overactivation of the rod pathway.

Clustered Volleys Stimulus Presentation for Multifocal Objective Perimetry

Purpose

Multifocal pupillographic objective perimetry (mfPOP) is being developed as an alternative to subjective threshold perimetry for the management of visual and neurological disorders. Here, we evaluate, in normal subjects, differences in signal quality between the original mfPOP method of spatially sparse Continuous stimulus presentation and the new Clustered Volleys (CVs) method. We hypothesized that the CVs method would lead to increased signal-to-noise ratios (SNRs) over the original method due to the stabilization of gain within the pupillary system.

Methods

Data were collected from six separate studies where otherwise-identical pairs of mfPOP tests using either the original Continuous stimulus presentation method or the new CVs method were undertaken; 440 6-minute tests from 96 normal subjects of varying ages were included. Per-region SNRs were compared between the two methods.

Results

Mean SNRs for the CVs mfPOP variants were between 35% and 57% larger than the original Continuous mfPOP variants (P < 0.001 in five of six studies). Similarly, the goodness-of-fit measure (r²) demonstrated large and significant fold increases of between 2.3× and 3.4× over the original method (all P < 0.001). Significant improvements in SNRs were present in all of the 88 test regions (44/eye), ranging between 8.4% and 93.7%; mean SNRs were significantly larger in 98% of test subjects.

Conclusions

The CVs mfPOP stimulus presentation method produced substantial increases in signal quality over the original method. This is likely due to the stabilization of pupillary gain during stimulus presentation.

Translational Relevance

These improvements increase diagnostic accuracy and have enabled shorter, 80-second mfPOP tests to be developed.

Assessing migraine patients with multifocal pupillographic objective perimetry

Background

To establish the effects of stimulating intrinsically-photosensitive retinal ganglion cells (ipRGCs) on migraine severity, and to determine if migraine produces objectively-measured visual field defects.

Methods

A randomized, open labelled, crossover study tested migraineurs and normal controls using multifocal pupillographic objective perimetry (mfPOP) with 44 test-regions/eye. A slow blue protocol (BP) stimulated ipRGCs, and a fast yellow protocol (YP) stimulated luminance channels. Migraine diaries assessed migraine severity. Per-region responses were analyzed according to response amplitude and time-to-peak.

Results

Thirty-eight migraineurs (42.0 ± 16.5 years, 23 females) and 24 normal controls (39.2 ± 15.2 years, 14 females) were tested. The proportion of subjects developing a migraine did not differ after either protocol, either during the 1st day (odds ratio 1.0; 95% confidence interval 0.2–4.4, p = 0.48) or during the first 3 days after testing (odds ratio 0.8; 95% confidence interval 0.3–2.1, p = 0.68). Migraine days/week did not increase following testing with either protocol in comparison to the baseline week (1.4 ± 1.6 pre-testing (mean ± SD), 1.3 ± 1.4 post-BP, and 1.3 ± 1.2 post-YP; p = 0.96), neither did other measures of severity. Migraine occurring up to 2 weeks before testing significantly lowered amplitudes, − 0.64 ± 0.14 dB (mean ± SE), while triptan use increased amplitudes by 0.45 ± 0.10 dB, both at p < 0.001.

Conclusions

Stimulating ipRGCs did not affect migraine occurrence or severity. Pupillary response characteristics were influenced by the occurrence of a recent migraine attack and a history of triptan use.