Effect of norfloxacin and clonidine on human trabecular meshwork cells in vitro

We evaluated the effect of norfloxacin and clonidine on the morphology, DNA synthesis and phagocytic activity of cultured human trabecular meshwork cells in the 3rd-5th generations. Exposure to norfloxacin at a concentration of 1.5 × 10^–4 g ml-1 for 6 h led to retraction of cytoplasmic processs and rounding of cell profile, and exposure for 48 h caused cell death. Exposure to clonidine at 1.0 × 10^–3 g ml^–1 for 12 h caused cell degeneration, and exposure for 72 h led to cell death. The morphologic changes were dose-time dependent. Tritiated thymidine incorporation was determined as an index of DNA synthesis, which was significantly inhibited by 1.5 × 10^–5 g ml^–1 norfloxacin or 1.0 × 10^–3 g ml^–1 clonidine, but obviously enhanced by 1.0 × 10^–4 and 1.0 × 10^–5 g ml^–1 clonidine. Both drugs inhibited phagocytosis of latex microspheres in a dose-dependent mode. According to the presented results and the pharmacokinetic data reported in the literature, we suggest that the topical use of norfloxacin should not be too frequent or continued too long, especially when the corneal epithelium was not intact; clonidine has no deleterious effect on trabecular cells in its conventional use.     

Protective effect of captopril on the blood-retina barrier in normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy

The effect of 18 months' inhibition of angiotensin-converting enzyme by captopril on the leakage of fluorescein through the blood-retina barrier was examined in a prospective, randomized control study of 20 normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy. After 18 months, 15 patients remained in the study. Fluorescein leakage remained nearly unchanged in the captopril-treated group, being 4.1 ± 4.1 (mean ± SD) × 10^–7 cm/s at baseline and 4.2±4.1 × 10^–7 cm/s after 18 months' treatment. The permeability increased significantly (P<0.01) from 3.3±2.2 × 10^–7 cm/s to 5.6±3.5 × 10^–7 cm/s at 18 months in the control group. Arterial blood pressure was nearly constant in both groups throughout the study. The results indicate that angiotensin-converting enzyme inhibition with captopril can arrest or delay a progressive breakdown of the blood-retina barrier in normotensive insulin-dependent diabetic patients with nephropathy and background retinopathy.The authors have no commercial or proprietory interest in the drugs or instruments used in this study     

Alteration of the blood-retinal barrier and vitreous in sickle cell retinopathy

Nineteen eyes with background sickle cell retinopathy, eleven from patients with SC disease, eight from patients with SS disease, and twelve eyes with proliferative sickle cell retinopathy were examined by direct and indirect ophthalmoscopy, slit-lamp, fluorescein angiography and vitreous fluorophotometry. Calculation of the alteration of the blood-retinal barrier (BRB) and estimation of the diffusion coefficients of fluorescein in the vitreous were performed by fluorophotometry.In background sickle cell retinopathy, the results show a normally functioning BRB in the posterior pole. Abnormally increased fluorescence values to the mid-vitreous (peripheral leakage) were found only in 3 of these 19 eyes, at the two-hour examination (all SC patients). Similarly, mid-vitreous fluorescence values at the two-hour examination were 4.19 ± 1.52 ng/ml in eyes of patients with SC disease, compared with 2.65 ± 0.56 ng/ml in eyes of patients with SS disease. All eyes with background sickle cell retinopathy, except one, showed values for the coefficient of diffusion of fluorescein within normal limits, indicating normal vitreous gel structure.In proliferative retinopathy, the mid-vitreous fluorophotometry readings were abnormally increased, correlating well with the extent of the peripheral angiographic changes (neovascularization). The coefficient of diffusion of fluorescein in the vitreous was generally increased in the eyes with proliferative retinopathy (15.0 ± 8.4 × 10^–4cm²/min) in comparison with a mean value of 5.4 ± 1.4 × 10^–4cm²/min in the eyes wi background sickle cell retinopathy, suggesting an alteration of the vitreous structure eyes with proliferative retinopathy.Fluorophotometry is considered a useful tool to follow patients with sickle cell retinopathy by quantitating peripheral retinal vascular leakage.     

