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Results for “Aqueous Humor”

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At least 415 records · Page 23Linked to original sources

PubMed1998

Aqueous humor lidocaine concentrations in topical and intracameral anesthesia.

PURPOSE: To assess aqueous humor lidocaine concentrations in 2 common regimens of topical anesthesia and after intracameral injection of the anesthetic agent. SETTING: University hospital eye clinic. METHODS: Twenty patients having routine cataract surgery were randomized into 3 groups: 1 given 3 drops of lidocaine 4% before surgery; 1 given 6 drops; 1 given 3 drops plus an intracameral injection of 0.1 mL lidocaine 1%. Lidocaine concentration was measured in aqueous humor samples taken before surgery. RESULTS: With 3 drops, aqueous lidocaine concentration was 1.4 micrograms/mL +/- 0.5 (SD) and with 6 drops, 4.3 +/- 1.5 micrograms/mL (P = .0015). With an intracameral injection, it was 341.8 +/- 152.6 micrograms/mL. CONCLUSION: Measurable amounts of lidocaine entered the anterior chamber in topical anesthesia, and more entered when more drops were given. It is likely that concentrations in this range could anesthetize the iris, but they are far lower than concentrations after an intracameral injection.

Administration, Topical↗

PubMed2001

Aqueous humor and plasma vascular endothelial growth factor in uveitis-associated cystoid macular edema.

PURPOSE: To determine the association between cystoid macular edema and vascular endothelial growth factor concentration in the aqueous humor and plasma of uveitis patients. METHODS: Cross-sectional study. Vascular endothelial growth factor concentrations were measured by enzyme-linked immunosorbent assay in the aqueous humor of 20 uveitis patients (9 with and 11 without cystoid macular edema), and in the plasma of 40 uveitis patients (20 with and 20 without cystoid macular edema) and 20 healthy volunteers. RESULTS: Mean aqueous humor vascular endothelial growth factor concentrations for uveitis patients with and without cystoid macular edema were 152.3 and 109.5 pg/ml, respectively, P =.044. Mean plasma vascular endothelial growth factor concentrations in uveitis patients with and without cystoid macular edema and in healthy volunteers were 32.2, 29.6, and 55.0 pg/ml, respectively. Uveitis patients had lower plasma vascular endothelial growth factor levels than did healthy volunteers, P =.0002. CONCLUSION: In uveitis patients, vascular endothelial growth factor concentration is increased in the aqueous humor of eyes with cystoid macular edema. It may be useful to investigate vascular endothelial growth factor antagonists as a treatment for uveitis-associated cystoid macular edema.

Adolescent↗

PubMed1994

Effects of endothelin-1 on intraocular pressure and aqueous humor dynamics in the rabbit eye.

The effects of endothelin-1 (ET-1) on intraocular pressure (IOP) and aqueous humor dynamics were studied in the rabbit eye. The intravitreal injection of 10(-5) M ET-1 (20 microliters) produced a biphasic IOP response consisting of an initial rise of 1 to 2 hours in duration, and a subsequent prolonged reduction lasting for more than 96 hours. Aqueous humor dynamics were determined 24 hours after the 10(-5) M ET-1 injection. Aqueous humor formation, measured fluorophotometrically, was decreased by 58%. Total outflow facility increased by 94%, according to measurement by two-level constant pressure perfusion. The change of uveoscleral outflow determined by fluorescein-dextran perfusion was not significant. The decrease in aqueous flow and the increase in total facility accounted for most of the IOP reduction after the ET-1 injection. Endothelin, which is endogenously present in the eye, may play a role in the regulation of intraocular pressure.

Animals↗

PubMed1994

Effect of foscarnet induction treatment on quantitation of human cytomegalovirus (HCMV) DNA in peripheral blood polymorphonuclear leukocytes and aqueous humor of AIDS patients with HCMV retinitis. The Italian Foscarnet Study Group.

