Dysfunctional Tear Syndrome Research Articles

Indications and outcomes of keratoplasty ≤ 5.5 mm diameter (“mini-keratoplasty”)

PurposeTo report indications and clinical outcomes of corneal grafts ≤ 5.5 mm in diameter (“mini-KP”) in a German tertiary referral center.MethodsPatients who had undergone mini-KP to treat corneal ulcers with or without perforation between 2011 and 2018 at the Department of Ophthalmology, University of Düsseldorf, Germany, were identified from the local keratoplasty registry. All patient records were reviewed for age, gender, laterality, systemic and ophthalmological diseases, etiology of the corneal ulcerative disease, pre- and postoperative visual acuity over a follow-up time of up to 12 months, graft size, postoperative complications and the need for and timing of further corneal interventions.Results37 eyes of 37 patients (male: n = 20; female: n = 17) with a mean age (± standard deviation) at presentation of 70 ± 18.8 years (range: 22–92 years) were identified. Most common etiologies were neurotrophic keratopathy (n = 15), dysfunctional tear syndrome (n = 9) and atopic keratoconjunctivitis (9). Mean graft diameter was 4.51 ± 0.63 mm (range: 3-5.5 mm). 23/37 eyes (62%) required no further intervention in the acute phase. 14/37 patients (38%) required secondary corneal intervention, due to complications. One-year graft survival was 78.4%. One eye had to be eviscerated due to recurrent corneal ulceration and endophthalmitis. 36 of 37 eyes were preserved. We found a highly significant correlation between type 2 diabetes and the development of postoperative complications (r = .46; p = .005). Corrected distance visual acuity (CDVA) improved from 1.42 ± 0.75 logMAR to 0.9 ± 0.65 logMAR postoperatively (t (23) = 5.76; p < .001).ConclusionMini-KP can be used successfully in eyes with advanced corneal ulcers due to various infectious and noninfectious etiologies to restore tectonic stability in the long-term and with moderate visual gains.

Biophysical properties of tear film lipid layer I. Surface tension and surface rheology

Tear film lipid layer (TFLL) is the outmost layer of the tear film. It plays a crucial role in stabilizing the tear film by reducing surface tension and retarding evaporation of the aqueous layer. Dysfunction of the TFLL leads to dysfunctional tear syndrome, with dry eye disease (DED) being the most prevalent eye disease, affecting 10%–30% of the world population. To date, except for treatments alleviating dry eye symptoms, effective therapeutic interventions in treating DED are still lacking. Therefore, there is an urgent need to understand the biophysical properties of the TFLL with the long-term goal to develop translational solutions in effectively managing DED. Here, we studied the composition-function correlations of an artificial TFLL, under physiologically relevant conditions, using a novel experimental methodology called constrained drop surfactometry. This artificial TFLL was composed of 40% behenyl oleate and 40% cholesteryl oleate, representing the most abundant wax ester and cholesteryl ester in the natural TFLL, respectively, and 15% phosphatidylcholine and 5% palmitic-acid-9-hydroxy-stearic-acid (PAHSA), which represent the two predominant polar lipid classes in the natural TFLL. Our study suggests that the major biophysical function of phospholipids in the TFLL is to reduce the surface tension, whereas the primary function of PAHSA is to optimize the rheological properties of the TFLL. These findings have novel implications in better understanding the physiological and biophysical functions of the TFLL and may offer new translational insight to the treatment of DED.

Severe dysfunctional tear syndrome patients and resolution of central corneal staining: retrospective cohort study

PurposeSevere dry eye is widely prevalent yet difficult to treat. This study aims to evaluate for improvement in epithelial status and the risk factors for lack of improvement in a...

The levels of 12 cytokines and growth factors in tears: hyperthyreosis vs euthyreosis.