Blood-retinal barrier permeability and its relation to progression of retinopathy in patients with type 2 diabetes. A four-year follow-up study

Forty patients with late-onset diabetes (age at diagnosis 30 years or more) and minimal retinopathy as found by fundus photography were followed prospectively by repeated examination (baseline, 1 year, and 4 years). The study shows that early retinopathy changes are not permanent or invariably progressive. In the 1st year of follow-up microaneurysms worsened in 25%, improved in 10%, and remained stabilized in 65%. Vitreous fluorometry was able to detect an overall increase of 0.84 ± 1.06 × 10^–6 min^–1 in blood-retinal barrier (BRB) penetration ratios. After 4 years, 16 of the 40 patients had undergone photocoagulation (focal photocoagulation in 11 and pan retinal photocoagulation in 5). The eyes that needed photocoagulation were the eyes that had higher fluorometry penetration ratios at the patient's entry into the study and showed a higher rate of deterioration during the 1st year of the study (5.54 ±1.97 vs 3.11± 1.22 × 10^–1 min^–1,P<0.001, initial values; 1.52 ± 0.76 vs 0.45 ± 0.99 × 10^i–6 min^–1,P< 0.001, annual increase in leakage). The eyes that did not need photocoagulation, 24 out of 40, showed stable fluorometry readings within the 4-year period of follow-up (+0.02 ± 0.98 10^–6 min^–1). Abnormally high vitreous fluorometry values and their rapid increase over time appear to be good indicators of rapid progression and worsening of the retinopathy.     

A fluorophotometric study of corneal endothelium after trabeculectomy using different concentrations of Mitomycin-C

The aim of the study was to determine the corneal endothelial permeability coefficient (Pac) in subjects after trabeculectomies using different concentrations of Mitomycin-C (MMC). MMC, a highly toxic drug, is not without drawbacks and complications such as corneal damage. To ascertain a possible relationship between a level of endothelial permeability (Pac) and concentrations of MMC used, we performed, in a prospective study, trabeculectomies in cases of primary open-angle glaucoma (POAG), younger than 50 years, with either concentrations of 0.5 mg/ml of MMC (group 1: 11 eyes) or 0.2 mg/ml of MMC (group 2: 10 eyes). Group 3 consisted of 8 patients after a typical trabeculectomy without MMC and served as a control group (8 eyes). In all groups, before surgery and again 1, 3 and 6 months after surgery, corneal endothelial permeability (Pac) was determined by using anterior segment fluorophotometry (Fluorotron Master). The thickness of the cornea (CT) was measured with a DGH Technology ultrasonic pachymeter. One month after surgery the mean values of Pac were statistically significantly higher in groups 1 and 2 (group 1: 4.78 × 10^–4 cm/min, group 2: 4.67 × 10^–4 cm/min) in comparison with the control group (group 3: 3.37 × 10^–4 cm/min), but the differences between groups 1 and 2 were not statistically significant (p = 0.05). Six months after operation the mean values of Pac in all groups were normalized. In eyes that underwent trabeculectomy with MMC, higher concentrations of MMC were likely to have a transient adverse effect on corneal endothelial permeability.In light of the resulting toxic intraocular effect of MMC, the damage in the function of the corneal endothelial barrier is greater with greater concentrations of MMC.     

Blood-aqueous barrier permeability determination in HLA B27-positive acute anterior uveitis patients