The aim of this study was to investigate peripheral blood polymorphonuclear leukocytes and, whenever possible, aqueous humor from 65 AIDS patients with ophthalmoscopically diagnosed human cytomegalovirus (HCMV) retinitis to determine (i) whether patients consistently carry viral DNA and (ii) to what extent foscarnet induction treatment decreases viral DNA levels. HCMV DNA was quantified by PCR using densitometric analysis of hybridization products obtained from external standards and a standard curve from which the number of genome equivalents of test samples, normalized by using an internal amplification control, was interpolated. Results showed that 56 of 65 patients (86.1%) were positive for HCMV DNA prior to induction treatment. Of 41 of the 56 patients (73.2%) whose blood had become DNA negative after induction, only 5 had a high viral load (> 5,000 genome equivalents per 2 x 10(5) polymorphonuclear leukocytes) prior to induction, whereas as many as 13 of the 15 (26.8%) patients remaining DNA positive after induction had a high viral load prior to induction. Finally, of the nine patients (13.8%) with DNA-negative blood prior to induction treatment, three were shifted to foscarnet from ganciclovir, while six were erroneously enrolled in the study. Pre- and postinduction aqueous humor samples were obtained from 12 patients; all of these were DNA positive prior to induction, whereas after induction, 4 became negative, 6 showed a marked decrease in viral DNA, and 2 had nearly stable low DNA levels. In conclusion, PCR is a valuable tool for etiologic diagnosis and monitoring of HCMV retinitis treatment in AIDS patients. HCMV DNA is consistently present in the blood and aqueous humor of all patients with HCMV retinitis. Foscarnet induction treatment is highly effective in suppressing or reducing DNA levels in both blood leukocytes and aqueous humor.

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Vacuoles in the Acrysof intraocular lens as factor of the presence of serum in aqueous humor.

OBJECTIVE: Acrysoftrade mark (Alcon) foldable lenses (IOLs) have been shown to be highly biocompatible and exhibit a low incidence of posterior capsular opacification. However, minute vacuoles or 'glistenings' have been observed in some Acrysof IOLs. The clinical relevance of vacuole formation is presently unclear. To help clarify the influence of factors present under in vivo conditions on vacuole formation, the present experimental study examines the influence of aqueous humor components on the occurrence of vacuoles in Acrysof IOLs. METHODS: A total of 12 sterile Acrysof IOLs (Alcon, MA60BM) were incubated at body temperature (37 degrees C) for 3 or 6 months in anterior-chamber aqueous humor with or without human serum. The center portion was cut from two unconditioned, unhydrated, sterile control IOLs and the 12 conditioned IOLs and examined using light microscopy for vacuole formation. A third unconditioned, hydrated control IOL was examined using light and scanning electron microscopy. MEASURES: The incidence of vacuoles was quantified by two independent investigators using light microscopy. After hydration with balanced salt solution, the surface quality of a control IOL was examined using scanning electron microscopy. RESULTS: The control IOLs exhibited no or very few vacuoles. Scanning electron microscopy revealed that the control IOLs had normal surface texture without any surface vacuoles. IOLs that had been conditioned in aqueous humor without serum exhibited no great increase in the number of vacuoles, whereas IOLs conditioned in aqueous humor with serum exhibited a greater number of vacuoles that increased over time. CONCLUSIONS: The number of vacuoles increases with incubation time in aqueous humor containing serum. The addition of serum increased the proportion of lipids and proteins in the solution, which also occurs with a breakdown in the blood-aqueous barrier. The results of the present study point to a physiological factor that may lead to vacuole formation in IOLs and may aid clinicians in identifying risk factors involved in the formation of vacuoles.

Acrylates↗

PubMed2001

Beta endorphin-like immunoreactivity in human aqueous humor and crystalline lens.

We measured the concentration of beta-endorphin (beta-End) in plasma, as well as in aqueous humor and crystalline lens removed during cataract surgery. beta-End was detected both in the aqueous humor and in the crystalline lens. The concentration of beta-End in the aqueous humor corresponded to almost the half of the plasma level (2.18 fmol/l and 4.55 fmol/l). Endogenous beta-End is presumed to enter the intraocular structures by passive diffusion.

