Objective characterization of the relative afferent pupillary defect in MS

Basics, benefits, and pitfalls of pupillometers assessing visual function

Numerous commercially and non-commercially available pupillometers are nowadays able to assess various biological functions in humans, by evaluating pupils' dynamics in response to specific stimuli. However, the use of pupillometers for ophthalmic afferent evaluations (i.e., photoreceptoral responses) in real-world settings is relatively limited. Recent scientific and technological advances, coupled with artificial intelligence methods have improved the performance of such devices to objectively detect, quantify, and classify functional disturbances of the retina and the optic nerve. This review aims to summarize the scientific principles, indications, outcomes, and current limitations of pupillometry used for evaluation of afferent pathways in ophthalmic clinical settings.

Dynamic Pupillary Response in Multiple Sclerosis Patients with and without Optic Neuritis

Multiple sclerosis (MS) is a neurodegenerative disease that affects the central nervous system which produces abnormalities in visual function, as disturbed pupillary responses, even after an episode of optic neuritis (ON). The aim was to assess different parameters of the pupillary response in MS subjects with and without ON. Therefore, 24 eyes of healthy age-matched subjects were included, 22 eyes of subjects with MS (MS group), and 13 subjects with MS with previous ON (MSON group). Pupillary parameters (ratio pupil max/min; latency; velocity and duration; contraction and dilation; and amplitude of contraction) were recorded with the MYAH topographer. Statistical analysis was performed by IBM SPSS Statistics, and parametrical or non-parametrical tests were used according to the normality of the data. MS patients did not significantly differ from healthy patients in any of the parameters analyzed (p > 0.05). Only patients with previous ON were different from healthy patients in the amplitude (40.71 ± 6.73% vs. 45.22 ± 3.29%, respectively) and latency of contraction (0.35 ± 0.13 s vs. 0.26 ± 0.05 s, respectively). The time to recover 75% of the initial diameter was abnormal in 9% of the MS subjects and 12% of MSON subjects. Based on the results of this study, the contraction process, especially latency and amplitude, was found to be affected in subjects with MS and previous ON. The degree of disability and the relation of the decrease in pupil response with other indicators of MS disease should be further investigated considering other comorbidities such as ON in the affection.

A double-blind, placebo-controlled, single-ascending-dose intravenous infusion study of rHIgM22 in subjects with multiple sclerosis immediately following a relapse

Background

Recombinant human immunoglobulin M22 (rHIgM22) has promoted remyelination in animal models and was well tolerated in people with clinically stable multiple sclerosis.

Objective

Safety/tolerability of a single rHIgM22 dose was investigated following an acute relapse and to determine whether this enhanced CNS/CSF concentrations.

Methods

Adults (N = 27) with acute relapse were assigned to rHIgM22 (0.5 or 2.0 mg/kg) or placebo. Study included screening/steroid administration periods and 10 study visits over 6 months. rHIgM22 CSF concentrations were assessed on days 2 and 29. Pharmacokinetic and safety samples were taken for up to 60 days. Assessments included adverse events and other clinical measures. Brain magnetic resonance imaging was performed with/without gadolinium.

Results

rHIgM22 CSF levels were consistent with dose-dependent concentration on both days 2 and 29. Infusion was generally well tolerated during an acute relapse. Immunogenicity was mild. Most adverse events did not appear to be dose dependent, were mild/moderate, and were events often associated with multiple sclerosis.

Conclusion

Although limited by high variability and small sample size, the data suggest enhanced CNS uptake associated with a drop in CSF levels. This study demonstrated safety of an antibody directed to myelin and oligodendrocytes in the course of active demyelinating disease. Further research into rHIgM22 is warranted.

ClinicalTrials.gov: NCT02398461 https://clinicaltrials.gov/ct2/show/study/NCT02398461?term=M22&draw=2&rank=8

Static and dynamic pupillary characteristics in multiple sclerosis

PURPOSE

To examine the static and dynamic pupillary functions with automated pupillography in multiple sclerosis (MS) patients with preserved visual acuity.

METHODS

Forty-seven MS patients with preserved visual acuity were included in the study group and 43 healthy volunteers in the control group. The visual evoked potential of the patients was obtained. After routine ophthalmologic examination contrast sensitivity and the retinal nerve fiber layer (RNFL) thickness were measured. Finally scotopic, mesopic, and photopic pupillographies followed by dynamic pupillography were undertaken, and the pupillary dilatation speed was calculated.

