Analysis of tear fluid proteins in insulin-dependent diabetes mellitus

Differences in aqueous humor protein profiles in patients with proliferative diabetic retinopathy before and after conbercept treatment

To investigate the changes in aqueous humor (AH) protein profiles before and after intravitreal conbercept (IVC) treatment in proliferative diabetic retinopathy (PDR) patients. Ten PDR patients provided 20 samples of AH before (pre group) and after (post group) IVC treatment. Liquid chromatography-tandem mass spectrometry was performed to identify proteins. Bioinformatics analysis was used to explore the functional relevance of differentially expressed proteins (DEPs) and hub proteins. Parallel reaction monitoring (PRM) method was used to verify the hub proteins in another 8 samples of AH before and after IVC treatment in 4 PDR patients. A total of 30 DEPs were identified, consisting of 14 downregulated proteins and 16 upregulated proteins. Bioinformatics analysis indicated that DEPs mostly involved in neutrophil degranulation, antioxidant activity, secretory granule lumen, cytoplasmic vesicle lumen, vesicle lumen, and fluid shear stress. HP, VEGFA, CTSD, and LYZ were identified as hub proteins, among which HP and CTSD were verified by PRM. In addition to decreasing the intravitreal vascular endothelial growth factor level, IVC may alter the AH protein profile in PDR patients, especially HP and CTSD, with the DEPs involved in neutrophil degranulation, antioxidant activity, secretory granule lumen, cytoplasmic vesicle lumen, vesicle lumen, and fluid shear stress. SIGNIFICANCE: Patients with proliferative diabetic retinopathy (PDR) regularly receive intravitreal conbercept treatment these days. The effect of this treatment has been determined by previous studies. However, the mechanism of IVC in PDR is not eventually determined. No studies have compared the aqueous humor (AH) protein profile before and after IVC treatment in the same patient. This is a topic deserving of further exploration. A proteomic method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was utilized in this study to analyze and assess the AH samples to explore the mechanism underlying the effects of IVC treatment on PDR.

A Meta-Analysis of Wearable Contact Lenses for Medical Applications: Role of Electrospun Fiber for Drug Delivery

In recent years, wearable contact lenses for medical applications have attracted significant attention, as they enable continuous real-time recording of physiological information via active and noninvasive measurements. These devices play a vital role in continuous monitoring of intraocular pressure (IOP), noninvasive glucose monitoring in diabetes patients, drug delivery for the treatment of ocular illnesses, and colorblindness treatment. In specific, this class of medical devices is rapidly advancing in the area of drug loading and ocular drug release through incorporation of electrospun fibers. The electrospun fiber matrices offer a high surface area, controlled morphology, wettability, biocompatibility, and tunable porosity, which are highly desirable for controlled drug release. This article provides an overview of the advances of contact lens devices in medical applications with a focus on four main applications of these soft wearable devices: (i) IOP measurement and monitoring, (ii) glucose detection, (iii) ocular drug delivery, and (iv) colorblindness treatment. For each category and application, significant challenges and shortcomings of the current devices are thoroughly discussed, and new areas of opportunity are suggested. We also emphasize the role of electrospun fibers, their fabrication methods along with their characteristics, and the integration of diverse fiber types within the structure of the wearable contact lenses for efficient drug loading, in addition to controlled and sustained drug release. This review article also presents relevant statistics on the evolution of medical contact lenses over the last two decades, their strengths, and the future avenues for making the essential transition from clinical trials to real-world applications.

Human tear fluid analysis for clinical applications: progress and prospects

Introduction: Human blood and saliva are increasingly under investigation for the detection of biomarkers for early diagnosis of non-communicable (e.g.cancers) and communicable diseases like COVID-19. Exploring the potential application of human tears, an easily accessible body fluid, for the diagnosis of various diseases is the need of the hour.Areas covered: This review deals with a comprehensive account of applications of tear analysis using different techniques, their comparison and overall progress achieved till now. The techniques used for tear fluid analysis are HPLC/UPLC/SDS-PAGE, CE, etc., together with ELISA, Mass Spectrometry, etc. But, with advances in instrumentation and data processing methods, it has become easy to couple the various separation methods with highly sensitive optical techniques for the analysis of body fluids.Expert opinion: Tear analysis can provide valuable information about the health condition of the eyes since it contains several molecular constituents, and their relative concentrations may alter under abnormal conditions. Tear analysis has the advantage that it is totally non-invasive. This study recommends tear fluid as a reliable clinical sample to be probed by highly sensitive optical techniques to diagnose different health conditions, with special emphasis on eye diseases.

