The effect of the water-drinking test on aqueous humor dynamics in healthy volunteers

In 19 healthy volunteers (9 men, 10 women) we studied the effect of drinking 1000 ml of water within 10 min on aqueous humor dynamics. Fluorescein was applied topically five times, 6 h before measurements. All readings were taken during the afternoon. The Wilcoxon signed-rank test was used to evaluate the statistical relevance of the data. Aqueous humor flow was measured 60 min before (F1) and 10 min (F2), 30 min (F3), 60 min (F4) and 90 min (F5) after drinking 11 of water. Flow (mean ± SD) changed as follows: F1, 2.25 ± 1.2 ll/min ; F2, –3.29 ± 3.4 /min (P < 0.0000); F3, 1.69 ± 1.0 gml/min (P=0.007); F4, 2.39±0.9 l/min (P=0.25); F5, 2.64±0.9 l/min (P=0.02). Three to four days later the identical procedure was performed in each individual: F1, 2.06 ± 1.0 l/min F2, –3.12 ± 2.4 l/min (P < 0.0000); F3, 1.09 ± 0.6 l/min (P < 0.0001); F4, 1.76 ± 0.6 l/min (P=0.15); F5, 2.54±0.8 l/min (P=0.01). The correlation coefficient for the left and night eyes (F1–F5, both days) was r=0.85. The mean flow in the 19 healthy volunteers during the afternoon hours was 2.25 ± 1.0 l/min. Water load consistently led to a reflux of unbound fluorescein into the eye about 10 min later. This is documented as a negative flow. Ninety minutes after drinking 1000 ml of water there is a significant increase in flow, which is in contrast to the normal diurnal curve of aqueous humor dynamics. Water load causes hydremia and an increase in episcleral venous pressure. Fluorophotometry together with water load may be useful to study the aqueous humor dynamics in healthy and glaucomatous eyes and eyes with ocular hypertension.     

Vitreous laser absorption following fluorescein angiography in diabetic patients

Background: Sodium fluorescein staining of the vitreous following fluorescein angiography may interact with laser photocoagulation. Methods: We evaluated the laser absorption by fluorescein in the vitreous when photocoagulation is performed following fluorescein angiography in 15 eyes of nine diabetic patients. Axial fluorescein concentration in the vitreous was measured by a scanning vitreal fluorophotometer. The amount of light absorbed by the fluorescein within the vitreous was calculated according to the Lambert-Beer law. Results: The mean fluorescein concentration ranged from 2.93 ng cm^–3 to 105.16 ng cm^–3 at 1 h after injection of fluorescein and from 8.03 to 188.56 ng cm^–3 after 4 h. Maximum laser absorption at 488 nm ranged from 6.79% (after 1 h) to 14.53% (after 4 h); at 514.5 nm it ranged from 0.96% to 2.14%; at 532 nm it ranged from 0.03% to 0.07%. At >550 nm, laser absorption was found to be negligible. Conclusions: In order to optimize the effect of photocoagulation, especially during long photocoagulation sessions, argon blue laser (488 nm) should be avoided following fluorescein angiography. Argon green laser (514.5 nm) should be used within 1 h after fluorescein injection. Frequency-doubled Nd:YAG laser (532 nm), krypton laser (647 nm) or semiconductor diode laser (810 nm) may be used at any time.Presented at the Association for REsearch in Vision and Ophthalmology Annual Meeting, Sarasota, Florida, 1–6 May 1994     

Vitreous Fluid Levels of β-Amyloid(1–42) and Tau in Patients with Retinal Diseases