The blood-aqueous barrier (BAB) permeability was studied by fluorophotometry in 17 healthy control subjects and in 27 eyes from 27 patients with HLA-B27-positive acute anterior uveitis (HLA-B27 AAU). Twenty of these patients had an associated spondyloarthropathy. BAB permeability was studied during the ocular inflammatory crisis and in the disease-free periods in the same patients. Anterior chamber fluorophotometric scans were performed before and 30 minutes after the intravenous injection of 14 mg/kg of sodium fluorescein. The diffusion coefficient (Kd) was obtained from the ratio between the fluorescein concentration in the anterior chamber and the NPBF. Data were analyzed using the Student's t test and analysis of variance. A statistically significant difference (P < 0.001) was found between the Kd of active HLA-B27 AAU (61.4±16.8×10^–4 min^–1) and the Kd of inactive HLA-B27 AAU (4.8±1.6×10^–4 min^–1). No statistically significant differences were found between the Kd of inactive HLA-B27 AAU and the Kd of the control subjects (4.3±1.0×10^–4min^–1). We also failed to detect significant differences between patients with and without spondyloarthropathy either during the acute attack or during the disease-free period. On the basis of these results we conclude that the permeability of the BAB remains intact in inactive HLA-B27-positive AAU. The parallel fluorophotometric behaviour of HLA-B27-positive AAU with spondyloarthropathy and without spondyloarthropathy suggests that both share a common pathogenetic mechanism.Presented in part at the ARVO meeting, Sarasota, USA, May 1993.     

Sehschärfenprüfung mit testzeichen hoher leuchtdichte

Zusammenfassung Wird die Sehschärfenprüfung mit hellen Testzeichen vor dunklem Hintergrund vorgenommen, so tritt bei Leuchtdichten über 10² bis 10³ cdm^–2 eine zunehmende stärkere Blendungsstörung auf, die Eigenblendung, die zu einer Verminderung der Sehschärfe führt. Die Bedeutung der Eigenblendung für das Erkennen bestimmter Verkehrssignale wird diskutiert. Mit Testzeichenleuchtdichten von 10² bis 10⁶ cdm^–2 wurden Sehschärfenuntersuchungen bei Normalpersonen sowie bei Patienten mit Brechungsfehlern und verschiedenen Trübungen der brechenden Medien durchgeführt. Zusätzliche Untersuchungen wurden mit Trübungsfiltern und nach sphärischer Def okussierung vorgenommen. Es ergaben sich charakteristische Kurvenverläufe, die auf unterschiedliche optische Eigenschaften der Medientrübungen hinweisen.

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Summary When visual acuity is tested with bright test-objects on a dark background, self-glare is noted beyond a luminance of 10² to 10³ cdm^–2, leading to an increasing impairment of the visual acuity. The importance of this self-glare for the detection of traffic signals is discussed. Visual acuity-tests have been carried out with test-objects at a luminance, ranging from 10² to 10⁶ cdm^–2 in normals and in patients suffering from refraction anomalies and various opacities of the dioptrical apparatus. Additional exeriments have been conducted with opaque filters and with spherical defocussation. Typical curves have been elaborated which characterize the distinct optical properties of the opacities of the media.

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Résumé Lorqu'on mesure l'acuité visuelle avec des tests clairs sur fond foncé, les luminosités supérieures à 10²–10³ cdm^–2 produisent des phénomènes d'éblouissement de plus en plus prononcés; ceux-ci diminuent l'acuité visuelle. On discute l'importance de cet éblouissement pour la reconnaissance de certains signaux luminaux de la circulation. L'examen de l'acuité visuelle a été pratiquée chez des sujets normaux, chez des amétropes et des patients atteints de troubles des milieux oculaires avec des tests de 10² à 10⁶ cdm^–2. D'autres expériences ont été faites avec des filtres opaques ou avec une défocussation préalable. On a obtenu des courbes caractéristiques qui paraissent être en rapport avec les différentes propriétés optiques des troubles des milieux.

     

