Evaluation of the corneal epithelium in non-Sjögren's and Sjögren's dry eyes: an in vivo confocal microscopy study using HRT III RCM

Diagnostic features of Acanthamoeba keratitis via in vivo confocal microscopy

In vivo confocal microscopy (IVCM) offers a non-invasive, rapid method for diagnosing Acanthamoeba keratitis (AK) by detecting cysts or trophozoites in the initial clinic visit images. In this retrospective observational study, we reviewed HRT3 IVCM images from patients presenting to Manchester Royal Eye Hospital with clinically- suspected AK for IVCM morphological features (IVCM-MF) of both Acanthamoeba and corneal cells. Twenty-seven patients were included in the study: median age 29 years (range 16-71 years), female gender (59%; n = 16/27) and contact lens wear as the main risk factor. Median symptom duration before the initial ophthalmologist visit was 9 days (range 2 to 42 days). IVCM had a higher detection rate for AK in 85% of patients (n = 23/27), with culture positivity in only 74% (n = 20/27; 17 of whom were also IVCM-positive). Acanthamoeba IVCM-MF included: bright spots (87%, n = 20/23), double-walled cysts (56%, n = 13/23), signet-ring (22%, n = 5/23) and trophozoites (30%, n = 7/23). Bright spots and double-walled cysts coalesced in lines/clusters in 1 patient. Corneal epithelial cells had a "koilocyte" appearance in 64% (n = 14/22). Microtubules connecting adjacent keratocytes were visible in 52% (n = 12/23), particularly associated with A. polyphaga ulcers (p = 0.02). These IVCM features observed in corneal epithelial cells and keratocytes may represent potential imaging biomarkers for AK diagnosis and warrant further investigation to validate their diagnostic utility. By demonstrating IVCM's superior diagnostic performance, providing rapid and accurate diagnostics, this study advocates for its inclusion in standard diagnostic workflows for AK, paving the way for future advancements in clinical practice.

CD4+ T cells drive corneal nerve damage but not epitheliopathy in an acute aqueous-deficient dry eye model

Dry eye disease (DED) is characterized by a dysfunctional tear film in which the corneal epithelium and its abundant nerves are affected by ocular desiccation and inflammation. Although adaptive immunity and specifically CD4+ T cells play a role in DED pathogenesis, the exact contribution of these cells to corneal epithelial and neural damage remains undetermined. To address this, we explored the progression of a surgical DED model in wild-type (WT) and T cell-deficient mice. We observed that adaptive immune-deficient mice developed all aspects of DED comparably to WT mice except for the absence of functional and morphological corneal nerve changes, nerve damage-associated transcriptomic signature in the trigeminal ganglia, and sustained tear cytokine levels. Adoptive transfer of CD4+ T cells from WT DED mice to T cell-deficient mice reproduced corneal nerve damage but not epitheliopathy. Conversely, T cell-deficient mice reconstituted solely with naïve CD4+ T cells developed corneal nerve impairment and epitheliopathy upon DED induction, thus replicating the WT DED phenotype. Collectively, our data show that while corneal neuropathy is driven by CD4+ T cells in DED, corneal epithelial damage develops independently of the adaptive immune response. These findings have implications for T cell-targeting therapies currently in use for DED.

Confocal Microscopy of the Cornea in Aqueous-Deficient Dry Eye Disease-A Literature Review

BACKGROUND

In vivo confocal microscopy (IVCM) is a vital tool in studying dry eye disease (DED), providing insights into morphological changes at ocular surface unit levels. This review presents the main differences in corneal structure between aqueous-deficient dry eye disease (AD-DED) and normal eyes.

METHODS

A comprehensive search of PubMed, Web of Science, Embase, and MEDLINE databases from January 2000 to December 2023 was conducted. The study selection process, as well as data selection and examination, were independently performed by two members of the review team.

RESULTS

The review reveals a consistent decrease in corneal surface epithelial cell density in AD-DED cases compared to a control group, but conflicting data on basal epithelial cell density. Notably, the abnormal hyperreflectivity of keratocytes in patients with Sjogren's syndrome was recorded, and there was a significant keratocyte density in AD-DED subjects compared to evaporative DED and control groups. Studies also found a decrease in sub-basal nerve density, increased tortuosity, and the fragmentation of nerve fibers. Dendritic cell density and dendritic cell dendrites increase in AD-DED patients compared to healthy subjects.

