Patients with more severe symptoms of neuropathic ocular pain report more frequent and severe chronic overlapping pain conditions and psychiatric disease

Corneal neuropathic pain: a review to inform clinical practice

Corneal neuropathic pain (CNP) is a poorly defined disease entity characterised by an aberrant pain response to normally non-painful stimuli and categorised into having peripheral and central mechanisms, with the former responding to instillation of topical anaesthetic. CNP is a challenging condition to diagnose due to numerous aetiologies, an absence of clinical signs and ancillary tests (in vivo confocal microscopy and esthesiometry), lacking the ability to confirm the diagnosis and having limited availability. Symptomatology maybe mirrored by severe and chronic forms of dry eye disease (DED), often leading to misdiagnosis and inadequate treatment. In practice, patients with suspected CNP can be assessed with questionnaires to elicit symptoms. A thorough ocular assessment is also performed to exclude any co-existent ocular conditions. A medical and mental health history should be sought due to associations with autoimmune disease, chronic pain syndromes, anxiety and depression. Management begins with communicating to the patient the nature of their condition. Ophthalmologists can prescribe topical therapies such as autologous serum eyedrops to optimise the ocular surface and promote neural regeneration. However, a multi-disciplinary treatment approach is often required, including mental health support, particularly when there are central mechanisms. General practitioners, pain specialists, neurologists and psychologists may be needed to assist with oral and behavioural therapies. Less data is available to support the safety and efficacy of adjuvant and surgical therapies and the long-term natural history remains to be determined. Hence clinical trials and registry studies are urgently needed to fill these data gaps with the aim to improve patient care.

Genome Wide Association Study of Neuropathic Ocular Pain

Purpose

To conduct a genome-wide association study (GWAS) of individuals with neuropathic ocular pain (NOP) symptoms to identify genomic variants that may predispose to NOP development.

Design

Prospective study of individuals with NOP.

Participants

Three hundred twenty-nine patients recruited from the Miami Veterans Affairs eye clinic.

Methods

The Neuropathic Pain Symptom Inventory modified for the eye (NPSI-Eye) was completed to calculate a NPSI-Eye-Sub-Score (summed ratings of burning and wind sensitivity) as an indicator of NOP severity. A GWAS was performed for the NPSI-Eye-Sub-Score with a significance threshold of P < 5 × 10-8. A gene-based analysis was performed using the multimarker analysis of genomic annotation software (in the functional mapping and annotation of GWAS online platform). The 13 865 778 single nucleotide polymorphisms (SNPs) from our GWAS analysis were mapped to 10 834 protein coding genes, and significant genes were run through gene set enrichment analysis.

Main Outcome Measures

Identification of SNPs and protein products that may be associated with the development of NOP.

Results

One hundred seventy-one SNPs reached a threshold of P < 10-5, of which 10 SNPs reached the suggestive level of significance of P < 5 × 10-7 and 1 SNP met our genome-wide significance threshold of P < 5 × 10-8. This lead SNP, rs140293404 (P = 1.23 × 10-8), is an intronic variant found within gene ENSG00000287251 coding for transcript ENST00000662732.1. Rs140293404 is in linkage disequilibrium with exon variant rs7926353 (r2 > 0.8) within ENSG00000279046 coding for transcript ENST00000624288.1. The most significant genes from gene-based tests were matrix metalloproteinase-19 (MMP19) (P = 1.12 × 10-5), zinc finger RNA-binding motif and serine/arginine rich-1 (ZRSR1) (P = 1.48 × 10-4), CTC-487M23.8 (P = 1.79 × 10-4), receptor expression-enhancing protein-5 (REEP5) (P = 2.36 × 10-4), and signal recognition particle-19 (SRP19) (P = 2.56 × 10-4). From gene set enrichment analysis, the sensory perception (false discovery rate = 6.57 × 10-3) and olfactory signaling (false discovery rate = 1.63 × 10-2) pathways were enriched with the most significant genes.

Conclusions

Our GWAS revealed genes with protein products that may impact sensory perception, lending biological plausibility to a role for SNPs identified by our GWAS in the development of NOP. A better understanding of the biological relevance of these genes and pathways in the pathophysiology associated with NOP may facilitate future novel mechanism-based treatments.

Financial Disclosures

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

Neurophysiology of corneal neuropathic pain and emerging pharmacotherapeutics

The altered activity generated by corneal neuronal injury can result in morphological and physiological changes in the architecture of synaptic connections in the nervous system. These changes can alter the sensitivity of neurons (both second-order and higher-order projection) projecting pain signals. A complex process involving different cell types, molecules, nerves, dendritic cells, neurokines, neuropeptides, and axon guidance molecules causes a high level of sensory rearrangement, which is germane to all the phases in the pathomechanism of corneal neuropathic pain. Immune cells migrating to the region of nerve injury assist in pain generation by secreting neurokines that ensure nerve depolarization. Furthermore, excitability in the central pain pathway is perpetuated by local activation of microglia in the trigeminal ganglion and alterations of the descending inhibitory modulation for corneal pain arriving from central nervous system. Corneal neuropathic pain may be facilitated by dysfunctional structures in the central somatosensory nervous system due to a lesion, altered synaptogenesis, or genetic abnormality. Understanding these important pathways will provide novel therapeutic insight.

Disentangling the neurological basis of chronic ocular pain using clinical, self-report, and brain imaging data: use of K-means clustering to explore patient phenotypes

Introduction

The factors that mediate the expression of ocular pain and the mechanisms that promote chronic ocular pain symptoms are poorly understood. Central nervous system involvement has been postulated based on observations of pain out of proportion to nociceptive stimuli in some individuals. This investigation focused on understanding functional connectivity between brain regions implicated in chronic pain in persons reporting ocular pain symptoms.

Methods

We recruited a total of 53 persons divided into two cohorts: persons who reported no ocular pain, and persons who reported chronic ocular pain, irrespective of ocular surface findings. We performed a resting state fMRI investigation that was focused on subcortical brain structures including the trigeminal nucleus and performed a brief battery of ophthalmological examinations.

Results

Persons in the pain cohort reported higher levels of pain symptoms relating to neuropathic pain and ocular surface disease, as well as more abnormal tear metrics (stability and tear production). Functional connectivity analysis between groups evinced multiple connections exemplifying both increases and decreases in connectivity including regions such as the trigeminal nucleus, amygdala, and sub-regions of the thalamus. Exploratory analysis of the pain cohort integrating clinical and brain function metrics highlighted subpopulations that showed unique phenotypes providing insight into pain mechanisms.

Discussion

Study findings support centralized involvement in those reporting ocular-based pain and allude to mechanisms through which pain treatment services may be directed in future research.

Ocular surface itch and pain: key differences and similarities between the two sensations

PURPOSE OF REVIEW

To review the pathophysiology and treatment of ocular itch and pain, encompassing nociceptive and neuropathic categories.

RECENT FINDINGS

Ocular itch and pain are sensations that arise from activation of ocular surface polymodal nerves. Nociceptive itch, commonly comorbid with ocular pain complaints, is mainly driven by a histamine-mediated type 1 hypersensitivity reaction. Beyond topical therapy, novel drug delivery systems are being explored to improve ocular residence time of nonsteroidal anti-inflammatory drugs (NSAIDs) and antihistamines. Nociceptive ocular pain can be driven by a variety of factors. Treatment focuses on addressing the causative sources of pain. Neuropathic ocular itch and pain are driven by nerve damage and dysfunction and as such, topical and oral neuromodulation have been explored as treatments. Oral neuromodulators include alpha 2 delta ligands, tricyclic antidepressants (TCAs), and low dose naltrexone. Novel therapies are being evaluated for both modalities such as difelikefalin (κ-opioid receptor agonist) for neuropathic itch and libvatrep (transient receptor potential vanilloid 1 antagonist) for neuropathic pain.

