Influence of magnesium doping on the phase transformation temperature of beta-TCP ceramics examined by Rietveld refinement.

The influence of Mg doping in Ca(3)(PO(4))(2) on the transformation temperature of beta-tricalcium phosphate (beta-TCP) to alpha-tricalcium phosphate (alpha-TCP) was examined. A maximum substitution by 14 mol% of Mg(2+) on Ca(2+) sites in the beta-TCP structure was determined for powders calcinated at 1025+/-10 degrees C. X-ray powder diffraction analysis (XRPD) in combination with Rietveld method (TOPAS 2.1) was employed for quantitative phase analysis and structural refinement. The synthesized and characterized Mg-doped samples were sintered in air atmosphere in a vertical tube furnace at suitable temperatures ranging from 1460 to 1680 degrees C and subsequently quenched to room temperature, in order to stabilize alpha-TCP. The beta to alpha transformation temperatures were determined by differential temperature analysis and XRPD analysis.

A new technique for tear film fluorophotometry.

AIM: To develop a reliable and objective non-touch technique for determination of tear volume and tear secretion by means of tear film fluorophotometry. METHODS: 10 defined concentrations of sodium fluorescein were given in an artificial chamber and measured by the Fluorotron Master (Coherent Radiation Inc). A calibration line was established and the calibration equation was programmed into the Fluorotron Master computer software. In 28 patients (56 eyes) with dry eye symptoms and 15 volunteers (30 eyes) tear volume and tear secretion were then measured directly without taking a tear sample, using the new technique. RESULTS: The values obtained by the Fluorotron Master measuring 10 defined fluorescein concentrations within an artificial chamber are approximately 100 times lower than the actual concentrations. The calibration line led to a calibration equation: y = 36 + 0.01 x X. The mean tear secretion in 56 eyes of patients with dry eye symptoms was 2.48 microl/min, compared to 3.4 microl/min in healthy volunteers. The difference was statistically significant. Average tear volume was 7.0 microl in patients and 7.2 microl in healthy volunteers with no statistically significant difference. CONCLUSION: The method developed is a simple and reliable non-touch technique without the need for taking a tear sample, which makes the examination faster and more comfortable for the patient.

[Clinical study of the effectiveness of a dexpanthenol containing artificial tears solution (Siccaprotect) in treatment of dry eyes]. / Klinische Studie zur Wirksamkeit eines dexpanthenolhaltigen Tränenersatzmittels (Siccaprotect) bei der Behandlung Trockener Augen.

PURPOSE: In this controlled, randomized, double-masked study the effect of dexpanthenol-containing artificial tears (Siccaprotect) on patients with dry eyes was examined. PATIENTS AND METHODS: 50 patients applied either dexpanthenol-containing artificial tears (Siccaprotect) or the identical, but free of dexpanthenol, eye drops five times daily into the conjunctival sac. No other ophthalmics were administered. The corneal epithelial permeability was measured by fluorophotometry and Schirmer-Test, Rose Bengal staining, tear film break-up time and the patients' subjective complaints were determined before and after 6 weeks of treatment. RESULTS: The dexpanthenol-containing artificial tears (Siccaprotect) improved disturbances of the corneal epithelial permeability significantly in comparison to the dexpanthenol-free eyes drops. The other parameters didn't show relevant differences. CONCLUSION: These data suggest that, in dry eyes, treatment with dexpanthenol-containing eye drops leads to a favorable and comparing with dexpanthenol-free eye drops superior improvement in disturbances of corneal epithelium permeability.

Oxidative reactions in the tear fluid of patients suffering from dry eyes.

PURPOSE: To evaluate whether products of oxidative and inflammatory reactions are detectable in the tear fluid of patients suffering from dry eyes. METHODS: The tear fluid of 217 patients (397 eyes) was sampled. Criteria for grouping of the patients were (1) basic secretion test ("sicca 1": BST = 0-5 mm, n = 78 eyes; "sicca 2": BST = 6-10 mm, n = 109 eyes) and (2) subjective symptoms (normal BST, burning, foreign body sensations, tearing, dryness of the eyes: n = 78 eyes). One group of healthy patients (normal BST, n = 132 eyes) served as controls. Lipid peroxide levels and myeloperoxidase activity, as parameters for oxidative tissue damage and inflammatory activity, were determined in the tear fluid. Those patients whose consent could be obtained were subjected to the rose bengal test (sicca 1: 56 eyes; sicca 2: 97 eyes; subjective symptoms: 44 eyes; controls: 49 eyes). The correlation between BST and rose bengal test results was calculated. RESULTS: Lipid peroxides were significantly (P < 0.05) higher in the groups sicca 1 and subjective symptoms than in healthy controls, as was the inflammatory activity in groups sicca 1, sicca 2 and subjective symptoms. Additionally, the inflammatory activity in the group sicca 1 was significantly (P < 0.05) higher than in the groups sicca 2 and subjective symptoms. No evidence of a significant correlation between BST and rose bengal test results was observed. CONCLUSIONS: Both oxidative tissue damage and polymorphonuclear leukocytes indicating an oxidative potential occur in the tear film of patients suffering from dry eyes. These reactions lead to severe damage of the involved tissue. Free radicals and inflammation may be involved in the pathogenesis or in the self-propagation of the disease.

