Tear Constituents Research Articles

What's new in ocular and oral aspects of Sjögren's syndrome and do new treatments work?

Primary SS (pSS) is a systemic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands leading to glandular dysfunction, resulting in dryness of the eyes, mouth and other mucosal surfaces. Systemic manifestations also occur in the majority of patients. There has been increasing interest in recent years, with a number of publications regarding the classification criteria, diagnostic tools, disease activity, damage, impact and potential treatments. This article reviews recent advances in the diagnosis and treatment of ocular and oral involvement in pSS. Recent stand-out developments include measurement of tear osmolarity as a marker in dry eye disease diagnosis, new devices measuring tear constituents and meibomian gland structure and treatment of its dysfunction. Lip biopsy is still valuable despite emerging evidence of non-invasive diagnostic techniques, notably salivary gland ultrasound.

Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses

PurposeThe aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs). MethodThe barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (TNW) of non-wearers, tears (TW_etaf) of regular wearers of etafilcon A CLs, and tears (TW_omaf) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 μL of tears of different subjects of the same group with 85 μL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized. ResultsWithin an error of about 0.05, IEPs were found to be 2.90 (TNW), 2.80 (TW_omaf), and 3.16 (TW_etaf). On average, a lower H+ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both TNW and TW_omaf. ConclusionIEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The TW_etaf results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.

Photon correlation spectroscopy applied to tear analysis

This study aims to deepen the knowledge on tear film properties by the development of a protocol for analyses of Photon Correlation Spectroscopy (PCS) on human tears and by the comparison between PCS results obtained on tears of contact lens wearers and non-wearers. Tears (5μL) were collected by a glass capillary. The analyses provide the hydrodynamic diameter of tear components by analyzing intensity fluctuations in time of scattered light. PCS appears a promising technique for studying tear features and for shedding light on specific eye conditions, such as on the clinical effects of CL wear. In fact, statistical difference (p<0.001) was found between the measured mean hydrodynamic diameter of tear components of wearers and non-wearers, the resulting value significantly higher for CL wearers. The scenario does not substantially change after (25±5)min from the CL removal. The difference is attributed to changes in the interactions between tear constituents due to CL wear. In order to get deeper insights on the influence of CL wear on aggregation and structure of tear components, a preliminary Electron Spin Resonance (ESR) investigation was performed, monitoring Fe3+ species. ESR spectra on tears of both CL wearers and non-wearers showed the presence of intense signals, probably associated to iron (III) centers in proteins such as lactoferrin, and a weaker resonance attributable to Fe3+ species interacting with S–S bridges of lysozyme. Differences in ESR spectra between CL wearers and non-wearers were detected and tentatively ascribed to changes in coordination or in local environment of Fe3+ centers connected to aggregation phenomena induced by CL wear, which promote their interaction with other neighboring iron species.

Paper-based microfluidic system for tear electrolyte analysis.

The analysis of tear constituents at point-of-care settings has a potential for early diagnosis of ocular disorders such as dry eye disease, low-cost screening, and surveillance of at-risk subjects. However, current minimally-invasive rapid tear analysis systems for point-of-care settings have been limited to assessment of osmolarity or inflammatory markers and cannot differentiate between dry eye subclassifications. Here, we demonstrate a portable microfluidic system that allows quantitative analysis of electrolytes in the tear fluid that is suited for point-of-care settings. The microfluidic system consists of a capillary tube for sample collection, a reservoir for sample dilution, and a paper-based microfluidic device for electrolyte analysis. The sensing regions are functionalized with fluorescent crown ethers, o-acetanisidide, and seminaphtorhodafluor that are sensitive to mono- and divalent electrolytes, and their fluorescence outputs are measured with a smartphone readout device. The measured sensitivity values of Na+, K+, Ca2+ ions and pH in artificial tear fluid were matched with the known ion concentrations within the physiological range. The microfluidic system was tested with samples having different ionic concentrations, demonstrating the feasibility for the detection of early-stage dry eye, differential diagnosis of dry eye sub-types, and their severity staging.