SUMMARY

Both ocular itch and pain can be driven by nociceptive and/or neuropathic mechanisms. Identifying contributors to abnormal ocular sensations is vital for precise medical care. Novel therapeutics for these conditions aim to improve patient outcomes and quality of life.

Chemical toxic exposures and chronic ocular pain

Chronic ocular pain is a common, debilitating chronic pain condition with significant morbidity and negative impact in patients' quality of life. Several, diverse types of insults to the ocular surface can lead to acute, and under certain conditions to chronic ocular pain, and these include toxic irritants. Exposure of ocular surface to toxic irritants, in addition to direct tissue injury, carries the capacity to generated intense immune and neuronal responses with hyper-excitability, sensitization and chronic pain. Because, chronic ocular pain subsequent to toxic exposures is relatively unrecognized clinical entity, this brief review highlights pertinent concepts of its epidemiology, pathogenesis/pathophysiology, clinical progression, with recommendations for its clinical management that clinicians may find helpful. Suppression of pain signaling, generating neuronal sensitization, and prevention of chronicity of neuropathic pain is particularly emphasized in this respect.

Botulinum toxin A decreases neural activity in pain-related brain regions in individuals with chronic ocular pain and photophobia

Introduction

To examine the effect of botulinum toxin A (BoNT-A) on neural mechanisms underlying pain and photophobia using functional magnetic resonance imaging (fMRI) in individuals with chronic ocular pain.

Methods

Twelve subjects with chronic ocular pain and light sensitivity were recruited from the Miami Veterans Affairs eye clinic. Inclusion criteria were: (1) chronic ocular pain; (2) presence of ocular pain over 1 week recall; and (3) presence of photophobia. All individuals underwent an ocular surface examination to capture tear parameters before and 4-6 weeks after BoNT-A injections. Using an event-related fMRI design, subjects were presented with light stimuli during two fMRI scans, once before and 4-6 weeks after BoNT-A injection. Light evoked unpleasantness ratings were reported by subjects after each scan. Whole brain blood oxygen level dependent (BOLD) responses to light stimuli were analyzed.

Results

At baseline, all subjects reported unpleasantness with light stimulation (average: 70.8 ± 32.0). Four to six weeks after BoNT-A injection, unpleasantness scores decreased (48.1 ± 33.6), but the change was not significant. On an individual level, 50% of subjects had decreased unpleasantness ratings in response to light stimulation compared to baseline ("responders," n = 6), while 50% had equivalent (n = 3) or increased (n = 3) unpleasantness ("non-responders"). At baseline, several differences were noted between responders and non-responders; responders had higher baseline unpleasantness ratings to light, higher symptoms of depression, and more frequent use of antidepressants and anxiolytics, compared to non-responders. Group analysis at baseline displayed light-evoked BOLD responses in bilateral primary somatosensory (S1), bilateral secondary somatosensory (S2), bilateral anterior insula, paracingulate gyrus, midcingulate cortex (MCC), bilateral frontal pole, bilateral cerebellar hemispheric lobule VI, vermis, bilateral cerebellar crus I and II, and visual cortices. BoNT-A injections significantly decreased light evoked BOLD responses in bilateral S1, S2 cortices, cerebellar hemispheric lobule VI, cerebellar crus I, and left cerebellar crus II. BoNT-A responders displayed activation of the spinal trigeminal nucleus at baseline where non-responders did not.

Discussion

BoNT-A injections modulate light-evoked activation of pain-related brain systems and photophobia symptoms in some individuals with chronic ocular pain. These effects are associated with decreased activation in areas responsible for processing the sensory-discriminative, affective, dimensions, and motor responses to pain.

TFOS Lifestyle: Impact of lifestyle challenges on the ocular surface

Many factors in the domains of mental, physical, and social health have been associated with various ocular surface diseases, with most of the focus centered on aspects of dry eye disease (DED). Regarding mental health factors, several cross-sectional studies have noted associations between depression and anxiety, and medications used to treat these disorders, and DED symptoms. Sleep disorders (both involving quality and quantity of sleep) have also been associated with DED symptoms. Under the domain of physical health, several factors have been linked to meibomian gland abnormalities, including obesity and face mask wear. Cross-sectional studies have also linked chronic pain conditions, specifically migraine, chronic pain syndrome and fibromyalgia, to DED, principally focusing on DED symptoms. A systematic review and meta-analysis reviewed available data and concluded that various chronic pain conditions increased the risk of DED (variably defined), with odds ratios ranging from 1.60 to 2.16. However, heterogeneity was noted, highlighting the need for additional studies examining the impact of chronic pain on DED signs and subtype (evaporative versus aqueous deficient). With respect to societal factors, tobacco use has been most closely linked to tear instability, cocaine to decreased corneal sensitivity, and alcohol to tear film disturbances and DED symptoms.

Clinical Neuroimaging of Photophobia in Individuals With Chronic Ocular Surface Pain

PURPOSE

To examine neural mechanisms underlying photophobia in individuals with chronic ocular surface pain by using functional magnetic resonance imaging (fMRI).

DESIGN

Cross-sectional case/control analysis.

METHODS

A total of 16 individuals from the Miami Veterans Affairs eye clinic underwent comprehensive ocular surface evaluations and were surveyed for ocular surface symptoms. Case patients included patients who reported chronic ocular surface pain symptoms and light sensitivity at least most of the time over 1 week. Controls included persons without chronic ocular surface pain who reported no or minimal light sensitivity. All patients viewed light stimuli during 2 fMRI scans, one before and one after topical anesthetic instillation, and rated their level of pain intensity to the stimulus at the end of each scan. Areas of brain activation in response to light stimuli presentation were correlated with pain responses and examined post- vs pre-anesthesia.

RESULTS

Case patients (n = 8) reported higher pain intensity ratings than controls (n = 8) in response to light stimuli during fMRI. Case patient ratings correlated more with light-evoked activation in pain-related areas within the trigeminal brainstem, primary somatosensory cortex (S1), anterior mid-cingulate cortex (aMCC), and insula than in controls. Topical anesthesia led to varying responses in pain ratings among case patients as well as decreased light-evoked activation in S1 and aMCC.

CONCLUSIONS

The trigeminal nociceptive system may contribute to photophobia in individuals with chronic ocular surface pain. We demonstrate modulation of cortical structures in this pathway with topically applied anesthetic to the eyes. Further understanding of modulatory interactions that govern ocular surface pain and photophobia is critical for developing effective, precision-based therapies.

Anxiety Disorders and Gut Dysbiosis in Primary Sjögren's Syndrome-Mediated Dry Eye Patients

Purpose

Primary Sjögren's syndrome (pSS), a disease that is associated with a high prevalence of psychological disorders, has become increasingly important. Interactions between the gut microbiota and ocular conditions have been identified in pSS. As mental intervention is frequently needed, this study aims to investigate the relationship between anxiety disorders and the gut microbiome in patients with pSS-mediated dry eye.

Methods

Demographics and self-administered questionnaires were obtained. Faecal samples were evaluated using 16S ribosomal RNA gene sequencing.

Results

The Hospital Anxiety and Depression Scale (HADS-A) cut-off point of ≥ 8 points showed a sensitivity and specificity of 76.5% and 80.0%, respectively. In all participants, we found that the prevalence of anxiety disorder was 30.4%. Dry eye discomfort could promote an anxious state, and conversely, anxiety could threaten tear film and increase the risk of pSS activity. There was a certain correlation between anxiety disorder and gut dysbiosis. Prevotella was associated with dry eye severity (p <0.001). Bacteroidetes (p =0.046) and Odoribacter (p =0.001) were correlated with pSS activity.

Conclusion

There is a bidirectional relationship between anxiety disorder and the gut microbiota in pSS-mediated dry eye. Alterations in certain classes of gut microbiota are associated with pSS activity and dry eye severity. Main gut microbiota alterations that have a facilitating impact on anxiety are emerging in pSS-mediated dry eye. Future studies are needed to explore specific therapeutic targets for improving mental health in pSS-mediated dry eye by microbiota intervention.

