Neuropathic Ocular Pain due to Dry Eye is Associated with Multiple Comorbid Chronic Pain Syndromes

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.

Evaluation of dry eye disease symptomatology and mental health status among patients with different COVID-19 statuses

AIM

To evaluate dry eye disease (DED) symptomatology and mental health status in different COVID-19 patients.

METHODS

A cross-sectional observational design was used. Totally 123 eligible adults (46.34% of men, age range, 18-59y) with COVID-19 included in the study from August to November, 2022. Ocular Surface Disease Index (OSDI), Five-item Dry Eye Questionnaire (DEQ-5), Hospital Anxiety and Depression Scale (HADS), and Pittsburgh Sleep Quality Index (PSQI) were used in this study.

RESULTS

OSDI scores were 6.82 (1.25, 15.91) in asymptomatic carriers, 7.35 (2.50, 18.38) in mild cases, and 16.67 (4.43, 28.04) in recurrent cases, with 30.00%, 35.56%, and 57.89%, respectively evaluated as having DED symptoms (χ2=7.049, P=0.029). DEQ-5 score varied from 2.00 (0, 6.00) in asymptomatic carriers, 3.00 (0, 8.00) in mild cases, and 8.00 (5.00, 10.00) in recurrent cases, with 27.50%, 33.33%, and 55.26%, respectively assessed as having DED symptoms (χ2=8.532, P=0.014). The prevalence of clinical anxiety (50.00%) and depression (47.37%) symptoms were also significantly higher in patients with recurrent infection (χ2=24.541, P<0.001; χ2=30.871, P<0.001). Recurrent infection was a risk factor for high OSDI scores [odds ratio, 2.562; 95% confidence interval (CI), 1.631-7.979; P=0.033] and DEQ-5 scores (odds ratio, 3.353; 95%CI, 1.038-8.834; P=0.043), whereas having a fixed occupation was a protective factor for OSDI scores (odds ratio, 0.088; 95%CI, 0.022-0.360; P=0.001) and DEQ-5 scores (odds ratio, 0.126; 95%CI, 0.039-0.405; P=0.001).

CONCLUSION

Patients with recurrent COVID-19 have more severe symptoms of DED, anxiety, and depression.

Rethinking Sjögren Beyond Inflammation: Considering the Role of Nerves in Driving Disease Manifestations

ABSTRACT

Sjögren syndrome (SS) is a chronic inflammatory autoimmune disease characterized by destruction of mucosal glands resulting in dry eye and dry mouth. Ocular presentations can be heterogenous in SS with corneal nerves abnormalities that are structural, functional, or both. Some individuals present with corneal hyposensitivity, with a phenotype of decreased tear production and epithelial disruption. Others present with corneal hypersensitivity, with a phenotype of neuropathic pain including light sensitivity and pain out of proportion to signs of tear dysfunction. A similar correlate can be found outside the eye, with dry mouth predominating in some individuals while pain conditions predominate in others. Understanding how nerve status affects SS phenotype is an important first step to improving disease management by targeting nerve abnormalities, as well as inflammation.

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.

Eye Pain Caused by Epithelial Damage in the Central Cornea in Aqueous-Deficient Dry Eye

In this study, the severity of eye pain (EP) and associated objective findings were evaluated in aqueous-deficient dry eye (ADDE) patients using PainVision®, a quantitative pain-measuring device. This study involved 53 eyes of 53 ADDE patients (6 males and 47 females; mean age: 64.4 ± 13.4 [mean ± SD] years). Of those, 18 eyes of 18 patients underwent punctal occlusion, and EP and objective findings in those patients were evaluated before and after treatment. In all patients, the severity of EP as measured by PainVision® was assessed using the Pain Degree (PD). The median PD for the 53 patients was 30.6 µA/µA (interquartile range, 16.9-93.2), and the nasal and central corneal staining score and the upper lid-wiper epitheliopathy score were significantly correlated with PD (R = 0.33, 0.33, and 0.28, respectively) (all: p < 0.05). Using the least squares method, the central corneal staining score most significantly affected PD. In the 18 cases that underwent punctal occlusion, PD was significantly reduced (median PD: 24.8 to 7.1 µA/µA; p < 0.0001). Using the least squares method, the central corneal staining score and tear meniscus radius were significantly more influential as factors contributing to PD before and after treatment, and central corneal epithelial damage was the factor most associated with ADDE-related EP.

