Efficacy and safety of trigeminal parasympathetic pathway stimulation for dry eye: A systematic review and meta-analysis.

This study aimed to investigate the efficacy and safety of trigeminal parasympathetic pathway (TPP) stimulation in the treatment of dry eye. A comprehensive search for randomized clinical trials was performed in seven databases (MEDLINE, Embase, CENTRAL, etc.) up to 28 February 2023. After screening the suitable studies, the data were extracted and transformed as necessary. Data synthesis and analysis were performed using Review Manager 5.4, and the risk of bias and quality of evidence were evaluated with the recommended tools. Fourteen studies enrolling 1714 patients with two methods (electrical and chemical) of TPP stimulation were included. Overall findings indicate that TPP stimulation was effective in reducing subjective symptom score (standardized mean difference [SMD], -0.45; 95% confidence interval [CI], -0.63 to -0.28), corneal fluorescence staining (mean difference [MD], -0.78; 95% CI, -1.39 to -0.18), goblet cell area (MD, -32.10; 95% CI, -54.58 to -9.62) and perimeter (MD, -5.90; 95% CI, -10.27 to -1.53), and increasing Schirmer's test score (SMD, 0.98; 95% CI, 0.65 to 1.31) and tear film break-up time (SMD, 0.57; 95% CI, 0.19 to 0.95). Compared to inactive or low-activity stimulation controls, it has a higher incidence of adverse events. Therefore, TPP stimulation may be an effective treatment for dry eye, whether electrical or chemical. Adverse events are relatively mild and tolerable. Due to the high heterogeneity and low level of evidence, the current conclusions require to be further verified.

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.

Review of clinical outcomes of a cationic emulsion tear substitute in patients with dry eye disease.

First-line options for the treatment of dry eye disease (DED) rely on artificial tears (ATs), among which cationic emulsion (CE)-based ATs have been developed in order to mimic the healthy tear film for an improved restoration of the ocular surface homeostasis. In this review, we describe the outcomes reported in several studies, assessing the mode of action, ocular tolerance and clinical performance of a CE-based AT. Pilot studies have revealed that CE-based ATs can increase the volume and stability of the tear film while limiting its evaporation rate. Larger studies have demonstrated that CE-based ATs play a significant role in the improvement of both objective and subjective DED parameters, including superior efficacy on DED symptoms compared to several other available AT formulation types. Concomitantly, CE-based ATs have been shown to help patients to prevent or recover from corneal defects associated with refractive surgery. These positive outcomes on ocular surface epithelia are likely due to the combination of unique rheological behaviour and intrinsic anti-inflammatory properties. Based on all clinical findings, CE-based ATs represent a valuable treatment option for patients with various etiologies of DED including evaporative forms and would deserve evaluation of benefits in other surgical intervention types triggering DED.

Is the Sex Difference a Clue to the Pathomechanism of Dry Eye Disease? Watch out for the NGF-TrkA-Piezo2 Signaling Axis and the Piezo2 Channelopathy.

Dry eye disease (DED) is a multifactorial disorder with recognized pathology, but not entirely known pathomechanism. It is suggested to represent a continuum with neuropathic corneal pain with the paradox that DED is a pain-free disease in most cases, although it is regarded as a pain condition. The current paper puts into perspective that one gateway from physiology to pathophysiology could be a Piezo2 channelopathy, opening the pathway to a potentially quad-phasic non-contact injury mechanism on a multifactorial basis and with a heterogeneous clinical picture. The primary non-contact injury phase could be the pain-free microinjury of the Piezo2 ion channel at the corneal somatosensory nerve terminal. The secondary non-contact injury phase involves harsher corneal tissue damage with C-fiber contribution due to the lost or inadequate intimate cross-talk between somatosensory Piezo2 and peripheral Piezo1. The third injury phase of this non-contact injury is the neuronal sensitization process with underlying repeated re-injury of the Piezo2, leading to the proposed chronic channelopathy. Notably, sensitization may evolve in certain cases in the absence of the second injury phase. Finally, the quadric injury phase is the lingering low-grade neuroinflammation associated with aging, called inflammaging. This quadric phase could clinically initiate or augment DED, explaining why increasing age is a risk factor. We highlight the potential role of the NGF-TrkA axis as a signaling mechanism that could further promote the microinjury of the corneal Piezo2 in a stress-derived hyperexcited state. The NGF-TrkA-Piezo2 axis might explain why female sex represents a risk factor for DED.

