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At least 109 records · Page 6Linked to original sources
PubMed1989

Human tear film pre-rupture phase time (TP-RPT)--a non-invasive technique for evaluating the pre-corneal tear film using a novel keratometer mire.

A non-invasive method of assessing the stability of the human pre-corneal tear film is described using a novel keratometer mire designed in the form of a grid pattern (HIR-CAL Grid). In a laboratory environment, the technique measures with ease and little variability the time taken for the tear film to loose stability and enter the pre-rupture phase (TP-RPT) before rupturing (BUT). This technique may prove useful in evaluating the stability or otherwise of the pre-corneal tear film of prospective contact lens wearer and the pre-contact lens tear film stability on differing current and new contact lens materials.

Blinking↗
PubMed1990

Determination of plasminogen activator activities in normal and pathological human tears. The significance of tear plasminogen activators in the inflammatory and traumatic lesions of the cornea and the conjunctiva.

Plasminogen activator activity in normal human tears was found to be 0.03 +/- 0.02 IU/ml with casein plate, and 0.06 +/- 0.04 IU/ml with a spectrophotometric method. Elevated levels of plasminogen activator activity (range 0.11-2.05 IU/ml) were detected in the tear fluid of patients suffering from various corneal and conjunctival diseases including corneal ulcers, superficial keratitis, persistent epithelial defects, recurrent erosions, bullous keratopathy, contact lens associated erosions, alkali burns of the cornea, Mooren's ulcer, conjunctival pemphigoid, acute keratoconus, and corneal melanoma. Plasminogen activator activity, determined in the absence of fibrin in tear samples collected by capillary tubes at low flow rates, is considered to be the result of the presence of urokinase-type plasminogen activator (uPA) deriving from the epithelial cells of the cornea and the conjunctiva. It is suggested that an increase in the level of uPA in tears plays an important role not only in ulceration (the formation and repair of epithelial and stromal defects), but also in the development and healing of a number of other inflammatory processes, infections, immunological processes, chemical burns, contact lens associated lesions; in the invasion of microorganisms and leukocytes, in edema formation, in neovascularization, and in the invasive growth of tumors in the cornea and the conjunctiva.

Conjunctival Diseases↗
PubMed1984

Study of the human blood-tear barrier and the biochemical changes in the tears of 30 contact lens wearers (50 eyes).

50 eyes were fitted with contact lenses of different materials. The tears were taken from different surgical departments specializing in the fitting of contact lenses. The tears were analyzed by electrophoresis. Albumin, and filtered and synthesized IgG were assayed in order to find out whether there is a modification in the permeability of the blood-tear barrier in individuals wearing contact lenses. In 40% (A2, B2 b + d) of the cases there were modifications in the permeability of the barrier and in 84% (group A2 + B2 b + c + d), the tears were found to be pathological.

Albumins↗
PubMed2003

The cavernous body of the human efferent tear ducts contributes to regulation of tear outflow.

PURPOSE: To test the hypothesis that the surrounding vascular plexus of the lacrimal sac and the nasolacrimal duct contributes to the regulation of tear outflow. METHODS: Experiments in 30 probands aged between 15 and 37 years were performed in both nasolacrimal systems of each subject by observing with an endoscope the transit time of an applied tear drop containing fluorescein dye until its entry into the inferior meatus of the nose. Four different experiments were performed to determine the median transit time under normal conditions and the influence on transit time of a decongestant drug, a foreign body on the ocular surface, and a decongestant drug applied together with a foreign body on the ocular surface. Comparisons were made between the right and left nasolacrimal system, in males and females, eyeglass wearers and non-eyeglass wearers, and the different experiments and the results statistically analyzed. RESULTS: The tear transit time was independent of side (right or left), gender, or eyeglass wear. It showed great individual variability. Application of a decongestant drug or placement of a foreign body on the ocular surface both prolonged the dye transit time significantly. Application of a decongestant drug simultaneously with placement of a foreign body shortened the dye transit time significantly compared with the effect of the decongestant drug alone but revealed no significant difference compared with application of a foreign body alone. CONCLUSIONS: The cavernous body of the lacrimal sac and nasolacrimal duct plays an important role in the physiology of tear outflow regulation. It is subject to autonomic control and is integrated into a complex neuronal reflex feedback mechanism starting with the dense innervation of the cornea. Moreover, its function can be pharmacologically influenced.

