Photophobia: When Light Hurts, a Review

Modified Sodium hyaluronate conjugated to riboflavin (Har® 0.1 %) as lubricant eyedrops in the treatment of dry eye: A prospective randomised study

Background

This study evaluates the therapeutic efficacy of HAr® (a novel ophthalmic solution containing modified hyaluronic acid covalently linked to riboflavin) compared to hyaluronic acid eye drops in patients with dry eye disease (DED).

Methods

Sixteen consecutive patients with bilateral medium to severe DED were divided into two groups. Group 1 received HAr® 0.1 % (Ribohyal®), while Group 2 received HA 0.1 % eye drops. Parameters such as Ocular Surface Disease Index (OSDI) score, osmolarity, break-up time (BUT), non-invasive BUT (NIBUT), tear meniscus measurement, Schirmer test, and Oxford Staining were evaluated. This study has been successfully registered on ClinicalTrials.gov public (Identifier NCT06122428).

Results

The Ribohyal group showed faster improvement in OSDI scores, with a statistically significant difference at 2 h (mean classification difference: -51.75; p = 0.0003). Photophobia significantly reduced at 2 h, 4 weeks, and 8 weeks in the Ribohyal group compared to baseline (p < 0.0001). Osmolarity improved significantly after 8 weeks in both groups (p < 0.0001).

Conclusions

HAr® 0.1 % (Ribohyal®) effectively reduced DED symptoms and improved photophobia within 2 h of instillation, lasting up to 8 weeks.

Hypersensitivity of Intrinsically Photosensitive Retinal Ganglion Cells in Migraine Induces Cortical Spreading Depression

Migraine is a complex disorder characterized by episodes of moderate-to-severe, often unilateral headaches and generally accompanied by nausea, vomiting, and increased sensitivity to light (photophobia), sound (phonophobia), and smell (hyperosmia). Photophobia is considered the most bothersome symptom of migraine attacks. Although the underlying mechanism remains unclear, the intrinsically photosensitive retinal ganglion cells (ipRGCs) are considered to be involved in photophobia associated with migraine. In this study, we investigated the association between the sensitivity of ipRGCs and migraines and cortical spreading depression (CSD), which may trigger migraine attacks. The pupillary responses closely associated with the function of ipRGCs in patients with migraine who were irradiated with lights were evaluated. Blue (486 nm) light irradiation elicited a response from ipRGCs; however, red light (560 nm) had no such effect. Melanopsin, a photosensitive protein, phototransduces in ipRGCs following blue light stimulation. Hypersensitivity of ipRGCs was observed in patients with migraine. CSD was more easily induced with blue light than with incandescent light using a mouse CSD model. Moreover, CSD was suppressed, even in the presence of blue light, after injecting opsinamide, a melanopsin inhibitor. The hypersensitivity of ipRGCs in patients with migraine may induce CSD, resulting in migraine attacks.

Visual Snow Syndrome in Patient with Migraine: Case Report and Literature Review

Visual snow syndrome (VSS) is a rarely diagnosed neurological phenomenon. It is a visual disorder characterised by the presence of numerous white, black, or translucent dots in the visual field, resembling the 'snow' of an analogue TV set experiencing reception interference. According to The International Classification of Headache Disorders, 3rd edition, visual snow is defined as a pattern of continuous small dots across the visual field lasting >3 months and accompanied by at least two of the following four additional symptoms: palinopsia, increased entoptic phenomena, photophobia, and nyctalopia. These complaints are not consistent with a typical migraine with visual aura and cannot be better explained by another disorder. The authors present the case of a 39-year-old woman who was diagnosed with VSS. The symptoms appeared after a migraine attack and had not alleviated. The patient reported a sensation of constant 'TV screen snow'. A neurological examination found no signs of focal damage to the nervous system. The results of the ophthalmological examination, MRI of the brain with contrast, MRI of the eye sockets, and EEG were normal. VSS is a phenomenon that is still not fully understood, different from migraine aura and associated with a number of additional symptoms. VSS is very difficult to treat. In this case, a lot of drugs were used without improvement. Further research must be conducted to determine the best treatment options for these patients.

Psychometric Properties of the Persian Translation of the 12-Item Utah Photophobia Symptom Impact Scale Questionnaire

To translate the the Utah Photophobia Symptom Impact Scale-12 questionnaire into Persian and assess the psychometric aspects to check its validity and reliability based on the Rasch modelling method. Translation and cultural adjustment of the English language UPSIS-12 questionnaire to Persian was undertaken. A total of 61 patients with complaints of photophobia participated in evaluating validity and reliability aspects. All the participants were asked to complete the Persian translation of the UPSIS-12 questionnaire. Rasch analyses of the survey items were conducted using WINSTEPS. All items fit the Rasch model. Point-measure correlation values varied from 0.41 to 0.77, providing a preliminary indication of adequate construct validity. All factor loadings were found more than 0.4. All items obtained infit and outfit mean square (MnSq) values of < 2.0. All participants except 5 had normal outfit values. Patients' abilities relative to the items' difficulty were analysed. Item difficulty was estimated and item characteristic curves were included. Sufficient unidimensionality, hierarchical order, and equal interval scoring were obtained. In conclusion, the Persian UPSIS-10 questionnaire has excellent psychometric properties and it will be valuable in both clinical practice and research. It will help Persian practitioners to assess their patients' photophobia.