Different perception of dry eye symptoms between patients with and without primary Sjogren's syndrome.

Here, we investigated the different perception of dry eye symptoms between in patients with and without primary Sjogren's syndrome (pSS). In this study, 221 patients with dry eye disease (DED) without pSS (non-SS DED group) and 55 patients with DED with pSS (SS DED group) were included. The ocular discomfort was evaluated using ocular surface disease index (OSDI) questionnaire and patients were further divided into 3 severity subgroups according to OSDI scores. The OSDI score was higher in the non-SS DED group even after matching corneal erosion scores despite the ocular surface erosions and tear deficiency was worse in the SS DED group. The corneal sensitivity was nearly normal in both groups without inter-group difference (Non-SS DED group: 5.82 ± 0.54 cm, SS DED group: 5.90 ± 0.29 cm, p = 0.217). Moreover, all clinical parameters were not significantly correlated with OSDI scores in both non-SS DED group and SS DED group. In the mild and severe OSDI subgroups, the ocular surface erosions and tear deficiency were worse in the SS DED group whereas the OSDI scores were not different between groups. In conclusion, clinicians should be aware that pSS patients may complain less of their discomfort unlike their actual severe status of DED.

Pathogenic Mechanism of Dry Eye-Induced Chronic Ocular Pain and a Mechanism-Based Therapeutic Approach.

Purpose: Dry eye-induced chronic ocular pain is also called ocular neuropathic pain. However, details of the pathogenic mechanism remain unknown. The purpose of this study was to elucidate the pathogenic mechanism of dry eye-induced chronic pain in the anterior eye area and develop a pathophysiology-based therapeutic strategy. Methods: We used a rat dry eye model with lacrimal gland excision (LGE) to elucidate the pathogenic mechanism of ocular neuropathic pain. Corneal epithelial damage, hypersensitivity, and hyperalgesia were evaluated on the LGE side and compared with the sham surgery side. We analyzed neuronal activity, microglial and astrocytic activity, α2δ-1 subunit expression, and inhibitory interneurons in the trigeminal nucleus. We also evaluated the therapeutic effects of ophthalmic treatment and chronic pregabalin administration on dry eye-induced ocular neuropathic pain. Results: Dry eye caused hypersensitivity and hyperalgesia on the LGE side. In the trigeminal nucleus of the LGE side, neuronal hyperactivation, transient activation of microglia, persistent activation of astrocytes, α2δ-1 subunit upregulation, and reduced numbers of inhibitory interneurons were observed. Ophthalmic treatment alone did not improve hyperalgesia. In contrast, continuous treatment with pregabalin effectively ameliorated hypersensitivity and hyperalgesia and normalized neural activity, α2δ-1 subunit upregulation, and astrocyte activation. Conclusions: These results suggest that dry eye-induced hypersensitivity and hyperalgesia are caused by central sensitization in the trigeminal nucleus with upregulation of the α2δ-1 subunit. Here, we showed that pregabalin is effective for treating dry eye-induced ocular neuropathic pain even after chronic pain has been established.

Hypochlorous Acid Can Be the Novel Option for the Meibomian Gland Dysfunction Dry Eye through Ultrasonic Atomization.