CONCLUSIONS

IVCM is a powerful tool for enhancing our understanding of the pathophysiological mechanisms underlying DED. However, the review underscores the urgent need to standardize the terminology, analysis, and units used for accurate interpretation, a crucial step in advancing our knowledge of DED.

24-Hour Evaluation of the Effectiveness and Tolerability of Preservative-Free Tafluprost-Timolol Fixed Combination in Open-Angle Glaucoma or Ocular Hypertensive Patients Previously Treated with Preserved Latanoprost

Purpose

The effectiveness, safety and tolerability of the preservative-free fixed combination of tafluprost and timolol (PF-TTFC) were evaluated over the 24-h in patients with open-angle glaucoma or ocular hypertension showing signs and symptoms of Ocular Surface Disease (OSD) and uncontrolled intraocular pressure (IOP) on prior benzalkonium chloride (BAK) - Latanoprost monotherapy.

Methods

In this multi-center, prospective, interventional, non-comparative clinical trial, patients treated with BAK-Latanoprost underwent 24-h IOP measurements (8 am, 11 am, 2 pm, 5 pm, 8 pm, 11 pm, 2 am, 5 am) at baseline and after 3 months from switch to PF-TTFC. Mean 24-h IOP and daytime (8 am-8 pm) vs nighttime (11 pm - 5 am) IOP were compared. Changes in OSD signs and symptoms, quality of life (QoL) and in-vivo corneal confocal microscopy (IVCM) were also evaluated.

Results

Thirty-eight patients were analyzed. The mean 24-h IOP significantly decreased after 3 months from 17.8 mmHg (95% CI: 17.1-18.6) to 15.3 mmHg (95% CI: 14.6-16.1, p < 0.001). IOP was significantly reduced both at daytime (p < 0.001) and nighttime (p < 0.001), with better IOP control at night [-2.9 (95% CI: -3.5 to -2.1) mmHg vs -2.3 (95% CI: -2.9 to -1.6) mmHg]. In 20 patients (52.6%), corneal fluorescein staining improved, whereas in 4 patients (10.5%) it worsened. Hyperemia has improved in 24 (63.3%) patients and worsened in 2 (5.3%). Breakup time, Schirmer test and QoL scores showed no changes. At IVCM, the mean corneal wing-cell size was found significantly decreased (p < 0.005).

Conclusion

The switch from BAK-Latanoprost to PF-TTFC significantly reduced IOP over the 24-h and improved OSD signs and symptoms.

Confocal Microscopy Abnormalities Preceding Antibody Positivity and Manifestations of Sjogren's Syndrome

An asymptomatic 26-year-old woman underwent confocal microscopy as part of a control population for a research study. Images revealed reduced sub-basal corneal nerve density and multiple activated dendritic cells. Three years later, she presented with a self-limited cutaneous vasculitis in her lower extremities which prompted an evaluation for autoimmune diseases. Laboratory testing revealed positive antinuclear antibodies (1:320, thick granular pattern), and anti-SSA/SSB (SSA, 53.6 U/mL, moderately positive; SSB, 142.7 U/mL, strongly positive). Two weeks later, she presented with ocular pain and an ophthalmologic examination revealed ocular surface staining. An ocular ultrasound was consistent with posterior scleritis. Based on this picture, a diagnosis of Sjögren syndrome (SS) was made. SS is a chronic autoimmune disease that can present with symptoms that diminish the patient's quality of life. Confocal microscopy might be a valuable tool for the early diagnosis of disease.

Evaluating the Efficacy of Polyglycolic Acid-Loading Tetrandrine Nanoparticles in the Treatment of Dry Eye

INTRODUCTION

Dry eye disease (DED) is a multifactor-induced disease accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Traditional anti-inflammation agent corticosteroids applied in DED treatment could result in high intraocular pressure, especially in long-term treatment. Therefore, we explored a nano drug that aimed to block the formation pathway of DED which had anti-inflammatory, sustained release, and good biocompatibility characteristics in this study.