소프트콘택트렌즈 재질과 착색에 따른 눈물성분 침착과 칸디다균 흡착의 상관관계

목적: 본 연구에서는 소프트콘택트렌즈의 재질 특성과 착색 여부가 눈물 성분이 침착된 소프트콘택트렌즈에 칸디다균 흡착에 미치는 영향을 알아보았다. 방법: Etafilcon A, hilafilcon B, nelfilcon A 재질의 투명 소프트콘택트렌즈와 써클 소프트콘택트렌즈를 대상으로 하여 인공눈물에 침착시키기 전과 후의 흡착 균 수를 측정하였다. 또한, 주사전자현미경을 통해 렌즈에 흡착된 균을 관찰하였다. 결과: 칸디다균의 흡착은 콘택트렌즈 재질에 따라 통계적으로 유의하게 차이가 있었다. Etafilcon A 재질에서는 투명 소프트콘택트렌즈와 써클 콘택트렌즈간 균 흡착양 차이가 없었으며, hilafilcon B 및 nelfilcon A 재질에서는 써클 소프트콘택트렌즈에 흡착된 균 수가 다소 많았다. 투명 중심부와 착색부를 비교하였을 때 투명 중심부에 칸디다균 흡착이 더 많았으며, 투명 중심부와 투명 주변부를 비교하였을 때 투명 주변부에서의 균 흡착양이 더 많았다. 눈물 단백질이 침착되었을 경우 흡착된 칸디다균의 수가 감소하였으며 눈물 단백질의 칸디다균에 대한 항균력 유지는 재질에 따라 차이가 있어 etafilcon A 재질 렌즈에서 유지 기간이 가장 길었다. 결론: 본 연구에서는 소프트콘택트렌즈의 재질 특성, 착색여부 및 부위에 따라 흡착되는 칸디다균수가 달라진다는 것을 밝혔으며, 칸디다균의 흡착 특성에 따라 관리 방법을 달리해야 할 것을 제안한다. Purpose: The aim of this study was to figure out how the characteristics of soft contact lens materials and pigmentation affect the adherence of C. albicans on soft contact lenses pre-deposited with tear constituents. Methods: The adherent number of C. albicans on clear soft contact lenses (hereinafter clear lenses) and circle soft contact lenses (hereinafter circle lenses) made of etafilcon A, hilaiflcon B and nelfilcon A, respectively, was measured before and after the deposition of artificial tear. Also, bacteria adherence on lenses were observed by a scanning electron microscope. Results: Adherence of C. albicans was significantly different according to lens materials. The amount of adsorption was not different between clear lenses and circle lenses made of etafilcon A however, the number of bacteria absorption was bigger in hilafilcon B and nelfilcon A lenses. More absorption of C. albicans was found in the non-pigmented central area compared the pigmented area, and non-pigmented peripheral area has more bacterial absorption than non-pigmented central area. The number of C. albicans decreased in the case that tear protein was pre-deposited. The maintenance of antibacterial activity against C. albicans was different according to lens materials thus, etafilcon A has the longest period of its maintenance. Conclusions: It was revealed that the number of C. albicans was different according to the characteristics of lens materials, pigmentation or non-pigmentation, the pigmented area of soft contact lenses. Thus, it is suggested that the management method should be different according to the adsorption characteristics of C. albicans.

Proteomics of tear fluid

SummaryThe tear film overlying the delicate ocular surface epithelial cells are a complex extra‐cellular fluid with components from the orbital and accessory lacrimal glands, ocular surface epithelial cells, goblet cells, Meibomium glands and as an ultrafiltrate of the blood. Molecular information regarding the health of the ocular surface is reflected in both the quantity and quality of the tear constituents. Moreover, this information can be acquired quantitatively and used for the diagnosis, prognosis and treatment of ocular surface disease and can be used as biomarkers for precision medicine. Recent studies have shown that the tear proteome contains over 1,500 identifiable proteins. Highly abundant proteins include lysozyme, lactoferrin, lipocalin, lacritin, and the proline rich proteins. The tear proteome is clearly shown not to be a simple reflection of the blood. As an extracellular fluid, inflammation is revealed in the tear fluid by upregulation of the pro‐inflammatory proteins S100A8 and S100A9.

소프트콘택트렌즈 재질과 착색에 따른 눈물성분 침착과 포도상구균 흡착의 상관관계

소프트콘택트렌즈 재질과 착색에 따른 눈물성분 침착과 포도상구균 흡착의 상관관계

Dry eye treatment: choosing the best product for your patient

Dry eye disease (DED) is a multifactorial condition that is complex to diagnose and treat. Over the last two decades, major advances have occured in the treatment of DED and ocular surface disease. There has also been an equal increase in knowledge concerning the processes or mechanisms whereby the condition develops and progresses. This has led to a paradigm shift in DED management from simply lubricating and hydrating the ocular surface with artificial tears to strategies that stimulate natural production of tear constituents, maintain ocular surface epithelial health and barrier function, and inhibit the inflammatory factors that adversely impact the ability of the ocular surface and glandular epithelia to produce tears. Preliminary experience with this new therapeutic approach suggests that quality of life can be improved for many patients with dry eye, and that initiating these strategies early in the course of the disease may prevent potentially blinding complications of DED.