Xenogene Hornhaut-Transplantation

Zusammenfassung Xenogene, interlamelläre Hornhaut-Transplantate wurden mit einer speziell dafür entwickelten Methode bei LEW-Ratten durchgeführt, um erstmals an Inzuchttieren die transplantationsimmunologischen Vorgänge bei der Keratoplastik verfolgen zu können. Die Transplantatreaktionen wurden mit dem Spaltlampenmikroskop beobachtet und nach Ausmaß und Geschwindigkeit der Vascularisation, Zeitpunkt der Eintrübung und Abstoßung des Transplantates in 5 Grade eingeteilt und ausgewertet: 1. 20 Meerschweinchen-Hornhaut-Transplantate auf unvorbehandelten Empfängern waren nach 26–33 Tagen unter Ulceration abgestoßen. 2. Transplantate auf aktiv sensibilisierten Empfängern wurden nach 7–12 Tagen, d.h. signifikant beschleunigt abgestoßen, in 15/15 Fällen nach Haut-Transplantation und in 8/8 Fällen nach Hornhaut-Transplantation in das andere Auge. 3. Transplantate auf passiv sensibilisierten Empfängern wurden ebenfalls beschleunigt abgestoßen: i.v. Injektion von 2,5 bzw. 7,5 ml LEW-anti-Meerschweinchenhaut-Serum bewirkte bei je 6 Versuchstieren Transplantatabstoßung nach 19–22 Tagen; Injektion von 2,5×10⁸ Lymphknotenzellen syngener, aktiv sensibilisierter Tiere bewirkte bei 5/5 Tieren etwa dieselbe Beschleunigung; Kombination von 2,5 ml Antiserum mit 2,5×10⁸ Zellen bewirkte in 6/6 Fällen Transplantatabstoßung nach 9–11 Tagen, d.h. signifikant stärkere Beschleunigung. Der Nachweis des second-set-Phänomens sowie die Übertragbarkeit gesteigerter Reaktionsfähigkeit durch Serum, lymphatische Zellen und insbesondere durch deren Kombination werden als Beweis immunologischer Reaktivität bei xenogener Keratoplastik angesehen.

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Xenogeneic corneal graftingI. Active and passive sensitizing of the rat against guinea pig cornea

Summary A newly developed method for interlamellar, xenogeneic corneal grafting in rats was applied to enable thorough immunological analysis of keratoplasty for the first time using inbred animals (LEW rats). Graft reactions were studied under a slit-lamp microscope and graded according to extent and speed of corneal vascularization, time of clouding, and graft rejection. 1. 20 guinea pig corneal grafts were rejected by previously untreated recipients after 26–33 days, leaving a corneal ulcer. 2. Grafts applied to actively presensitized recipients were rejected after 7–12 days, i.e. significantly accelerated: in 15/15 experiments following skin grafting and in 8/8 cases following corneal grafting of the other eye. 3. Grafts applied to passively presensitized recipients were also rejected in an accelerated fashion: i.v. injection of 2.5 ml or 7.5 ml of LEW-anti-guinea pig skin-serum induced in 2 × 6 experiments graft rejection after 19–22 days; injection of 2.5 × 10⁸ lymph node cells from syngeneic, actively sensitized rats induced in 5 cases nearly the same; combination of 2.5 ml antiserum and 2.5 × 10⁸ lymphoid cells induced in 6/6 experiments graft rejection after 9–11 days, i.e. a significantly increased acceleration. The above evidence of a second-set-phenomenon and for transfer of increased anti-graft reactivity by serum, lymphoid cells, and especially by their combination is presented as proof of immunological reactivity in xenogeneic keratoplasty.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Hyperosmolarity response of ocular standing potential as a clinical test for retinal pigment epithelium activity normative data

The standing potential of the eye is decreased by intravenous administration of hypertonic solutions. This hyperosmolarity-induced response has been recorded in normal subjects by the use of electro-oculography (EOG) in the dark. An intravenous administration of Fructmanit^® (1.4 × 10³ mOsmol) (150 500ml, 2.37 9.70ml/kg, 0.08 0.36 ml/kg/min) was used to evoke the hyperosmolarity response. The amplitude of the response was expressed in percentage, V₀ – V_min/V₀ × 100, where V₀ is the base value of the EOG before administration of the hypertonic solution and V_min is a minimum EOG amplitude after administration. The distribution of the amplitude of the hyperosmolarity response was approximated by the normal distribution in normal subjects. The minimum, the maximum, the mean and the standard deviation of the amplitude of the hyperosmolarity response were respectively 34.2%, 52.3%, 42.6% and 4.6% in normal subjects. The normal range of the hyperosmolarity response would be 33.4 51.8% (M ± 2SD). The hyperosmolarity response, which originates mainly in the retinal pigment epithelium, is a useful new quantitative and specific test of the activity of the retinal pigment epithelium in clinical practice.     