Factors affecting the prevalence, severity, and characteristics of ocular surface pain

Introduction

Ocular surface pain has been traditionally lumped under the umbrella term "dry eye" (DE) but is now understood as its own entity and can occur in the absence or presence of tear dysfunction. Identifying patients at risk for the development of chronic ocular surface pain, and factors contributing to its severity are important in providing precision medicine to patients.

Areas covered

In this review, we discuss factors linked to the presence and severity of ocular surface pain, including eye related features, systemic characteristics, and environmental findings. We discuss corneal nerves, whose anatomic and functional integrity can be characterized through in vivo confocal microscopy images and testing of corneal sensitivity. We review systemic diseases that are co-morbid with ocular surface pain, including physical and mental health diagnoses. Finally, we identify environmental contributors, including air pollution, previous surgeries, and medications, associated with ocular surface pain.

Expert opinion

Intrinsic and extrinsic factors contribute to ocular surface pain and must be considered when evaluating an individual patient. These factors can inform the suspected etiology of the pain, and guide management decisions such as tear replacement or medications targeting nerve pain.

Impact of meibomian gland dysfunction on quality of life and mental health in a clinical sample in Ghana: a cross-sectional study

OBJECTIVES

This study aimed to determine the impact of meibomian gland dysfunction (MGD) on quality of life and psychosomatic conditions.

DESIGN

This was a clinic-based cross-sectional study.

SETTING

This study was conducted at the eye clinic of the University of Cape Coast, Ghana.

PARTICIPANTS

215 clinical subjects visiting the clinic for a comprehensive eye examination.

PRIMARY AND SECONDARY OUTCOME MEASURES

Symptomatic MGD, asymptomatic MGD, quality of life scores, depression, anxiety and stress.

RESULTS

215 clinical subjects consented to participate in the study, but 212 were included in the analysis. The mean age was 21.9 (± 3.8) years, 54 had MGD and 158 did not have MGD served as controls. There was no statistically significant difference in the mean quality of life scores between subjects with MGD and subjects without MGD (t=1.57, p=0.12). The quality of life scores (DEQS) (p=0.022) were significantly higher in the symptomatic MGD group compared with the asymptomatic MGD group. There was no significant difference in quality of life scores (DEQS) (p=0.251) in the asymptomatic MGD group compared with healthy controls. Using Pillai's trace in the MANOVA, there was a significant effect of MGD on depression, anxiety and stress (V=0.05, F(3,208)=3.76, p=0.012). Furthermore, Pillai's trace in the MANOVA showed a significant difference between asymptomatic and symptomatic MGDs for depression, anxiety and stress scores stress (V=0.24, F(3, 51)=5.24, p=0.003).

CONCLUSION

The study revealed no difference in the quality of life scores between MGD and non-MGD groups. However, the symptomatic MGD group had worse quality of life and psychosomatic symptoms than the asymptomatic MGD group and non-MGD group.

Understanding chronic ocular surface pain: An unmet need for targeted drug therapy

Chronic ocular surface pain (COSP) may be defined as a feeling of pain, perceived as originating from the ocular surface, that persists for >3 months. COSP is a complex multifactorial condition associated with several risk factors that may significantly interfere with an individual's daily activities, resulting in poor quality of life (QoL). COSP is also likely to have a high burden on patients with substantial implications on global healthcare costs. While patients may use varied terminology to describe symptoms of COSP, any ocular surface damage in the ocular sensory apparatus (nociceptive, neuropathic, inflammatory, or combination thereof) resulting in low tear production, chronic inflammation, or nerve abnormalities (functional and/or morphological), is typically associated with COSP. Considering the heterogeneity of this condition, it is highly recommended that advanced multimodal diagnostic tools are utilized to help discern the nociceptive and neuropathic pain pathways in order to provide targeted treatment and effective clinical management. The current article provides an overview of COSP, including its multifactorial pathophysiology, etiology, prevalence, clinical presentation, impact on QoL, diagnosis, current management, and unmet medical needs.

Corneal sub-basal nerve plexus microneuromas in individuals with and without dry eye

BACKGROUND/AIM

An objective marker is needed to detect when corneal nerve abnormalities underlie neuropathic corneal pain (NCP), as symptoms often overlap with those of dry eye (DE). This study evaluated microneuroma (MN) frequency in various populations and investigated relationships between MN presence and DE clinical features in individuals with DE symptoms but without a history of refractive surgery, in order to eliminate refractive surgery as a potential confounder of nerve abnormalities.

METHODS

This was a retrospective study that included individuals with and without DE symptoms who underwent a clinical evaluation for DE (symptom surveys and ocular surface evaluation) and in vivo confocal microscopy imaging. DE clinical features (including those suggestive of neuropathic pain) were compared based on MN presence using t-tests, χ2 analyses and Pearson's correlation coefficients with 0.05 alpha level.

RESULTS

MN frequencies did not significantly differ between individuals with DE symptoms (Dry Eye Questionnaire 5 score ≥6) and a history of refractive surgery (n=1/16, 6%), individuals with DE symptoms without a history of refractive surgery (n=26/119, 22%) and individuals without DE symptoms (n=2/18, 11%, p=0.22). Among individuals with DE symptoms without a history of refractive surgery, DE clinical features, including those indicative of NCP (burning sensation and sensitivity to light, wind and extreme temperatures), did not significantly differ based on MN presence (p>0.05).

CONCLUSION

MN frequencies did not significantly differ between individuals with and without DE symptoms. Their presence alone could not distinguish between DE subtypes, including features of NCP in our study population.

Self-Report of Severity of Ocular Pain Due to Light as a Predictor of Altered Central Nociceptive System Processing in Individuals With Symptoms of Dry Eye Disease

Dry eye disease (DED) is a diagnosis given to individuals with a heterogeneous combination of symptoms and/or signs, including spontaneous and evoked ocular pain. Our current study evaluated whether and which ocular pain assessments could serve as screening tools for central sensitization in individuals with DED. A cohort of individuals with DED symptoms (n = 235) were evaluated for ocular pain, DED signs (tear production, evaporation), evoked sensitivity to mechanical stimulation at the cornea, and evidence of central sensitization. Central sensitization was defined for this study as the presence of pain 30 seconds after termination of a thermal noxious temporal summation protocol (ie, aftersensations) presented at a site remote from the eye (ventral forearm). We found that combining ratings of average intensity of ocular pain, ratings of average intensity of pain due to light, response to topical anesthetic eye drops, and corneal mechanical pain thresholds produced the best predictive model for central sensitization (area under the curve of .73). When examining ratings of intensity of ocular pain due to light alone (0-10 numerical rating), a cutoff score of 2 maximized sensitivity (85%) and specificity (48%) for the presence of painful aftersensations at the forearm. Self-reported rating of pain sensitivity to light may serve as a quick screening tool indicating the involvement of central nociceptive system dysfunction in individuals with DED. PERSPECTIVE: This study reveals that clinically-relevant variables, including a simple 0 to 10 rating of ocular pain due to light, can be used to predict the contribution of central sensitization mechanisms in a subgroup of individuals with DED symptoms. These findings can potentially improve patient stratification and management for this complex and painful disease.

Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons

This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.

Ocular Pain Symptoms in Individuals With and Without a History of Refractive Surgery: Results From a Cross-Sectional Survey

PURPOSE

This study characterized ocular pain symptoms in individuals with and without a history of refractive surgery (RS) using a cross-sectional survey of individuals with ocular pain.

METHODS

A link to an anonymous survey was posted on a corneal neuralgia Facebook group that included individuals with ocular pain from any etiology and sent to individuals seen in our clinic with ocular pain. The survey asked about medical history, ocular pain symptoms (using standardized questionnaires), and treatment responses. Respondents were split into 2 groups based on a history of RS.