Real Life Impact of Dry Eye Disease

Dry Eye Disease (DED) is an increasingly common condition that affects between 5% and 50% of the global population. Even though DED is most frequently diagnosed in older people, it has also been diagnosed in young adults and adolescents more frequently in recent years (employees, gamers). People can experience different types of symptoms and find it challenging to read, watch TV, cook, climb stairs, and meet friends. Mild and severe dry eye can reduce quality of life similarly to mild psoriasis and moderate-to-severe angina. Furthermore, DED patients experience serious difficulties driving vehicles, especially at night, and show a decrease in work productivity, which, when combined with the relevant indirect cost that this condition produces, poses a serious challenge in our days. In addition, DED patients are more likely to develop depression and suicidal ideations and experience frequent sleep disorders. Finally, it is discussed how lifestyle changes, such as increased physical activity, blinking exercises, and a proper diet, have positive implications for the management of this condition. Our aim is to draw attention to the negative effects of dry eye in real life, which are unique to each patient, especially as they relate to the non-visual symptoms experienced by DED patients.

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

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.

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.

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.

Oxytocin and secretin receptors - implications for dry eye syndrome and ocular pain

Dry eye syndrome, a form of ocular surface inflammation, and chronic ocular pain are common conditions impacting activities of daily living and quality of life. Oxytocin and secretin are peptide hormones that have been shown to synergistically reduce inflammation in various tissues and attenuate the pain response at both the neuron and brain level. The oxytocin receptor (OXTR) and secretin receptor (SCTR) have been found in a wide variety of tissues and organs, including the eye. We reviewed the current literature of in vitro experiments, animal models, and human studies that examine the anti-inflammatory and anti-nociceptive roles of oxytocin and secretin. This review provides an overview of the evidence supporting oxytocin and secretin as the basis for novel treatments of dry eye and ocular pain syndromes.

Lid wiper epitheliopathy in patients with blepharospasm and/or hemifacial spasm

OBJECTIVE

To evaluate the presence of wiper epitheliopathy in patients with blepharospasm and/or hemifacial spasm before and 4 weeks after routine treatment with botulinum toxin.

METHODS

Prospective study comprising 31 eyes of 20 patients with neurological diagnosis of hemifacial spasm (9 eyes of 9 patients) and essential blepharospasm (22 eyes of 11 patients). Various ocular surface parameters were assessed before and 4 weeks after infiltration with botulinum toxin using the OSDI questionnaire, Schirmer's test, tear break-up time (BUT), fluorescein and lissamine green staining assessed with the Oxford test and the degree of involvement of the palpebral wiper.

RESULTS

100% of the patients had palpebral wiper involvement before (30% mild and 70% moderate) and after toxin treatment (100% mild). 75% of patients had mild-normal OSDI before treatment, after treatment it was 80%. The BUT was 7.2 ± 0.2 sg before and 7.5 ± 0.7 sg after treatment. Schirmer's test was 11.4 ± 5.5 and 12.5 ± 5.5 mm before and after treatment. The Oxford test was initially pathological in 69.3% of patients, after 4 weeks it was pathological in only 54%.

CONCLUSION

Wiper epitheliopathy is present in 100% of patients with blepharospasm and/or hemifacial spasm. The main pathophysiological mechanism that triggers it in these patients is the increase in the coefficient of friction, as tear volume and stability are normal.

Evidence for a phenotypic switch in corneal afferents after lacrimal gland excision

Dry eye is a common cause of ocular pain. The aim of this study was to investigate corneal innervation, ongoing pain, and alterations in corneal afferent phenotypes in a mouse model of severe aqueous tear deficiency. Chronic dry eye was produced by ipsilateral excision of the extra- and intraorbital lacrimal glands in male and female mice. Tearing was measured using a phenol thread and corneal epithelial damage assessed using fluorescein. Changes in corneal ongoing ocular pain was evaluated by measuring palpebral opening ratio. Corneal axons were visualized using Nav1.8-Cre;tdTomato reporter mice. Immunohistochemistry was performed to characterize somal expression of calcitonin gene-related peptide (CGRP), the capsaicin sensitive transient receptor potential vanilloid 1 (TRPV1), and activating transcription factor-3 (ATF-3) in tracer labeled corneal neurons following lacrimal gland excision (LGE). LGE decreased tearing, created severe epithelial damage, and decreased palpebral opening, indicative of chronic ocular irritation, over the 28-day observation period. Corneal axon terminals exhibited an acute decrease in density after LGE, followed by a regenerative process over the course of 28 days that was greater in male animals. Corneal neurons expressing CGRP, TRPV1, and ATF3 increased following injury, corresponding to axonal injury and regeneration processes observed during the same period. CGRP and TRPV1 expression was notably increased in IB4-positive cells following LGE. These results indicate that dry eye-induced damage to corneal afferents can result in alterations in IB4-positive neurons that may enhance neuroprotective mechanisms to create resiliency after chronic injury.

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.

Correlation between global prevalence of vision impairment and depressive disorders

PURPOSE

To assess the correlation of the worldwide prevalence of visual impairment and depressive disorders.

METHODS

This is an ecologic study on Global Burden of Disease 2019 data. Global and national prevalence numbers and rates of vision impairment (VI) and depressive disorders were obtained from database. The human development index (HDI) and socio-demographic index (SDI) were derived from international open databases. Main outcome measures were the correlation of the VI and depressive disorders in total and different age, sex, and socioeconomic subgroups.