RESULTS

The contrast sensitivity and RNFL thickness of the MS group were significantly lower than those of the control group (p < 0.05; for both). In the MS and control groups, the scotopic pupil diameters were 5.48 ± 1.03 and 5.28 ± 0.78 mm, mesopic pupil diameters were 4.82 ± 0.83 and 4.48 ± 0.70 mm, and photopic pupil diameters were 3.84 ± 0.79 and 3.42 ± 0.49 mm, respectively (p = 0.315, p = 0.044, and p = 0.004, respectively). In dynamic pupillography, the pupil in the MS group was more dilated than control group at all time sections examined except the sixth second (p < 0.05; for all). Although the mean pupillary dilation speed in the first second was higher in the MS group (p = 0.044), there was no significant difference between the groups for the other time intervals examined (p > 0.05; for all). There was no correlation between pupillary parameters and P100-wave latency, RNFL thickness, or contrast sensitivity (p > 0.05; for all).

CONCLUSIONS

Static and dynamic pupillary functions may be affected in MS patients with preserved visual acuity. Although scotopic pupillary functions are preserved, mesopic, and photopic pupil functions are weakened.

Pupillary light reflex as a diagnostic aid from computational viewpoint: A systematic literature review

This work presents a detailed and complete review of publications on pupillary light reflex (PLR) used to aid diagnoses. These are computational techniques used in the evaluation of pupillometry, as well as their application in computer-aided diagnoses (CAD) of pathologies or physiological conditions that can be studied by observing the movements of miosis and mydriasis of the human pupil. A careful survey was carried out of all studies published over the last 10 years which investigated, electronic devices, recording protocols, image treatment, computational algorithms and the pathologies related to PLR. We present the frontier of existing knowledge regarding methods and techniques used in this field of knowledge, which has been expanding due to the possibility of performing diagnoses with high precision, at a low cost and with a non-invasive method.

A 30 s test for quantitative assessment of a relative afferent pupillary defect (RAPD): the infrared pupillary asymmetry (IPA)

BACKGROUND

Detection of a relative afferent pupillary defect (RAPD) by the swinging-light test can be challenging in clinical practice (dark eyes, anisocoria, dark environment). We developed a new method of RAPD quantification based on the recording of the infrared pupillary asymmetry (IPA) with a standard optical coherence tomography (OCT) device.

METHODS

The diagnostic value of the IPA for detection of the RAPD was determined by receiver-operating characteristic (ROC) curves and area under the curve (AUC).

RESULTS

Twenty-nine subjects were included in this study (17 controls and 12 unilateral optic neuropathies). The IPA was significantly greater in unilateral optic neuropathies (0.39) compared to controls (0.18, p = 0.001). The diagnostic value was good with a ROC-AUC of 0.843. Importantly, the IPA correlated significantly with the inter-eye percentage difference of the macular ganglion cell-inner plexiform layer (mGCIPL) thickness (R = 0.53, p = 0.01). Assessment of the IPA took less than 30 s.

CONCLUSION

The present data show that the IPA is a practical and rapid test that can be applied in a clinical setting. The IPA may be a valuable functional outcome measure for clinical trials, complementing structural retinal OCT data in a biological meaningful way. The IPA should be further investigated for suitability for optic neuritis treatment trials.

Retinal Architecture and Melanopsin-Mediated Pupillary Response Characteristics: A Putative Pathophysiologic Signature for the Retino-Hypothalamic Tract in Multiple Sclerosis

Importance

A neurophysiologic signature of the melanopsin-mediated persistent constriction phase of the pupillary light reflex may represent a surrogate biomarker for the integrity of the retinohypothalamic tract, with potential utility for investigating alterations in homeostatic mechanisms associated with brain disorders and implications for identifying new treatments.

Objective

To characterize abnormalities of retinal architecture in patients with multiple sclerosis (MS) and corresponding alterations in the melanopsin-mediated sustained pupillary constriction response.

Design, Setting, and Participants

The case-control study was an experimental assessment of various stimulus-induced pupillary response characteristics and was conducted at a university clinical center for MS from September 6, 2012, to February 2015. Twenty-four patients with MS (48 eyes) and 15 individuals serving as controls (30 eyes) participated. The melanopsin-mediated, sustained pupillary constriction phase response following cessation of a blue light stimulus was compared with the photoreceptor-mediated pupillary constriction phase response following cessation of a red light stimulus. Optical coherence tomography was used to characterize the association between pupillary response characteristics and alterations in retinal architecture, specifically, the thickness of the retinal ganglion cell layer and inner plexiform layer (GCL + IPL).

Main Outcomes and Measures

Association of pupillary response characteristics with alterations in retinal architecture.