Lactoferrin Concentration in Human Tears and Ocular Diseases: A Meta-Analysis

Purpose

To evaluate the potential of lactoferrin (Lf) as a diagnostic biomarker for ocular diseases using a meta-analytic approach.

Methods

All original studies reporting an estimate of the average Lf concentration in healthy subjects and those affected by ocular diseases were searched up to March 2020. The DerSimonian and Laird method was used to calculate the random effects pooled mean difference and the corresponding 95% confidence interval (CI) in Lf concentration between healthy subjects and those affected by dry eye (DE), Sjögren syndrome (SS), and diabetic retinopathy, separately. The presence of between-study heterogeneity was evaluated using the Cochran's Q test and the I2 index. Stratified analyses were performed to assess potential sources of heterogeneity and influence and cumulative analyses to evaluate the robustness of the results obtained. Publication bias was also evaluated using funnel plot and the Egger's test.

Results

The pooled mean differences in Lf concentrations between healthy subjects and those with DE, Sjögren syndrome, and diabetic retinopathy were respectively 0.62 (95% CI, 0.35-0.89) for DE, 3.78 (95% CI, -6.64 to 14.17), and 0.19 (95% CI, -4.00 to 4.39). Regarding DE, the stratified analysis showed that geographical area (P value Q test < 0.0001) and sample size (P < 0.0005) were sources of heterogeneity. Moreover, no study substantially influenced the results obtained and the pooled mean difference became statistically significant after a sample size of 220. Publication bias may affect the results of DE.

Conclusions

The results of the current meta-analysis suggest that Lf level in tears is a good candidate as dry eye syndrome diagnostic biomarker.

Tears - more to them than meets the eye: why tears are a good source of biomarkers in Parkinson's disease

Tears are a known source of biomarkers for both ocular and systemic diseases with particular advantages; specifically, the noninvasiveness of sample collection and a unique and increasingly better-defined protein composition. Here, we discuss our rationale for use of tears for discovery of biomarkers for Parkinson's disease (PD). These reasons include literature supporting changes in tear flow and composition in PD, and the interconnections between the ocular surface system and neurons affected in PD. We highlight recent data on the identification of tear biomarkers including oligomeric α-synuclein, associated with neuronal degeneration in PD, in tears of PD patients and discuss possible sources for its release into tears. Challenges and next steps for advancing such biomarkers to clinical usage are highlighted.

Evaluation of tear and aqueous humor level, and genetic variants of connective tissue growth factor as biomarkers for early detection of pseudoexfoliation syndrome/glaucoma