Reduction in retinal microvascular perfusion during migraine attacks

OBJECTIVE

To determine if there are changes in structure and function of the retinal vasculature during and between migraine attacks using optical coherence tomography angiography (OCTA).

BACKGROUND

Migraine attacks commonly include visual symptoms, but the potential role of the retina in these symptoms is not well understood. OCTA is a rapid, non-invasive imaging technique that is used to visualize the retinal microvasculature with high spatial resolution in a clinical setting. In this study we used OCTA to quantify different features of the retinal vasculature in patients with migraine during and between attacks, as well as in healthy controls (HCs).

METHODS

We performed a prospective cohort study of 37 patients with migraine with aura (MA) (median [interquartile range, IQR] age of 37 [14] years, 86% female) and 30 with migraine without aura (MO) (median [IQR] age of 37 [17] years, 77% female) and 20 HCs (median [IQR] age of 35 [7] years, 50% female). Macular OCTA scans were obtained for all participants for the interictal analysis. In 12 MA and eight MO, scans were captured both during and outside of migraine attacks and five HCs had initial and repeat scans. In addition to analyzing the morphology of the foveal avascular zone, we calculated the vessel flux index (VFI), which is an indicator of retinal perfusion and conventional metrics (such as vessel area density) in the foveal and parafoveal regions.

RESULTS

There was a significant difference in the parafoveal VFI in the ictal state between the groups (p = 0.009). During migraine attacks there was a significant reduction in the parafoveal region VFI in MA (-7%, 95% confidence interval [CI] -10% to -4%; p = 0.006) and MO (-7%, 95% CI -10% to -3%; p = 0.016) from their interictal baseline as compared to the change between repeat scans in HCs (2%, 95% CI -3% to 7%). Interictally, there was a mean (standard deviation [SD]) 13% (10%) (p = 0.003) lower blood perfusion in the MA group as compared to the MO group in the foveal region (mean [SD] 0.093 [0.023] vs. 0.107 [0.021], p = 0.003). Interictal analysis also revealed higher circularity in the superficial foveal avascular zone in the MA group compared with the MO group (mean [SD] 0.686 [0.088] vs. 0.629 [0.120], p = 0.004). In addition, interictal analysis of the patients with MA or MO and unilateral headache showed increased retinal vascular parameters consistent with greater perfusion in the eye ipsilateral to the side of the pain as compared with the contralateral eye.

CONCLUSIONS

These results indicate that perfusion is reduced in MA and MO in the parafoveal retina during the ictal period. Interictally, the foveal retina in MA has reduced perfusion when compared to the foveal retina in MO. Patients with unilateral headache showed interictal asymmetry of retinal perfusion between eyes. These results indicate that changes in retinal perfusion could be a part of migraine pathophysiology, and that distinct retinal vascular signatures identified with OCTA could represent biomarkers for migraine.

The photic blink reflex as an index of photophobia

Two recent studies of eye closure triggered by intense luminance increase suggest that this behavior reflects the melanopsin-based retinal activity known to underlie photophobia, the pathological aversion to light (Kardon, 2012; Kaiser et al., 2021). Early studies of the photic blink reflex (PBR) are reviewed to help guide future research on this possible objective index of photophobia. Electromyographic recordings of the lid-closure muscle, orbicularis oculi, reveal distinct bursts with typical onset latencies of 50 and 80 ms, R50 and R80, respectively. The latter component appears to be especially sensitive to visual signals from intrinsically photosensitive retinal ganglion cells (ipRGCs) and to prior trigeminal nociceptive stimuli. The authors argue that the R80's function, in addition to protecting the eyeballs from physical contact, is to shape the upper and lower eyelids into a narrow slit to restrict incoming light. This serves to prevent retinal bleaching or injury, while allowing continued visual function.

Photophobia and migraine outcome during treatment with galcanezumab

Background

Calcitonin gene-related peptide (CGRP) plays a pivotal role in migraine physiology, not only regarding migraine pain but also associated symptoms such as photophobia. The aim of the present study was to assess monoclonal antibodies targeting CGRP efficacy not only in terms of headache and migraine frequency and disability but also in reducing ictal photophobia.

Material and methods

This is a retrospective observational study, conducted at the Headache Center-ASST Spedali Civili Brescia. All patients in monthly treatment with galcanezumab with at least a 6-month follow-up in September 2022 with reported severe photophobia during migraine attacks were included. Data regarding headache frequency, analgesics consumption, and migraine disability were collected quarterly. Moreover, patients were asked the following information regarding photophobia: (1) whether they noticed an improvement in photophobia during migraine attacks since galcanezumab introduction; (2) the degree of photophobia improvement (low, moderate, and high); and (3) timing photophobia improvement.