BACKGROUND: Dry eye is a multifactor disease which needs comprehensive treatments to keep the homeostasis of ocular surface. OBJECTIVE: To explore the effect of hypochlorous acid on the meibomian gland dysfunction dry eye through ultrasonic atomization. METHODS: We set this study of 0.01% HOCL and 0.1% hyaluronate by ultrasonic atomization. All the data was recorded at the 1st, 15th, 30th, and 55th days. The patients' complains, the meibum analysis, conjunctive congestion, corneal staining, Schirmer's I test, and NIBUT were recorded by K5M, the MMP-9, and IL-2 of tear by inflammation kit; the Demodex was recorded by microscopy. RESULTS: 53 patients have joined this study. There is no statistic difference between them on OSDI (day 15: p = 0.061, 30: p = 0.055, 55: p = 0.052); results show the 10.57 ± 0.13 and 12.54 ± 0.17 reduction on OSDI; the differences of both treatments are significant (∗∗ p < 0.01). Increased Schirmer's and TBUT are 3.27 ± 0.10 and 6.29 ± 0.10 (∗∗ p < 0.01) or 7.32 ± 1.72 s and 9.22 ± 1.41 s (∗ p < 0.05); the decreased conjunctive and corneal staining are 0.23 ± 0.07 and 0.45 ± 0.06 (∗∗ p < 0.01) or 0.42 ± 0.03 and 0.37 ± 0.02 (∗ p < 0.05) at both groups. The differences of MMP-9 and IL-2 negative rate are significant (Z = 0.896, ∗∗ p = 0.002 < 0.01; Z = 0.659, ∗∗ p = 0.001 < 0.01); the number of Demodex mites at first is 10 or 11, while the last is 2 or 6 (Z = -4.642, ∗∗ p < 0.01; Z = 2.742, p > 0.05). The Demodex count between them is significant (Z = -2.310, ∗ p = 0.032 < 0.05). The survival times (ST) of each stage at the HOCL are 110.75 (108.50 ± 24.50), 95.50 (90.25 ± 14.50), and 75.25 (73.48 ± 8.50) min which are shorter than those of control which are 155.50 (160.10 ± 21.50), 130.25 (128.25 ± 16.50), and 105.75 (102.50 ± 14.50) min (∗∗ p < 0.01). The Demodex eradication rate of HOCL is statistic significant (∗ p15th vs. 1stday = 0.028 < 0.05; ∗∗ p30th vs. 1stday = 0.002 < 0.01; ∗∗ p55th vs. 1stday = 0.0018 < 0.01). CONCLUSIONS: 0.01% HOCL improves the Demodex eradication by shortening the survival time; the HOCL acts on the ocular surface by reducing the inflammation. The ultrasonic atomization helps for the drug usage.

Investigation of changes in the activity and function of dry eye-associated brain regions using the amplitude of low-frequency fluctuations method.

OBJECTIVE: The local characteristics of spontaneous brain activity in patients with dry eye (DE) and its relationship with clinical characteristics were evaluated using the amplitude of low-frequency fluctuations (ALFF) method. METHODS: A total of 27 patients with DE (10 males and 17 females) and 28 healthy controls (HCs) (10 males and 18 females) were recruited, matched according to sex, age, weight and height, classified into the DE and HC groups, and examined using functional magnetic resonance imaging (fMRI) scans. Spontaneous brain activity changes were recorded using ALFF technology. Data were recorded and plotted on the receiver operating characteristic (ROC) curve, reflecting changes in activity in different brain areas. Finally, Pearson correlation analysis was used to calculate the potential relationship between spontaneous brain activity abnormalities in multiple brain regions and clinical features in patients with DE. GraphPad Prism 8 (GraphPad Software, Inc.) was used to analyze the linear correlation between the Hospital Anxiety and Depression Scale and ALFF value. RESULTS: Compared with HCs, the ALFF values of patients with DE were decreased in the right middle frontal gyrus (MFG)/right inferior orbitofrontal cortex (OFC), left triangle inferior frontal gyrus, left MFG, and right superior frontal gyrus. In contrast, the ALFF value of patients with DE was increased in the left calcarine. CONCLUSION: There are significant fluctuations in the ALFF value of specific brain regions in patients with DE versus HCs. This corroborates previous evidence showing that the symptoms of ocular surface damage in patients with DE are related to dysfunction in specific brain areas.

Differential effect of maximal incremental treadmill exercise on tear secretion and tear film stability in athletes and non-athletes.