Purpose A decrease in -amyloid_1–42 (A42) and an increase in tau in the cerebrospinal fluid are reported to be characteristic phenomena in Alzheimers disease patients. To test the idea that A42 and tau contribute to the development of retinal diseases, we measured A42 and tau concentrations in the vitreous fluid from patients with macular hole (n = 13), diabetic retinopathy (n = 15), or glaucoma concurrent with other ocular diseases (n = 8).Methods Vitreous samples were collected from patients who underwent vitrectomy, and sensitive and specific enzyme-linked immunosorbent assays were used to determine the concentrations of A42 and tau.Results By comparison with the levels in the control macular-hole patients (33.9 ± 7.1pg/ml for A42; 3.3 ± 3.2pg/ml for tau), there was a significant decrease in the A42 level and a significant increase in the tau level in patients with diabetic retinopathy (1.8 ± 1.9pg/ml for A42, P = 0.002; 153.7 ± 71.6pg/ml for tau, P = 0.041) or glaucoma concurrent with other ocular diseases (2.8 ± 1.8pg/ml for A42, P = 0.006; 113.6 ± 43.1pg/ml for tau, P = 0.023).Conclusions Our findings indicate the possibility of a role for A42 and tau in the pathogenesis of some retinal diseases. Jpn J Ophthalmol 2005;49:106–108 © Japanese Ophthalmological Society 2005     

Ultrasound biomicroscopic analysis of the effect of pilocarpine on the anterior chamber angle

Background: This study was carried out to determine the effects of pilocarpine on the anterior chamber angle in healthy volunteers. Methods: We measured changes in anterior chamber depth (ACD), trabecular-iris angle (TIA), angle opening distance at 250 and 500 m from the scleral spur (AOD250 and AOD500), and iris thickness using ultrasound biomicroscopy in 48 eyes of 48 normal volunteers (ages 18–57 years, mean 34.8 years) before and 1 h after instillation of 2% pilocarpine. Results: Pilocarpine altered the TIA by –18.6° to + 10.5° (mean –4.16°), and change in the TIA increased significantly and linearly in relation with decrease in the pretreatment TIA (r = 0.929). Pilocarpine altered AOD250 change by –136 to +94 m (mean –38 m) and AOD500 by –151 to +157 m (mean –42 m); changes in the AOD250 and AOD500 were significantly correlated to the pretreatment AOD250 and AOD500 values, respectively (r = 0.923 andr = 0.896, respectively). The pilocarpine-induced change in the ACD showed a linear relationship to the pretreatment ACD (r = 0.887). The changes in the TIA, AOD250 and AOD500 showed greater increases in association with lower pretreatment ACD (r = 0.848,r = 0.891,r = 0.842) and smaller change in the ACD (r = 0.834,r = 0.839,r = 0.812). Conclusions: The response of the anterior chamber angle to pilocarpine, narrowing or widening, depended on its pretreatment state. The ability to predict the pilocarpine-induced change in the angle before the instillation of pilocarpine would be helpful in treating patients with glaucoma.     

Phacoemulsification and implantation of posterior chamber intraocular lens in eyes with quiescent proliferative diabetic retinopathy

A phacoemulsification procedure, combined with an in-the-bag lens implantation, was performed on ten eyes that once had proliferative diabetic retinopathy (PDR). The ten eyes were in eight patients who had a 20-plus year history of either type I or type II diabetes mellitus. All eyes had reached the quiescent state of diabetic retinopathy 2–13 years before the cataract surgery through either argon laser pan retinal photocoagulation and/or pars plana vitrectomy. Nine of ten eyes remained completely free of retinal neovascularization and rubeosis iridis, with follow-up periods between 1.5 and 5 years. One eye has been lost to recurrent vitreous hemorrhages and an inoperable retinal detachment.Presented in part at the XVth Meeting of the Club Jules Gonin, Copenhagen, 10–15 August 1986     

Die Stereo-Ultrastruktur der Cornealoberfläche bei der Ratte

Zusammenfassung Die dreidimensionale Beschaffenheit der Cornealoberfläche der Ratte wurde mittels des Scanning Electron Microscope und anhand konventioneller elektronenmikroskopischer Schnittpräparate untersucht. Dabei konnte das Vorhandensein von Mikrovilli (0,15 breit, bis 1,0 hoch) und von Mikroplicae (0,1–0,2 breit, 0,3–0,4 hoch, 1–3 lang) nachgewiesen werden. Bei diesen Strukturen dürfte es sich um während der Desquamation entstandene Ausstülpungen der Epithelzellmembran im Bereiche der Desmosomen handeln.