Results

Forty-seven patients were enrolled in the present study as they met the inclusion criteria. Seventeen patients had a diagnosis of high-frequency episodic migraine and 30 of chronic migraine. From baseline to T3 and T6, a significant improvement in terms of headache days (19.2 ± 7.6 vs. 8.6 ± 6.8 vs. 7.7 ± 5.7; p < 0.0001), migraine days (10.4 ± 6.7 vs. 2.9 ± 4.3 vs. 3.6 ± 2.8; p < 0.0001), analgesics consumption (25.1 ± 28.2 vs. 7.6 ± 7.5 vs. 7.6 ± 8.1; p < 0.0001), MIDAS score (82.1 ± 48.4 vs. 21.6 ± 17.6 vs. 18.1 ± 20.5; p < 0.0001), and HIT-6 score (66.2 ± 6.2 vs. 57.2 ± 8.6 vs. 56.6 ± 7.6; p < 0.0001) was found. Thirty-two patients (68.1%) reported a significant improvement in ictal photophobia, with over half of the patients reporting it within the first month of treatment. Photophobia improvement was more frequent in patients with episodic migraine (p = 0.02) and triptans responders (p = 0.03).

Conclusions

The present study confirms previous reports regarding galcanezumab efficacy beyond migraine frequency. In particular, over 60% of patients, in our cohort, documented a significant improvement also in reducing ictal photophobia. This improvement was, in most patients, moderate to high, and within the first 6 months of treatment, regardless of the clinical response on migraine frequency.

Intercritical photophobia in the migrainous patient. Proposal for diagnostic criteria

INTRODUCTION

Photophobia is a symptom of abnormal light intolerance without pain sensation that requires an anamnesis and an examination to diagnose an underlying etiology.

BASIC PROCEDURE

This article focuses on 30 clinical cases with isolated intense photophobia and on the review of the literature.

OBJECTIVE

The purpose of this article is to establish diagnostic criteria for photophobia.

RESULTS

The etiology of photophobia appears to be at the level of the intrinsically photosensitive retinal ganglion cells known as melanopsin cells and at a neurochemical level mediated by calcitonin-related peptide and the pituitary activating peptide cyclase.

CONCLUSION

The treatment of photophobia could consist of monoclonal antibodies against calcitonin-related peptide and/or pituitary activating peptide cyclase.

Photophobia and disability glare in adult patients with Marfan syndrome: a case-control study

PURPOSE

The aim of the present study was to investigate photophobia and disability glare in adult patients with Marfan syndrome (MFS).

METHODS

In this case-control study, 44 patients with MFS (87 eyes) were compared to 44 controls (88 eyes), who were matched for age and sex. The subjects were asked to grade their photophobia and glare using 10-cm visual analogue scales (VAS), which were marked with 'never' at zero and 'always' at 10 -cm. In addition, disability glare was measured with C-Quant straylight meter.

RESULTS

The patients with MFS had significantly higher VAS scores than the controls in four out of seven statements related to photophobia and glare. When including cataract, spherical equivalent, iris colour, axial length and corneal curvature, three of the seven statements were still significantly different between the two groups. The mean straylight values were 1.29 ± 0.03 log(s) in the MFS group and 1.01 ± 0.03 log(s) in the control group (p < 0.001, mixed model). These differences remained significant after adjusting for cataract, spherical equivalent, iris colour, axial length and corneal curvature.

CONCLUSION

Patients with MFS reported more photophobia and had a higher straylight value than the control group. Awareness of these findings of more photophobia and glare in the MFS patients is important when counselling and treating these patients.

Impact of Greater Occipital Nerve Block on Photophobia Levels in Migraine Patients

BACKGROUND

To study the effect of greater occipital nerve (GON) block on migraine-associated photophobia levels. Photophobia is one of the most bothersome symptoms reported by migraine patients. Studies investigating the impact of migraine treatment on this symptom are scarce.

METHODS

This is an observational prospective case-control study. Patients with migraine and photophobia attending a Headache Clinic were recruited. Cases were defined as patients in whom GON block was performed, following usual clinical practice guidelines. All patients were evaluated with the Hospital Anxiety and Depression Scale, the Migraine Specific Quality of Life Questionnaire, the Utah Photophobia Symptom Impact Scale (UPSIS-12), and the Korean Photophobia Questionnaire (KUMC-8); both in the first visit (V1) and one week after (V2).