The study investigated the differential response to a single bout of maximal incremental treadmill exercise between athletes and non-athletes without dry eyes regarding tear secretion, tear film stability, visual acuity (VA), and stereoacuity. Additionally, the study examined the effect of gender and the duration of exercise on exercise-induced changes. Study participants included young university students aged 18-25 years who were athletes (male/female: 13/13) or non-athletes (male/female: 17/9). Participants underwent an aerobic exercise session using a treadmill and following the laid down Bruce treadmill test protocol till exhaustion. Measurements were taken in the order of distance VA, stereopsis, non-invasive tear break-up time (TBUT), and phenol red thread test, at baseline and after the exercise regimen. Within- and between-subject analyses using multiple t-tests with correction for multiple comparisons were performed to determine differences before and after exercise in athletes and non-athletes. Subsequently, ANCOVA was used to assess the influence of gender and the duration of exercise. The mean age (SD) of the athletes and the non-athletes was 22.4 ± 2.1 years and 21.8 ± 2.1 years, respectively (p = 0.357). Before exercise, the athletes had higher TBUT than non-athletes (14.6 ± 2.9 s vs. 11.9 ± 3.8 s; p = 0.021), but no difference was observed in any other ocular measurements. After exercise, the athletes showed significant improvement in tear secretion with the basal tear secretion increasing from 22.3 ± 2.5 mm to 25.8 ± 1.7 mm (p < 0.001). The non-athletes on the other hand had a borderline increase in tear secretion from 21.42 ± 2.85 mm to 23.73 ± 2.68 mm (p = 0.08). Also, the TBUT was much improved in the athletes after exercise compared to the non-athletes (17.7 ± 2.7 s vs. 14.8 ± 2.9 s, p = 0.004). Additionally, exercise improved the VA indifferently between the groups, while stereoacuity was unchanged after exercise in either group. Gender had no influence on the differences in the tear function measures between athletes and non-athletes after exercise. The duration of exercise, however, showed a borderline effect on the tear film stability (p = 0.068) after exercise. Our findings support the differential effect of maximal incremental treadmill exercise on tear secretion and tear film stability between athletes and non-athletes. Thus, increased physical fitness and the duration of exercise might be crucial in the improvement of tear function through aerobic exercise.

Impact of Graves Disease on Ocular Surface and Corneal Epithelial Thickness in Patients With and Without Graves Orbitopathy.

PURPOSE: Our aim was to assess ocular surface and tear film stability and corneal epithelial thickness (CET) in patients with Graves disease (GD) with and without Graves orbitopathy (GO). METHODS: This study included healthy age-matched controls and patients with GD. Symptoms (Ocular Surface Disease Index questionnaire) and signs (schirmer test and tear breakup time test) of dry eye disease were determined, according to the International Dry Eye Workshop II criteria of DED. CET map was also assessed. RESULTS: Twenty-four eyes were included in the control group, with a mean age of 41.00 ± 13.65 years, and 34 in the GD group, 18 with GO and 16 without GO, with a mean age of 44.44 ± 13.95 and 45.75 ± 10.59 years, respectively. All patients with GO had inactive disease (mean clinical activity score: 1.33 ± 0.69). Patients with GD had higher proportion of clinical diagnosis of dry eye disease (GO vs. GD without GO vs. controls: 77.77% vs. 75.00% vs. 4.17%), with higher Ocular Surface Disease Index (GO vs. GD without GO vs. controls: 15.44 vs. 15.06 vs. 9.88) and lower tear breakup time test (GO vs. GD without GO vs. controls: 6.33 s vs. 7.25 s vs. 11.63 s). Superior CET was lower in patients with GD (P < 0.05). No differences were found between patients with and without GO (P > 0.05). CONCLUSIONS: GD negatively influenced ocular surface and CET, with a higher level of eye dryness and corneal thinning regardless of GO status, suggesting that subclinical chronic inflammation may play a role in the pathogenesis of tear film and ocular surface stability.

TearCare for the Treatment of Meibomian Gland Dysfunction in Adult Patients With Dry Eye Disease: A Masked Randomized Controlled Trial.

PURPOSE: The aim of this study was to demonstrate the safety and effectiveness of a single TearCare procedure compared with a single LipiFlow procedure in treatment of the dry eye disease associated with meibomian gland dysfunction. METHODS: In a multicenter, masked, randomized controlled trial, 135 subjects received a single TearCare (TC) treatment (n = 67) or a single LipiFlow (LF) treatment (n = 68) at baseline and were followed up for 1 month posttreatment. Tear film breakup time, meibomian gland function, and corneal and conjunctival staining scores were assessed as dry eye signs at baseline, 2 weeks, and 1 month; dry eye symptoms were assessed using the Ocular Surface Disease Index, Symptom Assessment in Dry Eye, and eye dryness questionnaires at baseline and 1 month. RESULTS: At 1 month posttreatment, both groups demonstrated significant improvements (P < 0.0001) in mean tear film breakup time and meibomian gland secretion score to 3.0 ± 4.4 and 11.2 ± 11.1 in the TC group and 2.6 ± 3.3 and 11.0 ± 10.4 in the LF group, respectively. The mean eye dryness, Symptom Assessment in Dry Eye, and Ocular Surface Disease Index scores were significantly reduced (P < 0.0001) by 35.4 ± 34.1, 38.2 ± 31.0, and 27.9 ± 20.5 in the TC group and 34.9 ± 26.9, 38.0 ± 25.9, and 23.4 ± 17.7 in the LF group, respectively. There were no statistically significant differences for any result between the groups. However, the TC group demonstrated numerically greater improvements consistently in all signs and symptoms. Device-related ocular adverse events were reported in 3 patients in the TC group (superficial punctate keratitis, chalazion, and blepharitis) and 4 patients in the LF group (blepharitis, 2 cases of foreign body sensation, and severe eye dryness). CONCLUSIONS: A single TearCare treatment significantly alleviates the signs and symptoms of dry eye disease in patients with meibomian gland dysfunction and is equivalent in its safety and effectiveness profile to LipiFlow treatment as shown in this 1-month follow-up study.