Pseudoexfoliation syndrome (PEX) may lead to the development of pseudoexfoliative glaucoma (PEG), a potential cause of irreversible blindness, if left untreated. This type of glaucoma often presents with much higher intraocular pressure (IOP) values than observed in primary open angle glaucoma, and patients are often unaware of their condition. Therefore, early diagnosis is of utmost importance in PEX and PEG. Unfortunately, no valid objective biomarkers are available that can be used for this purpose. The excessive synthesis and deposition of elastic microfibrillar pseudoexfoliation material is observed in the pathophysiology of PEX, therefore, growth factors may play roles in this pathology. Thus, in this study, we sought to determine the roles of phenotypes and genotypes of connective tissue growth factor (CTGF) as objective biomarkers for early diagnosis of PEX and PEG. Thus, we investigated possible associations involving tear and aqueous humor CTGF concentrations and four single nucleotide polymorphisms (SNPs) of the CTGF gene in PEX and PEG. The study was designed as a 2-year case-control study in the Turkish population. Study population was composed of 214 patients with PEG, 214 patients with PEX, and 214 age-matched controls for CTGF SNP analysis. Tear fluid study group consisted of 78 patients with PEG, 77 patients with PEX, and 78 controls. Aqueous humor analysis included 8 patients with PEG, 17 patients with PEX, and 23 controls. Tear fluid was collected using Schirmer strips, and aqueous humor samples were taken during cataract surgery. CTGF concentration was determined by ELISA, and total protein concentration was determined by Bradford assay in tear and aqueous humor samples. PCR followed by restriction fragment length polymorphism analysis was used for genotyping of rs6918698 G/C and rs9399005 C/T, while real-time PCR was used for rs9402373 C/G and rs12526196 T/C. Intraocular pressure, visual field score, mean deviation, and pattern standard deviation parameters were also evaluated. CTGF concentration in tear fluid was significantly higher in PEG patients compared with controls (P = 0.001), while it was lower in PEX patients. Similarly, total protein concentration in tear fluid was significantly increased in PEG patients relative to PEX patients (P = 0.026) and controls (P = 0.004). CTGF concentration in aqueous humor did not differ markedly between the groups, whereas total protein was significantly higher in the PEG group compared with the PEX group (P = 0.012) and controls (P = 0.003). Receiver operating characteristic analysis revealed that total protein in aqueous humor was a robust classifier for evaluating the presence of PEG against controls (Area under the curve = 0.897, P = 0.001). The genotypes of the studied SNPs were not significantly correlated with CTGF concentration in aqueous humor or tear fluid, and did not exhibit significant association with PEG or PEX. In conclusion, this was the first study to investigate tear fluid CTGF concentration in PEX and PEG, which came out not to be a good classifier for PEG or PEX. Total protein level in tear fluid and CTGF SNPs also did not predict PEG or PEX status successfully.

Effects of Type 2 Diabetes Mellitus on Gene Expressions of Mouse Meibomian Glands

Purpose: Type 2 Diabetes mellitus (DM) is a major health problem and its ocular complications like orbital infections, cataract and diabetic retinopathy cause blindness. Meibomian gland (MG) dysfunction and dry eye disease are also important ocular complications of type 2 DM but not enough research has been conducted on these complications. Our hypothesis suggests type 2 DM can alter significant gene expressions of MG. In our study, MGs of leptin-deficient spontaneous diabetic and non-diabetic mice were extracted, and gene expression profiles were analyzed with microarray technology.Methods: Mice were divided into two groups; nine Lep ^b/ob spontaneous diabetic mice as type 2 DM group and nine non-diabetic Balb/c mice as controls. Blood glucose levels, tearfilm break-up time and fluorescein scores were measured in both two groups for 12 weeks. MGs were dissected and RNAs were isolated for microarray gene expression analysis. We filtered probes with standard deviation of more than 0.1 and we used 40452 of 45281 probes for processing. We performed fold change analysis and identified which genes are affected, and we analyzed the impact of genes on proteins, pathways and gene ontologies by using various databases.Results: We observed 172 up-regulated and 118 down-regulated genes in type 2 diabetic mice when compared to non-diabetic mice. Interestingly, expression of collagen type I, integrin beta-I binding protein-I, pyruvate dehydrogenase kinase, TNF receptor genes up-regulated with DM; on the other hand, IL-33, cholecystokinin, plasminogen activator, IL-1 and serine peptidase inhibitor genes down-regulated significantly. Also, we have seen a significant decrease in WNT signaling and pentose phosphate pathways-related genes.Conclusion: Our data show these changes in gene expression caused by endocrine and immune mechanisms of type 2 DM which result disrupted homeostasis of epithelial cells of MG. Increased expressions of apoptosis and inflammation-related genes and their effects on related pathways have proven that MGs were negatively affected by type-2 DM.