Effect of topical 0.5% timolol on tear flow in patients with primary open-angle glaucoma as assessed by fluorophotometry.

The question as to whether or not topical medication with beta blockers causes a decrease in tear production remains unanswered. Earlier studies using filter-paper strip tests have yielded contradictory results. In the present study, computerized objective fluorophotometry was used to assess the effect of topical medication with 0.5% timolol (b.i.d.; OU) on tear volume and tear production in 24 consecutive patients with bilateral primary open-angle glaucoma. Tear-film fluorophotometry was performed before treatment as well as at 7 days, 14 days, and 4-7 months after the onset of treatment. The results showed that by 7 days after the initiation of timolol treatment, both tear volume (-29%, P < 0.01) and tear secretion (-36%, P < 0.01) had decreased significantly. However, at both 14 days and 4-7 months after the onset of treatment, none of the values differed significantly from those obtained before treatment. Thus, topical antiglaucomatous treatment with 0.5% timolol eye drops leads to a transient decrease in tear production. This effect, however, lasts no longer than 14 days after the beginning of treatment.

[Reversible mydriasis and cycloplegia after isocyanate exposure]. / Reversible Mydriasis und Akkommodationslähmung nach Isocyanateinwirkung.

We saw three patients working in the production of polyurethanes, who showed mydriasis and cycloplegia of unknown origin. In one patient there was also a transient opacification of corneal stroma. After discontinuation of working both mydriasis and cycloplegia resolved completely within 3-5 days. Because of the history and the analysis of chemical reactions involved in the production of polyurethanes there is strong evidence that both mydriasis and cycloplegia have been caused by topical and (/or) systemic intoxication with the aryl diet of the isocyanate molecule.

Corneal epithelial permeability of dry eyes before and after treatment with artificial tears.

PURPOSE: The question of whether artificial tears can lead to objective improvement of ocular surface disease in dry eyes is still unanswered. The aim of the current study is to assess the influence of artificial tears on corneal epithelial permeability of dry eyes. Furthermore, the effect of benzalkonium chloride, used as a preservative of artificial tears, on corneal epithelial permeability is investigated. METHODS: The corneal epithelial permeability of 40 dry eye patients (80 eyes) was measured by computerized objective fluorophotometry before and 6 weeks after treatment with artificial tears containing either polyvinyl pyrrolidone 2% without preservative (20 patients) or polyvinyl pyrrolidone 2% preserved with benzalkonium chloride 0.005% (20 patients). RESULTS: Before treatment, the epithelial permeability of the dry eye patients was found to be 2.7 times that of a control group. After treatment, the epithelial permeability of patients treated with unpreserved polyvinyl pyrrolidone 2% had decreased significantly (-37%; P less than 0.001), whereas patients who had been treated with polyvinyl pyrrolidone 2% preserved with benzalkonium chloride 0.005% showed an increase in epithelial permeability (+21%; P = 0.05%). CONCLUSION: These data suggest that, in dry eyes, treatment with unpreserved artificial tears may lead to an objective improvement in corneal surface disease. However, this effect may be counteracted by preservation of tear substitutes with benzalkonium chloride.

Tear secretion in dry eyes as assessed by objective fluorophotometry.

To date, little information has been available about the actual amount of tear secretion in dry eyes. In the present study tear secretion was studied in 20 consecutive dry eye patients [40 eyes; Schirmer test after topical anesthesia < 5.5 mm/5 min; at least moderate squamous metaplasia of the conjunctival epithelium; bengal rose staining (Bijsterveld score > 4); severe dry eye complaints]. Tear secretion was evaluated by automated, computerized objective fluorophotometry and compared with that in an age-matched healthy control group. Tear secretion of the dry eyes examined was found to have decreased drastically (0.2 +/- 0.2 microliters/min) compared with that in healthy control eyes (1.2 +/- 0.5 microliters/min; P < 0.001). None of the dry eyes had a tear secretion of > 0.4 microliters/min.