RESULTS

In 2019, the worldwide prevalence of total VI and total depressive disorders were 9.6% (95% Uncertainty Interval (UI): 8.0-11.3) and 3.8% (95% UI: 3.4-4.2), respectively. The prevalence rates of total VI (r = 0.38, P < 0.001) as well as cataract (r = 0.43, P < 0.001), age-related macular degeneration (AMD) (r = 0.32, P < 0.001), refractive disorders (r = 0.19, P < 0.001) and near vision loss (r = 0.33, P < 0.001) correlated, positively, with dysthymia. In addition, the prevalence rates of glaucoma (r for total depressive disorders = 0.37, P < 0.001 and r for major depressive disorders (MDD) = 0.38, P < 0.001) and AMD (r for total depressive disorders = 0.37, P < 0.001 and r for MDD = 0.28, P < 0.001) had a positive correlation with MDD and total depressive disorders. The correlations remained significant in sociodemographic subgroups.

CONCLUSION

There was a significant correlation between national prevalence rates of VI and ocular disabilities with depressive disorders, worldwide.

Beyond dry eye: how co-morbidities influence disease phenotype in dry eye disease

Dry Eye Disease (DED) is a complex and multifactorial disorder of tear homoeostasis that results in pain, visual disturbance, and ocular surface damage. It is highly prevalent around the world and is associated with many co-morbidities that may contribute to or exacerbate symptoms and signs of disease and affect disease phenotype. However, DED is not one disease and can manifest with a variety of symptoms and/or signs. In this review, we discuss relationships between various co-morbidities and DED phenotypes. For example, individuals with immune mediated diseases, like Sjögren's Syndrome and Graft versus Host Disease, often present with aqueous tear deficiency (ADDE) in the setting of lacrimal gland dysfunction. Individuals with disorders that affect the periocular skin, like rosacea and seborrhoeic dermatitis, often present with evaporative dry eye (EDE) in the setting of eyelid and/or meibomian gland abnormalities. Individuals with pain related disorders, such as chronic pain syndrome and migraine, often present with ocular pain out of proportion to tear film abnormalities, often with accompanying corneal nerve hypersensitivity. Individuals with diabetes mellitus often present with an epitheliopathy in the setting of decreased sensation (neurotrophic keratitis). While not absolute, understanding relationships between co-morbidities and DED phenotypes can help tailor a therapeutic plan to the individual patient.

Efficacy of Intense Pulsed Light Combined Blood Extract Eye Drops for Treatment of Nociceptive Pain in Dry Eye Patients

Purpose: To investigate the efficacy of intense pulsed light (IPL) combined with deproteinized calf blood extract (DCBE) eye drops for dry eye disease (DED) patients with nociceptive ocular pain. Methods: In this prospective, one-center, interventional study, 23 subjects with DED and ocular pain were treated with a combination of IPL and DCBE eye drops for four sessions at a four-week interval. Subjective and objective assessments on nociceptive pain and dry eye were examined and analyzed. Results: The visual analog scale (VAS), ocular surface disease index, ocular pain assessment survey (OPAS), patient health questionnaire-9 items, generalized anxiety disorder (GAD-7), Athens insomnia scale, corneal fluorescein staining score, meibomian gland secretion quality, and expressibility scores were significantly reduced after the treatment. Tear break-up time and Schirmer I test increased significantly. The brand density of corneal nerves and neuropeptide substance P also significantly increased. OPAS, GAD-7, meibomian gland secretion quality, and expressibility scores were essential factors affecting the VAS changes. Conclusions: IPL combined with DCBE drop therapy was effective for DED patients with ocular pain. With such treatment, both DED symptoms and the sensation of ocular pain may be improved.

How Should Corneal Nerves be Incorporated Into the Diagnosis and Management of Dry Eye?

Purpose

a)Confocal microscopy and aethesiometry have allowed clinicians to assess the structural and functional integrity of corneal nerves in health and disease. This review summarizes literature on nerves in dry eye disease (DED) and discusses how this data can be applied to DED diagnosis and treatment.

Recent findings

b)Subjects with DED have a heterogenous symptom and sign profile along with variability in nerve structure and function. Most studies have reported lower nerve density and sensitivity in aqueous tear deficiency, while findings are more inconsistent for other DED subtypes. Examining nerve status, along with profiling symptoms and signs of disease, can help categorize subjects into disease phenotypes (structural and functional patterns) that exist under the umbrella of DED. This, in turn, can guide therapeutic decision-making.

Summary

c)Due to the heterogeneity in symptoms and signs of DED, corneal nerve evaluations can be valuable for categorizing individuals into disease sub-types and for guiding clinical decision making.

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.