RESULTS

One hundred one individuals responded to the survey. The mean age for all respondents was 41.6 ± 15.6 years, and 50% reported a history of RS. A total of 46% of individuals with a history of RS reported that their ocular pain started within 1 month of surgery, with median pain duration of 36 (interquartile range 22-84) months. The median Dry Eye Questionnaire-5 (range 0-22) scores were 16 and 15 for the RS and no-RS groups, respectively. Most individuals in both groups characterized their pain as burning (score ≥1: RS, 86%; no-RS, 80%) and reported evoked pain to wind, light, or temperature (score ≥1: RS, 97%; no-RS, 85%). Fifty-nine of 101 individuals responded to treatment questions. Individuals in both groups reported >30% improvement in pain symptoms with some topical and systemic approaches.

CONCLUSIONS

Individuals with a history of RS developed ocular pain soon after surgery, which persisted for years. Symptom profiles were similar between those with and without RS. Topical and systemic approaches can treat pain in both groups.

Differential Effects of Treatment Strategies in Individuals With Chronic Ocular Surface Pain With a Neuropathic Component

Background: Dysfunction at the ocular system via nociceptive or neuropathic mechanisms can lead to chronic ocular pain. While many studies have reported on responses to treatment for nociceptive pain, fewer have focused on neuropathic ocular pain. This retrospective study assessed clinical responses to pain treatment modalities in individuals with neuropathic component ocular surface pain. Methods: 101 individuals seen at the University of Miami Oculofacial Pain Clinic from January 2015 to August 2021 with ≥3 months of clinically diagnosed neuropathic pain were included. Patients were subcategorized (postsurgical, post-traumatic, migraine-like, and laterality) and self-reported treatment outcomes were assessed (no change, mild, moderate, or marked improvement). One-way ANOVA (analysis of variance) was used to examine relationships between follow up time and number of treatments attempted with pain improvement, and multivariable logistic regression was used to assess which modalities led to pain improvement. Results: The mean age was 55 years, and most patients were female (64.4%) and non-Hispanic (68.3%). Migraine-like pain (40.6%) was most common, followed by postsurgical (26.7%), post-traumatic (16.8%) and unilateral pain (15.8%). The most common oral therapies were α2δ ligands (48.5%), the m common topical therapies were autologous serum tears (20.8%) and topical corticosteroids (19.8%), and the most common adjuvant was periocular nerve block (24.8%). Oral therapies reduced pain in post-traumatic (81.2%), migraine-like (73%), and unilateral (72.7%) patients, but only in a minority of postsurgical (38.5%) patients. Similarly, topicals improved pain in post-traumatic (66.7%), migraine-like (78.6%), and unilateral (70%) compared to postsurgical (43.7%) patients. Non-oral/topical adjuvants reduced pain in postsurgical (54.5%), post-traumatic (71.4%), and migraine-like patients (73.3%) only. Multivariable analyses indicated migraine-like pain improved with concomitant oral α2δ ligands and adjuvant therapies, while postsurgical pain improved with topical anti-inflammatories. Those with no improvement in pain had a shorter mean follow-up (266.25 ± 262.56 days) than those with mild (396.65 ± 283.44), moderate (652 ± 413.92), or marked improvement (837.93 ± 709.35) (p < 0.005). Identical patterns were noted for number of attempted medications. Conclusion: Patients with migraine-like pain frequently experienced pain improvement, while postsurgical patients had the lowest response rates. Patients with a longer follow-up and who tried more therapies experienced more significant relief, suggesting multiple trials were necessary for pain reduction.

Assessment and Management of Dry Eye Disease and Meibomian Gland Dysfunction: Providing a Singapore Framework

ABSTRACT

The purpose of this article is to provide a framework for general ophthalmologists in Singapore to manage dry eye. This framework considers the evidence in the literature as well as recommendations from expert panels such as the Tear Film & Ocular Surface Society Dry Eye Workshop II and the Asia Cornea Society Workgroup.This article covers the assessment of patient medical history and ask triage questions to identify local and systemic causes of dry eye disease (DED), excluding other possible causes, as well as the risk factors for DED and ocular surface inflammation. Evaluation of clinical signs to establish the diagnosis of DED and differentiation from other causes of irritable, red eyes are described. Tests for understanding the underlying disease processes and severity of DED are also presented.Management of dry eye should involve patient education and engagement. Information about the natural history and chronic nature of DED should be provided to improve long-term management of the disease and enhance compliance. Aggravating factors should be removed or lessened.We provide a guide to determine the most appropriate treatment (or combination of treatments) based on the severity and cause(s) of the disease, as well as the patient's needs and preferences. The aim of the management is to relieve ocular discomfort and prevent worsening of symptoms and signs, as well as to optimize visual function and minimize structural ocular damage. We also discuss the systematic follow-up and assessment of treatment response, as well as monitoring side effects of treatment, bearing in mind continuous support and reassurance to patients.

Concurrent ocular pain in patients with neurotrophic keratopathy

PURPOSE

To illustrate that ocular pain may occur in patients with neurotrophic keratopathy (NK) that typically are thought to lack symptoms of discomfort, and that aa subset of these patients may also present with neuropathic corneal pain (NCP).

METHOD

Retrospective Case series of 7 stage 1 NK patients who presented with concurrent ocular pain, as confirmed by clinical examination, proparacaine challenge test, and in vivo corneal confocal microscopy (IVCM). Records were assessed for results of ocular surface disease index (OSDI), pain on visual analog scale (VAS), ocular pain assessment survey (OPAS), best-corrected visual acuity (BCVA), corneal fluorescein staining (CFS) score, and IVCM findings. IVCM findings were compared to that of 20 healthy reference controls.

RESULTS

Mean age of patients was 63.7 ± 11.6 (range 44-76) years and 56.9 ± 8.6 (range 42-74) years in reference controls (p = 0.11). At presentation, ocular discomfort was 8.0 ± 1.3 (range 7-10) on VAS and mean OSDI scores were 72.26 ± 6.81 (range 62.50-79.54). Mean BCVA was 20/40, and mean CFS scores were 3.43 ± 0.79 (range 2-4) on the Oxford scale. IVCM analysis showed significant decrease in mean total, main and branch nerve densities in ranges consistent with NK as compared to normal controls (p < 0.001 for all), increased dendritiform cell density in three patients (p < 0.001), and the presence of microneuromas in six of the patients.

CONCLUSION

Patients with NK are thought to present with hypoesthesia. However, nerve damage and inflammation, which play a role in the development of NK may result in the development of chronic ocular pain, such as NCP, resulting in potential underdiagnosis of either disease.

Anxiety and depression in inflammatory eye disease: exploring the potential impact of topical treatment frequency as a putative psychometric item

Objective

To evaluate whether topical therapy is linked to scores related to anxiety, depression and quality of life (QoL) in inflammatory eye disease (IED).

Methods and analysis

Patients with ocular surface disease (OSD, N=100) and Uveitis (N=100) completed self-administered validated questions on ocular symptoms and well-being, with supplemental questions on eye drop frequency.

Results

Forty (20%) patients had scores consistent with depression and 33 (17%) anxiety. Anxiety, depression, QoL and OSD index (OSDI) scores did not differ significantly between OSD and Uveitis groups. In those with anxiety or depression, QoL was significantly reduced in all WHO Quality Of Life-BREF domains (all p<0.001). Multivariable analysis considering demographic and disease-related factors found daily topical drop frequency to be independently associated with anxiety (p=0.009) but not depression (p=0.300).

Conclusion

A high proportion of patients with IED demonstrated scores indicative of anxiety and depression. Preliminary evidence suggests that the frequency of topical eye drops potentially plays a significant role in the psychological health status of patients with IED.

Neuropathic Corneal Pain Following LASIK Surgery: A Retrospective Case Series

Introduction

Transient dry eye symptoms have been reported following laser in situ keratomileusis (LASIK). Very rarely, patients may present with debilitating symptoms of dry eye syndrome (DES) with limited or no evidence of ocular surface disease. These patients are diagnosed with a form of DES known as neuropathic corneal pain (NCP).

