Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tears”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2005

Phospholipid transfer protein is present in human tear fluid.

The human tear fluid film consists of a superficial lipid layer, an aqueous middle layer, and a hydrated mucin layer located next to the corneal epithelium. The superficial lipid layer protects the eye from drying and is composed of polar and neutral lipids provided by the meibomian glands. Excess accumulation of lipids in the tear film may lead to drying of the corneal epithelium. In the circulation, phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) mediate lipid transfers. To gain insight into the formation of tear film, we investigated whether PLTP and CETP are present in human tear fluid. Tear fluid samples were collected with microcapillaries. The presence of PLTP and CETP was studied in tear fluid by Western blotting, and the PLTP concentration was determined by ELISA. The activities of the enzymes were determined by specific lipid transfer assays. Size-exclusion and heparin-affinity chromatography assessed the molecular form of PLTP. PLTP is present in tear fluid, whereas CETP is not. Quantitative assessment of PLTP by ELISA indicated that the PLTP concentration in tear fluid, 10.9 +/- 2.4 microg/mL, is about 2-fold higher than that in human plasma. PLTP-facilitated phospholipid transfer activity in tears, 15.1 +/- 1.8 micromol mL(-)(1) h(-)(1), was also significantly higher than that measured in plasma. Inactivation of PLTP by heat treatment (+58 degrees C, 60 min) or immunoinhibition abolished the phospholipid transfer activity in tear fluid. Size-exclusion chromatography of tear fluid indicated that PLTP eluted in a position corresponding to a size of 160-170 kDa. Tear fluid PLTP was quantitatively bound to Heparin-Sepharose and could be eluted as a single peak by 0.5 M NaCl. These data indicate that human tear fluid contains catalytically active PLTP protein, which resembles the active form of PLTP present in plasma. The results suggest that PLTP may play a role in the formation of the tear film by supporting phospholipid transfer.

Apolipoprotein A-I↗
PubMed1998

Effect of storage on protein concentration of tear samples.

PURPOSE: To determine the effect of storage on protein concentration of tear samples stored at room temperature (RT), 4 degrees C, -20 degrees C and -70 degrees C. METHODS: Total protein concentration of closed, open (basal tears) and reflex tears (stimulated tears) was measured by modified Bradford's method. SDS-PAGE gel electrophoresis was used to determine the intensity of protein bands. Quantity of various tear proteins was determined by HPLC analysis. RESULTS: Compared to control samples (0 h) protein concentrations decreased significantly in tear samples stored beyond 4 h (for closed) and 8 h (for open and reflex) at RT. However, no significant change in protein concentrations was observed in closed and reflex tears when stored up to 1 week at 4 degrees C, up to 2 months at -20 degrees C; and up to 4 months at -70 degrees C. Multiple freeze-thaw procedures (6 x per day at 2 h intervals) resulted in 8% decrease (at -20 degrees C) and 10% decrease (at -70 degrees C) of protein concentrations in closed eye tears. SDS-PAGE analysis of tear samples stored at -20 degrees C and -70 degrees C for 4 months greatly affected the intensity of the protein bands. HPLC analysis of tear samples stored at these conditions showed the significant reduction in the peak corresponding to secretory IgA in closed eye tears and a split in the peak corresponding to lysozyme in case of reflex tears. CONCLUSIONS: Reduction in the total protein concentration, intensity of the protein bands as well as changes in the quantity of tear proteins were observed in the tear samples stored for longer duration of time at various temperatures.

Chromatography, High Pressure Liquid↗
PubMed2005

Onset and pattern of tear secretions in full-term neonates.