New developments in dry eye treatment

Abstract Purpose This study summarizes the management and therapeutic options for treating dry eye disease. Goals of this review is to identify appropriate therapeutic methods for the management of dry eye disease and recommend a sequence or strategy for their application, based on evidence‐based review of the literature. Methods To achieve this a comprehensive review of clinical textbooks and scientific literature was performed and the quality of published evidence graded according to an agreed standard, using objective criteria for clinical and basic research studies. Results There have been tremendous advances in the treatment of dry eye and ocular surface disease in the last decades related to the increase in knowledge regarding the pathophysiology of dry eye. This has led to a paradigm shift in dry eye management from simply lubricating and hydrating the ocular surface with artificial tears to strategies that stimulate natural production of tear constituents, maintain ocular surface epithelial barrier function, and inhibit the inflammatory factors that adversely impact the ability of ocular surface and glandular epithelia to produce tears. Conclusion The authors will present current and future treatment options for dry eye disease.

Electrolytes and Electrophoretic Studies of Tear Proteins in Tears of Patients with Nasolacrimal Duct Obstruction

This study was performed to determine whether there are differences in tear constituents between normal persons and patients with primary acquired nasolacrimal duct obstruction (PANDO) and to correlate differences in tear composition with the degree of PANDO. We tested 30 normal persons (mean age 42.0 ± 21.4 years) and 34 PANDO patients (mean age 44.8 ± 17.9 years) consisting of 18 cases with complete obstruction and 16 cases with partial obstruction. We measured the pH, the concentration of Na⁺, K⁺, Cl^–, total calcium and total protein of the tears. The composition of tear protein was assessed by cellulose acetate electrophoresis. The data were analyzed by a t test. The pH was more alkaline in patients with PANDO (7.11 ± 0.38), especially in cases with complete obstruction (7.14 ± 0.30, p = 0.47) compared with the normal persons (6.94 ± 0.35). The concentration of Na⁺, K⁺, Cl^– and total protein were similar in normal and PANDO cases, while total calcium concentration was significantly higher in PANDO (2.62 ± 1.70 mg/dl) compared with the normal cases (1.73 ± 0.97 mg/dl), (p = 0.015). This change was found in both cases with complete obstruction (2.47 ± 1.25 mg/dl, p = 0.027) and cases with partial obstruction (3.00 ± 2.16 mg/dl, p = 0.009). PANDO patients had lower levels of tear protein fraction (TPF) 1 (p = 0.006) and higher levels of tear TPF 4 (p = 0.000) than normal persons. Tears in PANDO cases were more alkaline, higher in calcium concentration, and unstable in the proportion of tear proteins compared with normal persons. These results may improve our understanding of tear physiology and the pathogenesis of PANDO.

Measurement of pH, Electrolytes and Electrophoretic Studies of Tear Proteins in Tears of Patients with Dacryoliths: A Novel Concept for Dacryoliths

Dacryolithiasis is one of the causes of acquired nasolacrimal duct obstruction, although its origin is unclear. The purpose of this study was to investigate the differences in tear constituents between patients with nasolacrimal duct obstruction with dacryoliths and those without dacryoliths. In a prospective case-control study, undiluted tears were collected from 30 eyes from 30 patients with partial acquired nasolacrimal duct obstruction (PANDO) consisting of 17 PANDO patients with dacryoliths and 13 PANDO patients without dacryoliths. The pH, and the Na⁺, K⁺, Cl^–, total calcium and total protein concentrations were determined. The composition of the tear proteins was assessed by cellulose acetate electrophoresis. In the tear samples from 17 eyes with PANDO/dacryoliths, the mean ± SD K⁺ level was 15.6 ± 3.1 mEq/l. In the tear samples from 13 PANDO controls, the mean ± SD K⁺ level was 19.8 ± 4.9 mEq/l. The difference between the two groups was statistically significant (p = 0.02). In the tear samples from PANDO/dacryolith patients, the mean ± SD total protein level was 129.0 ± 72.9 mg/dl. In the tear samples from the PANDO controls the mean ± SD total protein level was 261.6 ± 132.5 mg/dl. The difference between the two groups was statistically significant (p = 0.00). In the tear protein fractions from electrophoresis, a low level of lysozyme was observed in the PANDO/dacryolith samples compared with the PANDO control samples (p = 0.03). The tears from patients with PANDO due to dacryoliths showed a change in the concentrations of electrolytes and protein, particularly lysozyme, compared with that of the patients with PANDO without dacryoliths, which may be related to the pathogenesis of dacryoliths.