Simultaneous analyses of the contents and ratios of 12 cytokines and growth factors in single samples of human tears were performed, and the results were compared between a group of healthy subjects and a group of patients with Graves' hyperthyreosis (GH) without thyroid-associated orbitopathy (TAO). Determinations and concentration measurements of interleukins (IL-2, IL4, IL-6, IL-8, IL-10, IL-1α, and IL-1β) interferon (IFN-γ), tumor necrosis factor (TNF-α), monocyte chemoattractant protein (MCP-1), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were performed with single tear samples from 21 patients with hyperthyreosis and 22 healthy subjects. The analyses were performed using a Randox microchip with an Evidence Biochip Array Analyzer. We found significant differences between the healthy donor group and the hyperthyreosis group in the levels of IL-6, IL-10, VEGF, IL-1α, and MCP-1. The concentration of IL-6 was considerably higher in the hyperthyreosis group, IL-10 was higher in the healthy donor group, and VEGF and MPC-1 were higher in the hyperthyreosis group. The IL-8 and IFN-γ levels were higher in the hyperthyreosis group. The ratios of all of the cytokines to anti-inflammatory IL-10 were significantly elevated in the hyperthyreosis group. There are clear differences in the levels of cytokines and growth factors in the tears of healthy subjects and patients with GH without TAO. Tear cytokine changes and related dysfunctional tear syndrome (DTS) could be an early sign of occult TAO in Graves' hyperthyreosis patients.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment.

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

Inflammatory cytokines regulate secretion of VEGF and chemokines by human conjunctival fibroblasts: Role in dysfunctional tear syndrome

Ocular surface inflammation is one of the primary mechanisms associated with dysfunctional tear syndrome (DTS), also known as dry eye disease. DTS, more prevalent in older populations, causes ocular discomfort and visual disturbance due to dryness on the surface layer in the eye. We used human conjunctival fibroblast cultures (HCJVF) to investigate the effects of inflammatory cytokines IFN-γ, TNF-α and IL-1β (ITI) on the secretions of VEGF and chemokines. Our results demonstrate the elevated secretion of angiogenic VEGF molecules by ITI without affecting anti-angiogenic molecules, PEDF, endostatin, thrombospondin and sVEGF-R1. The secretion of interferon-γ inducible chemokines, CXCL9, -10, -11 by HCJVF were significantly enhanced by ITI. Our in vitro study supports previously reported observations of elevated VEGF and chemokines in tear fluids of DTS patients, reiterating the role of inflammatory reactions in DTS.

Artificial tears potpourri: a literature review.

Numerous brands and types of artificial tears are available on the market for the treatment of dysfunctional tear syndrome. Past literature has focused on comparing the components of these products on patient’s clinical improvement. The wide array of products on the market presents challenges to both clinicians and patients when trying to choose between available tear replacement therapies. Different formulations affect patients based on etiology and severity of disease. In order to provide an unbiased comparison between available tear replacement therapies, we conducted a literature review of existing studies and National Institutes of Health clinical trials on commercially available, brand name artificial tears. Outcomes evaluated in each study, as well as the percent of patients showing clinical and symptomatic improvement, were analyzed. Fifty-one studies evaluating different brands of artificial tears, and their efficacy were identified. Out of the 51 studies, 18 were comparison studies testing brand name artificial tears directly against each other. Nearly all formulations of artificial tears provided significant benefit to patients with dysfunctional tear syndrome, but some proved superior to others. From the study data, a recommended treatment flowchart was derived.

Low levels of 17-β-oestradiol, oestrone and testosterone correlate with severe evaporative dysfunctional tear syndrome in postmenopausal women: a case–control study

AimsTo evaluate the role of 17-β-oestradiol, oestrone and total testosterone (TT) deficiency in the pathogenesis of severe evaporative dry eye syndrome (DES), investigating the relationship between tear osmolarity, tear film...

Effects of amino acids enriched tears substitutes on the cornea of patients with dysfunctional tear syndrome

To evaluate the effect of aminoacid enriched artificial tears on the ocular surface of patients with dysfunctional tear syndrome (DTS). Forty patients were divided into two groups: group 1 treated for 90 days with sodium hyaluronate (SH) 0.15% 1 drop × 5 times/day; group 2 treated for 90 days with SH 0.15% + aminoacids mixture 1 drop × 5 times/day. Symptom score questionnaire, tear break-up time (TBUT), corneal fluorescein stain, Shirmer's I test and confocal microscopy were performed at baseline and after 30 and 90 days. Confocal images underwent morphometric analysis. Both treatments improved symptoms after 1 month. Group 2 patients showed at 1 month an improvement of TBUT and corneal stain, maintained throughout the study. Also Shirmer's I test improved after 3 months. In group 1, an improvement of TBUT and corneal stain was observed after 3 months. The morphometric analysis of confocal images demonstrated at month 1 an improvement of nerve tortuosity in group 2; after 3 months both groups showed a significant improvement versus baseline. The epithelium showed, in both groups, a reduction in hyperreflective large cells starting from 1 month; the area of the cells was significantly reduced after 3 months, with a significant higher reduction in group 2. The perineural stromal opacity was significantly increased after 3 months, particularly in group 2. This is the first study addressing corneal changes after amino acids administration in a DTS population. The treatment with amino acids enriched SH can be considered a useful tool in the treatment of DTS.