RESULTS

Forty-one patients were recruited, 28 (68.3%) cases and 13 (31.7%) controls. At V1, there were no significant differences in the median [p25-p75] score of UPSIS-12 in cases vs controls (32.0 [21.0-34.0] vs 30.5 [22.0-37.0], P = 0.497) or KUMC-8 (6.5 [5.5-7.0] vs 7.0 [6.0-8.0], P = 0.463). At V2, cases experimented a significant improvement in UPSIS-12 of -5.5 [-8.8 to -1.3] and in KUMC-8 of -0.5 [-2.0 to 0], whereas there were no significant changes in the control group. Migraine with aura patients presented higher UPSIS-12 score at V1 (33.5 [24.5-37.0] vs 26.0 [16.0-35.0]) and lesser improvement at V2 after GON block compared with migraine without aura patients (-4.0 [-6.0 to -1.0] vs -8.0 [-17.0 to -2.0]), although statistical significance was not achieved (P = 0.643 and P = 0.122, respectively). There was no significant variation in the remaining scales.

CONCLUSIONS

Greater occipital nerve block improves migraine-associated photophobia, measured with UPSIS-12 and KUMC-8. Patients without aura may exhibit a greater improvement. Physicians could consider GON block for management of photophobia in migraine patients.

Supraspinal Mechanisms Underlying Ocular Pain

Supraspinal mechanisms of pain are increasingly understood to underlie neuropathic ocular conditions previously thought to be exclusively peripheral in nature. Isolating individual causes of centralized chronic conditions and differentiating them is critical to understanding the mechanisms underlying neuropathic eye pain and ultimately its treatment. Though few functional imaging studies have focused on the eye as an end-organ for the transduction of noxious stimuli, the brain networks related to pain processing have been extensively studied with functional neuroimaging over the past 20 years. This article will review the supraspinal mechanisms that underlie pain as they relate to the eye.

Multi-professional Neurorehabilitation after Covid-19 Infection Should Include Assessment of Visual Function

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Visual function should be considered when reviewing the rehabilitation needs of patients after COVID-19.

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The association between vision-related issues and coexisting symptoms with an effect on body function and activity and/or participation highlights the need for multiprofessional rehabilitation assessment and intervention after COVID-19.

Objective

To report vision-related symptoms and neuro-visual clinical signs in patients approximately 4 months after discharge from hospitalization after COVID-19 infection. To report on coexisting functional and activity limitations.

Design

The study is part of an ambidirectional population-based cohort study.

Setting

An outpatient setting in a hospital environment.

Participants

Patients from a population-based cohort study including all patients with laboratory-confirmed COVID-19 admitted to hospital during a 3-month period in a health care region in Sweden. Among patients who, based on a standardized telephone interview, were identified as having persisting rehabilitation needs 4 months after discharge (n=185), several (n=57) reported vision-related symptoms. All 57 patients were invited to a neuro-visual examination. Six patients declined, 6 were unavailable, and 3 did not fulfil the inclusion criteria. Thus, 42 patients were included in the analysis (N=42).

Interventions

Not applicable.

Main Outcome Measures

Vision-related symptoms, neuro-visual function, and coexisting impairments affecting activities of daily life and participation.

Results

A total of 31% of patients with rehabilitation needs after COVID-19 reported vision-related symptoms. Reading-related issues (73.8%), blurry vision (69.0%), and light sensitivity (66.7%) were the most common symptoms. Patients with reading-related issues showed a higher level of eye strain (P<.001). Neuro-visual deficits were found in 83.3% of the patients, mainly concerning eye teaming (23.1%-66.7%) and eye movement (28.6%-30.8%) functions. Patients with vision-related symptoms reported fatigue and 18 other coexisting symptoms to a greater extent (P≤.0001 to .049).

Conclusions

Neuro-visual symptoms and signs should be considered when assessing rehabilitation needs after COVID-19. The association between vision-related issues and coexisting symptoms with an effect on body function and activity and/or participation underlines the need for multiprofessional rehabilitation assessment and intervention.

Photoaversion in inherited retinal diseases: clinical phenotypes, biological basis, and qualitative and quantitative assessment

Severe light sensitivity is a feature common to a range of ophthalmological and neurological diseases. In inherited retinal diseases (IRDs) particularly, this may be accompanied by significant visual disruption. These symptoms are extremely debilitating for affected individuals and have significant implications in terms of day-to-day activities. Underlying mechanisms remain to be fully elucidated. Currently, there are many assessments of photoaversion (PA), however, all have limitations, with quantitative measurement in particular needing further evaluation. To understand the complexities associated with photoaversion from different pathologies, qualitative and quantitative assessments of the light aversion response must be standardized. There is no treatment to date, and strategies to alleviate symptoms focus on light avoidance. With respect to IRDs, however, gene therapy is currently being investigated in clinical trials and promising and further treatments may be on the horizon. The better characterization of these symptoms is an important end point measure in IRD gene therapy trials.