PURPOSE: Serial evaluations of total, basal and emotional tear secretion in full-term normal neonates to determine the time after birth when these parameters attain normal adult values. METHOD: Both eyes of 102 full-term normal neonates were prospectively evaluated for tear secretions in the Department of Ophthalmology, over a period of one year. Serial recording of the Schirmer I test (total tear secretions), Basal Secretion Test, and Schirmer II test (emotional tears) was done, the first one being within 6 hours of birth. All the tests were repeated in each infant until normal adult values for each test were obtained. RESULTS: The average values of the Schirmer I test, Basal Secretion Test and Schirmer II test at birth were 23.2 (+/- 3.96) mm, 6.2 (+/- 2.15) mm and 19.2 (+/- 4.94) mm, respectively. A statistically significant correlation of birth weight but not of gestational age was found with basal secretions (p = 0.004) as well as with emotional tears (Schirmer II test, p = 0.010). At birth, 98% of infants had total tear secretion, 3.9% had basal tear secretion and 2.9% had emotional tear secretion comparable to normal adult values. All the parameters of tear secretions increased with time, so that 100% of infants had total tear secretion comparable to normal adult values within 12 hours of birth. The basal secretions took three weeks and emotional tears took four weeks to attain normal adult values in all the neonates. CONCLUSION: Total tear secretions were the earliest to reach normal adult values, followed by basal secretions and, lastly, emotional tears. Reduced basal tears at birth may predispose neonates to corneal drying during prolonged ocular examinations such as indirect ophthalmoscopy and procedures under general anesthesia.

Analysis of Variance↗
PubMed2003

Reflex tear ascorbate in Hong Kong Chinese subjects: method comparison and biological variation.

BACKGROUND: Tear ascorbate is important for corneal health. A rapid and simple method for measurement of ascorbate in tears is needed, and adequate knowledge of physiological variation of tear ascorbate is important to facilitate comparative studies of the effect of, for example, contact lens wear and environmental conditions and stresses. However, there are currently no data on physiological variation of tear ascorbate. This study validated a simple and speedy method for tear ascorbate and investigated between-eye and between-day variation in tear ascorbate in healthy young adults. METHODS: Yawn-induced reflex tears were collected from 32 healthy Hong Kong Chinese subjects and measured by both high-performance liquid chromatography (HPLC) and by an enzyme-linked colorimetric method known as FRASC (total ferric reducing (antioxidant) activity and ascorbate concentration measurement). For between-eye variation, yawn reflex tears were collected from each eye of the same 32 healthy subjects, and ascorbate was measured using HPLC; in a separate experiment for between-day variation, tears were collected on two separate days from 14 subjects, and ascorbate was measured by FRASC. RESULTS: Both HPLC and FRASC showed high precision, and results obtained using FRASC were not statistically different from those using HPLC; mean +/- SD were, respectively, 18.5 +/- 4.4 microM and 18.5 +/- 4.8 microM for HPLC and FRASC methods (p = 0.943). No significant between-eye difference in tear ascorbate was found (p = 0.386), and no significant between-day variation was found overall: mean +/- SD ascorbate was 20.0 +/- 6.2 microM on day 1 and 19.3 +/- 6.8 microM on day 2 (p = 0.772). However, between-day variation was large in seven of 14 subjects. CONCLUSION: FRASC is an acceptable alternative to HPLC for measurement of tear ascorbate. Tears for ascorbate investigation can be collected from either eye or, if necessary, from both eyes and pooled. However, tear ascorbate may vary widely from day to day in the same individual. The reasons for this variation require further study but may relate to differences in ascorbate supply or demand within the precorneal tear layer.

Adult↗
PubMed2003

Fenestrations enhance tear mixing under silicone-hydrogel contact lenses.

PURPOSE: Extended wear of conventional hydrogel soft contact lenses (SCLs) is associated with adverse ocular responses. Some of these ocular events are thought to result from inadequate tear mixing in the postlens tear film (PoLTF). Therefore, strategies to increase tear mixing may improve the safety of extended-wear SCLs. Recently, it has been suggested that placing fenestrations in soft lenses increases tear mixing. In the present study, hydrodynamic modeling and tear-mixing measurements were used to explore the effects of fenestrations on tear exchange under an SCL. METHODS: Tear mixing, expressed as the time to deplete 95% of fluorescent dye from the PoTLF (T(95)), was measured in 20 subjects fitted with two pairs of silicone hydrogel SCLs. The lenses were identical except that one pair was fenestrated (F) with 40 holes each 100 microm in diameter. The effect of fenestrations on improving tear mixing is explained and enhancement of tear mixing is predicted, with the use of hydrodynamic modeling. RESULTS: T(95) estimates were significantly lower (P < 0.001) in the F (mean T(95) = 18.3 minutes) lenses compared with the standard unfenestrated (S-uF) (mean T(95) = 22.6 minutes) lenses (DeltaT(95) = 4.3 minutes, 95% CI = 2.5-6.2) and were in general agreement with the proposed mixing model. Optimization of tear mixing can be achieved by selectively placing fenestrations in the pooling regions before the thinnest regions. The model predictions were sensitive to the distribution of tear-film thickness under the lens. CONCLUSIONS: Fenestrations improve tear-mixing efficiency. Accurate prediction of the effects of lens parameters on tear mixing, however, demands quantitative measurement of the postlens distribution of tear-film thickness.