METHODS

We prepared a novel nanomedicine (Tet-ATS@PLGA) by the thin film dispersion-hydration ultrasonic method and detected its nanostructure, particle size, and zeta potential. Flow cytometry was used to detect the cell survival rate of each group after 24 h of drug treatment on inflammed Statens Seruminstitut Rabbit Corneal (SIRC) cells. Observed and recorded corneal epithelial staining, tear film rupture time, and Schirmer test to detect tear secretion on the ocular surface of rabbits. The corneal epithelial thickness, morphology, and number of bulbar conjunctival goblet cells were recorded by H&E staining. Finally, we detected the expression of VEGF, IL-1β, PGE2, and TNF-α by cellular immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The encapsulation efficiency and drug loading of Tet-ATS@PLGA were 79.85% and 32.47%, respectively. At eye surface temperature, Tet can easily release from Tet-ATS@PLGA while that it was difficult to release at storage temperature and room temperature. After 2 weeks medication, Tet-ATS@PLGA can effectively improve the tear film rupture time and tear secretion time in a DED model (p <0.05). Compared with the normal group (62.34 ± 4.86 mm), the thickness of corneal epithelium in ATS (29.47 ± 3.21 mm), Tet-ATS (46.23 ± 2.87 mm), and Tet-ATS@PLGA (55.76 ± 3.95 mm) gradually increased. Furthermore, the flow cytometry indicated that Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory SIRC cells, and the cellular immunofluorescence and ELISA experiments showed that the expression intensity of inflammatory factors such as VEGF, IL-1β, PGE2, and TNF-α decreased in this process. Interestingly, Tet also had the effect of reducing intraocular pressure.

CONCLUSION

Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory corneal epithelial cells, thus inhibiting the expression of inflammatory factors to block the formation of DED and improve the secretion of tear on the ocular surface.

Mapping the research on Sjögren's syndrome-related dry eye disease: a bibliometric network analysis of the past 20 years

PURPOSE

Our study aimed to make a bibliometric analysis on Sjögren's syndrome-related dry eye disease (SS-DED), explore its potential research hotspots, and provide critical information for future research interest and undeveloped topics in this field, which can benefit clinicians and researchers.

METHODS

We extracted all publications relating to SS-DED from 2003 to 2022 from the Web of Science Core Collection database. Original articles and reviews in English were included. The contributions of different countries, institutions, journals, and authors were compared, and the research hotspots were visualized for network analysis through GraphPad Prism, CiteSpace, and VOSviewer.

RESULTS

We enrolled a total of 987 publications. The United States contributed the most publications (281, 28.5%), followed by China (157, 15.9%) and Japan (80, 8.11%). Publications from the United States were cited more frequently (13,060 citations), with the highest H-index of 57. China ranked second in the total number of publications, the papers were not cited frequently (3790 citations), and the H-index ranked second (H-index = 31). PLoS One (32, 3.24%) published the most papers, and the University of California system had the highest number of publications (45, 4.56%). Bootsma H from the Netherlands published the most papers. The trend of research hotspots evolved mainly from the basic manifestation to pathogenesis and treatment of SS-DED and paid more attention to distinguishing SS-DED from that dry eye disease without SS.

CONCLUSIONS

Based on the bibliometric, co-citation, and network analyses in this study, we obtained the annual publications and citations, the growth trends of publications, the productivity of countries, organizations, journals, and authors, high-quality publications, and the emerging hotspots of SS-DED, which may open new doors for promising research directions.

Corneal subbasal nerve analysis in patients with primary Sjogren's syndrome: a novel objective grading method and clinical correlations

PURPOSE

To investigate corneal sub-basal nerve morphology changes in primary Sjogren's syndrome (SS) dry eye (SSDE) patients and determine the association with disease severity at microstructural level.

METHODS

Twenty-eight eyes of 17 SSDE and 82 eyes of 47 age- and sex-matched non-SS dry eye (NSSDE) patients were included. The Ocular Surface Disease Index questionnaire (OSDI), Schirmer's test (ST), tear meniscus height (TMH), non-invasive breakup time (NIBUT), meibomian gland (MG) morphology, and ocular staining score (OSS) were assessed. In vivo confocal microscopy was performed to observe corneal sub-basal nerve morphology (length, reflectivity, width, and tortuosity). Associations between clinical features and nerve parameters were analysed.