Approach to Headache

There is a very high prevalence of headache in both outpatient and inpatient settings, in the United States and worldwide, due to an abundance of possible causes. Having a practical and systematic approach to evaluating and treating headache is, therefore, key to making the correct diagnosis, or possibly overlapping diagnoses. Taking a thorough and methodical headache history is the mainstay for diagnosis of both primary and secondary headache disorders. Evaluation and workup should include a complete neurological examination, consideration of neuroimaging in specific limited situations, and serum or spinal fluid analysis if indicated. Adopting a diagnostic approach to headache ensures that cannot-miss, or potentially fatal, headache syndromes are not overlooked, while resource-intensive tests are performed only on an as-needed basis.

Development and Feasibility of the Headache-Related Light and Sound Sensitivity Inventories in Youth

Youth with chronic headache disorders often experience sensitivities to light and sound that trigger or exacerbate their headaches and contribute to functional disability. At present, there are no known validated measures for assessing these sensitivities and their impact on functioning in youth with chronic headaches. This pilot study sought to develop and assess the feasibility of measures of headache-related light and sounds sensitivities in youth with chronic headache disorders. The initial item pools were generated via an intensive literature review, an informal quality improvement project, and a panel of experts in chronic pain. Then, youth (n = 20) presenting for clinical evaluation of headaches completed the revised items as well as assessments of the measures’ feasibility and items’ understandability. A subset (n = 2) completed formal cognitive interviews as well. The resulting 20-item Headache-Related Light Sensitivity Inventory (HALSI) and 18-item Headache-Related Sound Sensitivity Inventory (HASSI) for youth assess headache-related sensory sensitivities, as well as related emotional and behavioral responses. Through the iterative incorporation of feedback, these measures appear to be feasible to administer and understandable tools for assessing light and sound sensitivity in youth with chronic headache disorders. Once they are empirically validated, they have the potential to serve as important tools for understanding the patient experience, developing interventions, and assessing treatment response.

Managing Photophobia with the Utilisation of Smart Light Bulbs

Photophobia can affect a person's quality of life. We present a case of idiopathic photophobia that was successfully managed with smart light bulbs that allowed the patient to participate in daily activities. Smart light can complement other treatment options including tinted lenses. In conclusion, smart light is a novel way of treating photophobia and should be considered by clinicians.

Photophobia Associated with Traumatic Brain Injury: A Systematic Review and Meta-analysis

SIGNIFICANCE

This study reports the prevalence and relative risk of photophobia in patients with traumatic brain injury (TBI).

OBJECTIVES

This study aimed to conduct a systematic review and meta-analysis to determine the prevalence and relative risk of photophobia in patients with TBI.

DATA SOURCES

Three databases were used for literature search: PubMed, EMBASE, and Cochrane Library.

STUDY APPRAISAL AND SYNTHESIS METHODS

Publications reporting the prevalence of photophobia after TBI in patients of any age were included. A series of meta-regression analyses based on a generalized linear mixed model was performed to identify potential sources of heterogeneity in the prevalence estimates.

RESULTS

Seventy-five eligible publications were identified. The prevalence of photophobia was 30.46% (95% confidence interval [CI], 20.05 to 40.88%) at 1 week after the injury. Prevalence decreased to 19.34% (95% CI, 10.40 to 28.27%) between 1 week and 1 month after TBI and to 13.51% (95% CI, 5.77 to 21.24%) between 1 and 3 months after the injury. The rapid decrease in the prevalence of photophobia in the first 3 months after a TBI injury was significant (P < .001). Three months post-TBI, the prevalence of photophobia leveled off to a near plateau with nonsignificant variability, increasing between 3 and 6 months (17.68%; 95% CI, 9.05 to 26.32%) and decreasing between 6 and 12 months since TBI (14.85%; 95% CI, 6.80 to 22.90%). Subgroup analysis of 14 publications that contained control data showed that the estimated risk ratio for photophobia was significantly higher in the TBI than in the control group during the entire 12 months after TBI.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

This study demonstrates that photophobia is a frequent complaint after TBI, which largely resolves for many individuals within 3 months after the injury. For some patients, however, photophobia can last up to 12 months and possibly longer. Developing an objective quantitative methodology for measuring photophobia, validating a dedicated photophobia questionnaire, and having a specific photophobia International Classification of Diseases, Tenth Revision code would greatly improve data gathering and analysis.

Long-lasting disabling photophobia after uneventful cataract surgery

The case concerns a 54-year-old woman, with a history of fibromyalgia and normal preoperative ocular and systemic study, who presented with a long-lasting disabling photophobia, after sequential bilateral cataract surgery without complications. Photophobia was accompanied by good uncorrected VA, with no pain or subjective eye discomfort, without migraine or indicators of psychic conflict. It was refractory to any prescribed treatment of the ocular surface, finally responding to oral anticonvulsants (carbamazepine) that are frequently used in neuropathic pain. To the best of our knowledge this is the first reported case of a long-lasting disabling photophobia without pain and good VA after cataract surgery.