Aged↗

PubMed1996

Identification of a neuropeptide and neuropeptide-processing enzymes in aqueous humor confers neuroendocrine features to the human ocular ciliary epithelium.

The ocular ciliary epithelium, the site of aqueous humor secretion in the mammalian eye, is believed to play a key function in signaling mechanisms that regulate the rate of secretion, and thus intraocular pressure. One possible way of mediating these signaling functions is through neuropeptides and hormones secreted into the aqueous humor and acting on target tissues. We recently identified a cDNA clone sharing 100% identity with carboxypeptidase E (CPE), a neuropeptide-processing enzyme. Utilizing polymerase chain reaction, we further identified and characterized another processing enzyme, the peptidylglycine alpha-amidating monooxygenase (PAM), and the neuropeptide secretogranin II, a molecular marker restricted to neuroendocrine tissues. Using specific probes, we found that the nonpigmented ciliary epithelial cells express CPE, PAM, and secretogranin II mRNA, and protein. We also found that CPE and secretogranin II are abundant in aqueous humor. Treatment of cultured ciliary epithelial cells with veratridine and phorbol ester up-regulates CPE and PAM. Secretogranin II was found to be induced by veratridine, whereas phorbol ester had little effect, suggesting different mechanisms for secretion. The results demonstrate that secretogranin II, CPE, and PAM represent a specialized group of neuropeptide and neuropeptide-processing enzymes secreted by the ciliary epithelial cells which may confer to them neuroendocrine functions in cell-cell communication or cell signaling.

Adult↗

PubMed1990

[Hydrogen peroxide in the aqueous humor and cataract formation in human diabetes].

Hydrogen peroxide in the aqueous humor was measured in cataractous eyes from normal subjects and in cataractous eyes from diabetic subjects. The level of H2O2 in the aqueous humor was significantly higher in diabetes than in the idiopathic forms. It is likely that in the eye, impaired enzymic defenses lead to the accumulation of reactive species of O2, such as H2O2, which induces lipid peroxidation. This mechanism may be involved, as a direct consequence of retinal damage, in the pathogenesis of cataract in diabetes.

Aqueous Humor↗

PubMed1975

[A contribution to the study of the correlation between the depth of the anterior chamber and the coefficient of aqueous humor outflow (author's transl)].

The depth of the anterior chamber was measured and the coefficient of the aqueous humor outflow was ascertained by means of tonography in 88 normal eyes. The mean value of the depth of the anterior chamber established was 2095+/-0.42 and the median value of the outflow coefficient of the aqueous humor was found to be 0.27+/-0.07. Both values showed a regular distribution. A statistically significant correlation was established between the two values. Expressed through a correlation coefficient this would mean in practice that the coefficient of aqueous humor outflow is affected up to 10 percent by the value of the depth of the anterior chamber.

Adolescent↗

PubMed2001

[Analysis of the aqueous humor in keratoplasty patients with keratitis. Initial results].

OBJECTIVE: Herpetic keratitis is a common indication for corneal transplantation. In this patient group especially, there is a relatively high risk of graft failure, partly because of viral recurrence. It can be difficult to clinically distinguish stromal herpetic recurrence from early endothelial allograft rejection. Also a perioperative observation of viral activity seems advisable because of therapeutic consequences. For these reasons we use aqueous humor analysis in certain corneal transplant patients to determine intraocular antibody production. The aim of this study was to evaluate the diagnostic value of such an analysis of aqueous humor. MATERIAL AND METHODS: A total of 28 samples of aqueous humor were obtained from 24 eyes and all samples were tested for antibodies against herpes simplex virus (HSV), most samples (26/28) were tested for antibodies against varizella zoster virus (VZV) and some samples (6/28) for antibodies against cytomegalovirus. We used a modified micro-ELISA technique to detect intraocular IgG production. RESULTS: In 14 samples (50%) we found antibodies against HSV, in 7 samples (25%) against HSV and VZV, in 1 sample (3.6%) against VZV and 6 samples (21.4%) were negative for all antibodies tested. CONCLUSION: The results of aqueous humor analysis led to a specific local or systemic antiviral therapy perioperatively or in the case of postoperative recurrence of herpetic keratitis in most patients. Some patients could be spared long-term treatment with antiviral agents because of negative results in the aqueous humor analysis.