Adolescent↗
PubMed2006

Rotator cuff tears: assessment with MR arthrography in 275 patients with arthroscopic correlation.

We assessed the diagnostic performance of magnetic resonance (MR) arthrography in the diagnosis of articular-sided partial-thickness and full-thickness rotator cuff tears in a large symptomatic population. MR arthrograms obtained in 275 patients including a study group of 139 patients with rotator cuff tears proved by arthroscopy and a control group of 136 patients with arthroscopically intact rotator cuff tendons were reviewed in random order. MR imaging was performed on a 1.0 T system (Magnetom Expert, Siemens). MR arthrograms were analyzed by two radiologists in consensus for articular-sided partial-thickness and full-thickness tears of the supraspinatus, infraspinatus, and subscapularis tendons. At arthroscopy, 197 rotator cuff tears were diagnosed, including 105 partial-thickness (93 supraspinatus, nine infraspinatus, three subscapularis) and 92 full-thickness (43 supraspinatus, 20 infraspinatus, 29 subscapularis) tendon tears. For full-thickness tears, sensitivity, specificity, and accuracy were 96%, 99%, and 98%, respectively, and for partial tears 80%, 97%, and 95%, respectively. False negative and positive assessments in the diagnosis of articular-sided partial-thickness tears were predominantly [78% (35/45)] observed with small articular-sided (Ellman grade1) tendon tears. MR arthrography is highly accurate in the diagnosis of full-thickness rotator cuff tears and is accurate in the diagnosis of articular-sided partial-thickness tears. Limitations in the diagnosis of partial-thickness tears are mainly restricted to small articular-sided tears (Ellman grade 1) due to difficulties in differentiation between fiber tearing, tendinitis, synovitic changes, and superficial fraying at tendon margins.

Adolescent↗
PubMed2005

Accuracy of office-based ultrasonography of the shoulder for the diagnosis of rotator cuff tears.

BACKGROUND: This prospective multi-institutional study was designed to define the accuracy of ultrasonography, when performed in an orthopaedic surgeon's office, for the diagnosis of rotator cuff tears. METHODS: An anatomic diagnosis and a treatment plan were made on the basis of office-based shoulder ultrasonography, physical examination, and radiographs for ninety-eight patients (ninety-nine shoulders) with a clinical diagnosis of a rotator-cuff-related problem. The results of the ultrasonographic studies were then compared with the results of magnetic resonance imaging and the operative findings. RESULTS: Office-based ultrasonography led to the correct diagnosis for thirty-seven (88%) of forty-two shoulders with a full-thickness rotator cuff tear or both full and partial-thickness tears, twenty-six (70%) of thirty-seven shoulders with a partial-thickness rotator cuff tear only, and sixteen (80%) of twenty shoulders with normal tendons. In no case was the surgical approach (open or arthroscopic) that had been planned on the basis of the ultrasonography altered by the operative findings, but the operative finding of a full-thickness tear resulted in an arthroscopic cuff repair in four shoulders. Magnetic resonance imaging led to the correct diagnosis for forty (95%) of forty-two shoulders with a full-thickness rotator cuff tear or both full and partial-thickness rotator cuff tears, twenty-seven (73%) of thirty-seven shoulders with only a partial-thickness tear, and fifteen (75%) of twenty shoulders with normal tendons. There were no significant differences between magnetic resonance imaging and ultrasonography with regard to the correct identification of a full-thickness tear or its size. The sensitivity of ultrasonography for detecting tear size in the anterior-posterior dimension was 86% (95% confidence interval, 71% to 95%), and that of magnetic resonance imaging was 93% (95% confidence interval, 81% to 99%) (p = 0.26). The sensitivity of ultrasonography for detecting tear size in the medial-lateral dimension was 83% (95% confidence interval, 69% to 93%), and that of magnetic resonance imaging was 88% (95% confidence interval, 74% to 96%) (p = 0.41). CONCLUSIONS: A well-trained office staff and an experienced orthopaedic surgeon can effectively utilize ultrasonography, in conjunction with clinical examination and a review of shoulder radiographs, to accurately diagnose the extent of rotator cuff tears in patients suspected of having such tears. Errors in diagnosis made on the basis of ultrasonography most often consist of an inability to distinguish between partial and full-thickness tears that are approximately 1 cm in size. In this study, such errors did not significantly affect the planned surgical approach.