Patients and Methods

This study is a retrospective medical record review of a case series of 18 patients who developed NCP post-LASIK over the years 1996–2021. All patients who developed severe ocular pain following LASIK consistent with NCP were included. Patients with severe ocular pain who had evidence of severe ocular surface disease or other ophthalmic etiology to explain their debilitating symptoms were not included.

Results

The average age of patients in our study was 39.5 years. The majority of our patients were female (72.2%) and of Caucasian ancestry (83.3%). The average onset of symptoms was 9.6 months post-LASIK. Patients had past medical histories significant for neuropsychiatric conditions (50%), functional pain syndromes (22.2%), autoimmune diseases (33.3%), and hypothyroidism (27.8%), and the occurrence of these was higher than the national prevalence of these diseases. Symptoms were consistent with the severity and characteristics defining NCP. Treatment was multimodal, involved topical and systemic therapies, and was unique to each patient. Overall, the majority of patients had clinical improvement in symptoms following treatment with regular follow-up.

Conclusion

Although rare, the 26-year prevalence of NCP post-LASIK in our study was roughly 1 in 900 cases. The mean time to onset after surgery was delayed at 9.6 months. Certain risk factors such as neuropsychiatric conditions, history of functional pain syndromes, history of autoimmune conditions, and hypothyroidism may predispose patients to the development of this condition. Patients benefited from proper diagnosis and a multimodal approach to treatment.

Photophobia: shared pathophysiology underlying dry eye disease, migraine and traumatic brain injury leading to central neuroplasticity of the trigeminothalamic pathway

BACKGROUND

Photophobia is a potentially debilitating symptom often found in dry eye disease (DE), migraine and traumatic brain injury (TBI).

METHODS

We conducted a review of the literature via a PubMed search of English language articles with a focus on how photophobia may relate to a shared pathophysiology across DE, migraine and TBI.

RESULTS

DE, migraine and TBI are common conditions in the general population, are often comorbid, and share photophobia as a symptom. Across the three conditions, neural dysregulation of peripheral and central nervous system components is implicated in photophobia in various animal models and in humans. Enhanced activity of the neuropeptide calcitonin gene-related peptide (CGRP) is closely linked to photophobia. Current therapies for photophobia include glasses which shield the eyes from specific wavelengths, botulinum toxin, and inhibition of CGRP and its receptor. Many individuals have persistent photophobia despite the use of these therapies, and thus, development of new therapies is needed.

CONCLUSIONS

The presence of photophobia in DE, migraine and TBI suggests shared trigeminothalamic pathophysiologic mechanisms, as explained by central neuroplasticity and hypersensitivity mediated by neuropeptide CGRP. Treatment strategies which target neural pathways (ie, oral neuromodulators, transcutaneous nerve stimulation) should be considered in patients with persistent photophobia, specifically in individuals with DE whose symptoms are not controlled with traditional therapies.

Health outcomes among detoxification patients: The role of chronic pain

Understanding associations between chronic pain and health outcomes among detoxification patients may help improve treatment outcomes and abstinence rates. Exercise is a modifiable lifestyle factor that may reduce the effect of pain on outcomes in this population. The current study examined whether baseline pain, exercise, and their interaction were associated with psychiatric and medical severity, and abstinence self-efficacy, over six months following detoxification. Participants were veteran patients in alcohol or opioid detoxification treatment (N = 298) who were followed for six months (91.1%). Psychiatric severity and abstinence self-efficacy improved over the six months after detoxification; medical severity was stable. More intense pain at baseline was associated with poorer psychiatric and medical outcomes during the post-detoxification period. Regular exercise at baseline was associated with less psychiatric severity and more abstinence self-efficacy during the post-detoxification period. A significant pain by exercise interaction at baseline indicated that regular exercise was associated with more abstinence self-efficacy during the post-detoxification period only among participants with less intense pain. Pain by exercise interactions was not significant for the outcomes of psychiatric and medical severity. Among detoxification patients, exercise may be beneficial in improving outcomes among those with less intense pain.

Neuropathic corneal pain and dry eye: a continuum of nociception

Throughout the body, damage to peripheral nerves normally involved in nociception may produce a constellation of symptoms-including irritation, itchiness and pain. The neurobiological processes involved in corneal symptoms of dry eye (DE) and neuropathic corneal pain (NCP) have not been clearly considered in terms of nociceptive processing. The conventional underlying presumption is that a labelled line principle is responsible; that these distinct perceptions are hard coded by primary afferent inputs to the central nervous system. This presumption oversimplifies the neurobiological mechanisms underlying somatosensory perception. The labelled line perspective that DE represents a chronic pain condition does not make intuitive sense: how can an eye condition that is not painful in most cases be considered a pain condition? Does not chronic pain by definition require pain to be present? On the other hand, NCP, a term that clearly denotes a painful condition, has historically seemed to resonate with clinical significance. Both DE and NCP can share similar features, yet their differentiation is not always clear. As is often the case, clinical terms arise from different disciplines, with DE evolving from ophthalmological findings and NCP inspired by pain neurophysiology. This review evaluates the current definition of these terms, the rationale for their overlap and how the neurophysiology of itch impacts our understanding of these conditions as a continuum of the same disease. Despite the complexity of nociceptive physiology, an understanding of these mechanisms will allow us a more precise therapeutic approach.

Is gabapentin effective in dry eye disease and neuropathic ocular pain?

This study aims to evaluate the efficacy of gabapentin treatment in dry eye disease (DED) and neuropathic ocular pain. Our study was performed with 72 patients. The painDETECT questionnaire was used for neuropathic pain screening. Patients who were thought to have severe DED according to ocular surface disease index (OSDI) questionnaire, Schirmer's test type 1 and tear break up time test results were treated with artificial tear and cyclosporine drops. Gabapentin treatment was also initiated in addition to artificial tear and cyclosporine drops treatments to the patients with neuropathic component and DED findings. We divided the patients into two groups: group 1 (n: 36), patients treated with artificial tear and cyclosporine drops and group 2 (n: 36), patients treated with artificial tear, cyclosporine drops and gabapentin. In the first evaluation, no significant differences were found between groups in terms of OSDI score, Schirmer's test result and TBUT. After the 6 weeks of treatment, in both groups OSDI score, Schirmer's test result and TBUT statistically significantly improved. OSDI score, Schirmer's test result and TBUT significantly improved after the 6 weeks of gabapentin treatment than artificial tear and cyclosporine treatment group (p < 0.001). Dry eye patients should be screened for neuropathic ocular pain symptoms and individualized treatment has to be applied. Our study showed that the use of gabapentin is effective in severe dry eye patients with neuropathic ocular pain.

Electronic Delivery of Pain Education for Chronic Overlapping Pain Conditions: A Prospective Cohort Study

OBJECTIVE

To examine the impact of educational materials for chronic overlapping pain conditions (COPCs), the feasibility of delivering materials online, and to explore its impact on self-reported self-management applications at 3-month follow-up.

DESIGN

Prospective cohort study.

SETTING

Online.

SUBJECTS

Individuals from a university-wide active research repository with ≥1 coded diagnostic COPC by ICD-9/10 in the medical record.

METHODS

We determined the number of COPCs per participant as indicated by diagnostic codes in the medical record. Consenting participants completed self-report questionnaires and read educational materials. We assessed content awareness and knowledge pre- and post-exposure to education. Comprehension was assessed via embedded questions in reading materials in real time. Participants then completed assessments regarding concept retention, self-management engagement, and pain-related symptoms at 3-months.

RESULTS

N = 216 individuals enrolled, with 181 (84%) completing both timepoints. Results indicated that participants understood materials. Knowledge and understanding of COPCs increased significantly after education and was retained at 3-months. Patient characteristics suggested the number of diagnosed COPCs was inversely related to age. Symptoms or self-management application did not change significantly over the 3-month period.