Spatial sensitivity of human circadian response: Melatonin suppression from on-axis and off-axis light exposures

A better understanding of the spatial sensitivity of the human circadian system to photic stimulation can provide practical solutions for optimized circadian light exposures. Two psychophysical experiments, involving 25 adult participants in Experiment 1 (mean age = 34.0 years [SD 15.5]; 13 females) and 15 adult participants in Experiment 2 (mean age = 43.0 years [SD 12.6]; 12 females), were designed to investigate whether varying only the spatial distribution of luminous stimuli in the environment while maintaining a constant spectrally weighted irradiance at the eye could influence nocturnal melatonin suppression. Two spatial distributions were employed, one where the luminous stimulus was presented On-axis (along the line of sight) and one where two luminous stimuli were both presented Off-axis (laterally displaced at center by 14°). Two narrowband LED light sources, blue (λ_max  = 451 nm) for first experiment and green (λ_max  = 522 nm) for second experiment, were used in both the On-axis and the Off-axis spatial distributions. The blue luminous stimulus targeting the fovea and parafovea (On-axis) was about three times more effective for suppressing melatonin than the photometrically and spectrally matched stimulus targeting the more peripheral retina (Off-axis). The green luminous stimulus targeting the fovea and parafovea (On-axis) was about two times more effective for suppressing melatonin than the photometrically and spectrally matched stimulus targeting the more peripheral retina (Off-axis).

Mechanisms and Pathways of Pain Photobiomodulation: A Narrative Review

A growing body of evidence supports the modulation of pain by light exposure. As such, phototherapy is being increasingly utilized for the management of a variety of pain conditions. The modes of delivery, and hence applications of phototherapy, vary by wavelength, intensity, and route of exposure. As such, differing mechanisms of action exist depending upon those parameters. Cutaneous application of red light (660 nm) has been shown to reduce pain in neuropathies and complex regional pain syndrome-I, whereas visual application of the same wavelength of red light has been reported to exacerbate migraine headache in patients and lead to the development of functional pain in animal models. Interestingly visual exposure to green light can result in reduction in pain in variety of pain conditions such as migraine and fibromyalgia. Cutaneous application typically requires exposure on the order of minutes, whereas visual application requires exposure on the order of hours. Both routes of exposure elicit changes centrally in the brainstem and spinal cord, and peripherally in the dorsal root ganglia and nociceptors. The mechanisms of photobiomodulation of pain presented in this review provide a foundation in furtherance of exploration of the utility of phototherapy as a tool in the management of pain. PERSPECTIVE: This review synopsizes the pathways and mechanisms through which light modulates pain and the therapeutic utility of different colors and exposure modalities of light on pain. Recent advances in photobiomodulation provide a foundation for understanding this novel treatment for pain on which future translational and clinical studies can build upon.

Interventions for quality of life and related outcomes among unpaid caregivers of older adults with visual impairments: A scoping review

Unpaid family caregivers play a critical role in the care of older adults with visual impairments. Caring for older adults with visual impairments requires much time and energy, often resulting in psychological stress and reduced quality of life for the unpaid caregiver. However, there is a paucity of data on the impact of caregiving on quality of life and related outcomes among these caregivers. The purpose of this study was to conduct a scoping review examining issues of quality of life, health, stress, burden, and barriers among unpaid caregivers of older adults with visual impairments. The study also aimed to summarize interventions for addressing these issues. This study followed the Arksey and O’Malley five-stage approach for scoping reviews. We performed a search of published peer-reviewed articles available in PubMed, CINAHL Complete, and PsycINFO to identify relevant studies. Two reviewers conducted the screening of titles, abstracts, and full-texts. A total of 24 articles were eligible for full-text screening from the 452 records identified, and 5 articles met the final inclusion criteria. The following four themes were identified: (1) prevalence of quality of life–related barriers among unpaid caregivers of older adults with visual impairments; (2) adverse events among unpaid caregivers of older adults with visual impairments; (3) interventions for unpaid caregivers of older adults with visual impairments; and (4) potential impacts of intervention on unpaid caregivers of older adults with visual impairments. These findings point to a lack of interventions for unpaid caregivers of older adults with visual impairments, despite the prevalence of quality of life–related barriers and adverse events in this population. This study aligns with the social model of disability as it relates to the failure of the system to meet the needs of older adults with visual impairments. Research addressing these issues is urgently needed.