Effects of artificial tears on corneal epithelial permeability in dry eyes.

The aim of this study was to detect possible changes in the permeability of the corneal epithelium in dry eye patients treated with artificial tears. For this reason, corneal epithelial permeability was measured in 68 consecutive dry eye patients before and after 8 weeks of treatment with artificial tears by means of objective fluorophotometry (polyvinyl alcohol 1.4% + chlorobutanol 0.5%, 25 subjects; polyvinyl pyrrolidone 2% + benzalkonium chloride 0.005%, 25 subjects; polyvinyl pyrrolidone 2% without preservative, 18 subjects). Before treatment, the stromal fluorescein uptake of dry eyes was three times higher than that of healthy control eyes. Eight weeks after the beginning of treatment the corneal epithelial permeability of patients treated with polyvinyl alcohol 1.4% + chlorobutanol 0.5%, as well as of those treated with polyvinyl pyrrolidone 2% without preservative, was reduced significantly (-44.9% and -43.4%, respectively; P less than 0.001). However, patients who had been treated with polyvinyl pyrrolidone 2% + benzalkonium chloride 0.005% showed no significant change in corneal epithelial permeability after treatment (-7.9%; P = 0.3).

Effect of topically applied oxymetazoline on tear volume and tear flow in humans.

Vasoconstrictive, alpha-sympathicomimetic eye drops are ophthalmic drugs that are extensively used. However, patients often complain of typical dry eye symptoms, especially after long-lasting application of such eye drops. In the present study, the effect of sympathicomimetic eye drops (0.026% oxymetazoline) on the tear volume and tear flow of 38 healthy individuals was determined quantitatively by means of objective fluorophotometry. Both tear volume and tear flow were found to be significantly (P less than 0.001) decreased up to 6 h after instillation, reaching a minimum 90 min after application (tear volume: -63%; tear flow: -71%). Thus, alpha-sympathicomimetic eye drops containing 0.026% oxymetazoline lead to a marked and protracted decrease in tear volume and tear flow. After frequent or long-lasting application, this fact may be responsible for severe dry eye conditions.

[Effect of vasoconstrictor eyedrops on tear volume and tear secretion]. / Einfluss vasokonstriktiver Augentropfen auf Tränenvolumen und Tränensekretion.

Vasoconstrictive, alpha-sympathicomimetic eye drops are ophthalmic drugs that are extensively used. However, patients often complain of typical dry eye symptoms, especially after long-lasting application of such eye drops. In the present study, the effect of sympathicomimetic eye drops (oxymetazoline 0.026%) on the tear volume and tear flow of 16 healthy individuals was determined quantitatively by means of objective fluorophotometry. Both tear volume and tear flow were found to be significantly (p less than 0.001) decreased 3 h after instillation (tear volume: -52%; tear flow: -31%). Thus, alpha-sympathicomimetic eye drops containing oxymetazoline 0.026% lead to marked and protracted decrease in tear volume and tear flow. After frequent or long-lasting application, this fact may be responsible for severe dry eye conditions.

Effect of eledoisin on tear volume and tear flow in humans as assessed by fluorophotometry.

Topical application of the endekapeptide eledoisin has been reported to increase tear secretion in patients with dry eye. However, to date the efficacy of eledoisin has been proved only by methods that are not easily reproduced and have an enormous intraindividual scatter range (Schirmer test, basic secretion test). In the present study the effect of topically applied eledoisin on tear volume and tear flow was determined quantitatively by means of objective fluorophotometry in 40 subjects, 20 of whom suffered from severe dry eyes. Both tear volume and tear flow were found to be significantly increased up to 2 h after instillation, reaching a maximum 1 h after application (tear volume: +87% and +35% for dry eyes and healthy controls, respectively; tear flow: +250% and +27% for dry eyes and healthy controls, respectively).

[Visually evoked cortical potentials for early detection of optic neuritis in ethambutol therapy]. / Visuell evozierte kortikale Potentiale zur Früherkennung der Neuritis nervi optici unter Ethambutoltherapie.

Ethambutol leads to chronic, severe optic neuritis with sudden onset in approximately 5-14% of all patients. Therefore, the ability of visually (pattern) evoked potentials for the early diagnosis of ethambutol-induced optic neuritis was tested. During ethambutol therapy prolonged latency was documented in 5 of 15 cases (33%). One of these 5 cases showed a reversible decrease in visual acuity. Thus, during treatment with ethambutol visually (pattern) evoked potentials may reveal a surprisingly high percentage of subclinical optic neuritis. These patients need close supervision in order to facilitate early discontinuation of the drug when neuritis develops.