RESULTS

SSDE patients more frequently had increased nerve reflectivity (151.12 ± 17.07 vs. 139.37 ± 14.31 grey value), width (4.45 ± 0.87 vs. 3.92 ± 0.81 μm), tortuosity (132.90 ± 8.04 vs. 129.50 ± 7.33 degree), and higher reflectivity, width, and total nerve grades than NSSDE individuals (all P < 0.05). Significant associations were found between nerve reflectivity/width and anti-SSA [OR = 1.139 (1.013-1.281)/1.802 (1.013-4.465)]/labial gland biopsy [OR = 1.046 (1.002-1.161)/1.616 (1.020-3.243)]. Higher nerve width was associated with increased OSDI [β = 0.284 (0.187-0.455)], MG score [β = 0.185 (0.109-0.300)] and OSS [β = 0.163 (0.020-0.345)], but decreased NIBUT [β =  - 0.247 (- 0.548 ~  - 0.154)]. Higher nerve total grade was associated with increased OSDI [β = 0.418 (0.157-0.793)] and OSS [β = 0.287 (0.027-0.547)], but decreased ST [β =  - 0.410 (-0.857 ~  - 0.138)].

CONCLUSIONS

Corneal nerve morphology changes associated with clinical features in SS patients. These changes may facilitate severity evaluation and management of the disease.

Acute Foggy Corneal Epithelial Disease: Seeking Clinical Features and Risk Factors

(1) Purpose: Here, we describe the clinical characteristics and predisposing factors of acute foggy corneal epithelial disease, a rare disease newly found during COVID-19 pandemic; (2) Methods: In this single-arm, ambispective case series study, ten patients with acute foggy corneal epithelial disease admitted between May 2020 and March 2021 were enrolled. Their detailed medical history and clinical and ophthalmic findings were recorded and analyzed; (3) Results: All the patients were female (100%), aged from 28 to 61 years (mean age of 40.4 ± 9.3 years). Seven cases (70%) had excessive eye use, and six cases (60%) had stayed up late and were overworked. Ten subjects (100%) presented with acute onset and a self-healing tendency. There was a mild-to-moderate decrease in the corrected visual acuity (0.35 ± 0.21 (LogMAR)). Slit-lamp examination showed diffuse dust-like opacity and edema in the epithelial layer of the cornea. By in vivo confocal microscope, epithelial cells presented characteristically a “relief-like” appearance. Anterior segment optical coherence tomography examination revealed that the mean epithelial thickness was increased (69.25 ± 4.31 μm, p < 0.01); (4) Conclusions: Acute foggy corneal epithelial disease is a rare disease in clinic, which tends to occur in young and middle-aged females. The typical clinical symptom is sudden foggy vision, which occurs repeatedly and can be relieved without treatment. Sex, an abnormal menstrual cycle, overuse of the eyes, fatigue and pressure might be risk factors. Changes in lifestyle and eye use habit during the COVID-19 pandemic may have possibly contributed to this disease incidence.

Trigeminal Nerve Affection in Patients with Neuro-Sjögren Detected by Corneal Confocal Microscopy

Background: Patients with Sjögren’s syndrome and polyneuropathy more frequently develop cranial nerve affection when compared to patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We therefore aimed to analyze trigeminal corneal nerve fibre characteristics in both patient groups. Methods: A total of 26 patients with Sjögren’s syndrome associated neuropathy and 29 patients with CIDP were recruited at our university hospital and compared to 6 healthy controls. Dry eye symptoms and signs were assessed via clinical examination and the Ocular Disease Surface Index questionnaire. Trigeminal corneal nerve fibres were analyzed via corneal confocal microscopy (CCM) as a non-invasive in vivo microscopy. Results: CCM revealed significantly reduced corneal nerve fibre density and corneal nerve fibre main branch density in the Neuro-Sjögren group when compared with healthy controls. There were no significant group differences between the Neuro-Sjögren and the CIDP group for any of the microscopic parameters. Dry eye assessment showed similarly reduced scores for both patient groups, while healthy controls showed better results for objective dry eye signs. There was no correlation between microscopic parameters of the corneal confocal microscopy and parameters of dry eye assessment. Conclusions: Our data revealed trigeminal corneal nerve affection in patients with neuropathy associated with Sjögren’s syndrome and patients with CIDP detected by CCM. No difference was found between both neuropathy groups indicating that CCM is not able to distinguish between both entities.

The effects of the systemic isotretinoin treatment on ocular surface and meibomian glands: a prospective longitudinal study

PURPOSE

To assess the effects of systemic isotretinoin therapy (SIT) on the ocular surface, meibomian glands (MG) and cornea microstructure in acne vulgaris (AV) patients.