Arthroscopy↗
PubMed1995

MR diagnosis of rotator cuff tears of the shoulder: value of using T2-weighted fat-saturated images.

OBJECTIVE: The purpose of this study was to compare the use of fat-saturated T2-weighted spin-echo MR imaging with that of conventional T2-weighted spin-echo MR imaging to detect full- and partial-thickness tears of the rotator cuff of the shoulder, using arthroscopy as the standard for the diagnosis. SUBJECTS AND METHODS: Forty-nine consecutive patients with shoulder pain who had both MR imaging and arthroscopy of their affected shoulders were studied. The study group consisted of 10 patients with full-thickness tears of the rotator cuff, 20 with partial-thickness tears of the rotator cuff, and 19 with intact rotator cuff tendons proved arthroscopically. All patients had T1-weighted, conventional T2-weighted, and fat-saturated T2-weighted MR images obtained in a plane slightly oblique to the coronal plane along the long axis of the supraspinous tendon. The images were divided into two sets, one including both T1-weighted and conventional T2-weighted images, the other including T1-weighted and fat-saturated T2-weighted images. Two musculoskeletal radiologists reviewed each set of MR images in a blinded fashion. The reviewers were asked to decide whether the rotator cuff showed a full-thickness tear, a partial-thickness tear, or no tear on each set of images. In the case of partial-thickness tears, the reviewers were asked to indicate which surface (bursal or joint) of the rotator cuff was affected. These data were correlated with the arthroscopic findings and with each other using McNemar and kappa analysis. RESULTS: Detection of full-thickness tears was excellent for both reviewers using either imaging technique. However, when the fat-saturated technique was used, the sensitivity increased significantly, from 80% to 100%. Detection of partial-thickness tears was poor with conventional spin-echo MR imaging (15%). Although significantly improved when fat saturation was used (35%), detection rates were still lower than rates reported in the literature. Identification of the torn surface of the rotator cuff was correct in 50% of cases in which partial-thickness tears were successfully identified. Fat saturation decreased the specificity of identification of both partial and full-thickness tears of the rotator cuff but significantly increased the specificity with which intact rotator cuffs were identified. CONCLUSION: Use of the fat-saturation technique improved detection of both full-thickness and partial-thickness tears of the rotator cuff on MR images compared with standard spin-echo imaging techniques. Despite this improvement, detection of partial-thickness tears was poor with both techniques. Furthermore, correct identification of which surface of the rotator cuff was torn in patients with partial tears was nearly random.

Adult↗
PubMed1997

Using MR imaging to diagnose partial tears of the anterior cruciate ligament: value of axial images.

OBJECTIVE: The purpose of this study was to determine the usefulness of axial MR imaging for diagnosing partial anterior cruciate ligament (ACL) tears and to determine if patients could be categorized as having stable or unstable partial ACL tears on the basis of criteria of axial MR imaging. MATERIALS AND METHODS: We reviewed 238 patients who, over a 2-year period, underwent both MR imaging of the knee and arthroscopic evaluation of the ACL. According to arthroscopic examination, these patients had 143 normal ACLs, 67 complete ACL tears, and 28 partial tears. The 28 partial tears included 20 stable tears (no ACL deficiency) and eight unstable partial tears having ACL deficiency or requiring ACL reconstructive surgery. The axial MR images were retrospectively reviewed by two interpreters who were unaware of the arthroscopic findings, and decisions were reached by consensus. The ACL was classified according to its axial configuration and continuity. RESULTS: By axial MR imaging criteria, we found 109 elliptical ACLs, 45 attenuated ACLs, three ACLs with increased intrasubstance signal intensity, six isolated ACL bundle signs, 19 ACLs that could not be visualized, and 56 cloudlike mass signs. Arthroscopically normal ACLs and stable partial tears were difficult to distinguish reliably on axial MR images. Unstable partial ACL tears could not be distinguished from complete ACL tears. However, using axial MR imaging, our observers were able to segregate stable ACLs (normal ligaments and stable partial tears) from unstable ACLs (unstable partial tears and complete tears) with 100% sensitivity and 96% specificity. CONCLUSION: Axial MR imaging of the ACL may provide important diagnostic information for patients who have ACL injury. On axial MR images, stable ACLs were elliptical, attenuated, or showed as areas of increased intrasubstance signal intensity. At arthroscopy, attenuated ACLs represented normal ACLs (76%) and stable partial tears (24%). On axial MR images, the configurations that indicated unstable ligaments were isolated ACL bundle, nonvisualized ACL, and cloudlike mass.