Dry eye disease and psychiatric disorders: A systematic review and meta-analysis

The association between dry eye disease (DED) and psychiatric conditions is a highly researched topic. This work reviews the literature on this relationship, examining the prevalence and correlations of depression and anxiety with dry eye signs and symptoms. A comprehensive literature search of MEDLINE, EMBASE, PsycINFO, and gray literature was conducted, with keywords for dry eye and mood disorders, depression, anxiety, and suicide. Eligible studies underwent quality assessment using the Newcastle-Ottawa Scale. Meta-analysis was performed using STATA 15.0. Fixed- and random-effects models were computed based on the presence of heterogeneity. Thirty-two studies were included, with 31 reporting on depression and 19 on anxiety. Meta-analysis results found a depression prevalence of 40% (CI: [0.29, 0.52]) in DED patients, with 1.81 times higher odds of prevalence compared to controls (CI: [1.61, 2.02]). Prevalence of anxiety was 39% (CI: [0.15, 0.64]), with 2.32 times higher odds of prevalence compared to controls (CI: [1.67, 3.23]). Depression scores were significantly higher in patients with DED in all studies. Anxiety scores were significantly higher in DED patients in studies using all scales except the Hospital Anxiety and Depression Scale-Anxiety Subscale. DED symptom scores were significantly associated with depression (ES = 0.43; CI: [0.31, 0.55]) and anxiety (ES = 0.41; CI: [0.32, 0.50]) scores. In conclusion, depression and anxiety are more prevalent and severe in DED patients and are correlated with dry eye symptoms but not signs. These findings highlight the interrelationship between these disorders and have important implications for providing appropriate care to these patients.

Work productivity among Sjögren's Syndrome and non-Sjögren's dry eye patients: a systematic review and meta-analysis

BACKGROUND

Dry eye disease (DED) is one of the most common conditions presenting to eye care providers and is increasingly recognized to have poor outcomes on quality of life, activities of daily living, and social and emotional well-being. Here, we aim to understand the association between dry eye symptoms and workplace productivity experienced by patients with non-Sjögren's dry eye and Sjögren's Syndrome.

METHODS

MEDLINE, PubMed, Embase, Cochrane Library, CINAHL, Healthstar, and PsycINFO were searched from inception to May 2019.

RESULTS

Thirty-one studies consisting of 50,446 study participants from 14 countries were included in this systematic review. Among non-Sjögren's dry eye patients, there was significant absenteeism (ES = 0.19; 95% CI: [0.04, 0.35]), presenteeism (ES = 0.25; 95% CI: [0.15. 0.35]), productivity impairment (ES = 0.24; 95% CI: [0.20, 0.27]), activity impairment (ES = 0.30; 95% CI: [0.21, 0.38]), and subjective difficulties at work (ES = 0.58; 95% CI: [0.40, 0.75]). Patients with Sjögren's Syndrome demonstrated significant absenteeism (ES = 0.13, 95% CI: [0.10, 0.17]), presenteeism (ES = 0.28, 95% CI: [0.24, 0.32]), productivity impairment (ES = 0.31, 95% CI: [0.27, 0.35]), and activity impairment (ES = 0.39, 95% CI: [0.32, 0.47]) in the workplace. In addition, patients with Sjögren's Syndrome demonstrated significantly lower employment rate (ES = 0.42, 95% CI: [0.34, 0.50]), decreased number of hours worked (SMD = -0.21, 95% CI: [-0.39, -0.02]), and increased work disability (ES = 0.18; 95% CI: [0.09, 0.27]).

CONCLUSIONS

This is the first systematic review and meta-analysis to demonstrate the negative association between DED and several work productivity measures.

Association Between Dry Eye Syndrome and Osteoarthritis Severity: A Nationwide Cross-Sectional Study (KNHANES V)

OBJECTIVE

Recently, several researchers reported an association between osteoarthritis and dry eye syndrome (DES) and suggested that they may be related to central sensitization. We investigated the association between DES, osteoarthritis pain, and radiographic severity.

DESIGN

A nationwide, cross-sectional study.

SETTING

The Fifth Korean National Health and Nutrition Examination Survey.

SUBJECTS

8,664 participants in this survey.

METHODS

Osteoarthritis-associated radiographic changes were evaluated by trained radiologists. Multivariable logistic regression was performed to examine the relationship between osteoarthritis pain, radiographic severity, and DES. The odds ratios (ORs) of DES were analyzed in accordance with the presence of osteoarthritis-associated factors.

RESULTS

Radiographic knee osteoarthritis was significantly associated with lower ORs for DES (OR = 0.80, P = 0.046, for diagnosed/self-reported DES; OR = 0.84, P = 0.034, for symptoms of DES). Knee pain or stiffness was significantly associated with higher ORs for DES (OR = 1.28, P = 0.020, for diagnosed/self-reported DES; OR = 1.29, P = 0.003, for symptoms of DES). In patients with symptomatic osteoarthritis, DES was not significantly associated with radiographic severity of osteoarthritis. In patients with nonsymptomatic radiographic osteoarthritis, DES was inversely related with radiographic severity (Ptrend = 0.012 for diagnosed/self-reported DES; Ptrend < 0.001 for symptoms of DES).