METHODS

Patients with AV (n = 20) and healthy controls (n = 20) were enrolled in the study. All participants underwent ocular surface tests in the order of ocular surface disease index (OSDI) questionnaire, corneal sensitivity, tear break-up time (BUT), fluorescein and lissamine green (LG) staining and Schirmer II test with anaesthesia. MG alterations were evaluated with meibography for upper (UE) and lower eyelids (LE) separately. Corneal basal epithelium and subbasal nerve plexus (SNP) were evaluated using In Vivo Confocal Microscopy (IVCM).

RESULTS

Schirmer II test with anaesthesia, BUT, corneal sensitivity, fluorescein and LG staining grades and OSDI score results showed no difference between the control group and the baseline of the patient group. Whereas the meibomian gland dysfunction (MGD) grades, UE and LE meiboscores were higher in the patient group at the baseline (p = 0.013, p = 0.004, p = 0.008 respectively). The Control group possessed higher numbers of total and long nerve fibres compared with patients at the baseline (p ≤ 0.001 for both two values). Compared to the baseline and the third month, BUT decreased and fluorescein staining grades increased (p = 0.017 and p = 0.043, respectively). MGD grades, UE and LE meiboscores increased in the third month compared to the baseline (p < 0.001, p < 0.001, p = 0.008 respectively). Basal epithelial cell density (BECD) decreased in the third month of SIT (p = 0.043).

CONCLUSIONS

This prospective study showed that systemic Isotretinoin treatment effects not only ocular surface parameters but also corneal and Meibomian glands structure. Considering early alterations in the course of treatment, ophthalmological assessment and follow-up during SIT are mandatory.

In Vivo Confocal Microscopy in Different Types of Dry Eye and Meibomian Gland Dysfunction

In vivo confocal microscopy (IVCM) imaging is increasingly popular in ocular surface disease diagnosis and management. We conducted a systematic review to update the use of IVCM in the diagnosis and treatment of dry eye and meibomian gland dysfunction (MGD). A literature review was conducted on IVCM studies in MGD, dry eye disease, systemic disease causing dry eye, dry eye in glaucoma patients, contact lens-associated ocular conditions, graft-versus-host disease, and Sjogren’s syndrome-related dry eye. The articles were identified through PubMed and a total number of 63 eligible publications were analyzed in detail. All primary research studies on confocal microscopy on dry eye and related conditions from 2017 onwards were included. The reports were reviewed for their contribution to the existing literature as well as potential biases and drawbacks. Despite limitations such as small field of view, lack of population-based norms, and lack of standardization of image acquisition, interpretation, and quantification, IVCM is useful as a complementary technique for clinical diagnosis in various ocular surface disorders related to dry eye. With advances in hardware and software in the near future, it has the potential for further practical impact.

Dry eye in Sjögren's syndrome - characteristics and therapy

BACKGROUND

Sjögren's syndrome is an autoimmune disease, and its important feature is the lymphocyte infiltration of exocrine glands, including lacrimal glands. It contributes to defects of their activity and causes that one of the main manifestation of Sjögren's syndrome is dry eye. Unfortunately, the discrimination between dry eye related and non-related to Sjögren's syndrome is difficult at the initial stages of diseases. In addition, the available agents for the treatment of Sjögren's syndrome-related dry eye have limited efficacy.

AIM

The purpose of this study was to describe and emphasize differences between Sjögren's Syndrome-related dry eye and non-Sjögren's Syndrome-related dry eye together with the determination of novel therapeutic options for Sjögren's Syndrome-related dry eye.

METHOD

A review of the relevant papers describing characteristics of Sjögren's Syndrome-related dry eye and its therapy was conducted. This article is based on both pre-clinical and clinical evidences.

RESULTS

On the basis of our analysis, we indicated differences between Sjögren's Syndrome-related dry eye and non-Sjögren's Syndrome-related dry eye. Moreover, there are some novel markers that could be used in the diagnosis of Sjögren's Syndrome-related dry eye. In addition, expect artificial tear, other agents e.g. hydroxychloroquine can be effective in therapy of disease.

CONCLUSIONS

Sjögren's Syndrome-related dry eye is a disorder, whose diagnosis may be difficult and mistaken for non-Sjögren's Syndrome-related dry eye. However, Sjögren's Syndrome-related dry eye has some specific features. In addition, the development of newer and safer therapeutic agents for Sjögren's syndrome-related dry eye is needed, and therefore further clinical, randomized studies are necessary.