Toll-Like Receptor Expression and Activation in Mice with Experimental Dry Eye

To investigate the expression and/or function of toll-like receptors (TLRs) and antimicrobial peptides (AMPs) in dry eye inflammation. Experimental dry eye (EDE) was induced in C57BL/6 mice and TLR mRNA and protein expression were determined at the ocular surface and lacrimal gland. TLR agonist cocktail was applied to the ocular surface in untreated (UT), corneal scratched, and EDE mice. The corneal expression of cathelin-related antimicrobial peptide (CRAMP; human LL-37 orthologue), and mouse beta defensin (mBD)-3 and -4 (human BD-2 orthologue) was compared. LL-37, hBD-2, TLR4, 5, and TLR9 mRNA expression was examined in patients with dysfunctional tear syndrome (DTS) via conjunctival impression cytology. Murine central corneal thickness (CCT) and inflammatory cell recruitment into the stroma was determined by in vivo imaging. EDE upregulated TLR2-4 and 9 mRNA expression in the palpebral conjunctiva and with the exception of TLR4, a similar expression, occurred in the corneal epithelium. TLR2 and 5 were upregulated in lacrimal gland and overall, there was a corresponding change in TLR protein. EDE decreased CRAMP mRNA and protein. hBD-2 and TLR9 expression were modulated in DTS subjects. Topical TLR agonist increased inflammatory cells recruitment and CCT in mice with a cornea scratch. In EDE, TLR agonist treatment downregulated corneal mBD-4 protein caused corneal epithelial loss, and stromal ulceration resulting in decreased CCT. DTS modulates the expression of TLR and CRAMP and topical application of TLR agonists in EDE mice resulted in corneal epithelial loss and thinning. These results suggest that TLRs are involved in DTS inflammation.

Diagnostic Procedures and Management of Dry Eye

Dry eye disease or dysfunctional tear syndrome is among the most frequent diagnoses in ophthalmology. It is a multifactorial disease of the ocular surface and tear film which results in ocular discomfort, visual disturbances, and tear instability with potential damage to the cornea and conjunctiva. Risk factors for dry eye syndrome include age, sex (female gender), race, contact lens wear, environment with low humidity, systemic medications, and autoimmune disorders. The aim of this paper is to present the systematic classification, epidemiology, diagnostic procedures, and advances in the management of dry eye disease. The recent improvements in comprehending the underlying etiologic factors will inevitably improve future classifications and diagnostic abilities leading to more effective therapeutic options. Treatment of this highly prevalent condition can drastically improve the quality of life of individuals and prevent damage to the ocular surface.

Sensitivity and Specificity of a Point-of-Care Matrix Metalloproteinase 9 Immunoassay for Diagnosing Inflammation Related to Dry Eye