Protective effects of low-molecular-weight components of adipose stem cell-derived conditioned medium on dry eye syndrome in mice.

The present study demonstrated the protective effects of low-molecular-weight adipose-derived stem cell-conditioned medium (LADSC-CM) in a mouse model of dry eye syndrome. Mice subjected to desiccating stress and benzalkonium chloride had decreased tear secretion, impaired corneal epithelial tight junction with microvilli, and decreased conjunctival goblet cells. Topical application of adipose-derived stem cell-conditioned medium (ADSC-CM) stimulated lacrimal tear secretion, preserved tight junction and microvilli of the corneal epithelium, and increased the density of goblet cells and MUC16 expression in the conjunctiva. The low-molecular-weight fractions (< 10 kDa and < 3 kDa) of ADSC-CM (LADSC-CM) provided better protections than the > 10 kDa or > 3 kDa fractions of ADSC-CM. In the in vitro study, desiccation for 10 min or hyperosmolarity (490 osmols) for 24 h caused decreased viability of human corneal epithelial cells, which were reversed by LADSC-CM. The active ingredients in the LADSC-CM were lipophobic and stable after heating and lyophilization. Our study demonstrated that LADSC-CM had beneficial effects on experimental dry eye. It is worthy of further exploration for the active ingredient(s) and the mechanism.

Optogenetic Inhibition of Nav1.8 Expressing Corneal Afferents Reduces Persistent Dry Eye Pain.

Purpose: The aim of the present study was to investigate the contribution of Nav1.8 expressing corneal afferent neurons to the presence of ongoing pain in lacrimal gland excision (LGE)-induced dry eye. Methods: The proton pump archaerhodopsin-3/eGFP (ArchT/eGFP) was conditionally expressed in corneal afferents using Nav1.8-cre mice. Dry eye was produced by unilateral LGE. Real time place preference was assessed using a three-chamber apparatus. A neutral, unlit center chamber was flanked by one illuminated with a control light and one illuminated with an ArchT activating light. For real-time preference, animals were placed in the neutral chamber and tracked over five 10-minute sessions, with the lights turned on during the second and fourth sessions. In other studies, movement was tracked over three 10-minute sessions (the lights turned on only during the second session), with animals tested once per day over the course of 4 days. A local anesthetic was used to examine the role of ongoing corneal afferent activity in producing place preference. Results: The corneal afferent nerves and trigeminal ganglion cell bodies showed a robust eGFP signal in Nav1.8-cre;ArchT/eGFP mice. After LGE, Nav1.8-cre;ArchT/eGFP mice demonstrated a preference for the ArchT activating light paired chamber. Preference was prevented with pre-application to the cornea of a local anesthetic. Nav1.8-cre;ArchT/eGFP mice with sham surgery and LGE wild-type control mice did not develop preference. Conclusions: Results indicate LGE-induced persistent, ongoing pain, driven by Nav1.8 expressing corneal afferents. Inhibition of these neurons represents a potential strategy for treating ongoing dry eye-induced pain.

High Level of Inflammatory Cytokines in the Tears: A Bridge of Patients with Concomitant Exotropia and Dry Eye.