CONCLUSIONS

Radiographic osteoarthritis showed a significant association with decreased DES. Patients with less pain and severe radiographic OA were more likely to have less DES. Our results suggest that the degree of pain caused by osteoarthritis and central sensitization may be closely associated with DES.

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.

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.

Long-Term Trigeminal Nerve Stimulation as a Treatment for Ocular Pain

OBJECTIVES

Ocular pain symptoms (e.g., hypersensitivity to light and wind, "burning" sensations) can be debilitating and difficult to treat. Neuromodulatory therapies targeting sensory trigeminal and central pain pathways may help treat chronic ocular pain refractory to traditional therapies. The current study evaluates the long-term effects of a trigeminal neurostimulator (TNS) on ocular pain.

MATERIALS AND METHODS

Retrospective review of 18 individuals at the Miami Veterans Affairs Eye Clinic with chronic, severe ocular pain who were prescribed and used TNS at home for ≥3 months. The primary outcome measures were 1) ocular symptom intensity over a 24-hour recall period (dryness, pain, light sensitivity, wind sensitivity, burning; rated on 0-10 scales) captured pre-TNS and at monthly follow-up intervals and 2) side effects. The frequency and duration of TNS was a secondary outcome measure.

RESULTS

The mean age of the population (n = 18) was 57.5 years (range, 34-85 years) with a male majority (67%). Two individuals discontinued use due to lack of efficacy and one due to confounding health issues. Initial mean weekly frequency of TNS use was 3.7 ± 1.9 sessions of 25.8 min at month 1 and 2.7 ± 2.3 sessions of 28.0 min at month 6. At six months, pain intensity (↓ 31.4%), light sensitivity (↓ 36.3%), wind sensitivity (↓ 32.6%), and burning sensation (↓ 53.9%) were all decreased compared to baseline (p < 0.01 for all); greater decreases in ocular pain were noted in individuals with migraine (n = 10) than those without migraine (n = 8). No significant change was noted in mean dryness scores. Fifteen subjects experienced sedation with TNS use, persisting throughout the follow-up visits. No other adverse effects were communicated by any subjects.

CONCLUSION

Our study suggests TNS is a safe, adjunctive treatment option in individuals with severe, chronic ocular pain. Individuals demonstrated gradual, continual improvement in pain symptoms over time within a multimodal approach.

Ocular Neuropathic Pain: An Overview Focusing on Ocular Surface Pains

Objective

This paper reviews ocular pain with the main focus on ocular surface discomfort and dry eye pain. Anatomy, physiology, epidemiology, assessment, and treatment are discussed in this paper.

Methods

A PubMed search was conducted for studies published from 2000 to 2019 on the anatomy, pathophysiology, epidemiology, assessment, and treatment of ocular pain. Reviews, meta-analyses, and randomized clinical trials were included. Inclusion criteria focused on ocular surface discomfort, dry eye pain and neuropathic pain.

Results

A total of 112 articles were found through searches, 45 of which were selected and studied in this review.

Discussion

Pain in general can be acute or chronic. Acute pain is usually a physiologic response to a serious damage to the tissues and alleviates with pain relief treatments. Chronic pain is defined as the persistence of pain for more than three months. From another point of view, pain has been classified into either nociceptive or neuropathic. Nociceptive pain is a physiologic response to a noxious stimulus. Both central and peripheral nervous systems can be involved in the development of a neuropathic pain, which is characterized by positive or negative sensory signs, a pain perceived disproportionate to a noxious stimulus, and/or not responsive to analgesics. Chronic pain usually has a neuropathic component. Ocular surface pain is a well-known complaint after any corneal surgery. This is mainly due to abnormal regeneration of damaged corneal nerve endings and abnormal connections with adjacent nerve endings which produce spontaneous activity. Tear hyperosmolarity and the resultant ocular surface inflammation can also trigger voluntary activity of corneal nerve endings. Referral pain to the first and second division of the trigeminal nerve has been reported. Interference with vision and even sleep, which is out of proportion to the examination are among patients' complaints. All of these elements proposed the new concept of ocular neuropathic pain syndrome. The first step in conventional evaluation of ocular discomfort is search for tear insufficiency. Pathologies of lid and blinking as well as conjunctival irregularities should be addressed. Anti-inflammatory agents and, in resistant cases, systemic neuromodulators are shown to be helpful. Education on behavioral changes and reassurance are essential steps. Considering the neuropathic origin for the ocular pain, treatment modalities used for such pain in other parts of the body can be considered for this syndrome.

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.

Capsaicin-induced pain sensitivity in short tear break-up time dry eye

PURPOSE

To evaluate transient receptor potential vanilloid 1 (TRPV1)-mediated pain sensitivity in patients with short tear break-up time (TBUT) dry eye (DE) by using the capsaicin stimulus test.