[The dry eye. Status determination and prospects]. / Das trockene Auge. Standortbestimmung und Aussichten.

Dry eye is the most common cause of chronically red, irritated eyes. Thus, in cases of chronic conjunctivitis dry eye must be excluded. The noncritical use of vasoconstrictive eye drops and/or corticosteroids is obsolete. Up to now the diagnosis of dry eye has been based on a combination of the patient's history, slit-lamp examination, determination of tear film break-up time, the Schirmer test and basic secretion test. Unfortunately, there is enormous deviation in all of these tests, which means that they provide poor diagnostic reliability. Dry eyes are rarely associated with systemic diseases, e.g. Sjogren's syndrome. This autoimmunological disease is often first diagnosed by the ophthalmologist. Quantitative or qualitative deficiencies of one or more layers of the complex tear film can result in dry eyes, but inflammatory agents or primary ocular surface diseases may also be involved. Within the next few years analyses of tear-film proteins, toposcopy, tear-film fluorophotometry, impression cytology and corneal epithelial fluorophotometry may prove to be reliable tests for the detection of dry eye. The improved mucomimetic quality of artificial tears, the avoidance of toxic preservatives, tear production stimulants (eloisin, physaelamin), fibronectin or the epithelial growth factor may facilitate the management of dry eye.

[Barrier function of the corneal epithelium of contact lens patients]. / Barrierefunktion des Hornhautepithels bei Kontaktlinsenträgern.

The corneal epithelium of contact lens wearers is permanently under stress. The aim of the present study was to examine the following questions prospectively and quantitatively: (1) whether or not wearing contact lens leads to a disturbance of corneal epithelial barrier function and (2) if there is a difference between CAB and HEMA contact lenses in this respect. For this reason, the corneal epithelial permeability to sodium fluorescein in 50 individuals was measured before and 8 weeks after fitting contact lens using an automated computerized fluorophotometer (Coherent Radiation Fluorotron Master). Twenty five of the 50 individuals were provided with CAB or HEMA (38%) contact lenses, respectively. Eight weeks after fitting the contact lens corneal epithelial permeability was found to be increased about 1.5 times (p less than 0.001). There was no significant difference between the HEMA and CAB group before and 8 weeks after wearing contact lens (p = 0.5 and p = 0.7, respectively). In conclusion, the corneal epithelium of contact lens wearers is obviously significantly more permeable to watery ionic substances, e.g., water-soluble drugs and toxic products.

[Endothelial function in contact lens-induced deep corneal opacities]. / Endothelfunktion bei kontaktlinsenbedingten tiefen Hornhauttrübungen.

Deep stromal and preendothelial corneal opacities have been described to be a problem of growing importance in contact lens wearers, above all in those with a more than ten-year-old history of contact lens wearing. In the present study the corneal endothelial permeability of 21 patients with a more than ten-year-old history of contact lens (HEMA 38%) wearing has been determined and compared with that of an age-matched group of 8 healthy individuals without ocular disease. The corneal endothelial permeability has been measured by a computerized automated fluorophotometer (Coherent Radiation Fluorotron Master) after topical application of a Na-fluorescein solution according to the method described by Jones and Maurice. The corneal endothelial permeability of contact lens wearers with deep corneal opacities has been found to be significantly (p = 0.05) increased when compared with contact lens wearers without corneal opacities. Contact lens wearers without corneal opacities showed no significant increase of their endothelial permeability in comparison to the control group.

Influence of artificial tears on corneal epithelium in dry-eye syndrome.

The corneal epithelium of patients with dry-eye syndrome is stressed by both tear film insufficiency and the frequent use of eye drops (artificial tears). In order to quantify corneal epithelial damage, the permeability of corneal epithelium to sodium fluorescein was determined in 40 consecutive patients with dry eyes (BST less than 10 mm), who did not exhibit visible corneal lesions upon slit-lamp examination. The corneal epithelial permeability of dry-eye patients was shown to be 2.8 times greater than that of individuals without ocular disease. Corneal epithelial permeability of patients using artificial tears containing benzalkonium chloride was increased 3.1 times and that of patients using drops preserved with chlorobutanol only 1.7 times.

Impairment of corneal epithelial barrier function in diabetics.

Corneal epithelial permeability was determined using an automatic fluorophotometer in 80 consecutive diabetic patients. The corneal epithelium, which is the most important part of the corneal diffusion barrier, showed a significant increase of permeability to watery, ionic substances (natrium fluorescein). The permeability was increased 5.4 times in comparison with nondiabetic individuals and a distinct correlation of increased permeability with the presence and duration of retinal nonperfusion areas was observed.