Clinical and metabolic factors associated with the blood retinal barrier permeability in insulin dependent diabetes mellitus without retinopathy

The authors assessed a study pointing out the relationship between the permeability of Blood Retinal Barrier (BRB), using vitreous fluorophotometry, and several risk clinical and laboratory data in Insulin Dependent Diabetes Mellitus (IDDM). Eighty eyes of 40 IDDM patients were evaluated. Their mean age was 14.8 ± 3.2 years. Twenty healthy volunteers served as control group (mean age 15.3 ± 3.2 years). Preexisting diabetic retinopathy was dismissed after funduscopy and fluorescein angiography. The studied risk factors were: age, duration of diabetes, HLA antigens, blood pressure, cholesterol and triglycerides levels, glycosylated hemoglobin, insulin dose/kg body weight and fructosamine. Vitreous and lens fluorophotometry was performed in both groups (VPRt). The mean VPRt in IDDM patients was 3.56 ± 1.47 × 10–6 min^–1. In healthy subjects it was 2.53 ± 0.55 × 10–6 min^–1, establishing a significant difference (p < 0.01). We found a statistically significant correlation between VPRt and duration of diabetes, insulin dose/kg body weight and HbAlc. No correlation was found between VPRt and the rest of parameters. We conclude that vitreous fluorophotometry is a valid method to measure BRB; and the three factors mentioned above are related to the BRB permeability.Abbreviations BRB blood retinal barrier - DR diabetic retinopathy - VF vitreous fluorophotometry     

Taxol treatment of experimental proliferative vitreoretinopathy

Taxol is a potent stabilizer of microtubules, and inhibitor of in vitro replication, migration, and contraction of fibroblasts. It has been found to limit the development of experimental tractional retinal detachments in nonvitrectomized rabbit eyes. We used taxol in vitrectomized, phakic rabbit eyes with experimentally induced proliferative vitreoretinopathy and tractional retinal detachments. Taxol was dissolved in 30% DMSO because of poor aqueous solubility. A single 0.1 ml intravitreal dose of 2 × 10^–4 M taxol in 30% DMSO was injected immediately after 250000 heterologous corneal fibroblasts had been injected; 0.1 ml of 30% DMSO was injected into control eyes. Taxol reduced the incidence of tractional retinal detachments seen 3–4 weeks later. When taxol injection was delayed for 3 days after the initial intravitreal injection of fibroblasts into nonvitrectomized eyes, the extent of retinal detachments was reduced, but the incidence of retinal detachment was unchanged from the untreated eyes at the end of 4 weeks. These data indicate that taxol may be most useful when given early in the course of proliferative vitreoretinopathy.Dr. Stewart Daniels was an Abe Meyer Fellow     

Spectral sensitivity of the blood-retinal barrier at the pigment epithelium for blue light in the 400–500 nm range

To specify the spectral sensitivity of the retinal pigment epithelium (RPE) for blue light damage, pigmented rabbits were exposed to light of 408, 418, 439, 455, 485, and 500 nm (half-peak bandwidth approximately 12 nm). The range of radiant exposure was 15–275 J cm^–2 (1.7–19 mW cm^–2 for 0.5–5 h). Vitreous fluorophotometry was used to functionally evaluate the blood-retinal barrier at the RPE in vivo, and electron microscopy to visualize RPE ultrastructure in vitro. A significant increase in permeability of the blood-retinal barrier was seen only after exposure to light of 418 nm. Radiant exposure at threshold for permeability increase was 18 J cm^–2. Electron microscopy of the RPE demonstrated dispersion and clumping of melanin granules. The results suggest that the RPE is most sensitive to light in the range 412–425 nm, possibly due to damage-mediating chromophores such as cytochromec oxidase and lipofuscin.     