METHODS

This prospective cross-sectional comparative study included 22 eyes of 22 patients with short TBUT DE and 11 eyes of 11 non-DE control subjects. Patients were divided into two groups based on response to standard DE treatments: 10 non-responders (intractable DE) and 12 responders (responsive DE). Mechanical touch (M-touch) and mechanical pain (M-pain) were measured using a Cochet-Bonnet esthesiometer. Capsaicin-induced pain (C-pain) and C-pain duration (C-pain DT) were measured using a capsaicin stimulus test. Psychological distress was also assessed.

RESULTS

M-touch sensitivity was similar among all three groups. M-pain sensitivity was higher in the responsive DE group than in the intractable DE and control groups (P < .001). C-pain sensitivity was lower (P < .001) in the intractable DE group than in the responsive DE and control groups, and C-pain DT was shorter (P = .006) in the intractable DE group than in the responsive DE group. Psychological distress was higher in the intractable DE group than in the control group (P < .001).

CONCLUSIONS

Patients with intractable short TBUT DE were less sensitive to the effects of capsaicin than patients with responsive short TBUT DE and controls. Altered neural activation may contribute to the development of DE symptoms in the short TBUT DE subjects. The capsaicin stimulus test may be used to better understand pain sensitivity in short TBUT DE patients.

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.

Unexplained ocular and visual symptoms: The need for a psychosomatic approach in Ophthalmology

INTRODUCTION

Psychogenic causes for some somatic symptoms have been widely recognised. In Ophthalmology however, there are few studies that address this issue, and current Ophthalmology Training Programs do not include formal teaching in Psychosomatics. Psychosomatic phenomena in ophthalmology are probably under-diagnosed, which may reduce therapeutic effectiveness, decrease patient and physician satisfaction, and increase health costs due to multiple consultations and prescriptions. The aims of this study were to describe patients with unexplained visual/ocular symptoms (UVOS), and to estimate the prevalence of psychological distress (PD) among them.

MATERIALS AND METHODS

Consecutive adults with UVOS were recruited over a 12 month period. Complete medical history and ocular examination were performed to rule out organic disease. Psychological Distress was defined by the presence of one or more of the following criteria: psychiatric diagnosis, use of psychotropic medication, psychosomatic disease in other organs, and biographical crisis in the last 6 months. Results were compared with a control group.

RESULTS

A total of 39 cases of UVOS were recruited, corresponding approximately to 3% prevalence. The large majority (74%) were female. The mean age was 41.8 years. The most common complaints were ocular surface irritation symptoms (51%) and unspecific visual disturbances (17%). At least 1 of the PD criteria was found in 100%, including 46.2% with psychiatric comorbidity, 48.7% with psychotropic medications, 64% with psychosomatic disease in other organs, and 48.7% with recent life-stressful events. PD indicators were statistically higher compared with control group (P<.05).

CONCLUSIONES

There was a high frequency of PD indicators in patients with UVOS. Although the causative role of PD remains unclear, the presence of UVOS should warn the ophthalmologist of an underlying psychic conflict and to make an appropriate psychological intervention.

Clinical and in vivo confocal microscopic features of neuropathic corneal pain

Aims

To describe clinical and in vivo confocal microscopy (IVCM) features of neuropathic corneal pain (NCP) without clinically visible signs.

Methods

Prospective, observational study of 27 eyes of 14 patients who had continuous severe ocular pain for one or more years, with minimal or no ocular surface signs and were non-responsive to topical lubricants, steroids and/or ciclosporin. All patients were evaluated using Ocular Surface Disease Index, Oxford grading scale, Schirmer test 1, Cochet Bonnet esthesiometry and response to topical anaesthesia. Central and paracentral regions of the cornea of patients and seven healthy controls were studied by IVCM. Corneal epithelial thickness and sub-basal nerve density were measured in patients and controls.

Results

Four patients responded to topical anaesthesia (responsive group (RG)), indicating peripheral NCP while 10 patients did not show any improvement (non-responsive group (NRG)), indicating central NCP. Schirmer-1 test was within normal limits in the RG but significantly greater in the NRG (p<0.001). None of the other clinical parameters nor corneal epithelial thickness were statistically significantly different. The sub-basal nerve density was significantly reduced (p<0.008) in patients compared with controls. Stroma of all patients demonstrated activated keratocytes and spindle, lateral and stump microneuromas. There was a statistically significant greater number of microneuromas (p<0.0001) and activated keratocytes in RG compared with NRG.

Conclusion

NCP without visible clinical signs does not represent typical dry eye disease. Distinct signs demonstrated on IVCM suggest that peripheral NCP, which responds to topical anaesthesia, and central NCP, which does not, are separate entities.

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.

The Case for a More Holistic Approach to Dry Eye Disease: Is It Time to Move beyond Antibiotics?