Concomitant exotropia have obvious symptoms of eye discomfort in adults, and the presence of ocular surface inflammation in patients may be important mediators between concomitant exotropia and dry eye. Oculus Keratograph eye comprehensive analyzer was performed to detect noninvasive tear break time, noninvasive tear height, and eye red index, while the ocular surface disease index and schirmer I testing were made. The levels of IL-6, IL-10, IL-17A, IL-12P70, INF-γ, and TNF-α were detected in tears in patients with concomitant exotropia and healthy controls matched by age and gender through the Simoa technology. IL-6 was significantly higher in patients with concomitant exotropia (4.683 ± 1.329) pg/mL than that in normal group (1.455 ± 0.391) pg/mL, p = 0.0304. TNF-α was also significantly higher in patients (0.2095 ± 0.0703) pg/mL than normal group (0.0513 ± 0.0149) pg/mL, p = 0.0397. The levels of inflammatory factors in strabismic patients vs. normal controls were as follows: IL-17A (0.1551 pg/mL︰0.0793 pg/mL), IL-10 (0.3358 pg/mL︰0.0513 pg/mL), IL-12p70 (0.0253 pg/mL︰0.0099 pg/mL), and INF-γ (0.0284 pg/mL︰0.009 pg/mL) were detected, and the median of them in concomitant strabismus was 1.96-6.55-fold as much as the control group. High levels of inflammatory cytokines in tears of patients with concomitant exotropia, which may be a potentially factor promoted the occurrence of dry eye in the patients with concomitant exotropia.

Comparative of meibomian gland morphology in patients with evaporative dry eye disease versus non-dry eye disease.

Many recent studies have showed that morphological changes are one of the key signs of meibomian gland disease (MGD). These changes can be seen even before symptom onset, potentially underestimating the prevalence of MGD; however, until now, there is no conclusive information about the impact of meibomian gland (MG) morphology in tear film physiology and disease. This study aimed to investigate the prevalence of anatomical and morphological MG alterations between patients with evaporative dry eye disease (DED) and healthy controls. Retrospective chart review of seventy-five patients with evaporative DED and healthy individuals who had dry eye assessments included Ocular Surface Disease Index questionnaire, meibum quality, meibum expressibility, lid margin abnormality, ocular staining, non-invasive tear film break-up time, and meibography. We did not find significant differences in MG alterations in the upper lid between healthy and DED subjects. Patients with evaporative DED presented MG alterations in the lower lid more frequently than healthy subjects (54.8 vs. 30.3%; p = 0.03). The presence of shortened glands was the only MG alteration that was more prevalent in the lower lid in dry-eye patients than in healthy subjects (p < 0.05). Subjects with evaporative DED presented more alterations in the lower lid than healthy subjects.

Epithelial stem cell homeostasis in Meibomian gland development, dysfunction, and dry eye disease.

Dry eye disease affects over 16 million adults in the US, and the majority of cases are due to Meibomian gland dysfunction. Unfortunately, the identity of the stem cells involved in Meibomian gland development and homeostasis is not well elucidated. Here, we report that loss of Krox20, a zinc finger transcription factor involved in the development of ectoderm-derived tissues, or deletion of KROX20-expressing epithelial cells disrupted Meibomian gland formation and homeostasis, leading to dry eye disease secondary to Meibomian gland dysfunction. Ablation of Krox20-lineage cells in adult mice also resulted in dry eye disease, implicating Krox20 in homeostasis of the mature Meibomian gland. Lineage-tracing and expression analyses revealed a restricted KROX20 expression pattern in the ductal areas of the Meibomian gland, although Krox20-lineage cells generate the full, mature Meibomian gland. This suggests that KROX20 marks a stem/progenitor cell population that differentiates to generate the entire Meibomian gland. Our Krox20 mouse models provide a powerful system that delineated the identity of stem cells required for Meibomian gland development and homeostasis and can be used to investigate the factors underlying these processes. They are also robust models of Meibomian gland dysfunction-related dry eye disease, with a potential for use in preclinical therapeutic screening.

A Water-free 0.1% Cyclosporine A Solution for Treatment of Dry Eye Disease: Results of the Randomized Phase 2B/3 ESSENCE Study.