Tear biomarkers for keratoconus

Keratoconus is a progressive corneal thinning, ectatic condition, which affects vision. Recent advances in corneal topography measurements has helped advance proper diagnosis of this condition and increased research and clinical interests in the disease etiopathogenesis. Considerable progress has been achieved in understanding the progression of the disease and tear fluid has played a major role in the progress. This review discusses the importance of tear fluid as a source of biomarker for keratoconus and how advances in technology have helped map the complexity of tears and thereby molecular readouts of the disease. Expanding knowledge of the tear proteome, lipidome and metabolome opened up new avenues to study keratoconus and to identify probable prognostic or diagnostic biomarkers for the disease. A multidimensional approach of analyzing tear fluid of patients layering on proteomics, lipidomics and metabolomics is necessary in effectively decoding keratoconus and thereby identifying targets for its treatment.

The potentialities proteomic analysis of ocular fluids and tissues in different ophthamic disordeers

The article presents a review of current researches in using the proteomic analysis for different eye diseases diagnosis. Special attention is paid to tear fluid and aqueous humor mass-spectrometry results in primary open-angle glaucoma, and to the possibility of using this method for diagnosis at disease early stages.

Characteristics of exosomes andmicroparticles discovered in human tears

Exosomes represent a sort of extracellular vesicles, which transfer molecular signals in organism and possess markers of producing cells. Our study was aimed at search of exosomes in the tears of healthy humans, confirmation of their nature and examination of exosome morphological and molecular-biological characteristics. The tears (110-340 ml) were collected from 24 healthy donors (aged 46-60 years); individual probes were centrifuged at 20000 g for 15 min to pellet cell debris. The supernatants were examined in electron microscope using negative staining; and they were also used for isolation and purification of the exosomes by filtration (100 nm pore-size) and double ultracentrifugation (90 min at 100000 g, 4°C). The “pellets” were subjected to electron microscopy, immunolabeling. The RNA and DNA were isolated from the samples, and their sizes were evaluated by capillary electrophoresis, the concentration and localization of nucleic acids were determined. Sequencing of DNA was performed using MiSeq (“Illumina”, USA), data were analyzed using CLC GW 7.5 (“Qiagen”, USA). Sequences were mapped on human genome (hg19). Electron microscopy revealed in supernatants of the tears cell debris, spherical microparticles (20-40 nm), membrane vesicles and macromolecular aggregates. The “pellets” obtained after ultracentrifugation, contained microparticles (17%), spherical and cup-shaped EVs (40-100 nm, 83%), which were positive for CD63, CD9 and CD24 receptors (specific markers of exosomes). Our study showed presence of high amount of exosomes in human tears, and relation of the exosomes with RNA (size less than 200 nt) and DNA (size was 3-9 kb). Sequencing of the DNA showed that about 92% of the reads mapped to human genome.

Unraveling the molecular repertoire of tears as a source of biomarkers: beyond ocular diseases

Proteomics and metabolomics investigations of body fluids present several challenges for biomarker discovery of several diseases. The search for biomarkers is actually conducted in different body fluids, even if the ideal biomarker can be found in an easily accessible biological fluid, because, if validated, the biomarker could be sought in the healthy population. In this regard, tears could be considered an optimum material obtained by noninvasive procedures. In the past years, the scientific community has become more interested in the study of tears for the research of new biomarkers not only for ocular diseases. In this review, we provide a discussion on the current state of biomarkers research in tears and their relevance for clinical practice, and report the main results of clinical proteomics studies on systemic and eye diseases. We summarize the main methods for tear samples analyses and report recent advances in "omics" platforms for tears investigations. Moreover, we want to take stock of the emerging field of metabolomics and lipidomics as a new and integrated approach to study protein-metabolites interplay for biomarkers research, where tears represent a still unexplored and attractive field.

Patient acceptability of tear collection in the primary healthcare setting

Purpose

The primary healthcare setting is well placed for health screening. Tear fluid composition gives valuable information about the eye and systemic health, and there is now significant interest in the potential application of tears as a tool for health screening; however, the acceptability of tear collection in the primary healthcare setting as compared with other methods of human sample collection has not been previously addressed. The objective of this study was to evaluate the patient acceptability of tear collection in a primary healthcare setting.

Methods

This was a cross-sectional study on 383 adult patients seeking primary healthcare, who were not diabetic and were not attending for an eye-related complaint. Tear collection was done using Schirmer strips, and an interviewer-administered questionnaire was conducted to collate information on the pain score (0–10) of the Schirmer tear collection, as well as to score the pain associated with their previous experience of antecubital venous puncture and finger prick test.