Adult↗
PubMed2005

Detection and measurement of rotator cuff tears with sonography: analysis of diagnostic errors.

OBJECTIVE: The purpose of this study was to analyze the causes of errors in the detection and measurement of rotator cuff tears in our patient population. SUBJECTS AND METHODS: Seventy-one consecutive patients with shoulder pain who were prospectively studied with sonography had subsequent arthroscopy that showed a full-thickness or partial-thickness tear or intact cuff. For sonography and arthroscopy, the length or degree of retraction and width of a tear, when present, was recorded. When there were discrepant findings, representative images were jointly evaluated by the radiologist and orthopedic surgeon to determine the cause of the error. RESULTS: Fifteen detection errors were found, including five misses (three < 5-mm subscapularis and two small partial-thickness tears), four errors inherent with the test (distinguishing large bursal side or extensive partial-thickness from full-thickness tears and tendinopathy from partial-thickness tears), three errors of an unknown cause, two due to misinterpretation, and one error inherent with the patient. Seventeen measurement errors occurred with full-thickness tears, 15 of those in patients with large or massive tears. Bursal thickening (n = 4), non-visualization of the torn tendon end (n = 2), nonretracted tear (n = 2), and complex tear (n = 1) contributed to the errors. Eight measurement errors occurred with partial-thickness tears. Difficulty distinguishing tendinopathy from partial-thickness tears (n = 3) and complex tears (n = 3) accounted for six errors. CONCLUSION: Although infrequent, detection errors were due to limitations inherent with the test or misses. Limitations inherent with the patient and misinterpretation of the findings were rare. Most measurement errors occurred in patients with large or massive cuff tears.

Arthroscopy↗
PubMed2004

Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.

BACKGROUND: Although many investigators have evaluated the accuracy of ultrasonography and magnetic resonance imaging for the detection of full and partial-thickness rotator cuff tears, few have directly compared the two tests. The purpose of our study was to compare the accuracy of the two tests for detection and measurement of the size of rotator cuff tears, with arthroscopic findings used as the standard. METHODS: One hundred and twenty-four consecutive patients with shoulder pain were prospectively studied with ultrasonography and magnetic resonance imaging. Seventy-one had subsequent arthroscopy, and they formed the study group. The arthroscopic diagnosis was a full-thickness tear in forty-six patients, a partial-thickness tear in nineteen, and no tear in six. The presence or absence of a full or partial-thickness tear and the tear size as demonstrated by each imaging test and at the time of arthroscopy were recorded. The findings of the imaging tests and arthroscopy were then compared for each parameter. RESULTS: Ultrasonography correctly identified forty-five of the forty-six full-thickness tears and magnetic resonance imaging, all forty-six. Ultrasonography correctly identified thirteen of the nineteen partial-thickness rotator cuff tears and magnetic resonance imaging, twelve of the nineteen. The overall accuracy for both imaging tests was 87%. Ultrasonography correctly predicted the degree of retraction of 73% of the full-thickness tears and the length of 85% of the partial-thickness tears, and magnetic resonance imaging correctly predicted the retraction and length of 63% and 75%, respectively. Ultrasonography correctly predicted the width of 87% of the full-thickness tears and 54% of the partial-thickness tears, and magnetic resonance imaging correctly predicted the width of 80% and 75%, respectively. No significant differences between ultrasonography and magnetic resonance imaging were demonstrated (p > 0.05). CONCLUSIONS: Ultrasonography and magnetic resonance imaging had comparable accuracy for identifying and measuring the size of full-thickness and partial-thickness rotator cuff tears. When an investigator has comparable experience with both imaging tests, the decision regarding which test to perform for rotator cuff assessment does not need to be based on accuracy concerns. The choice can be based on other factors, such as the importance of ancillary clinical information (regarding lesions of the glenoid labrum, joint capsule, or surrounding muscle or bone), the presence of an implanted device, patient tolerance, and cost.