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The stereo ultrastructure of the corneal surface in rat

Summary Combined morphological examination of the corneal surface of rat both with the scanning and the transmission electron microscope reveals two kinds of protrusions covering the polygonal, regularly arranged epithelial cells: Mikrovilli and Mikroplicae; the former being approximatively 0.15 large and up to 1.0 high, the latter being 0.1–0.2 large, 0.3–0.4 high and 1–3 long. These formations are with high probability the remnants of desmosomes having been formed during desquamation.

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Diese Untersuchungen wurden mit Unterstützung des Fonds National suisse de la recherche scientifique (Nr. 5322.3) durchgeführt.     

Methods of visual acuity determination with the spatial frequency sweep visual evoked potential

Purpose The spatial frequency sweep visual evoked potential (sVEP) is used to rapidly determine visual acuity in children or non-responsive patients. Two techniques have been used to separate signal from noise: (1) the 95% confidence interval for the signal amplitude (95% CI) or (2) the amplitude of a Fourier frequency adjacent to 2×the signal frequency (DFT). The purpose of this study is to determine if there is a significant difference in acuity estimates with these techniques.Methods Ten normal subjects (approximately 0.00logMAR acuity) and 11 patients with decreased visual acuity took part in this project. Stimulus production and data analysis were done with an Enfant 4010 (Neuroscientific Corp). Standard VEP recording techniques were employed. The stimulus was a horizontal-oriented, sine wave grating that swept up the spatial frequency spectrum (contrast 80%, temporal reversal rate 7.5Hz). Sweeps were repeated until the confidence intervals for the data were no longer decreasing. The Bailey LovielogMAR chart was used to determine visual acuity. A line was fit to the high spatial frequency data using either the 95% CI or the DFT as the noise estimate. By using these linear equations, acuity estimates were obtained at 0, 1, and 2V signal amplitudes.Results The average logMAR acuity for the subjects with normal acuity was –0.06±0.070 (SD). The sVEP acuity estimates were 0.08±0.098, 0.18±0.092, and 0.33±0.195 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.07±0.100, 0.18±0.103, and 0.33±0.202 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.10±0.098logMAR. The averagelogMAR acuity for the subjects with decreased visual acuity was 0.67±0.306 (SD). The sVEP acuity estimates were 0.53±0.175, 0.66±0.171, and 0.88±0.295 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.53±0.179, 0.65±0.176, and 0.86±0.268 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.57±0.186logMAR. No significant difference was found between the two acuity estimate techniques for all of the subjects (repeated measures ANOVA, p=0.16, F₂₀=2.131). The sVEP estimates of acuity to the 0V and noise levels were not significantly different from the logMAR acuity (paired t-test, all p values >0.05).Conclusions The results indicate that the sVEP acuity does not depend on the noise estimation technique. In agreement with prior studies, the sVEP acuity underestimates the logMAR acuity in normally sighted individuals by about an octave.     

Topical and intravenous gentamicin in traumatically lacerated eyes

Intravenous or topical gentamicin may be the initial mode of treatment for lacerated or ruptured eyes by emergency room physicians while awaiting ophthalmic consultation and surgical repair. The purpose of this study was to determine the possibility of having retinotoxic intravitreal gentamicin concentrations in experimentally lacerated rabbit eyes treated with either intravenous or topical gentamicin separately or in combination with each other. Nontoxic concentrations of gentamicin were found in the vitreous bodies by all routes of drug administration. After 3 h intravitreal concentrations of gentamicin were: 0.20–0.30 g/ml when treated intravenously, 0–2.9 g/ml when treated topically, and 0.20–0.51 g/ml when treated both intravenously and topically. While the upper range of topically applied gentamicin concentrations (2.9 g/ml) is therapeutic for some pathogens, the wide range of intravitreal concentrations (0–2.9 g/ml) achieved does not indicate that topically applied gentamicin with or without intravenously administered gentamicin can reliably achieve therapeutic concentrations. Offprint requests to: M.O. Yoshizumi

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The effects of β-adrenergic agonists on cone systems in the cat eye

The effects of the -adrenergic agonist nylidrin and the ₂-adrenergic agonist clenbuterol on electroretinogram and optic nerve response were studied in the isolated and arterially perfused, light-adapted cat eye. Two cone mechanisms, short wavelength-sensitive and long wavelength-sensitive, were functionally separated by means of intense yellow adaptation. A reversible increase in b-wave amplitude in response to nylidrin or clenbuterol was observed for the cone systems. Both drugs also caused a reversible alteration in configuration of the optic nerve response, mainly a depression of the late components related in time to the changes in the electroretinogram. These observations suggest that -adrenergic mechanisms are involved in cone systems. The greater increase in b-wave amplitude on 558-nm stimulation and preliminary evidence for greater increase in sensitivity observed in the V-log I function compared with 439 nm further suggest that the short and long wavelength cone systems are affected differently by -adrenergic agonists.     