Results

The pain score for Schirmer tear collection was significantly lower (p < 0.001) than antecubital venous puncture but higher (p < 0.001) than finger prick. The pain scores for all three procedures were significantly higher in participants of younger age, female gender, and higher education level. Among the participants, 70% did not mind their tears being collected to screen for eye problems, whereas only 38% did not mind this procedure being performed for general health screening. Nevertheless, 69% of the participants preferred tear to urine collection, and 74% of participants preferred tear to blood collection.

Conclusions

Tear collection using Schirmer strips is a highly acceptable form of investigation that has the potential for use in health screening in the primary healthcare setting. This study has implications on using tear collection as a method of ocular and systemic health screening in the primary healthcare setting.

Optimization of a fluorescence-based lysozyme activity assay for contact lens studies

PURPOSE

To optimize a fluorescence-based lysozyme activity assay to investigate the conformational state of lysozyme in solution and to determine the impact of extraction and evaporation procedures and the possible interference of contact lens materials on lysozyme activity.

METHODS

The fluorescence-based lysozyme activity assay, Enzchek (Molecular Probes Inc, Eugene, OR) which utilizes fluorescently quenched Micrococcus lysodeikticus, was compared to the gold standard, classical lysozyme turbidity assay, using four differently concentrated lysozyme samples (20, 10, 5.0 and 2.0 ng/µL). Furthermore, six differently concentrated lysozyme samples (2.0, 1.0, 0.5, 0.25, 0.125 and 0.01 µg/µL) were quantified using the fluorescence-based assay in the presence of extraction solvents consisting of 0.2% and 0.02% trifluroacetic acid/acetonitrile and following evaporation procedures.

RESULTS

A standard curve was generated by the fluorescence-based assay ranging from 2 to 150 ng. The total active lysozyme quantified in the four lysozyme samples was not significantly different between the two assays (p > 0.05) and the concordance correlation coefficient was determined to be 0.995. However an average discrepancy between the two assays was found to be 0.474 ng, with the turbidity assay typically reporting higher active lysozyme measurements. The sensitivity of the fluorescence-based assay was higher than the classical turbidity assay when quantifying 20 ng or less active lysozyme. Following the extraction and evaporation procedures and the addition of lens extracts, the total active lysozyme recovered was 95% or greater.

CONCLUSIONS

In comparison to the classical turbidity assay, the fluorescence-based assay is a very sensitive method, making it a favorable technique, particularly when studying contact lens materials that deposit relatively low levels of lysozyme.

Tear analysis in ocular surface diseases

The thin layer of tears covering the ocular surface are a complex body fluid containing thousands of molecules of varied form and function of several origins. In this review, we have discussed some key issues in the analysis of tears in the context of understanding and diagnosing eye disease using current technologies of proteomics and metabolomics, and for their potential for clinical application. In the last several years, advances in proteomics/metabolomics/lipidomics technologies have greatly expanded our knowledge of the chemical composition of tear fluid. The quickened pace of studies has shown that tears as a complex extra-cellular fluid of the ocular surface contains a great deal of molecular information useful for the diagnosis, prognosis, and treatment of ocular surface diseases that has the ability to addresses the emphasis on personalized medicine and biomarkers of disease. Future research directions will likely include (1) standardize tear collection, storage, extraction, and sample preparation; (2) quantitative proteomic analysis of tear proteins using multiple reaction monitoring (MRM)-based mass spectrometry; (3) population based studies of human tear proteomics/metabolomics; (4) tear proteomics/metabolomics for systemic diseases; and (5) functional studies of tear proteins.