Desensitization of the isolated bovine iris sphincter muscles by pilocarpine

We investigated the effect of pilocarpine on the bovine iris sphincter. This muscle contracted in a dose-dependent manner from 2 × 10^–6 M, with a maximal response at 3 × 10^–3 M. The ED₅₀ values was (1.6 ± 0.3) × 10^–4M. Pilocarpine generated a desensitization while desensitization was not significant in the case of other cholinergic agents such as acetylcholine (Ach) and carbachol. Desensitization was profoundly increased in the presence of Ach, neostigmine or eserine: the responses to the second and third trials of pilocarpine were reduced to approximately 8–10% or 30% of the corresponding first responses. Pilocarpine reportedly releases transmitters and alters choline-acetyltransferase activity.These results taken together suggest that either variable Ach synthesis, inhibitory transmitter release or possible toxic action in high concentrations may be involved in the pilocarpine-induced responses of the bovine iris sphincter muscle. The desensitization and parital agonist-antagonist action of pilocarpine could not explain the characteristics of the bovine iris sphincter muscle.     

Untersuchungen über den Gehalt von α-Ketoglutarsäure in Rinde und Kern verschieden alter Rinderlinsen

Zusammenfassung Es wird eine zur quantitativen Bestimmung von -Ketoglutarsäure in Augenlinsen ausgearbeitete optisch enzymatische Analysenmethode beschrieben; die Methode kann spezifisch und reproduzierbar verwendet werden.Der -Ketoglutarsäuregehalt wurde in Kälber- und Rinderlinsen, und zwar jeweils getrennt für Rinde und Kern bestimmt. Die Kälberlinse enthielt in der Rinde 2,44×10^–8 Mol/g (Frischgewicht) und im Kern 0,99×10^–8 Mol/g (Frischgewicht) -Ketoglutarsäure; die Rinderlinse enthielt in der Rinde 1,35×10^–8 Mol/g und im Kern 0,70×10^–8 Mol/g bezogen auf das Linsenfrischgewicht.     

Muscle tone and drug sensitivity of isolated bovine iris sphincter are enhanced at low temperatures

The effects of temperature on nerve-mediated or carbachol-induced contractions of isolated bovine iris-sphincter muscles were studied. A decrease in temperature (to below 36° C) led to contraction of the iris sphincter. The contractile responses induced by intramural cholinergic nerve stimulation were augmented by moderate cooling (29°–31° C), but were markedly inhibited by severe cooling (<22° C). On the other hand, after cooling the contractile amplitude induced by carbachol (3 × 10^–7 M) was enhanced to 258% ± 16% (29°–31° C), and 185% ± 12% (20°–21° C) of control levels. Whereas the cooling-induced development of muscle tone was inhibited by the presence of indomethacin and FPL-55712, the application of prostaglandins (10^–9 to 3 × 10^–8 M) led to restoration of the sensitivity of the muscle observed at low temperatures. As low temperatures increase the response of bovine iris-sphincter muscle, temperature might affect the state of the iris during intraocular clinical surgery and in cases of intraocular inflammation.     

MfERG waveform characteristics in the RS1h mouse model featuring a 'negative' ERG

Several retinal disorders lead to a relatively greater attenuation of the b-wave compared to the a-wave of the electroretinogram (ERG), a constellation called `negative' ERG. To determine the waveform characteristics of multifocal ERGs (mfERGs) and their dependence on recording parameters in such a case, we studied the Rs1h<sup>–/Y</sup> mouse, the model for x-linked juvenile retinoschisis. mfERGs were recorded with a VERIS 4 system connected to a piggyback stimulator prototype that added the stimulus to the optical pathway of a HRA scanning-laser ophthalmoscope (SLO) by means of a wavelength-sensitive mirror. Real-time fundus visualization was achieved with the infrared laser of the SLO (835 nm). High-pass filter settings and the time interval used by the `artefact removal' feature were varied to study their influence on the waveform. The mfERG in the Rs1h^–/Y mouse had a `negative' shape. However, the high-pass filter setting had to be lowered from the usual 10 Hz down to about 2 Hz in order to obtain that result, otherwise the negative shape was lost and mainly a positive peak remained. Similarly, a short time interval used by the `artefact removal' feature also removed the negative shape. The Rs1h^–/Y mouse was found to be a valuable model of diseases with a `negative' waveform shape also in mfERG. Our results underline the importance of a lower high-pass filter cutoff frequency when recording mfERGs in such disorders. In addition, if the `artefact removal' feature is used, it should be verified that it doesn't distort the waveform shape.     