Argon-Laser Coagulation der Kanincheniris

Zusammenfassung Beim Chinchilla-Kaninchen wurde das kammerwinkelnahe Drittel der Iris nach Ermittlung der Schwellenwerte mit Argon-Laser-Energien von 0,02–4,8 J und einem Brennfleckdurchmesser von 50 m coaguliert. Irisschädigungen, die mit einer Energie von 1,2 J erzielt werden konnten, untersuchten wir 30 min post coagulationem sowie 72 Std, 10 und 28 Tage nach der Exposition spaltlampen-, stereo- und rasterelektronenmikroskopisch. Nach 30 min findet sich ein zentraler Substanzdefekt von 50–80 m Durchmesser, der von einer intermediären Zone 30–60 m Breite stärkerer Zelldestruktion umgeben ist. Daran schließt sich eine periphere Zone abnehmender Zellstörung bis zu 200 m Breite an. Nach 72 Std lassen sich am Rand des zentralen Defektes entzündliche Zeichen nachweisen. Nach 10 bzw. 28 Tagen bleibt der zentrale Defekt erhalten, die oben genannten angrenzenden Zonen sind jedoch nicht mehr eindeutig abgrenzbar.

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Argon-laser coagulation in the rabbit irisDetermination of threshold dosis and respective scanning electron microscopic findings

Summary The lateral third of the iris near the chamber angle was photocoagulated after determination of the threshold dose with argon-laser energy of 0.02–4.8 J and spot diameters of 50 m. Iris lesions produced with energy levels of 1.2 J, were examined with slitlamp, dissecting microscope, and scanning electron microscope. After 30 minutes the following findings were recorded: central stromal defect 50–80 m in diameter, surrounded by an intermediary zone of 30–60 m with severe cell destruction; a peripheral zone up to 200 m in breadth with less cell fragmentation adjacent to the intermediary zone. After 72 hours the margin of the central defect showed inflammatory changes. After 10–28 days the central defect remained stable; the bordering zones described previously were no longer discernible.

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Auszugsweise vorgetragen auf der 45. Versammlung der Vereinigung Rhein-Mainischer Augenärzte am 14. und 15. Oktober 1972 in Mainz.

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Die Untersuchungen wurden in dankenswerter Weise unterstützt durch die Jung-Stiftung für Wissenschaft und Forschung und die Stiftung Volkswagen-Werk.     

Bemerkungen zuW. Burkl undF. Schwabs Arbeit: „Histologischer und immunhistologischer Nachweis der lokalen Antikörperbildung in der Hornhaut”

Zusammenfassung Die Bezeichnungen Wanderzellen und Leukocyten für die Entzündungszellen der Hornhaut sind falsch und experimentell widerlegt.Dem örtlichen Charakter der Keratitiden entspricht die vonBurkl undSchwab nachgewiesene örtliche Entstehung von Antikörpern in der Hornhaut.Albrecht v. Graefes Arch. Ophthal.161, 168–184 (1959).     

Cytotoxic effects of antiproliferative agents on human retinal glial cells in vitro