Adolescent↗
PubMed1989

Tear film stability and tear surface tension.

Surface tension has been measured by the method of Ferguson and Kennedy on small (0.3-0.4 microliter) samples of tears from 65 normal and 35 dry eyes. Non-invasive break-up time (NIBUT) was also measured on the same patients as an indication of tear film stability. The mean (+/- SD) surface tension value was 43.6 +/- 2.7 mN/m for normals, and 49.6 +/- 2.2 mN/m for dry eyes. All NIBUT values for dry eyes were below 20 sec (8.9 +/- 5.1 sec, mean +/- SD, n = 35) while 53% of normal values were 30 sec or over. A negative correlation was found between surface tension and NIBUT for both dry eyes and normals. Comparison of surface tension results for tears and a variety of standard solutions indicated that mucus makes the greatest contribution, even at low concentrations, but the effect of proteins can be large, especially in inflammatory states where serum proteins leak from conjunctival vessels. The measurement of surface tension is simple and direct, and in conjunction with the NIBUT value can help in classification of tear quality in questionably dry eye cases.

Adolescent↗
PubMed1975

The effect of tear substitutes on tear film break-up time.

Twelve commercial artificial tear solutions and a newly developed one were evaluated as to their effect on tear film breakup time (BUT) in ten normal subjects. Instillation of one drop of these solutions altered the BUT in such a way that serial BUT measurements could be used as an index of retention time. Results demonstrated significantly longer retention time for three related products (Adapt, Adapette, and Adsorbotear) and a newly developed product (Alcon 0413) [Tears Naturale (Alcon TM)]. This method appears to be an accurate nonirritative way of assessing retention time of tear substitute/vehicles and demonstrate values much longer than previously reported by other methods.

Cellulose↗
PubMed1992

Decreased tear osmolarity and absence of the inferior marginal tear strip after sleep.

To better understand some of the clinical syndromes that patients experience on eyelid opening in the morning, we examined four patients clinically and measured tear osmolarity immediately after sleep and later in the day. The inferior marginal tear strip was absent, and tear osmolarity was at its nadir on eyelid opening after sleep. We propose a mechanism whereby decreased osmolarity, together with a probable decrease in tear volume, may increase lid-corneal and soft contact lens-corneal adhesion during sleep, and help explain both the development of recurrent corneal erosions on awakening and the tendency of soft contact lenses to adhere to the cornea overnight.

Adult↗
PubMed1994

[Dynamics of fluoroquinolone agents in tear fluid--a comparison of the dynamic in tears of human and rabbit eyes].

We compared the dynamics of fluoroquinolones administered either systemically or locally, in the tears of human and rabbit eyes. The concentrations of locally administered ofloxacin (OFLX) in the human and rabbit tear fluid were similar. However, there was a difference between the norfloxacin (NFLX) concentrations in human and rabbit tear fluid measured after instillation. The NFLX concentrations in the tear fluid were significantly higher than the OFLX concentrations and they were retained longer with oral administration. On the other hand, the drug dynamics depended on the concentrations of the drug in the serum, and were better in the rabbit eyes than in the human eyes. Knowing the correlation of drug dynamics in rabbit and human eyes may supply useful information about drug dynamics in human eyes, and may be a useful index for clinical treatment.

Administration, Oral↗
PubMedDate not supplied

Arthroscopic repair of meniscal tears that extend into the avascular zone. A review of 198 single and complex tears.

We assessed the results of 198 meniscal tears that had a major segment in the central avascular region repaired with an arthroscopically assisted inside-out technique. There were 177 patients whose mean age was 28 years. Eighty-two percent were injured during sports, and 71% also required anterior cruciate ligament reconstruction. The menisci were evaluated by clinical examination (180 repairs) a mean of 42 months postoperatively, by follow-up arthroscopic evaluation (91 repairs) a mean of 18 months postoperatively, or both. At followup, 159 (80%) of the 198 tears were asymptomatic for tibiofemoral joint symptoms, and 39 (20%) required repeat arthroscopic surgery for these symptoms. Of the 91 repairs evaluated arthroscopically, 23 (25%) were classified as healed, 35 (38%) as partially healed, and 33 (36%) as failed. We recommend repair of meniscal tears that extend into the avascular region for select patients, including those in their 20s and 30s and highly competitive athletes. This study's reoperation rate of 20% should not be interpreted as the rate of meniscal healing, but as the incidence of tibiofemoral joint symptoms. Even though this is a higher rate than that reported for the repair of peripheral meniscal tears, we believe the benefits of a potentially functional meniscus outweigh the risks of reoperation.