Diabetes and contact lens wear

The literature suggests that diabetic patients may have altered tear chemistry and tear secretion as well as structural and functional changes to the corneal epithelium, endothelium and nerves. These factors, together with a reported increased incidence of corneal infection, suggest that diabetic patients may be particularly susceptible to developing ocular complications during contact lens wear. Reports of contact lens-induced complications in diabetic patients do exist, although a number of these reports concern patients with advanced diabetic eye disease using lenses on an extended wear basis. Over the past decade or so, there have been published studies documenting the response of the diabetic eye to more modern contact lens modalities. The results of these studies suggest that contact lenses can be a viable mode of refractive correction for diabetic patients. Furthermore, new research suggests that the measurement of tear glucose concentration could, in future, be used to monitor metabolic control non-invasively in diabetic patients. This could be carried out using contact lenses manufactured from hydrogel polymers embedded with glucose-sensing agents or nanoscale digital electronic technology. The purpose of this paper is to review the literature on the anterior ocular manifestations of diabetes, particularly that pertaining to contact lens wear.

Tearful relationships? Sex, hormones, the lacrimal gland, and aqueous-deficient dry eye

Sex and the endocrine system exert a significant influence on the physiology and pathophysiology of the lacrimal gland. The purpose of this article is to briefly review the nature and magnitude of these interactions between sex, hormones and lacrimal tissue, and to address how they may relate to the pathogenesis of aqueous-deficient dry eye. Towards this end, this article has a 3-fold approach: first, to summarize the influence of androgens, estrogens, glucocorticoids, mineralocorticoids, retinoic acid, prolactin, alpha-melanocyte stimulating hormone, adrenocorticotropic hormone, luteinizing hormone, follicle-stimulating hormone, growth hormone, thyroid-stimulating hormone, arginine vasopressin, oxytocin, thyroxine, parathyroid hormone, insulin, glucagon, melatonin, human chorionic gonadotropin and cholecystokinin on the structure and function of the lacrimal gland; second, to discuss the mechanism of action of each hormone on lacrimal tissue; and third, to discuss the clinical relevance of the endocrine-lacrimal gland interrelationship, with a particular focus on each hormone's role (i.e. if relevant) in the development of aqueous-tear deficiency.

Effects of multipurpose contact lens solutions on the protein composition of the tear film

OBJECTIVES

To analyze the influence of multipurpose contact lens cleaning solutions on tear proteins. Changes in tear film protein profiles of contact lens wearers who used several marketed brands of multipurpose contact lens care solutions, were assessed by ProteinChip analysis.

METHODS

Three studies were conducted. Study I was a comparison of Complete and OptiFree multipurpose solutions. Study II was a study with Complete Moisture Plus solution, Study II was a comparison of Renu and Solocare contact lens solutions. Wearers of soft contact lenses were assigned to use the contact lens care solutions for 4 weeks. Non-contact lens wearing patients were used as controls. Tear samples of each participant were analyzed with the ProteinChip (SELDI-TOF) system. Multivariate statistical analysis and artificial neural networks were used to determine the tear protein profiles of each study group.

RESULTS

Before starting the use of the solutions, the tear protein composition in all contact lens wearers deviated from the tear composition of the non-contact lens wearing controls. After 4 weeks of using the different care regimens, the tear protein composition of the patients using Complete or Complete Moisture Plus solutions tended to move toward that of the non-contact lens wearing controls. The tear protein composition of patients using the OptiFree, Renu or Solocare solutions did not undergo a measureable change in the protein level.

CONCLUSIONS

The ProteinChip system can analyze protein profiles for large-scale applications as in clinical studies. Two multipurpose solutions, Complete and Complete Moisture Plus, demonstrated a beneficial effect on the tear proteins in contact lens wearers.

Étude des atteintes de la surface oculaire chez les patients diabétiques

INTRODUCTION

Diabetes mellitus leads to microvascular complications and altered basement membranes, which are partly responsible for ocular complications. Corneal nerve impairment is involved in ocular surface disease as well. We examined the possible relation between ocular surface signs and retinal or neuronal degenerative complications due to diabetes.

PATIENTS AND METHODS

Diabetics and control subjects were compared for corneal sensitivity and tear function parameters such as the Schirmer test, tear film break-up time (BUT), and fluorescein and lissamine green stainings. The relation of the duration of the disease, the stage of retinopathy, metabolic control (HbA1c), and diabetic peripheral neuropathy with ocular surface disorders were noted.