CONCLUSIONS

The educational materials facilitated teaching of key pain concepts in self-management programs, which translated easily into an electronic format. Education alone may not elicit self-management engagement or symptom reduction in this population; however, conclusions are limited by the study's uncontrolled design. Education is likely an important and meaningful first step in comprehensive COPC self-management.

Pain sensitivity and autonomic nervous system parameters as predictors of dry eye symptoms after LASIK

PURPOSE

Differences in pain processing and autonomic function among patients have been implicated in the development of chronic pain after surgery. This study was designed to evaluate whether pain and autonomic metrics predict severity of chronic dry eye (DE) symptoms after LASIK, as there is increasing evidence that DE symptoms may be manifestations of persistent post-operative ocular pain.

METHODS

Secondary analysis of prospective randomized clinical trial. Patients were treated with either pregabalin or placebo. As no significant differences in DE symptoms were detected by treatment allocation at six months, all participants were grouped together for the present analyses. Subjects were evaluated pre-LASIK with regard to evoked pain sensitivity (utilizing quantitative sensory testing), autonomic metrics and DE and ocular pain symptoms (via validated questionnaires). Measures of DE and ocular pain were assessed post-LASIK, and the Dry Eye Questionnaire 5 (DEQ5) score 6-months after surgery was the primary outcome of interest.

RESULTS

43 individuals were randomized to pregabalin (n = 21) or placebo (n = 22). 42 completed the 6-month visit. Several baseline autonomic metrics correlated with 6-month post-operative DEQ5 scores, including lower systolic (r -0.37, p = 0.02) and diastolic blood pressure (r -0.32, p = 0.04). Ocular pain at 6 months was also negatively correlated with blood pressure (r -0.31, p = 0.047). The presence of painful aftersensations was a significant predictor of chronic DE symptoms at 6 months (mean DEQ5 scores: 8.0 ± 1.9 versus 5.0 ± 5.0, p = 0.009).

CONCLUSIONS

Heightened parasympathetic tone and prolonged pain sensitivity measured prior to surgery predicted greater DE symptom severity 6 months after LASIK.

TRIAL REGISTRATION

NCT02701764.

Ocular Surface Pain: A Narrative Review

Ocular surface pain is a frequent cause of visits to an eye care provider and has a substantial impact on healthcare cost, yet a complete understanding of its causative factors and tools for diagnostic workup are notably missing in many eye clinics. The cornea has the densest sensory innervation in the human body and has the potential to be a powerful producer of pain. Pain can manifest as a result of a noxious stimulus or disruption in the ocular surface anatomy (nociceptive pain), or it can result from abnormalities in the ocular surface neurosensory apparatus itself (neuropathic pain). Novel advances in neurobiology have sought to differentiate the two entities, particularly to identify when chronic dry eye symptomatology is driven by neuropathic ocular pain. In this review, we seek to provide an overview of the prevalence, physiologic factors, and management of ocular surface pain complaints.

Efficacy and tolerability of nortriptyline in the management of neuropathic corneal pain

PURPOSE

Neuropathic corneal pain (NCP) is a recently acknowledged disease entity. However, there is no consensus in potential treatment strategies, particularly in patients with a centralized component of pain. This study aims to assess the efficacy and tolerability of the tricyclic antidepressant, nortriptyline, among NCP patients.

METHODS

Patients with clinically diagnosed NCP and a centralized component of pain, treated with oral nortriptyline, who had recorded pain scores as assessed by the ocular pain assessment survey at the first and last visit were included. Patients were excluded if they had any other ocular pathology that might result in pain or had less than 4 weeks of nortriptyline use. Demographics, time between visits, concomitant medications, systemic and ocular co-morbidities, duration of NCP, side effects, ocular pain scores, and quality of life (QoL) assessment were recorded.

RESULTS

Thirty patients with a mean age of 53.1 ± 18.5 were included. Male to female ratio was 8:22. Mean ocular pain in the past 24 h improved from 5.7 ± 2.1 to 3.6 ± 2.1 after 10.5 ± 9.1 months (p < 0.0001). Twelve patients (40.0%) had equal to or more than 50% improvement, 6 patients (20.0%) had 30-49% improvement, 6 patients (20.0%) had 1-29% improvement, 4 patients (13.3%) did not improve, while 2 patients (6.7%) reported increase in pain levels. Mean QoL improved from 6.0 ± 2.5 to 4.3 ± 2.4 (p = 0.019). Eight patients (26.6%) discontinued treatment due to persistent side effects, despite improvement by 22.4%.

CONCLUSION

Nortriptyline was effective in relieving NCP symptoms in patients with centralized component and insufficient response to other systemic and topical therapies who tolerated the drug for at least 4 weeks. Nortriptyline may be used in the management of patients with NCP.

Comparison of clinical characteristics of post-refractive surgery-related and post-herpetic neuropathic corneal pain

Purpose:

To compare the clinical characteristics and in vivo confocal microscopy (IVCM) findings of patients with neuropathic corneal pain (NCP) due to refractive surgery (RS-NCP) and herpetic eye disease (H-NCP) to controls.

Methods:

Sixteen patients with RS-NCP and 7 patients with H-NCP, and 37 healthy reference age- and sex-matched healthy controls were included to the study. The medical records were reviewed for demographic features, detailed disease history, ocular surface disease index (OSDI), ocular pain assessment survey (OPAS) scores. IVCM images of patients were analyzed and compared to reference controls by two masked observers.

Results:

The mean pain intensity score for the last 24 h (5.1 ± 2.4 vs. 3.9 ± 1.2; p = 0.27), last 2 weeks (6.1 ± 2.5 vs. 4.8 ± 2.3; p = 0.13) for RS-NCP vs. H-NCP respectively, and quality of life scores (p = 0.23) were similar in both groups. Quality of life, especially mood (p = 0.06) and enjoying life/relations to others (p = 0.10) were affected in both groups, but were not statistically significant between groups. The mean total nerve density was lower in RS-NCP (5,702.4 ± 4,599.0 μm/mm²) compared to their respective controls (26,422.8 ± 4,491.0; p < 0.001) and in the H-NCP group (2,149.5 ± 2,985.9) compared to their respective controls (22,948.8 ± 3,169.0; p < 0.001). Alterations in DC density were similar between all groups (38.3 ± 48.0 cells/mm² in RS-NCP, 61.0 ± 76.9 in H-NCP, p = 0.95).

Conclusion:

Neuropathic corneal pain patients due to refractive surgery show similar clinical characteristics, pain levels, quality of life impact, and IVCM findings as patients with NCP due to herpetic eye disease.

Eye Pain and Dry Eye in Patients with Fibromyalgia

Objectives

The aim of this study was to examine visual function and eye symptoms in fibromyalgia patients, with a particular focus on dry eye syndrome and eye pain.

Methods

A tertiary care center-based cross-sectional study was carried out in chronic musculoskeletal pain patients diagnosed with fibromyalgia. Chronic musculoskeletal pain patients without fibromyalgia were enrolled as a comparison group. Self-reported eye pain was investigated with the McGill pain questionnaire and the numeric rating scale. In addition, we assessed corrected visual acuity, vision-related quality of life, and self-reported dry eye syndrome.

Results

A total of 90 musculoskeletal pain patients were included, with 66 patients fulfilling American College of Rheumatology 1990 criteria for fibromyalgia. Sixty-seven percent (95% confidence interval [CI] = 56%-78%) of the fibromyalgia patients reported eye pain, and 62% (95% CI = 43%-81%) of those were without fibromyalgia diagnosis. Sixty-seven percent (95% CI = 56%-78%) of the fibromyalgia patients reported an experience of dry eye compared with 76% (95% CI = 57%-95%) in the nonfibromyalgia group. Vision-related quality of life was noticeably reduced in both groups.