Purpose: Proliferative vitreoretinopathy (PVR) is characterizedby the formation of cellular membranes on the detached retina and also in the vitreous. Glial cellscan be found in epiretinal and subretinal membranes from eyes with PVR, proliferative diabeticretinopathy (PDR), idiopathic macular pucker, uveitis and other diseases affecting theretina. Proliferation and contraction of glial cells appears to play a role in the pathogenesisof PVR. This study is designed to inspect the effectiveness of harringtonine, as well as colchicine,daunomycin and fluorouracil, against cellular proliferation of cultured human retinal glial cellsthat might be involved in the retinal and/or vitreous proliferation. Methods: Cultures of human retinal glial cells were preparedusing the enzyme digesting method. Cells that had been in culture for 2–5 passages were usedin this study. Harringtonine (0.063 g/ml 2.0 g/ml), colchicines(0.5 g/ml 16.0 g/ml), daunomycin (0.1 g/ml 3.2 g/ml) and 5-fluorouracil(0.5 g/ml 16.0 g/ml) were added to cultures of human retinal glial cellsand the proliferation rates of the cells were measured by the MTT method. Results: Harringtonine at the dosage of 0.063 g/mlinduced suppression of cellular growth, but the changes were not statistically significant (p > 0.05).At a dosage ranging from 0.125 g/ml to 2.0 g/ml, harringtonine significantly suppressedcellular growth according to the test (p < 0.01). Likewise, other antiproliferativeagents inhibited cellular growth significantly at a dosage from 1.0 g/ml to 16.0 g/ml(colchicine), 0.2 g/ml to 3.2 g/ml (daunomycin) and 1.0 g/ml to 16.0 g/ml(5-fluorouracil), but not at 0.5 g/ml (colchicine), 0.1 g/ml (daunomycin) and0.5 g/ml (5-fluorouracil). The ID₅₀ were 0.33 g/ml (harringtonine), 3.11 g/ml (colchicine), 0.79 g/ml (daunomycin) and 5.23 g/ml (5-fluorouracil), respectively.Conclusions: Harringtonine was extremely effective ininhibiting human retinal glial cell proliferation, like other antiproliferative drugs such as colchicine,daunomycin and 5-fluorouracil. Harringtonine, therefore, may be a candidate for further studies regardingthe treatment of experimental PVR.     

A comparative study of the effects of argon and diode laser photocoagulation on retinal oxygenation

Background: The purpose of this study was to compare the effects of diode and argon laser photocoagulation (DLP and ALP) on the preretinal oxygen tension (P_O2): (1) directly over photocoagulated retina and (2) in between laser lesions. Methods: DLP or ALP was applied to avascular rabbit retina to produce grade II lesions. On the day of the oxygen measurement, a droplet of perfluorotributylamine was placed into the preretinal vitreous space over the lasered area of retina and the steady-state P_O2 was measured in normoxic animals using¹⁹F magnetic resonance spectroscopy. To determine the P_O2 directly over laser lesions, small (5l) droplets were placed over large ( 4 mm X 5 mm), confluent areas of treatment (burn area 95% of the treated retinal surface area). To determine the P_O2 in between laser lesions, a larger (10 –l) droplet was placed over a field of scatter photocoagulation (burn area 30% of the treated retinal surface area). The theoretical basis for this approach is discussed. Results: Untreated eyes had a preretinal P_O2 of 22±9 mm Hg (mean ± SD,n=15 eyes). The preretinal P_O2 was significantly higher over confluent, 12-day-old ALP or DLP lesions (51+13 mm Hg,n=8 eyes;P<0.01) compared to untreated eyes. However, at that time, DLP lesions had significantly higher P_O2 values (60±13 mm Hg,n=4 eyes) than did ALP lesions (42±6 mm Hg,n=4 eyes;P=0.04). The preretinal space in between laser lesions generally showed no significant increase in P_O2 (P>0.05) over controls on post-treatment days 1, 5, 14 and 47. The only exception was in the DLP group of eyes, in which a significant increase in P_O2 over untreated or ALP-treated eyes occurred on post-treatment day 5 (41±7 mm Hg,n=5 eyes;P=0.01). Over photocoagulation lesions in this study, DLP produced a greater increase in preretinal P_O2 compared to control values than did ALP. Conclusions: These results support the use of DLP as an alternative to ALP for the treatment of retinal vascular diseases in which hypoxia is suspected to play a role.     