Spreading of the Tears After a Blink

To quantify the tear spreading velocity and stabilization time after blinks in healthy patients. Video recordings (magnification, x130) were made of the movements of naturally occurring particles in the tear film while patients blinked naturally. After each blink, tear spreading velocity was computed every 40 milliseconds from particle displacements determined from a frame-by-frame analysis of the records. After a blink, tears moved rapidly upward over the cornea. Forty milliseconds after passage of the lid, the velocity was 7.34 +/- 2.73 mm/s (mean +/- standard deviation, n = 20). The time to tear stabilization (i.e., zero velocity) was 1.05 +/- 0.30 seconds. The decay of spreading velocity with time was well described by a logarithmic function for all individual patient data (R2 range, 0.88-0.99; n = 20). We have shown that initial velocity and stabilization time are independent descriptors of tear spreading. Meibomian gland expression markedly reduced initial velocity leaving a normal stabilization time, whereas inhalation of an irritant reduced stabilization time leaving a normal initial velocity. In a patient with Sjögren syndrome, punctal plugs rapidly restored initial velocity and stabilization time from near zero values to normal values. We provide normal values for two descriptors of tear spreading, namely initial velocity and time to stabilization. These values can be modified by manipulations that alter tear constituents. Consequently, these descriptors may provide a basis for quantitative, noninvasive tear assessment.

The effect of successful contact lens wear on mucosal immunity of the eye

Objective This study aimed to assess the effect of contact lens wear on the mucosal defenses of the outer eye against infection. Design A case-controlled study of daily contact lens wearers in their initial 6 months of contact lens wear. Participants Contact lens wearers (mean age, 23.1 years; 47 subjects) were compared with age-matched control subjects (mean age, 24.7 years; 44 subjects). Intervention Outer eye defenses were studied by assay of tear constituents and quantitative conjunctival microbiology. Main outcome measures Antimicrobial activity of tears was studied by assay of total immunoglobulin A (IgA), IgA isotype-specific antibodies reactive with Escherichia coli, Haemophilus influenzae, Staphylococcus epidermidis, albumin and lysozyme, and the ocular surface microbial load determined using quantitative microbiology of the conjunctival sac. Results The IgA isotype-specific antibodies reactive with E. coli ( P = 0.03) and S. epidermidis ( P = 0.068) were lower in contact lens wearers, but antibody:albumin ratios were not significantly different in the two groups. Contact lens wear also had no significant effect on tear IgA, albumin, or lysozyme or its ratios with albumin. Bacterial numbers and colonization rates for coagulase-negative staphylococci were greater in contact lens wearers than in age-matched control subjects. Corynebacterium sp. and non-Enterobacteriaceae ( P = 0.007) were isolated more frequently and in greater numbers from contact lens wearers. Colonization rates were increased for Corynebacterium sp., but non-Enterobacteriaceae were transient. In both daily contact lens wearers and age-matched control subjects, most conjunctival flora were transient rather than colonizing, and no subject developed an outer eye infection during the study. Conclusion These results suggest that daily contact lens wear does not significantly alter the mucosal defenses of the outer eye that function to eliminate organisms from the conjunctival sac and prevent outer eye infection.

Effects of lacrimal gland removal on squirrel monkey cornea.