Results

Of 24 patients with MS included in the analysis, 17 were women (71%); mean (SD) age was 47 (11) years. Compared with eyes from individuals with MS who had normal optical coherence tomography-derived measures of retinal GCL + IPL thickness, eyes of patients who had GCL + IPL thickness reductions to less than the first percentile exhibited a correspondingly significant attenuation of the melanopsin-mediated sustained pupillary response (mean [SD] pupillary diameter ratios at a point in time, 0.18 [0.1] vs 0.33 [0.09]; P < .001, generalized estimating equation models accounting for age and within-patient intereye correlations).

Conclusions and Relevance

In this case-control study, attenuation of the melanopsin-mediated sustained pupillary constriction response was significantly associated with thinning of the GCL + IPL sector of the retina in the eyes of patients with MS, particularly those with a history of acute optic neuritis. Melanopsin-containing ganglion cells in the retina represent, at least in part, the composition of the retinohypothalamic tract. As such, our findings may signify the ability to elucidate a putative surrogate neurophysiologic signature that correlates with a constellation of homeostatic mechanisms in both health and illness.

Autonomic Dysregulation in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, progressive central neurological disease characterized by inflammation and demyelination. In patients with MS, dysregulation of the autonomic nervous system may present with various clinical symptoms including sweating abnormalities, urinary dysfunction, orthostatic dysregulation, gastrointestinal symptoms, and sexual dysfunction. These autonomic disturbances reduce the quality of life of affected patients and constitute a clinical challenge to the physician due to variability of clinical presentation and inconsistent data on diagnosis and treatment. Early diagnosis and initiation of individualized interdisciplinary and multimodal strategies is beneficial in the management of autonomic dysfunction in MS. This review summarizes the current literature on the most prevalent aspects of autonomic dysfunction in MS and provides reference to underlying pathophysiological mechanisms as well as means of diagnosis and treatment.

Analysis of retinal nerve fibre layer, visual evoked potentials and relative afferent pupillary defect in multiple sclerosis patients

OBJECTIVE

The aim of this study was to analyse retinal nerve fibre layer (RNFL), pattern-reversal visual evoked potentials (pVEPs) and relative afferent pupillary defect (RAPD) changes in multiple sclerosis (MS) patients with the consideration of past optic neuritis (ON).

METHODS

Ophthalmological, neurological, OCT, RNFL and pVEP studies were conducted in 59 MS patients. RAPD tests were performed in 47 of them. Control group consisted of 28 healthy volunteers.

RESULTS

Abnormal RNFL was found in 59% of cases of eyes with ON and 28% of eyes without ON. In eyes with ON, significantly lower RNFL values were indicated in the temporal and lower quadrants. Elongation of pVEP latency was found in 83% of eyes with ON and 60% of eyes without ON. The average value of pVEP latency was larger and the amplitude was lower in the subgroup of eyes with RNFL at the borderline or below the norm. RAPD was observed only in eyes with ON and with RNFL thinning. No association was found between the RAPD and pVEP parameters.

CONCLUSIONS

VEPs were more frequently abnormal than RNFL in MS patients. RNFL damage in eyes without ON may indicate neurodegenerations in CNS of MS patients; it can also be the consequence of subclinical ON.

SIGNIFICANCE

An analysis of RNFL and VEP can be useful for evaluating the optic nerve in MS patients.

Re-evaluating the treatment of acute optic neuritis

Clinical case reports and prospective trials have demonstrated a reproducible benefit of hypothalamic-pituitary-adrenal (HPA) axis modulation on the rate of recovery from acute inflammatory central nervous system (CNS) demyelination. As a result, corticosteroid preparations and adrenocorticotrophic hormones are the current mainstays of therapy for the treatment of acute optic neuritis (AON) and acute demyelination in multiple sclerosis.Despite facilitating the pace of recovery, HPA axis modulation and corticosteroids have failed to demonstrate long-term benefit on functional recovery. After AON, patients frequently report visual problems, motion perception difficulties and abnormal depth perception despite 'normal' (20/20) vision. In light of this disparity, the efficacy of these and other therapies for acute demyelination require re-evaluation using modern, high-precision paraclinical tools capable of monitoring tissue injury.In no arena is this more amenable than AON, where a new array of tools in retinal imaging and electrophysiology has advanced our ability to measure the anatomic and functional consequences of optic nerve injury. As a result, AON provides a unique clinical model for evaluating the treatment response of the derivative elements of acute inflammatory CNS injury: demyelination, axonal injury and neuronal degeneration.In this article, we examine current thinking on the mechanisms of immune injury in AON, discuss novel technologies for the assessment of optic nerve structure and function, and assess current and future treatment modalities. The primary aim is to develop a framework for rigorously evaluating interventions in AON and to assess their ability to preserve tissue architecture, re-establish normal physiology and restore optimal neurological function.