Comparing Brimonidine 0.2% to Apraclonidine 1.0% in the Prevention of Intraocular Pressure Elevation and Their Pupillary Effects Following Laser Peripheral Iridotomy

Purpose To compare the effects of brimonidine 0.2% and apraclonidine 1% on intraocular pressure (IOP) and pupil size in patients undergoing laser peripheral iridotomy (LPI).Methods Forty patients (40 eyes) with occludable angle or angle-closure glaucoma requiring LPI were recruited. Patients were randomized to receive either brimonidine 0.2% or apraclonidine 1% before and after LPI. The IOPs were measured at 1, 2 and 3h after LPI, and pupil size was measured before and at 45min after eyedrop instillation. Both parameters were analyzed using the t test.Results There were 20 patients in each group. The baseline IOP was 17.1 ± 3.2mmHg for the brimonidine group and 16.7 ± 2.8mmHg for the apraclonidine group (P = 0.67) (t test). The mean IOP 3h after laser treatment was 18.2 ± 7.8mmHg for the brimonidine group and 15.7 ± 5.6mmHg for the apraclonidine group (P = 0.25) (t test). There was no statistically significant difference between the two groups in the mean IOP changes at 1, 2, or 3h after LPI. The mean change in pupil size after brimonidine was –0.33 ± 0.37mm and after apraclonidine was +0.90 ± 0.87mm. The difference was significant (P < 0.001).Conclusion Brimonidine 0.2% was found to have an efficacy comparable to that of apraclonidine 1.0% in preventing post LPI IOP spikes. Apraclonidine 1.0% tends to have a pupil dilating effect while brimonidine 0.2% tends to constrict the pupil. Jpn J Ophthalmol 2005;49:89–92 © Japanese Ophthalmological Society 2005     

Homocysteine and nitric oxide levels in plasma of patients with pseudoexfoliation syndrome,pseudoexfoliation glaucoma,and primary open-angle glaucoma

Purpose To evaluate plasma total homocysteine (tHcy) and nitric oxide (NO) marker levels in patients with pseudoexfoliation syndrome (PXS), pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG), and normal controls.Methods This cross-sectional, prospective study involved 19 patients with POAG, 18 with PXS, 22 with PXG, and 20 control subjects. Fasting tHcy levels of all study participants were determined using a fluorescence polarization immunoassay method. Quantitation of total nitrate was based on the Griess reaction, in which a chromophore with a strong absorbance at 545 nm is formed by reaction of nitrite with a mixture of naphthylethylenediamine and sulphanilamide.Results The mean plasma homocysteine level was statistically significantly elevated in the PXS (p=0.033) and the PXG (p=0.023) groups but not in the POAG group (p=0.996) when compared with the control group. Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in plasma homocysteine concentration was a significant risk factor for PXS (odds ratio per 1 mol/l increase in homocysteine concentration=2.05, 95% CI=1.19–3.52) and PXG (odds ratio per 1 mol/l increase in homocysteine concentration=1.36, 95% CI=1.00–1.85) but was not a significant risk factor for POAG (odds ratio per 1 mol/l increase in homocysteine concentration=0.99, 95% CI=0.78–1.26). NO markers levels were found to be slightly higher in PXS and PXG patients than control and POAG patients but the differences were not statistically significant (p=0.151). Multiple logistic regression analyses comparing the various patient groups with the single control group indicated that elevation in NO marker concentration was not a significant risk factor for PXS (odds ratio per 1 mol/l increase in NO concentration=1.00, 95% CI=0.99–1.01), PXG (odds ratio per 1 mol/l increase in NO concentration=1.00, 95% CI=0.99–1.00) and POAG (odds ratio per 1 mol/l increase in NO concentration=0.99, 95% CI=0.99–1.00). No statistically significant correlations were observed between plasma tHcy and NO markers in study groups (p>0.05).Conclusion Elevated levels of homocysteine in pseudoexfoliation patients with and without glaucoma may partly explain the increased risk of vascular disease among patients with pseudoexfoliation. No significant difference was found in plasma NO markers among the POAG, PXS, PXG, and the control subjects.     