Dry eye disease (DED) is one of the most frequent presentations to optometrists with over 16 million US adults (6.8% of adult population) diagnosed as having this disorder. The majority of associated marketed products offer relief from symptomatology but do not address aetiology. DED harbours many distinguishing features of a chronic inflammatory disorder. The recent explosion in human microbiome research has sparked interest in the ocular microbiome and its role in the preservation and extension of ocular surface health and in the contribution of the gut microbiome to chronic systemic inflammation and associated "Western life-style" diseases. With a significant lack of success for many patients using currently available DED treatments, in this era of the microbiome, we are interested in exploring potential novel therapies that aim to reconstitute healthy bacterial communities both locally and distally (in the gut) as a treatment for DED. Although this direction of investigation is in its infancy, burgeoning interest makes such a review timely. This paper considers a number of studies into the use functional foods and associated products to ameliorate dry eye.

Sjögren's Syndrome, Non-Sjögren's Syndrome, and Graft-Versus-Host Disease Related Dry Eye

I have reviewed available literature on dry eye related to Sjögren's syndrome (SS), non-Sjögren's syndrome (non-SS), and graft-versus-host disease (GVHD) to examine aqueous tear deficient dry eye as a subtype of dry eye. This section will focus on clinical studies regarding those subtypes of dry eye. I searched the PubMed database from 1990-2017 for discussion of clinical features, diagnostic criteria, and risk factors of SS, non-SS, and GVHD-related dry eye. In addition, therapeutic options for each subtype of dry eye are described. Although the clinical presentations of SS and chronic graft-versus-host disease (cGVHD) are similar, ocular surface fibrotic changes are characteristic of ocular GVHD but not SS- or non-SS-related dry eye. Recently, diagnostic criteria for each disease have been proposed and include the American College of Rheumatology/European League Against Rheumatism (ACR-EULAR) for SS and the International Chronic Ocular GVHD consensus criteria. Although there has been gradual progress, there are currently no specific therapies and few approved treatment options for these intractable diseases, including SS and GVHD. As judged by the findings, these subtypes of dry eye are different clinical entities from simple dry eye. Therefore, novel therapies, specific to these subtypes of dry eye, may be required in the future.

Latent Sensitization in a Mouse Model of Ocular Neuropathic Pain

Purpose

Chronic ocular pain is poorly understood and difficult to manage. We developed a murine model of corneal surface injury (CSI)-induced chronic ocular neuropathic pain. The study focuses on changes in corneal nerve morphology and associated short- and long-term pain-like behavior after CSI.

Methods

CSI was induced in mice by local application of an alkali solution (0.75 N NaOH). Corneal nerve architecture, morphology, density, and length were studied. Eye-wiping was evaluated before and after CSI in response to hypertonic saline (2 M NaCl). Naltrexone (NTX) or Naloxone-methiodide (NLX-me), opioid receptor antagonists, were given subcutaneously (s.c., 3 mg/kg) or topically (eye drop, 100 μM), and then an eye-wiping test was performed.

Results

CSI caused partial corneal deinnervation followed by gradual reinnervation. Regenerated nerves displayed increased tortuosity, beading, and branching. CSI enhanced hypertonic saline-induced eye-wiping behavior compared to baseline or sham-injury (P < 0.01). This hypersensitivity peaked at 10 days and subsided 14 days after CSI. Administration of NTX, or NLX-me, a selective peripheral opioid antagonist, reinstated eye-wiping behavior in the injury group, but not in the sham groups (P < 0.05).

Conclusions

This study introduces a model of chronic ocular pain and corneal neuropathy following CSI. CSI induces central and peripheral opioid receptor-dependent latent sensitization (LS) that is unmasked by systemic or topical administration of opioid antagonists.

Translational Relevance

This model of chronic ocular pain establishes LS as a new inhibitory mechanism in the oculotrigeminal system and may be used for potential diagnostic and therapeutic interventions for ocular neuropathy.

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.

What's new in dry eye disease diagnosis? Current advances and challenges

Dry eye disease (DED) is a commonly encountered condition in general ophthalmology practice and imparts a significant socioeconomic burden. Despite its prevalence, there remain challenges regarding its diagnosis and management. A major reason behind these challenges is the fact that DED represents an umbrella term that encompasses many different underlying conditions and pathophysiological mechanisms. The purpose of this article is to highlight aspects of DED pathophysiology and focus on targeted diagnostic and therapeutic approaches to this multifactorial, chronic condition.

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.