Adult↗
PubMed1995

Tear function index. A new measure of dry eye.

OBJECTIVE: To develop an efficient way to evaluate tear dynamics clinically. PARTICIPANTS: Three hundred fifty-two patients with dry eye, 64 of whom had Sjögren syndrome, and 55 normal subjects. DESIGN: Because various forces that affect tear drainage are reflected in the values of the Schirmer test with anesthesia and the tear clearance rate, we introduced a new measure of tear dynamics, the tear function index, which is the value obtained from dividing the value of the Schirmer test with anesthesia by the tear clearance rate. RESULTS: The tear function index was more specific (91.8%) and sensitive (78.9%) in diagnosing dry eye associated with Sjögren syndrome than was the Schirmer or tear clearance rate test alone. Tear function indexes below 96 were consistent with dry eye and those below 34 were seen primarily in patients with Sjögren syndrome. CONCLUSIONS: The tear function index offers a new method to evaluate tear production with the Schirmer test, introduces an extended way to measure tear flow combining with tear drainage, and gives a practical measure to diagnose dry eye.

Dry Eye Syndromes↗
PubMed1996

Analysis of human tear fluid components, inhibiting protein adhesion to plastic surfaces.

In a previous paper we reported the presence of components in human tear fluid that block the interaction of proteins with plastic surfaces, interfering with tear protein ELISA and proposed the term coating inhibiting activity. The purpose of the study presented here was to further analyse these components. Coating inhibitory activity in human reflex tears was analysed by lectin affinity chromatography, using the agarose bound lectin Artocarpus integrifolia agglutinin (Jacalin), gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), blotting and Jacalin staining. For coating inhibitory activity assay in experimental tear samples, the binding of the protein Avidin-conjugated horseradish peroxidase to the polystyrene surface of ELISA micro-titer plate wells, preincubated with the experimental tear samples was measured. In addition, tears were incubated with scrapings of the ELISA plates used in the assay and with six different types of contact lenses (two rigid gas permeable and four hydrogel soft contact lenses) for analysis of adsorbed components. Lectin affinity chromatography of tears yielded a Jacalin-binding and a non-Jacalin-binding preparation, both exhibiting coating inhibitory activity but representing chemically different preparations as observed by SDS-PAGE. After performing gel filtration, coating inhibitory activity eluted with similar retention in both preparations. In fractions exhibiting activity, tear proteins of low molecular weight (< 40 kDa) were detected. Among these, two Jacalin-binding glycoproteins were detected; a major component of approximately 28 kDa and a somewhat smaller minor component. All low molecular weight components were also detected on the scrapings, incubated with tears. The possibility that coating inhibitory activity in tears might reside in a component of larger molecular size can however not be excluded. The human tear proteins secretory Immunoglobulin A, lactoferrin and lysozyme are not involved in coating inhibition. On one of the two rigid gas permeable contact lenses incubated with the tears, the 28 kDa glycoprotein was detected. From the data obtained in our study we conclude that coating inhibitory activity in tears seems to be associated with multiple components of low molecular weight.

Adsorption↗
PubMed2002

The effect of sample treatment on separation profiles of tear fluid proteins: qualitative and semi-quantitative protein determination by an automated analysis system.