Experimental evaluation of online optical coherence pachymetry for corneal refractive surgery

Purpose Online optical coherence pachymetry (OCP) allows to monitor central changes of the corneal cross section intraoperatively. In this experimental evaluation the validity of the optical measurements for corneal refractive surgery was assessed.Methods Online OCP based on low-coherence interferometry with a wavelength of 1310 nm and a measurement frequency of 74 Hz was directly integrated in a clinical excimer laser. In 16 patients the central corneal thickness was measured with online OCP and ultrasound pachymetry (US). Furthermore, the ablation characteristics were assessed in corneoscleral discs unsuitable for transplantation (n=12) and PMMA samples (n=18).Results Online OCP was possible in all patients and materials studied. The mean central corneal thickness was 537±31 m (OCP) and 546±33 m (US). The corneal reproducibility was ±4.3 m (coefficient of variation [CV] 0.8%) with online OCP and ±3.7 m (CV 0.68%) with US. The reproducibility in PMMA samples was ±1.0 m (CV 0.16%). There was a significant correlation between online OCP and US measurements (r=0.93, P<0.001). The mean difference was 9.1 m or 1.69% (P=0.01), and the limits of agreement (95% CI) ranged from –15 m to 33 m. There was a significant linear relationship (r=0,95; P<0.001) between the calculated and the optically determined ablation depth with online OCP. Also ablation depth measurements in PMMA correlated positively with spectrophotometric values (r=0.98; P<0.001).Conclusion In this experimental evaluation, online OCP revealed to be a precise and reproducible method to assess the central corneal thickness and its changes intraoperatively. This could be important to monitor incisional and excimer laser-based corneal refractive procedures, such as PRK or LASIK.The authors have no commercial, proprietary or financial interest in any research or devices described in the presented study     

The Effect of the Corneal Epithelium on the Intraocular Penetration of Fluoroquinolone Ophthalmic Solution

Purpose Pharmacokinetic studies of antibacterial agents for infectious eye diseases have usually been performed on normal rabbit eyes. In this study, the intraocular penetration of fluoroquinolone ophthalmic solutions was determined in normal rabbit eyes and in rabbit eyes that had the corneal epithelium intentionally removed.Methods We determined the intraocular penetration of ofloxacin (OFLX), levofloxacin (LVFX), and norfloxacin (NFLX), fluoroquinolone ophthalmic solutions that are already on the market and undergoing clinical studies, by injecting 50µl of each solution into the cul-de-sacs of rabbit eyes three times at 15-min intervals. The drug concentration at 10, 30, 60, 120, and 240min after final instillation was determined by high-performance liquid chromatography.Results The maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 ± 1.56µg/ml (60min, OFLX), 2.57 ± 1.00µg/ml (30min, LVFX), and 0.42 ± 0.12µg/ml (120min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 ± 5.62µg/ml (30min, OFLX), 9.02 ± 2.45µg/ml (60min, LVFX), and 8.54 ± 5.17µg/ml (30min, NFLX). The drug penetration of the eye drops into eyes with removed corneal epithelium was around 6 times (OFLX), 3.5 times (LVFX), and 20 times (NFLX) higher than the penetration into the eye with normal cornea.Conclusion Among the pharmacokinetic parameters of the three ophthalmic solutions according to the one-compartment model, the maximum concentration in the aqueous and the area under the concentration–time curve in the aqueous tended to be higher in the eyes with intentionally removed corneal epithelia than in those with normal corneas. Jpn J Ophthalmol 2004;48:93–96 © Japanese Ophthalmological Society 2004     

Tierexperimentelle Untersuchungen zur Bestimmung der Dauer der „mechanisch-effektiven Periode“ des Muskelfasermembranaktionspotentials und der „elektro-mechanischen Latenzzeit“ der „fast fibres“ äußerer Augenmuskeln bei Kaninchen in vivo