Adolescent↗
PubMed1986

Differences between glycoprotein profiles of normal tear fluid and of tear fluid from patients with primary Sjögren's syndrome.

We present a method for tear glycoprotein characterization using lectins as probes. SDS-page of samples is followed by electrophoretic transfer of proteins from gels onto nitrocellulose paper. Biotinylated lectin is overlayed and visualized with avidin-conjugated horseradish-peroxidase. With the use of 10 lectins, pooled samples of normal tears were assayed and compared to pooled samples of tears from patients with Sjögren's syndrome. Significant differences in number of bands, molecular weights and lectin binding capacity were observed between the two tear samples.

Eye Proteins↗
PubMed2005

Conversion of cyclosporine A prodrugs in human tears vs rabbits tears.

The aim of this study was to evaluate the rate and mechanism of conversion of two water-soluble prodrugs of cyclosporine A (CsA) intended for topical delivery to the eye. The new molecules were designed according to the double prodrug concept: a solubilizing moiety was grafted onto CsA via an ester function, which could be hydrolysed via a two-step process (enzymatic and chemical). Prodrug solutions were prepared extemporaneously in an isotonic and neutral aqueous medium compatible with ophthalmic use. The rates of conversion into the parent molecule were determined by incubating the prodrugs in fresh rabbit or human tears or in a phosphate buffer solution (PBS) at pH 7.4. Both prodrugs were converted into CsA within the first minute in the presence of rabbit tears with rate constants of k=5.9x10(-3)min(-1) and k=3.8x10(-3)min(-1), respectively, for UNIL088 and UNIL089, whereas chemical conversion in PBS was negligible (k=0.5x10(-3)min(-1) for both molecules). Incubation of UNIL088 in human tears showed a significantly high conversion rate. It is concluded that the developed double prodrugs underwent a bioconversion in physiological media and thus represent promising candidates for topical delivery of CsA to the eye.

Animals↗
PubMedDate not supplied

The influence of religious fasting on basal tear secretion and tear break-up time.

Muslims abstain from food and drink from dawn to sunset during the holy month of Ramadan. An extended strict fasting may influence tear secretion and quality. We investigated changes in basal tear secretion (BTS) and tear break-up time (BUT) at the beginning and at the end of fasting on 32 healthy male patients with a mean age of 22.3 +/- 2.9 years. Body weight and urine specific gravity were also determined to assess the extent of dehydration due to fasting. Each case lost 0.1-1.25 kg of body weight while urine specific gravity changes were statistically insignificant. Mean BTS amount was 19.9 +/- 10.9 mm at the initial examination and 19.7 +/- 11.5 mm at the end of fasting (p = 0.9). BUT values were 20.1 +/- 9.3 sec at the beginning of fasting and 23.5 +/- 14.9 sec at the end of fasting (p = 0.19). We found that religious fasting in the winter season does not seem to affect BTS and BUT values in healthy individuals.

Adult↗
PubMed1999

Evaluation of tear secretion and tear film stability in pseudoexfoliation syndrome.

PURPOSE: In pseudoexfoliation syndrome, a material of unknown composition is deposited at the anterior structures of the eye and at periorbital tissues such as the conjunctiva, where goblet cells and accessory lacrimal glands are located. In this study, the possible effect of pseudoexfoliation on tear secretion and tear film stability was investigated. METHODS: Tear film break-up time and Schirmer tests were performed on 108 eyes of 57 patients with pseudoexfoliation and 120 eyes of 60 normal subjects. Results were statistically analyzed. RESULTS: Both Schirmer test and break-up time scores were significantly lower in the pseudoexfoliative patients (average values 10.13 mm and 6.91 sec, respectively) compared to the control group (average values 12.75 mm and 12.75 sec, respectively). The difference was more prominent in males. CONCLUSION: The lower scores in Schirmer and break-up time tests in the pseudoexfoliation group could be attributed to conjunctival involvement. Pseudoexfoliative patients could be more prone to developing xerophthalmia, especially if they are treated with beta blockers.