To determine the clinical sensitivity, specificity, negative predictive value, and positive predictive value of a rapid point-of-care diagnostic test to detect elevated matrix metalloproteinase 9 levels (InflammaDry). In a prospective, sequential, masked, multicenter clinical trial, InflammaDry was performed on 206 patients: 143 patients with clinical signs and symptoms of dysfunctional tear syndrome (dry eyes) and 63 healthy individuals serving as controls. Participants were assessed as healthy controls or for a clinical diagnosis of dry eye using the Ocular Surface Disease Index, Schirmer tear test, tear breakup time, and keratoconjunctival staining. The sensitivity and specificity of InflammaDry were compared with clinical assessment. InflammaDry showed sensitivity of 85% (in 121 of 143 patients), specificity of 94% (59 of 63), negative predictive value of 73% (59 of 81), and positive predictive value of 97% (121 of 125). Compared with clinical assessment, InflammaDry is sensitive and specific in diagnosing dry eye. Dry eye is often underdiagnosed resulting from poor communication between the clinical assessment of dry eye severity between clinicians and patients. This often leads to a lack of effective treatment. Matrix metalloproteinase 9 is an inflammatory biomarker that has been shown to be elevated in the tears of patients with dry eyes. The ability to accurately detect elevated matrix metalloproteinase 9 levels may lead to earlier diagnosis, more appropriate treatment, and better management of ocular surface disease. Preoperative and perioperative management of inflammation related to dry eyes may reduce dry eyes that develop after laser in situ keratomileusis, improve wound healing, and reduce flap complications. Recognition of inflammation may allow for targeted perioperative therapeutic management of care for patients who undergo cataract and refractive surgery and improve outcomes. clinicaltrials.gov Identifier: NCT01313351.

Spectrum of ocular toxicities from epidermal growth factor receptor inhibitors and their intermediate-term follow-up: a five-year review

Epidermal growth factor receptor (EGFR) inhibitors and kinases are commonly used in the treatment regimen of various solid tumors including non-small cell lung, colorectal, head and neck, breast, and pancreatic cancers. The aim of this study is to describe common ocular adverse effects associated with EGFR inhibitor treatment, outline successful management options, and provide data on intermediate-term follow-up of these patients. A retrospective chart review was performed of all patients presenting to the ophthalmology clinic with an adverse ocular effect while on an EGFR inhibitor. Duration of EGFR inhibitor treatment, symptoms, diagnosis, and treatment information were collected. Statistical analyses were done to ascertain differences in adverse effects based on duration and type of EGFR inhibitor treatment using the Fisher exact test. The two most common EGFR inhibitors in this group of patients were erlotinib and cetuximab. The most common adverse ocular effects for patients on EGFR inhibitors were dysfunctional tear syndrome (DTS), followed by blepharitis and eyelash changes (trichomegaly and trichiasis). Two patients had epithelial defects (corneal abrasions). There was no significant difference in adverse effects based on specific EGFR inhibitor medication or duration of treatment. Almost all patients were successfully managed with treatment regimens that we have outlined in this paper. Intermediate-term follow-up (range 6-17 months) showed a persistence of DTS and eyelash changes. We present what is, to our knowledge, the largest reported cohort of patients with ocular toxicities from EGFR inhibitors--the spectrum of eye toxicities, their management, and the intermediate-term follow-up of patients with eye toxicities. Awareness of this information is important for oncologists and oncology nurses to facilitate proper counseling and management/referral of patients developing eye toxicity while on EGFR inhibitors.

Complications of Cosmetic Wide Conjunctivectomy Combined With Postsurgical Mitomycin C Application

To raise awareness among clinicians about the risk of severe complications after cosmetic conjunctivectomy plus postsurgical topical mitomycin C (MMC) treatment. We retrospectively reviewed the medical records of 48 consecutive patients who received cosmetic wide conjunctivectomy plus postsurgical topical MMC treatment to eliminate conjunctival injection and visited our outpatient clinic between January 2009 and January 2011. Forty-four patients (91.67%) developed complications after cosmetic wide conjunctivectomy plus postsurgical topical MMC treatment. Complications included chronic conjunctival epithelial defects (22 patients), scleral thinning with (19 patients) or without (2 patients) calcified plaques, fibrovascular conjunctival adhesion at the muscle insertion site (15 patients), chronic dysfunctional tear syndrome (11 patients), avascular zones (10 patients), abnormal vessel growth (5 patients), lymphangiectasis (3 patients), adhesions of Tenon capsule and the conjunctiva at the extraocular muscle insertion site (1 patient), extraocular muscle fiber exposure (1 patient), and diplopia (9 patients). The mean time between surgery and the onset of diplopia was 1.67 months (range, 1-3 months), and the mean deviation was 11.0 prism diopters (range, 0-25 prism diopters) in the primary position. Three patients underwent strabismus surgery due to incomitant esotropia. Eight patients underwent calcified plaque removal because of severe progression of the calcification. Five patients underwent conjunctival flap operation because of severe progressive scleral thinning. Cosmetic wide conjunctivectomy, which has been advertised as a simple and effective surgical option for the treatment of conjunctival injection, has caused disruption in the normal physiology of the ocular surface, which leads to various devastating complications.