Zusammenfassung Es wird über tierexperimentelle Untersuchungen zur Bestimmung der Dauer der mechanisch-effektiven Periode des Muskelfasermembranaktionspotentials und der elektro-mechanischen Latenzzeit von fast fibres äußerer Augenmuskeln bei Kaninchen in vivo berichtet.Die Untersuchungen wurden mit einer international standardisierten Glasmikroelektrodentechnik durchgeführt. Die statistische Auswertung basiert auf 250 Einzelregistrierungen in Superpositionstechnik.Den Mittelwert der mechanisch-effektiven Periode des Muskelfasermembranaktionspotentials bestimmten wir mit ¯x=0,52 ms, Standardabweichung s=0,08 ms. Die Vertrauensgrenzen lagen bei 99 % statistischer Sicherheit bei 0,43 ms und bei 0,55 ms. Nach diesen Untersuchungen beträgt die Dauer der mechanisch-effektiven Periode der fast fibres äußerer Augenmuskeln nur 1/3 der mechanisch-effektiven Periode der vergleichbaren Skelettmuskeln.Der Mittelwert der Dauer der elektro-mechanischen Latenzzeit der fast fibres wurde mit ¯x=1,97 ms berechnet, Standardabweichung s=0,30 ms. Die Vertrauensgrenzen lagen bei 99 % statistischer Sicherheit bei 1,86 ms und 2,08 ms. Die elektromechanische Latenzzeit der fast fibres äußerer Augenmuskeln ist also wesentlich geringer als die vergleichbarer Skelettmuskeln, sie liegt unter der 50 %-Grenze der elektro-mechanischen Latenzzeit der analogen Skelettmuskulatur.Durch diese Untersuchungen konnten die wichtigsten elektrophysiologischen Parameter bestimmt werden, die den Grenzwert der maximalen Geschwindigkeit einer Blickrichtungsänderung bedingen.

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Animal experimental investigations for determining the duration of the mechanical-effective period of muscle action potentials and of the electro-mechanical latency period of fast fibres of external ocular muscles

Summary A report is given of an animal experimental study for determination of the duration of the mechanical effective period of the muscle fiber membrane action potential and the electromechanical latency period of fast fibers of the external ocular muscles in rabbits in vivo.The studies were carried out with an internationally standardized glass micro-electrode technique. The statistical values are based on 250 tests employing the superposition technique.The mean mechanical effective period of the muscular fiber membrane action potential was determined with SE=0.52 ms, SD=0.08 ms. The confidence thresholds were 99% statistically reliable with 0.43 ms and 0.55 ms. According to these studies, the duration of the mechanical effective period of the fast fibers of the external ocular muscles was only one-third off the mechanical effective period of the skeletal muscles.The mean duration of the electromechanical fast-fiber latency period was calculated with SE=1.97 ms, SD=0.30 ms. The confidence threshold was 99% statistically reliable with 1.86 ms and 2.08 ms. The electromechanical latency period of the fast fibers of the external ocular muscles was therefore significantly less than the skeletal muscles, lying under the 50% limit of the electromechanical latency period of the analogous skeletal musculature.These studies permit determination of the most important electrophysiological parameters which define a threshold value of maximal speed in vision direction changes.

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Die experimentellen Untersuchungen wurden im Physiologischen Institut der Martin-Luther-Universität Halle mit Unterstützung durch Herrn Dr. rer. nat. H. Opitz durchgeführt, damaliger Direktor: Prof. Dr. med. habil. B. Lueken     

Vitreous body affects activation and maturation of monocytes into macrophages

Background: Macrophages play an important role in several ocular diseases. Because macrophages localized in ocular tissues may be derived from blood monocytes, the effect of vitreous [containing transforming growth factor- 2 (TGF-2) and hyaluronic acid] on blood monocytes, maturating in the tissue to macrophages, was determined. Methods: Human monocytes were cultured with and without vitreous in RPMI 1640 medium containing human AB serum. As a parameter of activation the release of interleukin-6 was measured by the B9 bioassay; as an indication of maturation, the content of acid phosphatase and the increase in cell size were assessed. Results: Monocytes in vitreous-containing medium grew more slowly than did control monocytes. Monocytes cultured in 10% vitreous released 51% less, and in 20% vitreous 73% less, interleukin-6 than control monocytes. Vitreous at 20% significantly (P=.0075) reduced the amount of acid phosphatase by 80% over a 4-day culture period. This reduction was partially eliminated with neutralizing antibodies to TGF- (P=0.0014). Furthermore, human recombinant TGF-₂ increased the activity of acid phosphatase in monocytes at 1.25 ng/ml and reduced it (P<0.0001) at higher concentrations (5–10 ng/ml). Hyaluronic acid showed an effect additive to that of TGF- in further diminishing the amount of acid phosphatase (P=0.026). Conclusion: Vitreous exerts a regulatory effect on monocyte activation and maturation by its content of TGF- and possibly hyaluronic acid and may, thus, modify the inflammatory or immune response in the eye.     

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 l: 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.