Conclusions

Eye pain and dry eye are common in chronic pain patients, with comparable prevalence in musculoskeletal pain patients with and without fibromyalgia.

Iatrogenic opioid use disorder, chronic pain and psychiatric comorbidity: A systematic review

OBJECTIVE

A systematic review of the literature on the risks of developing iatrogenic opioid use disorders in chronic pain patients with psychiatric comorbidity.

METHODS

We conducted literature searches on Pubmed with key subjects: "chronic pain", "psychiatry", "opioids" and "opioid use disorder" and for original, English written articles published from 2000 until the first of September 2017. Final selection of the articles for review was made in a consensus between three reviewers.

RESULTS

Longitudinal studies showed a significant association between psychiatric comorbidity, especially depression and anxiety disorders and the development of problematic opioid use, more severe opioid craving and poor opioid treatment outcome (analgesia and side effects) in chronic pain patients. Cross-sectional studies showed a similar association between psychiatric disorders and problematic opioid use, where studies in specialized pain settings showed a higher prevalence of psychiatric disorders, compared to non-specialized settings.

CONCLUSIONS

This systematic review showed a significant association between psychiatric comorbidity, especially depression and anxiety disorders and the development of problematic opioid use in chronic pain patients. We therefore recommend psychiatric screening in chronic pain management. Chronic pain patients with comorbid psychiatric disorders need a multidisciplinary approach and monitoring opioid use is warranted in these patients.

Corneal pain and experimental model development

The cornea is a valuable tissue for studying peripheral sensory nerve structure and regeneration due to its avascularity, transparency, and dense innervation. Somatosensory innervation of the cornea serves to identify changes in environmental stimuli at the ocular surface, thereby promoting barrier function to protect the eye against injury or infection. Due to regulatory demands to screen ocular safety of potential chemical exposure, a need remains to develop functional human tissue models to predict ocular damage and pain using in vitro-based systems to increase throughput and minimize animal use. In this review, we summarize the anatomical and functional roles of corneal innervation in propagation of sensory input, corneal neuropathies associated with pain, and the status of current in vivo and in vitro models. Emphasis is placed on tissue engineering approaches to study the human corneal pain response in vitro with integration of proper cell types, controlled microenvironment, and high-throughput readouts to predict pain induction. Further developments in this field will aid in defining molecular signatures to distinguish acute and chronic pain triggers based on the immune response and epithelial, stromal, and neuronal interactions that occur at the ocular surface that lead to functional outcomes in the brain depending on severity and persistence of the stimulus.

Photophobia and neuropathic pain in Sudecḱs syndrome

The case is presented of a 14 year-old patient diagnosed with Sudeck's syndrome secondary to uneventful foot trauma. The patient complained of decreased visual acuity along with photophobia and intense ocular pain not correlated with the exploratory findings. Sudeck's syndrome is an idiopathic neuropathic inflammatory disease characterised by disproportionate pain, unrelated to a previous traumatic event, which can evolve to severe and generalised pain. A new explanation has recently described this as "neuropathic eye pain" for those patients with severe eye pain that do not correlate with clinical signs. In the case presented here, the pain became widespread and led to photophobia and very intense ocular neuropathic pain. It is believed that this was the cause of the visual decrease presented by this patient. It is proposed that the Sudeck syndrome should become part of the differential diagnosis of neuropathic eye pain.

Analysis of the association between the severity of ocular and systemic pain

PURPOSE

To evaluate the relationship between the severity of ocular and systemic pain.

METHODS

A cross-sectional study was conducted in patients with ocular pain symptoms who were observed in Keio University Hospital between April 2017 and September 2018. Evaluations consisted of the Dry Eye-Related Quality of Life Score (DEQS), Short-Form McGill Pain Questionnaire (SF-MPQ), visual analog scale (VAS), and ophthalmologic examination, including tear breakup time measurement and Schirmer I test. The revised Asia Dry Eye Society Dry Eye Disease (DED) diagnostic criteria were used.

RESULTS

The present study involved 41 participants (31 women; mean age, 57.6 ± 17.5 years). Thirteen participants had aqueous-deficient DED, 18 participants had short tear break-up time DED, and 10 participants had no DED. Multivariate regression analysis revealed that the DEQS was significantly associated with both the SF-MPQ total (Coefficient score β = 0.92, p < 0.01) and the VAS (β = 0.25, p = 0.01). In addition, correlation analysis revealed that the DEQS had a significant positive linear correlation with both the SF-MPQ total (Spearman correlation score rs = 0.70, p < 0.01) and the VAS (rs = 0.66, p < 0.01).

CONCLUSIONS

The findings of the present study suggested that the ocular pain score was significantly associated with systemic pain score. Participants with higher systemic pain scores have an increased risk of having ocular pain.

Comorbidities and Prescribed Medications in Patients With or Without Dry Eye Disease: A Population-Based Study

PURPOSE

To assess the proportion of comorbidities in patients with dry eye disease (DED) compared with matched patients without DED in a comprehensive US population.

DESIGN

Retrospective case-control study.

METHODS

Healthcare records for insurance claims data, detailing medical services incurred by military personnel and their families and dependents in military and civilian facilities across the United States from January 1, 2003, to March 31, 2015, were obtained from the Department of Defense (DOD) Military Health System (MHS). Diagnostic and procedural codes related to DED from selected International Classification of Diseases, Ninth Revision (ICD-9) Current Procedural Terminology codes and prescriptions for cyclosporine A ophthalmic emulsion were used to identify patients with newly diagnosed and prevalent DED in the MHS database. Age, sex, and geographically matched patients without DED were also identified from healthcare claims records. Medication use and comorbidities in these patient populations were assessed and compared.

RESULTS

In both the newly diagnosed and prevalent DED samples, the most common comorbidities were hypertension, cataracts, thyroid disease, type 2 diabetes, and glaucoma. All comorbidities were significantly higher in the DED vs non-DED groups (P < .001). Medication use (including, but not limited to, ophthalmic agents and drugs to treat comorbidities) was also significantly higher in the DED than in the non-DED groups (P < .001).

CONCLUSIONS

The high proportions of patients with DED with a range of comorbidities and prescribed medications highlight the need for a multidisciplinary approach to the management of these patients.

Dry Eye Disease: Consideration for Women's Health

Dry eye disease (DED) is a multifactorial disorder of the ocular surface and tear homeostasis that can result in discomfort, pain, and visual disturbance. Untreated, DED can become chronic, progressive, and significantly affect an individual's quality of life. Women are disproportionately affected by DED, are diagnosed at a younger age, and experience more severe symptoms compared with men. DED is associated with a wide range of comorbid conditions; there is a strong association between DED and autoimmune disorders, especially those that affect women at many times the rate of men. Treatment response questionnaires indicate women respond better to a wellness model of treatment for DED than men. Furthermore, women's health care-seeking behaviors provide opportunities for general practitioners, specialists, and women's health centers to help identify women with DED or at risk for DED for referral to an eye care specialist. This review of the prevalence of DED in women, and gender and sex-specific aspects of DED, highlight a significant opportunity for action. Earlier diagnosis and treatment of this common but burdensome condition could significantly improve a woman's quality of life.

Gray Matter Volume Changes in Patients With Acute Eye Pain: A Voxel-Based Morphometry Study

PURPOSE

The present study was attempted to compare the differences in gray matter volume (GMV) between the acute eye pain (EP) patients and the healthy controls (HCs) using voxel-based morphometry (VBM), and to explore the relationship with clinical features and behavioral performance.

METHODS

A total of 24 patients (17 males, 7 females) with acute EP and 24 (17 males, 7 females) age-, sex-, and education-matched HCs were recruited from the Ophthalmology Department of the First Affiliated Hospital of Nanchang University. Functional magnetic resonance imaging (fMRI) scans were conducted in all subjects. We analyzed the original three-dimensional (3D) T1 brain images by VBM and compared the GMV values with the HCs. The acute EP patients can be distinguished from the HCs by receiver operating characteristic (ROC) curve.