Analysis of the first tear film break-up point in Sjögren's syndrome and non-Sjögren's syndrome dry eye patients

Background

Tear film instability plays an important role in the course of Sjögren’s Syndrome dry eye (SSDE) even though it is generally classified as aqueous-deficient dry eye. The measurement of the first tear film break-up point (FTBUP) helps to evaluate the most unstable position of the tear film on ocular surface. We aim to investigate FTBUP in Sjögren’s Syndrome dry eye (SSDE) and non-Sjögren’s Syndrome dry eye (NSSDE) patients, and explore its correlation with dry eye indices.

Methods

Twenty-two SSDE patients (44 eyes) and 22 NSSDE patients (44 eyes) were enrolled in the study. Oculus Keratograph K5M was used to measure FTBUP, the first and average non-invasive keratographic breakup time (f-NIKBUT and av-NIKBUT), the tear meniscus height, and meibomian gland dropout. Other tests of tear film were also performed including Ocular Surface Dryness Index (OSDI), Schirmer I test, fluorescein break-up time and corneal fluorescein staining. Dry eye indices and the locations of the FTBUP were compared between SSDE and NSSDE patients. Generalized estimating equation (GEE) was used to ajusted the correlations between right and left eyes. The correlations between the FTBUP and ocular symptoms and signs were investigated using Pearson’s correlation coefficient test.

Results

The FTBUP occurred at the supranasal quadrant in 12/88 eyes, supratemporal quadrant in 8/88 eyes, inferonasal quadrant in 34/88 eyes, and inferotemporal quadrant in 34/88 eyes. The percentage eyes with inferior FTBUP was significantly higher in the SSDE than in the NSSDE subjects (86.3% vs 68.1%, P = .049). Moreover, in SSDE subjects, temporal breakup point was seen more often in those who presented corneal fluorescein staining in any location, while nasal breakup point was more frequent in those who did not present any corneal fluorescein staining (P = .045).

Conclusion

The location of the FTBUP in SSDE patients had specific characteristics. However, the diagnostic potential of FTBUP in early recognition of SSDE needs further validation.

Alteration of corneal biomechanical properties in patients with dry eye disease

Purpose

To evaluate the association between symptoms and signs of dry eye diseases (DED) with corneal biomechanical parameters.

Methods

This cross-sectional study enrolled 81 participants without history of ocular hypertension, glaucoma, keratoconus, corneal edema, contact lens use, diabetes, and ocular surgery. All participants were evaluated for symptoms and signs of DED using OSDI questionnaire, tear film break-up time (TBUT), conjunctival and corneal staining (NEI grading) and Schirmer test. Corneal biomechanical parameters were obtained using Corvis ST. Mixed-effects linear regression analysis was used to determine the association between symptoms and signs of DED with corneal biomechanical parameters. Difference in corneal biomechanical parameter between participants with low (Schirmer value ≤10 mm; LT group) and normal (Schirmer value >10mm; NT group) tear production was analyzed using ANCOVA test.

Results

The median OSDI scores, TBUT, conjunctival and corneal staining scores as well as Schirmer test were 13±16.5 (range; 0–77), 5.3±4.2 seconds (range; 1.3–11), 0±1 (range; 0–4), 0±2 (ranges; 0–9) and 16±14 mm (range; 0–45) respectively. Regression analysis adjusted with participants’ refraction, intraocular pressure, and central corneal thickness showed that OSDI had a negative association with highest concavity radius (P = 0.02). The association between DED signs and corneal biomechanical parameters were found between conjunctival staining scores with second applanation velocity (A2V, P = 0.04), corneal staining scores with second applanation length (A2L, P = 0.01), Schirmer test with first applanation time (A1T, P = 0.04) and first applanation velocity (P = 0.01). In subgroup analysis, there was no difference in corneal biomechanical parameters between participants with low and normal tear production (P>0.05). The associations were found between OSDI with time to highest concavity (P<0.01) and highest displacement of corneal apex (HC-DA, P = 0.04), conjunctival staining scores with A2L (P = 0.01) and A2V (P<0.01) in LT group, and Schirmer test with A1T (P = 0.02) and HC-DA (P = 0.03), corneal staining scores with A2L (P<0.01) in NT group.

