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At least 919 records · Page 51Linked to original sources
PubMed1983

Acute effects of topical phenylephrine on aqueous humor dynamics and corneal endothelial permeability in man.

Acute effects of topical phenylephrine, an alpha-1 adrenergic agonist, on the aqueous humor dynamics and corneal endothelial permeability were studied by means of the oral fluorescein method in 11 normal young volunteers. Twenty microliters of phenylephrine HCL (10%) was instilled in one eye and the placebo in the other eye in a double masked manner. The instillations were carried out 0.5 hour before, and 2, 4 and 6 hours after the fluorescein ingestion. Fluorophotometric measurements were carried out in the central cornea, anterior chamber and plasma ultrafiltrate, and the aqueous-cornea transfer coefficient in reference to the corneal volume (kc.ac), the transfer coefficient in the anterior chamber by diffusion (kd.pa) and by flow (kfa) were calculated in each eye. The thickness of the cornea (CT), intraocular pressure (IOP) and anterior chamber volume (Va) were also measured. No significant difference was found in the CT, kc.ac, corneal endothelial permeability (kc.ac x the thickness of the stroma), Va, IOP and kfa between the experimental and control eyes, while the kd.pa was significantly smaller in the experimental eyes (paired t-test, P less than 0.01). The iris permeability factor (kd.pa x Va) decreased significantly to 0.74 +/- 0.26 (Mean +/- SD) of the control (P less than 0.01). The aqueous flow rate (kfa x Va) averaged 0.95 +/- 0.21 of the control, and the difference from unity was not significant (P greater than 0.1).

Adult↗
PubMed1986

Acute effects of topical forskolin on aqueous humor dynamics in man.

Previous reports concerning the acute effects of topical forskolin on the intraocular pressure (IOP) and the aqueous humor dynamics in human eyes gave conflicting results, and this led us to reevaluate the effects of this drug in a total of 20 young normal Japanese volunteers. Fifty microliter of 1% forskolin was instilled in one eye, and the vehicle to the fellow control eye. After two instillations of the drug at an interval of 5 minutes, the maximum IOP fall of 2.4 +/- 1.3 mmHg occurred after 1 hour; a single instillation had no significant effect. The effects on the aqueous flow rate and iris permeability factor were determined by the oral fluorescein method. Two instillations of the drug reduced the aqueous flow rate to 87 +/- 7% of the control, while the iris permeability factor was increased to 114 +/- 11% (mean +/- SD, N = 10, P less than 0.005). Pretreatment with topical 0.25% 1-timolol in both eyes 1 hour prior to the drug administration did not significantly alter the forskolin effects.

Administration, Topical↗
PubMed1999

Effects of topical epinephrine on aqueous humor dynamics in the cat.

The purpose of this study was to investigate, in cats, the effects of topical epinephrine on aqueous humor dynamics as measured by the non-invasive method of fluorophotometry and by other methods. Measurements were carried out on 12 cats before and after one week of twice daily treatment with 2% epinephrine hydrochloride to one eye. Aqueous flow and outflow facility were determined using fluorophotometry. Uveoscleral outflow was calculated from these results and was evaluated with anterior chamber perfusion of FITC-dextran. Outflow facility also was measured by tonography. Epinephrine-treated eyes, compared with their baseline values, showed a 31% reduction in intraocular pressure (P<0.001), a 23% reduction in aqueous flow (P<0.05), a 60% increase in fluorophotometric outflow facility (P<0.05), and a 43% increase in tonographic outflow facility (P<0.05). Treated eyes, compared with contralateral control eyes, showed a 27% reduction in IOP (P<0.005), a 25% reduction in aqueous flow (P<0.005), a 38% increase in fluorophotometric outflow facility (P<0.05), and a 34% increase in tonographic outflow facility. When evaluated by both fluorophotometry and FITC-dextran tracer methods, epinephrine had no significant effect on uveoscleral outflow. It was concluded that, in cats treated with topical epinephrine twice daily for a week, a reduction in intraocular pressure is induced by an increase in outflow facility and decrease in aqueous flow.

Administration, Topical↗
PubMed2001

Penetration of ofloxacin and ciprofloxacin into the aqueous humor of eyes with functioning filtering blebs: a randomized trial.