Lacrimal tissue is responsible for providing the aqueous component of tears, as well as proteins that protect the surface from bacterial attack.1 Although the discussion of basal tear flow often considers the primary issue to be tear volume, the inclusion of specific tear constituents and their secretory source is equally important. The role of the main and accessory lacrimal glands in the production of basal tear flow and in dry eye conditions has been the subject of considerable research.1–4 However, this subject has not been completely explored, especially in relation to various types of ocular pathology.5 The aim of the present study was to determine if accessory lacrimal glands are able to provide the ocular surface with sufficient tears without a secretory contribution from the main lacrimal gland.6,7 In attempting to determine the relative importance of these two secretory tissues, we took advantage of an unusual anatomical formation found in the squirrel monkey: to provide room for the globe, the main lacrimal gland has migrated to a temporal location outside the bony orbit.KeywordsSquirrel MonkeyLacrimal GlandAccessory GlandKeratoconjunctivitis SiccaMeibomian Gland DysfunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Determination of dexamethasone in tears by capillary electrophoresis

A selective capillary zone electrophoresis (CZE) microassay was developed for the simultaneous determination of dexamethasone phosphate and its major metabolite, dexamethasone, in tears. The calibration was carried out in the biological matrix with indoprofen as an internal standard which allowed the separation of dexamethasone phosphate and dexamethasone from the tear constituents. The limits of detection and quantification of the assay were 0.5 and 2.0 μg ml −1, respectively. This quantification method is essential for the in vivo determination of dexamethasone concentration–time profiles in tears after application of the antiinflammatory drug.

Cholinergic Stimulation of Lactoferrin and Epidermal Growth Factor Secretion by the Human Lacrimal Gland

The human lacrimal gland produces tear proteins, such as lactoferrin and epidermal growth factor (EGF), that have presumed biologic activity on the ocular surface. We hypothesized that secretion of these tear proteins by the lacrimal gland is neurally mediated. To test this hypothesis, we evaluated the secretion of lactoferrin and EGF from the human lacrimal gland (LG) after cholinergic stimulation. Human LG biopsies from two donors were sliced into sections weighing approximately 100 mg and were serially placed in wells containing Dulbecco's modified Eagle's medium (DMEM/F12; with or without atropine), followed by media alone, media containing carbamylcholine chloride (carbachol), and then media alone, each for 10 min. Supernatants were then assayed for lactoferrin and EGF by antibody sandwich enzyme-linked immunosorbent assay (ELISA). Both sets of LG explants showed statistically significant increases in supernatant concentrations of lactoferrin and EGF 10 min after cholinergic stimulation. These returned to prestimulation concentrations by 20 min. Atropine-pretreated explants showed no significant change in supernatant concentrations of these proteins after carbachol stimulation. The results of these studies indicate that cholinergic stimulation of the human LG results in increased secretion of the tear proteins lactoferrin and EGF. This suggests that the LG can respond to the ocular surface environment by increasing secretion of biologically active tear constituents through neural stimulation.

Analysis of Tear Proteins in Graves' Ophthalmopathy by High Performance Liquid Chromatography

Using high performance liquid chromatography, we analyzed tears from 50 patients with Graves' ophthalmopathy and 20 controls. With this technique, tear constituents are separated according to size; a normal tear protein profile consists of five peaks. An increase in one or more peaks was observed in 14 patients (28%) and in none of the controls. No decreased values were observed. No relation was observed between abnormalities of tear composition and the clinical NO SPECS classification. There was a tendency for increased tear protein peaks in those patients with long-standing disease. Most patients with an increase in one or more tear protein levels had normal thyroid function after treatment for hyperthyroidism. Our findings suggested that the inflammatory process in the orbit occurring in Graves' ophthalmopathy also had an effect on the lacrimal gland, which was reflected in the composition of the tears.

Eyelid secretions and the prevention and production of disease.

Tears are necessary for the continued health of the ocular surface. Normal constituents include water, mucin, and lipids, electrolytes, non-electrolytes, and proteins. Lacrimal secretion is under cholinergic control and modulated by sympathetic adrenergic, peptidergic (VIP) and humoral influences; the meibomian glands are innervated, but the goblet cells are not. Retinoids are important for ocular health and prealbumin may be a carrier for vitamin A in the tears to supply corneal epithelium with its requirements. Changes in tear constituents may cause certain ocular disorders. In dry eyes increased osmolarity is thought to cause surface ocular damage but the presence of granulocytes and inflammatory mediators such as prostaglandins and super-oxide may contribute to inflammatory events in this and other external diseases.

The Influence of Systemic Drugs on Tear Constituents

Tears of patients and laboratory animals on systemic medications have been analyzed for the presence and influence of these agents on tear constituents. Antibiotic penetration into tears, drugs stimulating or retarding lacrimation, and effects on tear electrolytes, lysozyme, and immunoglobulins are reviewed from the literature. Important applications to clinical practice such as contact lens wear, general anesthesia, eye infections, and epiphora or dry eye symptoms are discussed.