Aged↗
PubMed2000

Assessment of drug concentrations in tears in therapeutic drug monitoring: I. Determination of valproic acid in tears by gas chromatography/mass spectrometry with EC/NCI mode.

A rapid and sensitive method for the quantitation of valproic acid in tears has been developed using gas chromatography/electron capture negative chemical ionization/mass spectrometry. Valproic acid was converted directly into its pentafluorobenzyl ester derivative without the need to perform any extraction from the biologic fluid. The concentrations in tears [C]t correlated very well with those of the free form in the plasma [Cf]p and those of the total form in the plasma [Cb+f]p. The ratios between valproic acid concentrations in tears and plasma were as follows: [C]t/[Cb+f]p = 0.10 +/- 0.02; [C]t/[Cf]p = 0.57 +/- 0.11. Ratios of [C]t/[Cb+f]p were in good agreement with previously published data.

Anticonvulsants↗
PubMed2000

The cavernous body of the human efferent tear ducts: function in tear outflow mechanism.

PURPOSE: To determine the structure and function of a system of large blood vessels integrated in the bony canal between the orbit and the inferior nasal duct. METHODS: Thirty-one dissected lacrimal systems of adults were analyzed by using gross anatomy, histology, and electron microscopy as well as corrosion vascular casts. RESULTS: More than two thirds of the bony canal between orbit and inferior nasal duct is filled by a plexus of wide-lumened veins and arteries. The vascular system is embedded in the wall of the lacrimal sac and nasolacrimal duct and is connected to the cavernous tissue of the inferior turbinate. Three types of blood vessels can be distinguished inside the vascular tissue that surrounds the lumen of the lacrimal passage: barrier arteries, capacitance veins, and throttle veins. CONCLUSIONS: The surrounding vascular plexus of the lacrimal sac and nasolacrimal duct is comparable to a cavernous body. While regulating the blood flow, the specialized blood vessels permit opening and closing of the lumen of the lacrimal passage, effected by the bulging and subsiding of the cavernous body, and at the same time regulate tear outflow. Other functions such as drainage of absorbed tear fluid components and a role in immunologic response are under discussion as well. Malfunctions in the cavernous body may lead to disturbances in the tear outflow cycle, ocular congestion, or total occlusion of the lacrimal passages. Variations in the conditions for swelling of the cavernous tissue may have led to the (mistaken) description of valves in the lacrimal passage.

Adult↗
PubMedDate not supplied

Ocular pathology, tear production, and tear lysozyme in rheumatoid arthritis.

Ninety-seven rheumatoid arthritis (RA) patients receiving investigational nonsteroidal antiinflammatory drugs were found to have a 31.9% prevalence and 24.5%/year incidence of ocular pathology. None of these ocular lesions were definitely related to their RA or drug therapy. Twenty-one of these patients were studied further for evidence of keratoconjunctivitis sicca. None of these patients had abnormal rose bengal staining, but over half had decreased tear production on both stimulated and unstimulated Schirmer's testing and many patients had high tear lysozyme levels. Increased tear lysozyme levels and decreased Schirmer's tests correlated with a modified rheumatoid activity index.

Adult↗
PubMed1993

The results of arthroscopic debridement of glenoid labral tears based on tear location.

A retrospective, average 2-year review of 14 patients with a primary glenoid labral tear treated by arthroscopic debridement was conducted to evaluate the long-term results of labral debridement based on tear location in preoperatively stable shoulders. All patients with concomitant pathology requiring an additional open or arthroscopic procedure were eliminated from this study. Every patient complained of shoulder pain mainly with overhead activities and nine patients (64%) also described "clicking" with shoulder movement. All shoulders were stable to translation in all quadrants during the preoperative examination and examination under anesthesia. The functional results at 6 months' follow-up were 93% excellent or good. However, the results at > 1 year's follow-up (average 2 years) were only 71% excellent or good, with a statistically significant 50% of patients decreased in function. The best results were in the superior and anterior-inferior regions. Three patients with large anterior-superior lesions (60%) developed postoperative instability noted at > 6 months postsurgery, representing a significant difference between groups. One of these patients was able to regain a good functional result with rotator cuff strengthening therapy. Close observation of patients after large anterior-superior labral tear arthroscopic debridement is advised because they are at risk for the delayed onset of instability.

Adolescent↗