Meibum Lipid Composition in Asians with Dry Eye Disease

BackgroundPrevious lipidomic analyses of the human meibum had largely focused on individuals from non-Asian populations, despite the higher prevalence of dysfunctional tear syndrome (DTS) observed across Asia. Information pertaining to the alterations in lipid profiles in relation to DTS onset and progression is also lacking and warrants comprehensive experimental analysis.Methodologies/Principal FindingsWe examined the meibum lipidome of 27 DTS patients and 10 control subjects for a total of 256 lipid species from 12 major lipid classes, including cholesteryl ester (CE), wax ester (WE), triacylglyceride (TAG), (O-acyl)-ω-hydroxy fatty acid (OAHFA), glycerophospholipids (phosphatidylcholine, PC; phosphatidylethanolamine, PE; phosphatidylinositol, PI; phosphatidylglycerol, PG) and sphingolipids (sphingomyelin, SM; ceramide, Cer; glucosylceramide, GluCer; dihexosylceramide, DihexCer). Neutral lipids were analysed using high-performance liquid-chromatography coupled with mass spectrometry (HPLC/MS) and tandem mass spectrometry (MS/MS) was used for the qualitative and quantitative analysis of polar lipid species. DTS patients were classified into three severity groups (i.e. mild, moderate and severe) based on the ocular surface disease index (OSDI). A significantly lower level of TAG (p<0.05) was observed in patients under the moderate category compared to the mild category. Notably, a number of OAHFA species displayed consistently decreasing levels that correlate with increasing disease severity. An attempt was also made to investigate the changes in meibum lipid profiles of DTS patients compared to normal individuals classified based on OSDI score. Several unsaturated TAG and PC species were found at significantly higher levels (p<0.05) in patients than controls.ConclusionThe current study presents, for the first time, a comprehensive lipidome of meibum from individuals of an Asian ethnicity, which can potentially offer new insights into the higher prevalence of DTS observed amongst Asian populations. This study also represents an attempt towards identification of lipid species in meibum which could serve as marker for DTS.

Effects of Topical Cyclosporine A Plus Artificial Tears Versus Artificial Tears Treatment on Conjunctival Goblet Cell Density in Dysfunctional Tear Syndrome

The aim was to compare the effects of topical cyclosporine A and artificial tears combination with artificial tears alone in patients with dysfunctional tear syndrome (DTS). Forty-two eyes of 42 patients with DTS were enrolled in the study. The inclusion criteria for the study were Schirmer I (without anesthesia) scores below 10 mm/5 min and tear film break-up time (BUT) below 10 sec. The patients were randomly divided into two groups. The study group (22 patients) underwent 0.05% cyclosporine A treatment twice a day and preservative-free artificial tears for four times a day for 4 months. The control group (20 patients) was administered only preservative-free artificial tears four times a day for 4 months. The BUT, Schirmer test scores, corneal fluorescein staining, conjunctival lissamine green staining, and goblet cell density derived by impression cytology were recorded before and after treatment in each group. In the study group, all parameters improved statistically significantly after treatment at the 4-month follow-up compared with the pretreatment values (P<0.001 for all). In the control group, corneal fluorescein staining (P<0.001) and conjunctival lissamine green staining (P=0.014) improved, but BUT and Schirmer scores did not change significantly after treatment. At the end of the 4-month follow-up, the study group demonstrated statistically significantly better BUT (P=0.020), Schirmer scores (P=0.002), goblet cell density (P=0.006), corneal fluorescein staining (P=0.003), and conjunctival lissamine green staining (P=0.017) scores than did the control group. Topical cyclosporine A and artificial tears treatment significantly increases goblet cell density, decreases the signs of DTS, and improves ocular surface health.