Photophobia in complex regional pain syndrome: visual discomfort is greater on the affected than unaffected side

ABSTRACT

In complex regional pain syndrome (CRPS), hyperalgesia encompasses uninjured sites on the ipsilateral side of the body and may also include the special senses because auditory discomfort often is greater on the CRPS-affected side. To determine whether this hemilateral hyperalgesia involves the visual system, the discomfort threshold to a light-source that increased in intensity at 100 lux/second from 500 to 3600 lux was investigated for each eye, and the nasal and temporal half of each visual field, in 33 patients with CRPS and 21 pain-free controls. Recent headache history was reviewed and, in patients with CRPS, sensitivity to mechanical and thermal stimuli was assessed in all 4 limbs and on each side of the forehead. In addition, the pupils were photographed in dim and bright light. The visual discomfort threshold was lower in patients than controls and was lower on the CRPS-affected than unaffected side (P < 0.001), indicating photophobia. Visual discomfort was unrelated to pupil diameter. Headache frequency was greater in CRPS patients than controls, and unilateral headaches were more likely to be on the CRPS-affected than contralateral side. Similarly, mechanical and thermal hyperalgesia was greater in the CRPS-affected than contralateral limb and was greater ipsilateral than contralateral to CRPS in the forehead and nonsymptomatic limbs. Ipsilateral photophobia was associated with mechanical and thermal hyperalgesia in the ipsilateral forehead but not the CRPS-affected limb. Together, these findings suggest that aberrant processing of nociceptive input in the ipsilateral trigeminal-medullary region of the brainstem contributes to visual discomfort in CRPS.

Intercritical photophobia in the migraineous patient. Proposal for diagnostic criteria

INTRODUCTION

Photophobia is a symptom of abnormal light intolerance without pain sensation that requires an anamnesis and an examination to diagnose an underlying etiology.

BASIC PROCEDURE

This article focuses on 30 clinical cases with isolated intense photophobia and on the review of the literature.

OBJECTIVE

The purpose of this article is to establish diagnostic criteria for photophobia.

RESULTS

The etiology of photophobia appears to be at the level of the intrinsically photosensitive retinal ganglion cells known as melanopsin cells and at a neurochemical level mediated by calcitonin-related peptide and the pituitary activating peptide cyclase.

CONCLUSION

The treatment of photophobia could consist of monoclonal antibodies against calcitonin-related peptide and/or pituitary activating peptide cyclase.

Connections between intrinsically photosensitive retinal ganglion cells and TBI symptoms

The majority of patients with traumatic brain injury (TBI) are classified as having a mild TBI. Despite being categorized as mild, these individuals report ongoing and complex symptoms, which negatively affect their ability to complete activities of daily living and overall quality of life. Some of the major symptoms include anxiety, depression, sleep problems, headaches, light sensitivity, and difficulty reading. The root cause for these symptoms is under investigation by many in the field. Of interest, several of these symptoms such as headaches, ocular pain, light sensitivity, and sleep disturbances may overlap and share underlying circuitry influenced by the intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells are light sensing, but non-image forming, and they influence corneal function, pupillary constriction, and circadian rhythm. In this review, we discuss these symptoms and propose a role of the ipRGCs as at least one underlying and unifying cause for such symptoms.

Favorable Effects of Tacrolimus Monotherapy on Myasthenia Gravis Patients

Background and Purpose: Tacrolimus (TAC) has been proven to be a rapid-acting, steroid-sparing agent for myasthenia gravis (MG) therapy. However, evidence related to the effectiveness of TAC alone is rare. Therefore, this study was performed to investigate the effect of TAC monotherapy in MG patients.

Methods: Forty-four MG patients who received TAC monotherapy were retrospectively analyzed. A mixed effect model was used to analyze improvements in MG-specific activities of daily living scale (MG-ADL), quantitative MG score (QMG) and MG-ADL subscores. Kaplan-Meier analysis was used to estimate the cumulative probability of minimal manifestations (MM) or better. Adverse events (AEs) were recorded for safety analyses.

Results: Of the patients receiving TAC monotherapy, MG-ADL scores were remarkably improved at 3, 6 and 12 months compared with scores at baseline (mean difference and 95% CIs: −3.29 [−4.94, −1.64], −3.97 [−5.67, −2.27], and −4.67 [−6.48, −2.85], respectively). QMG scores significantly decreased at 6 and 12 months, with mean differences and 95% CIs of −4.67(−6.88, −2.45) and −5.77 (−7.55, −4.00), respectively. Estimated median period to achieve “MM or better” was 5.0 (95% CIs, 2.8, 7.2) months. Ocular MG (OMG) and generalized MG (GMG) showed similar therapeutic effects in cumulative probabilities of “MM or better” (P-value = 0.764). A better response was observed in MG-ADL subscores for ptosis and bulbar symptoms. AEs occurred in 37.5% of patients and were generally mild and reversible.

Conclusions: TAC monotherapy is a promising option to rapidly alleviate all symptoms of MG, especially for ptosis and bulbar symptoms.

Performance of a new device for the clinical determination of light discomfort

PURPOSE

To assess the performance of a new device for the clinical determination of light discomfort on a large sample of healthy human subjects.

METHODS

A total of 489 subjects ranging from 20 to 70 years old (241 men, 248 women) were evaluated with the LUMIZ™ 100 to determine light discomfort. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Repeated measures ANOVA, Kruskal-Wallis, and correlation analysis were applied to test for differences between repeated measures, and effect of age on reliability.