RESULTS

Twelve healthy patients were compared to 48 diabetics. The Schirmer test value, BUT, and fluorescein and lissamine green impregnations were significantly modified in diabetics compared to controls (p<0.0001), with no relation to the duration of the disease or metabolic control. The mean corneal sensitivity was significantly lower in diabetic patients (p<0.01), diabetics with peripheral neuropathy (p=0.00008), and diabetics with preproliferative retinopathy (p=0.0003). Tear function parameters were more frequently altered in patients presenting preproliferative retinopathy and peripheral neuropathy (p<0.001).

CONCLUSIONS

Diabetes can lead to ocular surface impairments with qualitative and quantitative tear disorders, all of which seem to evolve in close relation with retinopathy and peripheral neuropathy. These lacrymal and corneoconjunctival abnormalities, even if not currently mentioned by diabetic patients, can result in severe neurotrophic complications.

High performance liquid chromatography analysis of tear protein patterns in diabetic and non-diabetic dry-eye patients

PURPOSE

To analyze and compare the high performance liquid chromatography (HPLC) runs of tear proteins from diabetic (DIDRY) and non-diabetic (DRY) dry-eye patients, and healthy subjects (CTRL). The patterns were analyzed using multivariate statistical methods.

METHODS

Tears (total 56 eyes: CTRL: n=16, DIDRY: n=21, and DRY: n=19) were analyzed by HPLC, using a size-exclusion column with an eluent of 0.5 M sodium phosphate buffer. The patients were primarily grouped according to the results of the basic secretory test (BST) in combination with subjective symptoms such as burning, foreign body sensations, tearing, and "dryness" of the eyes. Patients with BST values < or = 10 mm/5 min plus two subjective symptoms were grouped as dry-eye patients. Before statistical analysis, each HPLC run was quantitatively analyzed using ScanPacK software (ScanPacK, Göttingen, Germany), and a data set was created from each HPLC run. The data were then analyzed by multivariate analysis of discriminance.

RESULTS

The HPLC patterns of CTRL, DIDRY and DRY were significantly different (Wilks' lambda: 0.0209; p<0.01). The area of the sigA peak was significantly smaller (p<0.05) in dry-eye tears than controls. There was a good correlation between the extent of separation in the multivariate analysis and the BST value (r = -0.71). Classification of all samples resulted in 98% correct assignments.

CONCLUSIONS

The analysis of HPLC patterns and subsequent statistical evaluation are useful for the detection of dry eyes. The HPLC method and the statistical routines described allow a shorter analysis time than electrophoresis. HPLC analysis in combination with statistical analysis can be used as a diagnostic tool for the detection of dry eyes, and also improves the quality of analysis of disease-associated tear proteins in clinical research.

Is there a correlation between the severity of diabetic retinopathy and keratoconjunctivitis sicca?

PURPOSE

Patients with diabetic retinopathy (DRP) seldom report symptoms of ocular surface irritation, but evaluations of dryness are pathologic. This study was designed to evaluate the correlation between the severity of DRP and dry eyes.

METHODS

We included 144 eyes of 72 patients. Severity of retinopathy was graded according to the Early Treatment Diabetic Retinopathy Study. The examinations for dry eyes included Schirmer's test, break-up time, lipid layer thickness, fluorescein and rose bengal staining of the cornea, impression cytology, and a questionnaire. A sicca severity score was calculated using a point system of the results of these tests. Patients were divided into three groups: postpanretinal laser coagulation (PPL), postcentral laser coagulation (PCL), and those with no laser treatment (0-L). For statistics, we used the correlation coefficient to determine relationships and the unpaired Student t test for statistical difference.

RESULTS

The correlation (c) of keratoconjunctivitis sicca (KCS) and DRP after laser treatment was c = 0.24 and after central laser treatment was c = 0.22; the correlation without laser treatment was 0.54. The best correlation is 1 or -1, the worst was 0. The score of those patients with mild to moderate retinopathy was compared to that of patients with severe to proliferative disease. There was a significant statistical difference in the sicca severity score between both groups, (p < 0.006. Student t test).

CONCLUSION

KCS represents another manifestation of diabetes mellitus and its severity--measured by a many-membered score--correlates with the severity of the DRP.