PURPOSE: Qualitative and quantitative determination of tear fluid components is of increasing interest in ophthalmology. Until now, for diagnosis and course control of some diseases of the anterior parts of the eye, different methods for tear fluid protein analysis are available. Results can be obtained by polyacrylamide gel electrophoresis (PAGE), immunochemistry, and high-performance liquid chromatography (HPLC). A new method for protein separation, identification and semi-quantitative determination on a chip-based micro-fluidic technique is used for the first time to investigate tear fluids. METHODS: Normal human reflex tears were obtained by stimulation with China mint oil and collected using glass capillary tubes. A lab-on-a-chip technology (developed by Agilent Technologies, Waldbronn, Germany, in co-operation with Caliper Technologies, Mountain View, California, USA) was used for separation and semi-quantitative determination of tear proteins. Tear fluid was separated on the Agilent 2100 Bioanalyzer in combination with the Protein 200 LabChip kit and the dedicated protein assay software. Time and temperature of the incubation with sample buffer were varied, and the influence of these parameters on protein separation profiles was studied. Tear proteins were also analysed by PAGE, and the results obtained by both methods were compared. RESULTS: The different proteins of tear fluid can be separated by the Agilent 2100 Bioanalyzer method in very short time. By this method, the molecular weight as well as the concentration of proteins can be determined. Data are automatically stored in digital format and can be retrieved and shared. Results of this technology were comparable with the protein pattern obtained by PAGE. It was confirmed by both methods that, depending on incubation time of tear fluid with sample buffer and on temperature, different protein pattern can be obtained from the tears of one specimen. CONCLUSION: Tear proteins - in contrast to serum or aqueous humour proteins - are very sensitive to changes in sample buffer temperature as well as incubation time with buffer. To obtain comparable results for tear fluid proteins, the sample buffer applied and the incubation time and temperature must be observed carefully. This can be demonstrated by both the new Agilent 2100 Bioanalyzer method and PAGE. These results are of importance when comparing tear fluid protein pattern for the diagnosis and course control of dry-eye syndrome and of other diseases of the anterior part of the eye.

Aqueous Humor↗
PubMed2005

Lipid tear deficiency in persistent dry eye after laser in situ keratomileusis and treatment results of new eye-warming device.

PURPOSE: To determine whether lipid tear deficiency is a significant pathogenic factor in persistent dry eyes after laser in situ keratomileusis (LASIK). SETTING: Ocular Surface Center, Miami, Florida, USA. METHODS: Thirty-four eyes of 17 patients (mean 46.35 years +/- 11 [SD]) complaining of persistent dryness more than 12 months after LASIK were prospectively studied by symptom scoring and kinetic analysis of tear interference image, tear breakup time, and fluorescein clearance test. Once patients had been clear of inflammation and treated for aqueous tear deficiency, lipid tear deficiency was further confirmed and treated with Eyefeel (Kao, Inc.), an eye-warming device, 4 times daily for 4 weeks. RESULTS: Sixteen patients were asymptomatic before LASIK but dryness persisted for 41 +/- 19.3 months. Delayed tear clearance was observed in 15 patients (88.2%) and floppy lids in 12 patients (70.5%). Aqueous tear deficiency was reconfirmed in 16 eyes (53.3%). After Eyefeel treatment, there was a subjective improvement of ocular surface diseases index from 60.6 +/- 10.6 to 25.8 +/- 18.5 (P = .0007). Tear breakup time was improved from 2.4 +/- 3.9 seconds to 7.9 +/- 3.6 seconds (P = .004). There was a tear interference pattern change from a vertical lipid tear deficiency to a horizontal normal in 7 eyes. There was a mean lipid spread time improvement from 1.3 +/- 0.4 sec to 0.8 +/- 0.4 sec (P = .001), and there was a mean lipid thickness improvement from 63.5 +/- 23 nm to 79.5 +/- 27 nm (P = .04). CONCLUSION: Persistent nature of dry eye after LASIK is attributed to in part to delayed tear clearance, undercorrected aqueous tear deficiency, and nonrecognized lipid tear deficiency.

Adult↗
PubMed2000

The role of tear physiology in ocular surface temperature.