OBJECTIVE: To determine concentrations of ofloxacin and ciprofloxacin hydrochloride in aqueous humor after topical or combined topical and oral administration in eyes with filtering blebs. DESIGN: A prospective, investigator-masked, randomized, controlled comparative study involving 36 eyes of 34 patients with functioning filtering blebs who were to undergo cataract surgery. Treatment groups received either topical ofloxacin or topical ciprofloxacin (instillation of 0.3% ophthalmic solution every 30 minutes for 4 hours before surgery), or a combined topical plus oral regimen (ciprofloxacin hydrochloride, four 100-mg tablets, or ofloxacin, one 400-mg tablet, administered 24-26, 12-14, and 2 hours preceding surgery). The main outcome measure was antibiotic concentration measured by chromatographic separation and mass spectrometry of aqueous samples obtained during surgery. RESULTS: Topical antibiotic treatment yielded mean concentrations of ofloxacin, 0.75 microg/mL, and ciprofloxacin, 0.21 microg/mL, in aqueous. With combined topical and oral therapy, significantly more ofloxacin was measured than ciprofloxacin (3.84 microg/mL vs 0.35 microg/mL [P<.001]). The combination regimen produced significantly greater ofloxacin levels than did topical therapy alone (P =.007). CONCLUSIONS: Ofloxacin penetrates better than ciprofloxacin into the aqueous of eyes with filtering blebs, particularly after combined topical and oral administration, by which ofloxacin reaches more than a 10-fold greater concentration than does ciprofloxacin. Combined topical and oral therapy with ofloxacin may be beneficial in the treatment of bleb-associated infections.

Administration, Oral↗
PubMedDate not supplied

[Permeability of blood-aqueous humor barrier in primary open-angle glaucoma].

Biochemical changes in the chamber humor play an important role in the pathogenesis of primary open-angle glaucoma and are largely determined by the permeability of the blood-eye barrier. Comparative study of total protein content in the chamber humor in mature and far advanced glaucoma showed that the disease involves a progressive increase in the permeability of the blood-aqueous humor barrier, which may be due to dystrophic changes in ocular tissues in the course of glaucoma progress and accumulation of metabolites damaging the biological membranes in the chamber fluid or to antiglaucoma drugs increasing the permeability of the blood-humor barrier.

Aged↗
PubMed1982

Effect of chronically administered timolol on aqueous humor flow in patients with glaucoma.

A prospective analysis of the effect of chronically administered timolol on the rate of aqueous humor flow through the anterior chamber was performed in 15 eyes of 13 subjects with chronic open-angle glaucoma. After one week's treatment, the flow of each treated eye was lower than it had been prior to treatment. After one year's treatment, the flow of 13 of 15 treated eyes was lower than it had been prior to treatment. However, the flow was higher in 12 of 15 eyes after a year's treatment than it had been after a week's treatment. These data suggest that the ciliary body or other structures in the eye must partly adapt to the chronic administration of this drug. The mechanism of the adaptation is unknown.

Adult↗
PubMed2002

Aqueous humor dynamics in ocular hypertensive patients.

PURPOSE: To evaluate the mechanism of the intraocular pressure (IOP) elevation in ocular hypertension (OHT), aqueous humor dynamics were compared in patients with OHT versus age-matched ocular normotensive (NT) volunteers. METHODS: In this retrospective study, one group included patients diagnosed with OHT (IOPs > 21 mm Hg, n = 55) for at least six months. All eye medications were discontinued for at least three weeks before the study visit. A second group included age-matched NT subjects (n = 55) with no eye diseases. The study visit included measurements of IOP by pneumatonometry, aqueous flow and outflow facility by fluorophotometry, anterior chamber depth and corneal thickness by pachymetry and episcleral venous pressure by venomanometry. Uveoscleral outflow and anterior chamber volume were calculated mathematically. RESULTS: Significant differences in the OHT versus the NT groups were as follows: increased IOP (21.4 +/- 0.6 versus 14.9 +/- 0.3 mm Hg, respectively; P < 0.0001), reduced uveoscleral outflow (0.66 +/- 0.11 versus 1.09 +/- 0.11 microL/min; P = 0.005) and reduced fluorophotometric outflow facility (0.17 +/- 0.01 versus 0.27 +/- 0.02 microL/min/mm Hg; P < 0.0001). With respect to age, anterior chamber volume decreased in both groups at a rate of 2.4 +/- 0.3 microL/year (r(2) = 0.5, P <.001) and aqueous flow decreased at a rate of 0.013 +/- 0.005 microL/min/year (r(2) = 0.07, P = 0.005). CONCLUSIONS: The increased IOP in ocular hypertensive patients is caused by a reduction in trabecular outflow facility and uveoscleral outflow. Aqueous flow remains normal. When both ocular normotensive and hypertensive groups are combined, aqueous flow and anterior chamber volume decrease slightly with age.