Neurological and Inflammatory Manifestations in Sjögren's Syndrome: The Role of the Kynurenine Metabolic Pathway

For decades, neurological, psychological, and cognitive alterations, as well as other glandular manifestations (EGM), have been described and are being considered to be part of Sjögren's syndrome (SS). Dry eye and dry mouth are major findings in SS. The lacrimal glands (LG), ocular surface (OS), and salivary glands (SG) are linked to the central nervous system (CNS) at the brainstem and hippocampus. Once compromised, these CNS sites may be responsible for autonomic and functional disturbances that are related to major and EGM in SS. Recent studies have confirmed that the kynurenine metabolic pathway (KP) can be stimulated by interferon-γ (IFN-γ) and other cytokines, activating indoleamine 2,3-dioxygenase (IDO) in SS. This pathway interferes with serotonergic and glutamatergic neurotransmission, mostly in the hippocampus and other structures of the CNS. Therefore, it is plausible that KP induces neurological manifestations and contributes to the discrepancy between symptoms and signs, including manifestations of hyperalgesia and depression in SS patients with weaker signs of sicca, for example. Observations from clinical studies in acquired immune deficiency syndrome (AIDS), graft-versus-host disease, and lupus, as well as from experimental studies, support this hypothesis. However, the obtained results for SS are controversial, as discussed in this study. Therapeutic strategies have been reexamined and new options designed and tested to regulate the KP. In the future, the confirmation and application of this concept may help to elucidate the mosaic of SS manifestations.

Epidemiology of Persistent Postsurgical Pain Manifesting as Dry Eye-Like Symptoms After Cataract Surgery

PURPOSE

To evaluate the epidemiology of persistent postsurgical pain (PPP) manifesting as dry eye (DE)-like symptoms 6 months after surgery.

METHODS

This single-center study included 119 individuals whose cataract surgeries were performed by a single surgeon at the Bascom Palmer Eye Institute and who agreed to participate in a phone survey 6 months after surgery. Patients were divided into 2 groups: the PPP group was defined as those with a Dry Eye Questionnaire-5 score ≥6 and without PPP as those with a Dry Eye Questionnaire-5 score <6 at 6 months after cataract surgery.

RESULTS

Mean age of the study population was 73 ± 8.0 years; 55% (n = 66) were female. PPP was present in 34% (n = 41) of individuals 6 months after surgery. Factors associated with an increased risk of PPP were female sex [odds ratio (OR) = 2.68, 95% confidence interval (CI) = 1.20-6.00, P = 0.01], autoimmune disorder (OR = 13.2, CI = 1.53-114, P = 0.007), nonocular chronic pain disorder (OR = 4.29, CI = 1.01-18.1, P = 0.06), antihistamine use (OR = 6.22, CI = 2.17-17.8, P = 0.0003), antireflux medication use (OR = 2.42, CI = 1.04-5.66, P = 0.04), antidepressant use (OR = 3.17, CI = 1.31-7.68, P = 0.01), anxiolytic use (OR = 3.38, CI = 1.11-10.3, P = 0.03), and antiinsomnia medication use (OR = 5.28, CI = 0.98-28.5, P = 0.047). PPP patients also reported more frequent use of artificial tears (P < 0.0001), higher ocular pain levels (P < 0.0001), and greater neuropathic ocular pain symptoms, including burning (P = 0.001), wind sensitivity (P = 0.001), and light sensitivity (P < 0.0001).

CONCLUSIONS

PPP in the form of persistent DE-like symptoms is present in approximately 34% of individuals 6 months after cataract surgery. The frequency of PPP after cataract surgery is comparable to that of other surgeries including laser refractive surgery, dental implants, and genitourinary procedures.

The Association of Dry Eye Symptom Severity and Comorbid Insomnia in US Veterans

PURPOSE

To investigate the association between dry eye (DE) and insomnia symptom severity.

METHODS

Cross-sectional study of 187 individuals seen in the Miami Veterans Affairs eye clinic. An evaluation was performed consisting of questionnaires regarding insomnia (insomnia severity index [ISI]) and DE symptoms, including ocular pain, followed by a comprehensive ocular surface examination. Using a two-step cluster analysis based on intensity ratings of ocular pain, the patient population was divided into two groups (high and low ocular pain groups: HOP and LOP). A control group was ascertained at the same time from the same clinic as defined by no symptoms of DE (Dry Eye Questionnaire 5 [DEQ5], <6). The main outcome measure was the frequency of moderate or greater insomnia in the DE groups.

RESULTS

The mean age of the study sample was 63 years, and 93% were male. All insomnia complaints were rated higher in the HOP group compared with the LOP and control groups (P<0.0005). Most (61%) individuals in the HOP group experienced insomnia of at least moderate severity (ISI≥15) compared with the LOP (41%) and control groups (18%) (P<0.0005). Black race (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.2-6.0; P=0.02), depression severity (OR, 1.2; 95% CI, 1.1-1.3; P<0.0005), and DE symptom severity (DEQ5; OR, 1.1; 95% CI, 1.01-1.2; P=0.03) were significantly associated with clinical insomnia (ISI≥15) after controlling for potential confounders.

CONCLUSIONS

After adjusting for demographics and medical comorbidities, we show that DE symptom severity is positively associated with insomnia severity.

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.