Conclusions

According to in vivo observation with Corvis ST, patients with DED showed more compliant corneas. The increase in dry eye severity was associated with the worsening of corneal biomechanics in both patients with low and normal tear production.

Ocular Pathophysiology of Sjögren's Syndrome

The purpose of this review is to delve into the clinical and research understanding of the pathophysiology and presentation of Sjögren's-related keratoconjunctivitis sicca in order address the diagnostic and management challenge that it represents, as well as to provide a basis for appreciating the pharmacotherapies designed to treat the ophthalmic symptoms of Sjögren's disease.

In vivo Confocal Microscopic Evaluation of Corneal Dendritic Cell Density and Subbasal Nerve Parameters in Dry Eye Patients: A Systematic Review and Meta-analysis

Purpose: To conduct a systematic review and meta-analysis of the available research on evaluating changes in corneal dendritic cell density (CDCD) and the main subbasal nerve parameters (SNPs) on the ocular surface and assessing the diagnostic performance of in vivo confocal microscopy in patients with dry eye disease. Methods: A computerized systematic review of literature published in PUBMED, EMBASE, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials until May 8, 2020 was performed. All statistical analyses were conducted in RevMan V.5.3 software. The weighted mean differences (WMDs) and standardized mean differences (SMDs) with 95% confidence intervals (CI) between dry eye patients and healthy subjects were presented as results. Results: A total of 11 studies with 755 participants were recruited, and 931 eyes were included in this meta-analysis. However, not all studies reported both CDCD and SNPs. CDCD in the central cornea was higher (WMD = 51.06, 95% CI = 39.42-62.71), while corneal nerve fiber density (CNFD) and corneal nerve fiber length (CNFL) were lower (WMD = -7.96, 95% CI = -12.12 to -3.81; SMD = -2.30, 95%CI = -3.26 to -1.35) in dry eye patients in comparison with the corresponding values in healthy controls (all p < 0.00001). Conclusion: Taken together, while CNFD and CNFL were lower in dry eye patients, central CDCD showed a significant increase in these patients in comparison with the corresponding values in healthy controls.

The ocular surface immune system through the eyes of aging

Since the last century, advances in healthcare, housing, and education have led to an increase in life expectancy. Longevity is accompanied by a higher prevalence of age-related diseases, such as cancer, autoimmunity, diabetes, and infection, and part of this increase in disease incidence relates to the significant changes that aging brings about in the immune system. The eye is not spared by aging either, presenting with age-related disorders of its own, and interestingly, many of these diseases have immune pathophysiology. Being delicate organs that must be exposed to the environment in order to capture light, the eyes are endowed with a mucosal environment that protects them, the so-called ocular surface. As in other mucosal sites, immune responses at the ocular surface need to be swift and potent to eliminate threats but are at the same time tightly controlled to prevent excessive inflammation and bystander damage. This review will detail how aging affects the mucosal immune response of the ocular surface as a whole and how this process relates to the higher incidence of ocular surface disease in the elderly.

Ophthalmologic Manifestations of Primary Sjögren's Syndrome

Sjögren’s syndrome (SS) is a chronic, progressive, inflammatory, autoimmune disease, characterized by the lymphocyte infiltration of exocrine glands, especially the lacrimal and salivary, with their consequent destruction. The onset of primary SS (pSS) may remain misunderstood for several years. It usually presents with different types of severity, e.g., dry eye and dry mouth symptoms, due to early involvement of the lacrimal and salivary glands, which may be associated with parotid enlargement and dry eye; keratoconjunctivitis sicca (KCS) is its most common ocular manifestation. It is still doubtful if the extent ocular surface manifestations are secondary to lacrimal or meibomian gland involvement or to the targeting of corneal and conjunctival autoantigens. SS is the most representative cause of aqueous deficient dry eye, and the primary role of the inflammatory process was evidenced. Recent scientific progress in understanding the numerous factors involved in the pathogenesis of pSS was registered, but the exact mechanisms involved still need to be clarified. The unquestionable role of both the innate and adaptive immune system, participating actively in the induction and evolution of the disease, was recognized. The ocular surface inflammation is a central mechanism in pSS leading to the decrease of lacrimal secretion and keratoconjunctival alterations. However, there are controversies about whether the ocular surface involvement is a direct autoimmune target or secondary to the inflammatory process in the lacrimal gland. In this review, we aimed to present actual knowledge relative to the pathogenesis of the pSS, considering the role of innate immunity, adaptive immunity, and genetics.