RESULTS

Discomfort thresholds obtained are well distributed across the light intensity range available (25 to 10211 lux). Intrasession ICCs are higher than 0.849 for all thresholds, and 85% of CoV are below 10%. Thresholds obtained in the first set of measurements are highly correlated with the median of three sets (r2 > 0.8). Intersession, 64% of CoV are below 10%. Age does not affect discomfort thresholds (p = 0.30), nor affect reliability (variance on CoV, p = 0.368).

CONCLUSIONS

The new device provides good intrasession repeatability for the clinical determination of light discomfort thresholds, although variance is slightly greater between sessions. The system is useful for the clinical determination of light discomfort.

Wavelength of light and photophobia in inherited retinal dystrophy

Inherited retinal dystrophy (IRD) patients often experience photophobia. However, its mechanism has not been elucidated. This study aimed to investigate the main wavelength of light causing photophobia in IRD and difference among patients with different phenotypes. Forty-seven retinitis pigmentosa (RP) and 22 cone-rod dystrophy (CRD) patients were prospectively recruited. We designed two tinted glasses: short wavelength filtering (SWF) glasses and middle wavelength filtering (MWF) glasses. We classified photophobia into three types: (A) white out, (B) bright glare, and (C) ocular pain. Patients were asked to assign scores between one (not at all) and five (totally applicable) for each symptom with and without glasses. In patients with RP, photophobia was better relieved with SWF glasses {"white out" (p < 0.01) and "ocular pain" (p = 0.013)}. In CRD patients, there was no significant difference in the improvement wearing two glasses (p = 0.247-1.0). All RP patients who preferred MWF glasses had Bull's eye maculopathy. Meanwhile, only 15% of patients who preferred SWF glasses had the finding (p < 0.001). Photophobia is primarily caused by short wavelength light in many patients with IRD. However, the wavelength responsible for photophobia vary depending on the disease and probably vary according to the pathological condition.

Blue light activates pulvinar nuclei in longstanding idiopathic photophobia: A case report

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Increased fMRI activation of bilateral pulvinar nuclei with symptomatic light.

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Pulvinar nuclei are associated with melanopsin visual pathway and migraine.

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First demonstration of fMRI activation of melanopsin pathway during photophobia.

Numerous pathologies can contribute to photophobia. When considering light transduction alone, photophobia may be triggered through melanopsin pathways (non-image forming), rod and cone pathways (image-forming), or some combination of the two. We evaluated a 39 year old female patient with longstanding idiopathic photophobia that was exacerbated by blue light, and tested her by presenting visual stimuli in an event-related fMRI experiment. Analysis showed significantly greater activation in bilateral pulvinar nuclei, associated with the melanopsin intrinsically photosensitive retinal ganglion cell (ipRGC) visual pathway, and their activation is consistent with the patient's report that blue light differentially evoked photophobia. This appears to be the first demonstration of functional activation of the ipRGC pathway during photophobia in a patient.

Implication of Melanopsin and Trigeminal Neural Pathways in Blue Light Photosensitivity in vivo

Photophobia may arise from various causes and frequently accompanies numerous ocular diseases. In modern highly illuminated world, complaints about greater photosensitivity to blue light increasingly appear. However, the pathophysiology of photophobia is still debated. In the present work, we investigated in vivo the role of various neural pathways potentially implicated in blue-light aversion. Moreover, we studied the light-induced neuroinflammatory processes on the ocular surface and in the trigeminal pathways. Adult male C57BL/6J mice were exposed either to blue (400-500 nm) or to yellow (530-710 nm) LED light (3 h, 6 mW/cm2). Photosensitivity was measured as the time spent in dark or illuminated parts of the cage. Pharmacological treatments were applied: topical instillation of atropine, pilocarpine or oxybuprocaine, intravitreal injection of lidocaine, norepinephrine or "blocker" of the visual photoreceptor transmission, and intraperitoneal injection of a melanopsin antagonist. Clinical evaluations (ocular surface state, corneal mechanical sensitivity and tear quantity) were performed directly after exposure to light and after 3 days of recovery in standard light conditions. Trigeminal ganglia (TGs), brainstems and retinas were dissected out and conditioned for analyses. Mice demonstrated strong aversion to blue but not to yellow light. The only drug that significantly decreased the blue-light aversion was the intraperitoneally injected melanopsin antagonist. After blue-light exposure, dry-eye-related inflammatory signs were observed, notably after 3 days of recovery. In the retina, we observed the increased immunoreactivity for GFAP, ATF3, and Iba1; these data were corroborated by RT-qPCR. Moreover, retinal visual and non-visual photopigments distribution was altered. In the trigeminal pathway, we detected the increased mRNA expression of cFOS and ATF3 as well as alterations in cytokines' levels. Thus, the wavelength-dependent light aversion was mainly mediated by melanopsin-containing cells, most likely in the retina. Other potential pathways of light reception were also discussed. The phototoxic message was transmitted to the trigeminal system, inducing both inflammation at the ocular surface and stress in the retina. Further investigations of retina-TG connections are needed.