PURPOSE: To assess the efficacy, safety, and tolerability of a topical water-free cyclosporine A formulation (CyclASol 0.1% ophthalmic solution) in comparison with vehicle for the treatment of dry eye disease (DED). METHODS: Three hundred twenty-eight patients were enrolled in this prospective, 12-week, multicenter, randomized, double-masked, confirmatory, vehicle-controlled clinical study. After a 2-week run-in period, eligible DED patients were randomized 1:1 to either CyclASol 0.1% or vehicle twice daily. The primary efficacy endpoint was change from baseline in total corneal fluorescein staining (National Eye Institute scale), and the second hierarchical primary efficacy endpoint was change from baseline in the Ocular Surface Disease Index score, both at 4 weeks. Secondary efficacy and safety assessments included conjunctival lissamine green staining (Oxford scale), visual analog scales for dry eye symptoms, and adverse event. RESULTS: Treatment with CyclASol 0.1% was superior to vehicle in the primary endpoint: total corneal fluorescein staining at week 4 (Δ -0.8; 95% confidence interval, -1.3 to -0.4; P = 0.0002, analysis of covariance). This difference had already reached statistical significance after 2 weeks and was maintained throughout the study. The study did not statistically meet its second hierarchically tested primary endpoint: Ocular Surface Disease Index score (P = 0.2634). However, CyclASol 0.1% treatment showed statistically significant improvement compared with that of vehicle in the eye dryness score at week 4 (Δ -4.783; 95% confidence interval, -9.129 to -0.438; P = 0.0311). CONCLUSIONS: CyclASol 0.1% was effective in treating signs and symptoms of DED. It significantly reduced corneal and conjunctival staining and improved ocular dryness compared with vehicle. CyclASol 0.1% was safe and showed excellent tolerability.

Effect of Face Mask on Tear Film Stability in Eyes With Moderate-to-Severe Dry Eye Disease.

PURPOSE: The purpose of this study was to evaluate whether tear film stability worsens with the use of masks in patients with dry eye disease, objectively analyzing the tear film stability using noninvasive tear film breakup time (NITBUT) with and without a face mask. METHODS: A cross-sectional study including patients with moderate or severe dry eye disease was conducted. Tear stability was measured using an Oculus Keratograph 5M (Oculus, Wetzlar, Germany), which records NITBUT, both first and average NITBUT. Two measurements were taken: an initial measurement with a mask and a second measurement after 10 minutes without wearing the face mask. RESULTS: Thirty-one patients were included with a mean age of 57.6 ± 11.7 years (range 31-80) and 30 being female (97%). Mean first NITBUT with face mask was 6.2 ± 3.8 seconds (range 2.0-19.8), which increased to 7.8 ± 5.6 seconds (range 2.3-24.0) without the use of mask (P = 0.029), differences being -1.6 ± 0.7 seconds (CI 95% -3.1075 to -0.1770). Mean average NITBUT with a face mask was 12.3 ± 4.8 seconds (range 4.0-19.4) and increased to 13.8 ± 5 seconds (range 5.5-24.0) without the use of mask (P = 0.006), mean difference being -1.5 ± 0.5 seconds (CI 95% -2.5290 to -0.4458). CONCLUSIONS: Face mask use decreases tear film stability in patients with moderate-to-severe dry eye.

A systematic review assessing the quality of patient reported outcomes measures in dry eye diseases.

BACKGROUND: Patient-reported outcome measures (PROMs) can provide valuable insights on the impact of a disease or treatment on a patient's health-related quality of life. In ophthalmology, particularly in dry eye disease (DED) and ocular surface disease (OSD), it is unclear whether the available PROMs were developed using comprehensive guidelines. To address this, we evaluated the methodological quality of studies assessing the psychometric properties of PROMs in DED and OSD [PROSPERO registration number CRD42019142328]. METHODS: Four databases were searched; reference list and citation searching of included studies was also conducted. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist was used to appraise the quality of the studies evaluating the psychometric properties of PROMs used in DED and OSD. RESULTS: The search strategy (S3 Table) retrieved 5,761 records, 573 duplicates were removed, 5,188 abstracts were screened and 127 full-text articles were retrieved for further review. Of these, 118 full-text articles did not meet the eligibility criteria and were excluded. Reference list and citation searching, identified an additional 8 articles bringing the total numbers of papers reviewed to 17. In general, psychometric properties such as content validity, measurement error and structural validity were not assessed by the studies included in this review. Studies reviewing The Impact of Dry Eye on Everyday Life (IDEEL) presented with the highest quality scores together with the Ocular Surface Disease Index (OSDI) questionnaire. CONCLUSIONS: The quality of studies evaluating PROMs in DED and OSD was considered using the COSMIN standards. The majority of the studies evaluating PROMs included in this review did not meet the recommended COSMIN criteria and the quality of the PROMs evaluated is not assured. Further evaluation of their psychometric properties is required if these are going to be used in clinical practice or research.