Dynamic corneal biomechanics in different cell layers: in keratoconus and normal eyes

PURPOSE

This study aimed to determine the relationship between corneal cellular structures and biomechanical deformation parameters in keratoconic (KC) and healthy eyes.

METHODS

In this prospective comparative study, 29 eyes of 29 KC patients were age- and gender-matched with 28 eyes of 28 healthy individuals using frequency matching. Corneal parameters examined included the density of basal epithelial cells, anterior keratocytes, posterior keratocytes and endothelial cells as assessed by in vivo corneal confocal microscopy (HRT III-RCM, Heidelberg Engineering, www.heidelbergengineering.com). Additionally, the coefficient of variation of endothelial cell size (CV) and the percentage of hexagonal endothelial cells (HEX%) were measured by specular microscopy (Konan NSP-9900, Konan Medical, www.konanmedical.com). Further, biomechanical deformation parameters were derived from Corvis Scheimpflug Technology (Corvis ST, Oculus, www.oculus.de). All cellular and biomechanical deformation parameters in KC and normal groups were compared, and the relationship between cellular and biomechanical parameters calculated.

RESULTS

In the KC group, the highest concavity (HC) delta arc length and maximum delta arc length were associated with endothelial cell density (Beta = -0.39, p = 0.03 and Beta = -0.60, p ˂ 0.001, respectively). Furthermore, there was a significant association between HC deflection length and HEX% (Beta = -0.67, p = 0.001). In the normal group, HC delta arc length and HC deflection length were significantly associated with endothelial cell density (Beta = 0.46, p = 0.02; and Beta = -0.51, p = 0.01, respectively). HC time, HC deformation amplitude and applanation 1 delta arc length were associated with CV (Beta = 0.50, p = 0.01; Beta = 0.27, p = 0.009; and Beta = -0.57, p = 0.002, respectively). Applanation 1 and applanation 2 deformation amplitudes were associated with HEX% (Beta = -0.49, p = 0.005; and Beta = -0.46, p = 0.02).

CONCLUSIONS

Biomechanical deformation parameters were significantly correlated with endothelial cell properties in both KC and normal groups, thereby indicating the importance of the integrity of endothelial cells to the biomechanical properties of both KC and normal corneas.

Impact of Attrition, Intercellular Shear in Dry Eye Disease: When Cells are Challenged and Neurons are Triggered

The mechanical component in the pathophysiology of dry eye disease (DED) deserves attention as an important factor. The lubrication deficit induced impaired mechano-transduction of lid pressure to the ocular surfaces may lead to the dysregulation of homeostasis in the epithelium, with sensations of pain and secondary inflammation. Ocular pain is possibly the first sign of attrition and may occur in the absence of visible epithelial damage. Attrition is a process which involves the constant or repeated challenge of ocular surface tissues by mechanical shear forces; it is enhanced by the thinning of corneal epithelium in severe DED. As a highly dynamic process leading to pain and neurogenic inflammation, the identification of the impact of attrition and its potential pathogenic role could add a new perspective to the current more tear film-oriented models of ocular surface disease. Treatment of DED addressing lubrication deficiencies and inflammation should also consider the decrease of attrition in order to stimulate epithelial recovery and neural regeneration. The importance of hyaluronic acid, its molecular characteristics, the extracellular matrix and autoregulative mechanisms in this process is outlined. The identification of the attrition and recognition of its impact in dry eye pathophysiology could contribute to a better understanding of the disease and optimized treatment regimens.

Primary Sjögren's syndrome and the eye

Primary Sjögren syndrome is an autoimmune disease that mainly affects exocrine glands such as the salivary and lacrimal glands. In addition, systemic involvement is common. Primary Sjögren syndrome is of particular interest to ophthalmologists as it constitutes an important differential diagnosis in conditions with dry eye disease. In addition, ocular tests for more precisely diagnosing and monitoring primary Sjögren syndrome have become increasingly important, and new therapeutics for local and systemic treatment evolve as a result of increased understanding of immunological mechanisms and molecular pathways in the pathogenesis of primary Sjögren syndrome. We provide an update of interest to ophthalmologists regarding pathogenesis, diagnosis, investigative procedures, and treatment options.

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.