The Role of Elastase in Corneal Epithelial Barrier Dysfunction Caused by Pseudomonas aeruginosa Exoproteins

PurposeTo investigate the role of elastase in corneal epithelial barrier dysfunction caused by the exoproteins secreted by Pseudomonas aeruginosa.MethodsExoproteins obtained from Pseudomonas aeruginosa culture supernatant were analyzed by shotgun proteomics approach. In vitro multilayered rabbit corneal epithelial barrier model prepared by air-liquid interface technique (CECs-ALI) were treated with 2 µg/ml exoproteins and/or 8 mM elastase inhibitor. Then the epithelial barrier function was evaluated by transepithelial electrical resistance (TEER) assay and tight junction proteins immunofluorescence. Cell viability and the apoptosis rate were examined by CCK8 assay and flow cytometry. TNF-α, IL-6, IL-8, and IL-1β levels were measured by ELISA. Mice cornea treated with exoproteins and/or elastase inhibitor were evaluated in vivo and in vitro.ResultsElastase (24.2%) is one of the major components of exoproteins. After 2 µg/ml exoproteins were applied to CECs-ALI for two hours, TEER decreased from 323.2 ±  2.7 to 104 ± 6.8 Ω/cm² (P < 0.001). The immunofluorescence results showed a distinct separation in tight junction and significant degradation of ZO-1 and occludin (P < 0.05). Elastase inhibitor (8 mM) alleviated the decrease in TEER value (234 ± 6.8 Ω cm²) induced by exoproteins. Inhibition of elastase decreased the apoptosis rate of CECs treated with exoproteins from 30.2 ± 3.8% to 7.26 ± 1.3% and the levels of inflammatory factors (P < 0.05). Mice corneal epithelium defect could be induced by exoproteins and protected by elastase inhibitor.ConclusionsElastase plays a critical role in corneal epithelial barrier dysfunction caused by Pseudomonas aeruginosa exoproteins via damaging tight junctions. The inhibition of elastase could protect the corneal epithelial barrier via reducing virulence and inflammation.     

Histoautoradiographic and electron microscopic studies on short-term explant cultures of the glaucomatous trabecular meshwork

Explant cultures of 15 trabeculectomy specimens derived from glaucomatous eyes were studied, using electron microscopy and histoautoradiography. The morphology of the trabecular meshwork was monitored for 3–14 days after explanation. In 4 cases the trabeculectomy specimens were cut in 2–3 pieces each and then incubated with¹⁴C-glucosamine at different times during the observation period (2–10 days). The cells of the cribriform layer and the outer corneoscleral trabeculae become activated as soon as 3–4 days after explantation, developing a large amount of endoplasmic reticulum, Golgi material, and numerous mitochondria. Histoautoradiographically, intense labeling of the trabecular meshwork, especially the cribriform layer, was found after incubation with¹⁴C-glucosamine. We assume that under tissue culture conditions the activated cells of the glaucomatous meshwork produce various types of glycosaminoglycans (GAGs) but, based on the experiments alone, no final conclusions can be made in this respect.This study was supported by grants from the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Ro 81/18-2) and from the Academy of Science and Literature, Mainz Rhein     

Corneal endothelial permeability after implantation of angle-fitted anterior chamber lenses in myopic phakic eyes