MMP-9 and the perioperative management of LASIK surgery

Hyperosmolarity is a central mechanism causing ocular surface inflammation and eye irritation in typical patients suffering from tear dysfunction. Tear composition in dry eyes, or dysfunctional tear syndrome, may destabilize the tear film and cause ocular surface epithelial disease. Increased activity of matrix metalloproteinases (MMPs), especially MMP-9, plays a critical role in wound healing and inflammation and is primarily responsible for the pathologic alterations to the ocular surface that leads to a dysfunctional tear state. Altered corneal epithelial barrier function is the cause for ocular irritation and visual morbidity in dry eye disease. The increased MMP-9 activity in dry eyes may contribute to deranged corneal epithelial barrier function, increased corneal epithelial desquamation, and corneal surface irregularity. Dry eye is one of the most common complications of photorefractive keratectomy and laser in-situ keratomileusis (LASIK). LASIK has both a neurotrophic effect on the cornea and leads to a physical change in corneal shape that results in a change in tear dynamics, leading to ocular surface desiccation. The reduction in tear function after LASIK may induce an increase in osmolarity and consequently raise the concentration of proinflammatory cytokines and MMP-9 in the tear film, which results in dry eyes and insufficient attachment between the corneal flap and the corneal bed. Appropriate diagnosis and management of dysfunctional tear syndrome may lead to less postoperative LASIK complications.

Efeitos da blefaroplastia na síndrome da disfunção lacrimal

OBJETIVO:Avaliar a presenca da sindrome da disfuncao lacrimal e alteracoes na sensibilidade corneana no pre e pos-operatorio de pacientes com indicacao de blefaroplastia superior. METODOS: Foram avaliados 30 pacientes com indicacao cirurgica para correcao de dermatocalase em palpebra superior de ambos os olhos. Obtida historia clinica e realizado exame oftalmologico geral, incluindo exames como teste de Schirmer I, coloracao com Lissamina Verde, tempo de ruptura do filme lacrimal, coloracao com fluoresceina e teste da sensibilidade corneana com estesiometro de Cochet-Bonnet, alem de teste subjetivo pelo questionario ODSI. Os exames foram realizados antes e apos 90 dias da cirurgia. RESULTADOS: Apenas 23 pacientes completaram o seguimento, sendo o sexo feminino predominante. A idade dos pacientes variou de 63 a 87 anos. De acordo com o questionario ODSI aplicado, observou-se que houve melhora dos sintomas, mas a analise estatistica mostrou um resultado nao-significante. Com relacao a analise dos resultados obtidos com o estesiometro de Cochet-Bonnet, 7 pacientes apresentaram uma melhora na sensibilidade corneana, 9 pacientes diminuiram a resposta e 7 mantiveram seus valores. Os resultados do BUT lacrimal, coloracoes com Lissamina verde e Fluoresceina foram considerados estatisticamente nao-significantes. O teste de Schirmer I demonstrou uma melhora estatisticamente significativa da producao lacrimal no pos-operatorio. CONCLUSAO: Neste trabalho observou-se que os pacientes submetidos a blefaroplastia superior apresentaram uma melhora nos sinais e sintomas relacionados a SDL, apesar de ter sido diagnosticado uma diminuicao na sensibilidade corneana nao estatisticamente significante.

Treating ocular surface disease: new agents in development

This paper reviews recent advances and investigation in the treatment of ocular surface pathology. There is significant investment in this area, paralleling the growing demand for more effective alternatives to current treatments. Clinicians are becoming more aware of surface pathology, yet the ability to treat the most common forms of ocular pathology are still limited to the few medications approved by the US Food and Drug Administration. Medicines and devices currently under investigation are very promising. It is absolutely critical to understand the emerging options and think of their role in the treatment paradigm.

Pathophysiology of dry eye syndrome

AbstractDry eye or dysfunctional tear syndrome is a highly prevalent disease worldwide. It is related to a pathological condition of anyone of the parts of the “ocular surface system” that involves the cornea, conjunctiva, lacrimal gland, accessory lacrimal glands, nasolacrimal duct and the lids with the meibomian glands. These are linked as a functional system by innervation, the endocrine and immune system. Endogenous or exogenous caused alterations in one or several components of the ocular surface system or its secretions result in changes of the tear film or ocular surface provoking inflammation. With time, inflammatory reactions may lead to corneal neuropathy compromising the reflex response of the lacrimal glands. Additionally a self‐perpetuating vicious circle with loss of function and damage can be initiated also by an immune‐modulated inflammation.