Adult↗
PubMed2003

Tonography demonstrates reduced facility of outflow of aqueous humor in myocilin mutation carriers.

PURPOSE: To demonstrate the effect in vivo of the myocilin gene mutation Thr377Met on outflow facility of aqueous humor, as measured by tonography. MATERIALS AND METHODS: Forty-two members of a pedigree known to carry the Thr377Met mutation were examined for glaucoma, evaluated with tonography, and screened for myocilin mutations. Tonography was used to calculate the coefficient of aqueous outflow facility (C), as well as the ratio of the resting intraocular pressure to C (P(0)/C). Subjects were reexamined for glaucoma 5 years after tonography. RESULTS: Seven subjects were excluded because of previous treatment known to alter facility of aqueous outflow. The mean outflow facility of the eyes of the 12 subjects carrying the Thr377Met mutation was significantly reduced compared with the 23 non-carriers' eyes using both C (P<0.001) and P(0)/C (P<0.001). Reduced outflow facility was also demonstrated in those mutation carriers who were not yet expressing clinical signs of glaucoma or ocular hypertension when measured using C (P = 0.015) and P(0)/C (P = 0.001). After 5 years, progression towards glaucoma had occurred in 5 of the myocilin mutation-carriers, 2 of whom showed bilateral progression; 3 carriers remained completely normal. Four subjects had bilateral glaucoma at the outset and remained unchanged. The carriers' eyes that progressed towards glaucoma had reduced outflow facility compared with those that remained normal, although the difference was not statistically significant. CONCLUSIONS: Carriers of the myocilin Thr377Met mutation have reduced outflow facility, which may be detected prior to developing glaucoma. Tonography was not seen to be clinically useful in predicting progression towards glaucoma.

Aqueous Humor↗
PubMed1988

Terbutaline stimulates aqueous humor flow in humans during sleep.

A randomized, double-masked study of the effect of terbutaline sulfate, a selective beta 2-agonist, on the rate of aqueous humor formation was performed in awake and sleeping normal human subjects. The rate of aqueous formation was measured by fluorophotometry. Both the drug- and placebo-treated eyes showed a statistically significant nocturnal reduction of the flow rate (36% suppression in the terbutaline-treated eyes and 43% suppression in the placebo-treated eyes). Terbutaline had no effect on daytime aqueous flow rates, but stimulated flow by 15% during sleep. The drug had no significant effect on intraocular pressure. This study confirms past observations that beta-agonists exert their maximal effects during sleep, when endogenous adrenergic stimulation is at a minimum.

Adult↗
PubMed1975

[Current formation in the aqueous humor (author's transl)].

The localisation of deposits on the inner surface of the cornea can not be explained from the visible aqueous humor currents. Only with statistical methods could we find a flat vortex, which forms in a approximately triangular region behind the cornea and which is too slow to observe directly.

Aqueous Humor↗
PubMed1980

The effects of prostaglandins on aqueous humor dynamics.

PGE2, applied topically to the cornea of enucleated, arterially perfused cat eyes, produced an increase in the rate of aqueous humor (AH) production but only minimal changes in eye pressure, as observed in vivo. In contrast, PGE1, E2 and F2 alpha, administered intrarterially, induced no change in AH productin or arterial perfusate flow rate. In eyes which the AH inflow rate had been accelerated by prior administration of acetylcholine plus eserine, PGE1, E2 and F2 alpha caused a lowering of the inflow rate as well as vascular dilatation.

Acetylcholine↗
PubMed1998

Simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor with HPLC and electrochemical detection.

A sensitive and selective bioanalytical method for simultaneous determination of diclofenac and oxybuprocaine in human aqueous humor using reversed-phase HPLC and electrochemical detection is described. Chromatographic separation was achieved by using a Regis SPS 100 RP-8 column (5 microns; 150 x 4.6 mm I.D.). This support is coated with a hydrophilic polyoxyethylenepolymer. It allows protein-containing samples to be injected directly onto the column. The electrochemical detector permit a detection limit of 500 pg diclofenac per ml (daily relative standard deviation 6.3%) and 50 ng oxybuprocaine per ml (daily R.S.D. 2.6%), respectively. Results of administered and measured drug-concentrations in time dependent decrease are presented.

Anesthetics, Local↗