RESULTS

Compared with HCs, the acute EP patients had significantly lower GMV values in the brain regions of the left cerebellum posterior lobe, the left limbic lobe, the right insula, the left insula, the left thalamus, the left caudate, and the right cuneus. In addition, the WMV values of the whole brain in acute EP patients decreased slightly.

CONCLUSIONS

These results demonstrated that the acute EP patients showed an abnormal reduction in GMV in some brain regions, which might provide valuable information for further exploration of underlying neural mechanisms. These abnormal brain regions may reflect the functional disorders of acute EP patients in somatosensory, motor, cognitive functions, and so on.

TRANSLATIONAL RELEVANCE

The VBM study provides a diagnostic method for identifying the cause of acute EP, additionally, a novel direction was presented for further exploration of underlying neural mechanisms of acute EP.

Neuropathic-Like Ocular Pain and Nonocular Comorbidities Correlate With Dry Eye Symptoms

OBJECTIVE

To evaluate the association between dry eye (DE) symptoms and neuropathic-like ocular pain (NOP) features, chronic pain conditions, depression, and anxiety in patients presenting for routine ophthalmic examinations.

METHODS

Two hundred thirty-three consecutive patients ≥18 years of age presenting to a comprehensive eye clinic between January and August 2016 were included in this study. Information on demographics, chronic pain conditions, medication use, DE symptoms (dry eye questionnaire, DEQ5), NOP complaints (burning; wind, light, and temperature sensitivity), depression, and anxiety indices (patient health questionnaire 9, PHQ-9 and symptom checklist 90-revised, SCL-90-R) were collected for each individual. Pearson correlation was used to evaluate strengths of association. Logistic regression analysis examined risk factors for any (DEQ5≥6) and severe (DEQ5≥12) DE symptoms.

RESULTS

The mean age of the population was 46.3 years (±13.0); 67.8% (n=158) were female. Per the DEQ5, 40.3% (n=94) had mild or greater DE symptoms and 12% (n=24) had severe symptoms. Severity of DE symptoms correlated with NOP complaints: burning (Pearson r=0.37, P<0.001); sensitivity to wind (r=0.37, P<0.001), sensitivity to light (r=0.34, P<0.001), and sensitivity to temperature (r=0.30, P<0.001). Sex, race, and ethnicity were not significant risk factors for DE symptoms. Risk factors for mild or greater DE symptoms included a greater number of chronic nonocular pain conditions (odds ratio [OR]=1.38, P<0.001), arthritic pain (OR=6.34, P<0.001), back pain (OR=2.47, P=0.004), headaches (OR=2.14, P=0.02), depression (OR=1.17, P<0.001), and anxiety (OR=1.13, P=0.02).

CONCLUSION

Dry eye severity positively associated with NOP complaints, comorbid chronic pain conditions, and symptoms of depression and anxiety.

Comparison Between Viscous Teardrops and Saline Solution to Fill Orthokeratology Contact Lenses Before Overnight Wear

OBJECTIVE

To compare, in terms of efficacy, the differences between the use of saline solution and a viscous artificial tear to fill the lens during the first month of orthokeratology wear.

METHODS

A pilot, double-masked, crossed, randomized, and prospective study was conducted. In this study, 20 subjects (14 males and 6 females) with a mean age of 16.29±6.22 years (range, 10-26) were fitted with orthokeratology contact lenses. For the study, nonpreserved 0.9% NaCl commercial saline solution (Avizor, Madrid, Spain) and nonpreserved artificial teardrops with 0.3% of hyaluronic acid (Ocudry 0.3%; Avizor, Madrid, Spain) were used. Corneal staining, tear break up time (TBUT), topography, refraction, visual acuity, and subjective comfort and vision with the visual analog scale (score from 0 to 10, being 10 better comfort and vision) were evaluated at 1 day, 1 week, and 1 month of contact lens wear.

RESULTS

The corneal staining was statistically greater in the saline group than in the Ocudry group for the first day and during 1 week of wear (P<0.05). Comfort was found to be statistically better, with Ocudry 0.3% than saline solution, being 7.17±1.94 and 6.37±1.63, for the first day, and 8.78±0.43 and 8.15±0.62 for the day 28, respectively (P<0.05). However, no differences were found for subjective vision scores, TBUT, spherical equivalent, best-corrected visual acuity and uncorrected visual acuity, and mean keratometry between groups for any visit (P>0.05).

CONCLUSION

Viscous artificial tears improve the subjective comfort of patients and reduce the corneal staining, compared with saline solution during the orthokeratology lenses fitting process. However, no differences between solutions for the treatment efficacy, in vision and corneal topography, were found.

Evidence that Dry Eye Represents a Chronic Overlapping Pain Condition

Recent data suggest that corneal somatosensory dysfunction may be the underlying cause of severe dry eye symptoms in the absence of ocular surface pathology seen in a subset of patients diagnosed with “dry eye syndrome.” This subset of patients tends to demonstrate a unique constellation of symptoms that are persistent, more severe, and generally respond poorly to current dry eye therapies targeting inadequate or dysfunctional tears. A growing body of literature suggests that symptoms in these patients may be better characterized as neuropathic ocular pain rather than dry eye. In these patients, dry eye symptoms are often associated with numerous comorbid pain conditions and evidence of central pain processing abnormalities, where eye pain is just one of multiple overlapping peripheral manifestations. In this review, we discuss the concept and potential mechanisms of chronic overlapping pain conditions as well as evidence for considering neuropathic ocular pain as one of these overlapping pain conditions.

How Are Ocular Signs and Symptoms of Dry Eye Associated With Depression in Women With and Without Sjögren Syndrome?

PURPOSE

To determine whether ocular phenotypic features of keratoconjunctivitis sicca (KCS) and/or participant-reported symptoms of dry eye disease are associated with depression in women participants enrolled in the Sjögren's International Collaborative Clinical Alliance (SICCA).

DESIGN

Cross-sectional study.

METHODS

Women enrolled in the SICCA registry from 9 international research sites. Participants met at least 1 of 5 inclusion criteria for registry enrollment (including complaints of dry eyes or dry mouth, a previous diagnosis of Sjögren syndrome (SS), abnormal serology (positive anti-Sjögren syndrome antigen A and/or B [anti-SSA and/or anti-SSB]), or elevated antinuclear antibody and rheumatoid factor), bilateral parotid gland enlargement, or multiple dental caries). At baseline, participants had oral, ocular, and rheumatologic examination; blood and saliva collection; and a labial salivary gland biopsy (LSGB). They also completed an interview and questionnaires including assessment of depression with the Patient Health Questionnaire 9 (PHQ-9). Univariate logistic regression was used to assess the association between depression and demographic characteristics, participant-reported health, phenotypic features of Sjögren syndrome, and participant-reported symptoms. Mixed-effects modeling was performed to determine if phenotypic features of KCS and/or participant-reported symptoms of dry eye disease were associated with depression, controlling for health, age, country or residence, and sex and allowing for nonindependence within geographic site.

RESULTS

Dry eye complaints produced a 1.82-fold (95% confidence interval [CI] 1.38-2.40) higher odds of having depression compared to being symptom-free (P < .001). Additionally, complaints of specific ocular sensations were associated with a higher odds of depression including burning sensation (odds ratio 2.25, 95% CI 1.87-2.72, P < .001) compared to those without complaints. In both women with and without SS, the presence of symptoms of dry eyes and/or dry mouth rather than SS itself resulted in higher odds of depression. One particular ocular phenotypic feature of SS, a positive ocular staining score, was inversely correlated with depression.

CONCLUSIONS

Participant-reported eye symptoms, particularly specific ocular sensations such as burning, were found to be positively associated with individual American College of Rheumatology/EUropean League Against Rheumatism (ACR/EULAR) SS criteria items.