PURPOSE: To determine whether the more rapid cooling of the tear film in dry eyes is related to other tear film parameters, a battery of tear physiology tests was performed on dry eye patients and control subjects. METHODS: Tear evaporation rate was measured with a modified Servomed (vapour pressure) evaporimeter and ocular temperature with an NEC San-ei 6T62 Thermo Tracer in 9 patients diagnosed as having dry eye and in 13 healthy control subjects. Variability in temperature across the ocular surface was described by the temperature variation factor (TVF). Lipid layer structure and tear film stability were assessed with the Keeler Tearscope and tear osmolality was measured by freezing point depression nanolitre osmometry. RESULTS: The data were explored by principal component analysis. The subjects with and without dry eye could be separated into two distinct groups entirely on the basis of their tear physiology. Dry eye patients exhibited higher tear evaporation rates, osmolalities and TVF, lower tear film stabilities and poorer-quality lipid layers than the control subjects. A significant linear relationship was found to exist between tear evaporation rate and TVF for all subjects (R2 = 0.242, p = 0.024). CONCLUSIONS: Rapid cooling of the tear film in dry eyes appears to be related to the reduced stability of the tears and the increased rate of evaporation. The higher latent heat of vaporisation, associated with the increased evaporation in dry eyes, may account for the increased rate of cooling of the tear film in this condition.

Adult↗
PubMed2003

Antioxidants in tears and plasma: Inter-relationships and effect of vitamin C supplementation.

PURPOSE: To investigate inter-relationships between total antioxidant capacity and ascorbate concentration in plasma and tears, and the effect of antioxidant supplementation with reference to these variables. METHODS: Twenty-one subjects were studied in this placebo-controlled, cross-over intervention trial. Fasting plasma and tear ascorbate concentrations and total antioxidant capacity (as Ferric Reducing/Antioxidant Power (FRAP)) were measured pre- and post-supplementation with vitamin C (1 g/day). RESULTS: Mean +/- SD ascorbate in tears and plasma at entry were 17 +/- 6 and 52 +/- 13 micro M, respectively; FRAP values were, respectively, 273 +/- 94 and 1101 +/- 168 micro M. There was no significant correlation between tear and plasma levels (r = -0.068; P = 0.771 for ascorbate; r = 0.418; P = 0.059 for FRAP). Neither was significant correlation seen between the two variables in plasma (r = 0.162; P = 0.483) or tears (r = 0.353; P = 0.117). Acute responses (up to 3 hours) showed a similar pattern of increase in both fluids, however, peak response in tears (33 +/- 4 micro M) was much smaller and slightly later than in plasma (125 +/- 13 micro M). After 4 weeks' supplementation, ascorbate increased (P < 0.001) in both fluids, however, the increase in tear ascorbate was small (5 micro M), compared to plasma (38 micro M). The increase in tear ascorbate appeared to plateau after 2 days' supplementation; plasma levels were still increasing. Higher tear ascorbate at entry was associated (P < 0.05) with smaller supplementation-related response. No significant changes in FRAP were seen in either fluid (P > 0.05). CONCLUSIONS: Ascorbate concentration in both plasma and tears increased with vitamin C supplementation, but the total antioxidant capacity of these fluids did not. Furthermore, the increase in tear ascorbate was modest in comparison to that in plasma, and is suggestive of a "ceiling" for tear ascorbate of under 40 micro M. Results support the concept of a control mechanism for an integrated antioxidant defense system, and suggest that the amount of ascorbate in tears is both actively controlled and purposefully limited.

Adult↗
PubMed2005

Interaction of Pseudomonas aeruginosa with human tear fluid components.

PURPOSE: Reflex human tears bind Pseudomonas aeruginosa bacteria and prevent them from invading corneal epithelial cells. In this study, we assessed the effect of eye closure and the role of sialoglycoprotein (SG) in tears on bacterial binding and invasion. METHODS: Human tears (reflex and closed-eye) were collected using a microcapillary tube. Reflex tears were separated into 13 fractions by high-performance liquid chromatography while high-molecular-weight components from closed-eye tears were separated into an SG/mucin fraction and a nonmucin fraction. Bacterial binding was quantified by viable counts and bacterial invasion was tested using the gentamicin survival technique. RESULTS: Closed-eye tears bound significantly more bacteria than open-eye tears. Fractionation of reflex tears showed that 11 out of the 13 fractions bound bacteria, while all 13 fractions significantly reduced bacterial invasion of corneal epithelial cells. Surprisingly, the SG/mucin component of closed-eye tears resisted bacterial binding and had no significant effect on bacterial invasion. CONCLUSIONS: P. aeruginosa bacteria bind more efficiently to closed-eye tears than to open-eye tears. The mechanism by which tears bind bacteria and protect against invasion does not require SG/mucin, as this fraction of closed-eye tears does not contain either activity.

Bacterial Adhesion↗