This present study aimed to evaluate the corneal endothelium after implantation of angle-fixed anterior chamber lenses in myopic phakic eyes. Twelve eyes (9 patients) with high myopia (more than –14 diopters) were implanted with ZB5M lenses (Domilens, France). The corneal endothelium was studied by fluorophotometry (endothelial transfer coefficient: k_c.ca), specular microscopy and ultrasonic pachimetry. Tests were performed prior to and 3 and 6 months after the surgery. The Wilcoxon rank test was used for the statistical analysis of the data. There was a significant difference (p<0.05) between the preoperative k_c.ca (4.15 ± 0.72 × 10^–3 min^–1) and the k_c.ca three months after the implantation (4.43 ± 0.87 × 10^–3 min^–1). A statistically significant difference (p<0.01) was also found between the three and six months postoperative k_c.ca (5.31 ± 0.81 × 10^–3 min^–1). There was a significant difference (p<0.05) between the preoperative central endothelial cell density (2533 ± 219 cells/mm²) and the six months postoperative central endothelial cell density (2385 ± 191 cells/mm²). No significant differences were found in relation to the central corneal thickness. In conclusion, three months after the implantation of ZB5M lenses to correct high myopia in phakic eyes, the corneal endothelial function was altered and continued to be so six months after the operation.Partially presented at the Association for Eye Research in Vision and Ophthalmology Meeting, Sarasota, May 1993. The authors have no commercial or proprietary interest in the lens used in this study.     

Die spektrale Empfindlichkeit der für den Pupillenlichtreflex verantwortlichen Photoreceptoren beim Menschen

Zusammenfassung Der Kontraktionsablauf (phasische Komponente) und die Pupillenweite (tonische Komponente) des konsensuellen Lichtreflexes der Pupille des menschlichen Auges wurden IR-reflektometrisch bestimmt.In Abhängigkeit vom Adaptationszustand, der Dauer, Leuchtdichte und Wellenlänge der Lichtreize beginnt die Iriskontraktion bei kurzdauernder (0,1 sec) Ganzfeldbelichtung nach einer Latenz von 0,2–0,5 sec und erreicht ihr Maximum 0,35–1,7 sec nach Reizbeginn. Die zur Iriskontraktion dunkeladaptierter Augen notwendige Schwellenleuchtdichte liegt bei 1,2–3×10^–6 cd/m². Sie beträgt das 1,6–2,4fache der sensorisch gemessenen Schwelle. Die bei stufenweise gesteigerter Adaptationsleuchtdichte geprüfte Spektralsensitivität zeigt eine Purkinje-Verschiebung bei sensorischer und pupillographischer Messung oberhalb 10^–6 skot. Troland. Die spektrale Empfindlichkeit des Pupillenlichtreflexes auf kurzdauernde Lichtreizung ist mit der psychophysisch gewonnenen skotopischen bzw. photopischen Empfindlichkeitskurve weitgehend identisch.Die IR-photographisch gemessene Änderung der Pupillenweite bei Dauerlicht wird erst im photopischen Leuchtdichtebereich deutlich. Sie beginnt bei Bestrahlung mit weißem Licht bei geringerer retinaler Beleuchtung (10^–1 skot. Trol.) als bei Verwendung monochromatischen Lichtes (10² skot. Trol.). Die für eine konstante Pupillenweite von 5 mm notwendige relative Lichtenergie ist bei 488 nm am geringsten.

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The spectral sensitivity of retinal photoreceptors conducting the pupillary light reflex in man

Summary The spectral sensitivity of retinal photoreceptors subserving the pupillary light reflex in man was determined photoelectrically (in response to light flashes) and photographically (in response to constant lights) by using infrared radiation directed onto the iris of the contralateral eye.With illumination of the total retinal field light flashes of 0.1 sec duration were followed, after a latent period of 0.2 to 0.5 sec, by an iris contraction. The time necessary for the maximum amplitude was 0.15 to 1.2 sec and depended upon state of adaptation, duration, luminance and wavelength of the stimulus. The luminance needed for a threshold response of the iris contraction varied between 1.2×10^–6 and 3×10^–6 cd/m². Slightly (1.6–2.4 times) lower values were found for the absolute visual threshold. The spectral sensitivity of the pupillomotor reaction in response to light flashes was similar to the scotopic and photopic spectral sensitivity curves psychophysically determined.The luminosity function of the receptors governing the size of the pupillary diameter was determined by exposing the eye to steady lights of increasing luminances and of various wavelengths. Therefrom the relative energy for a constant pupillary diameter of 5 mm was determined. The sensitivity distribution followed a curve showing a peak wavelength at _max=488 nm. This was seen within the photopic range of illumination. It is suggested that during steady illumination mainly the blue and green cones act as the pupillomotor photoreceptors for the steady-state reactions in the human eye.