Adult↗

PubMed1975

Chloramphenicol in aqueous humor after topical application.

Chloramphenicol 0.5% ophthalmic solution was applied topically to patients at various times before cataract surgery. The aqueous humor was obtained at the time of surgery and analyzed for chloramphenicol content by thin-layer chromatography. Aqueous humor chloramphenicol levels ranged from 3.5mn-g/ml to 6.7mn-g/ml at the initial sampling period one to two hours following topical administration. Chloramphenicol was measurable in samples for up to five hours following administration. The compound measured in the aqueous humor samples was chemically identified as intact chloramphenicol, and no metabolites of chloramphenicol were shown.

Aged↗

PubMed1975

Electrolyte and acid-base status of aqueous humor in perinatal and adult goats.

These experiments were undertaken to determine electrolyte concentration and acid-base status of aqueous humor and arterial plasma H2O in perinatal and adult goats. The distribution of potassium, sodium, chloride, magnesium, and calcium between aqueous humor and plasma H2O in fetal, neonatal, and adult goats changed independently with age and could not be explained by passive Gibbs-Donnan equilibria. Anterior chamber aqueous humor has a reduced pH, PO2, HCO3-, and an elevated PCO2 compared to arterial blood in the neonate and adult.

Acid-Base Equilibrium↗

PubMed1981

Effect of thymoxamine on aqueous humor formation in the normal human eye as measured by fluorophotometry.

A double-blind, randomized, placebo-controlled study of the effect of 0.5% topical thymoxamine hydrochloride an alpha-adrenergic antagonist, on the rate of aqueous humor formation in the eyes of 25 normal human subjects was performed with fluorophotometry. The effect of thymoxamine on intraocular pressure and anterior chamber volume was also studied. four of the 25 subjects were used to study the effect of thymoxamine on the permeability to fluorescein of the blood-aqueous barrier. Pupillography was used to confirm that alpha blockade was present in the iris. Thymoxamine-treated eyes had 12% greater aqueous humor flow than placebo-treated eyes, but this difference was not statistically significant. No statistically significant difference was found in the rate of aqueous humor formation, intraocular pressure, anterior chamber volume, or premeability of the blood-aqueous barrier between thymoxamine-treated and placebo-treated eyes. The lack of an effect on the aqueous system could be interpreted as being a result of too low a concentration of thymoxamine in the ciliary body, lack of blockable receptors in the ciliary body, lack of physiologic tone in a blockable receptor system, or lack of a role of such a receptor system in the formation of aqueous humor.

Administration, Topical↗

PubMed1984

The effect of isoproterenol on aqueous humor formation in humans.

Isoproterenol was applied topically to one eye of each of 20 normal human volunteers. The rate of aqueous humor flow was measured with fluorophotometry. Intraocular pressure fell slightly in the treated eye, but the rate of aqueous humor flow was unaltered. Even when applied to the cornea in high concentrations, this beta-adrenergic agonist appeared to have no measurable effect on the flow of aqueous humor through the anterior chamber in the human eye.

Anterior Chamber↗

PubMedDate not supplied

Pediatric dosing considerations in ophthalmology--dosage adjustments based on aqueous humor volume ratio.

By simplifying a pharmacokinetic treatment, an equation can be derived which predicts that equal areas under aqueous humor concentration-time profiles can be obtained by administering a dose to infants which is some fraction of the normal adult dose. This fraction is obtained by dividing the aqueous humor volume of the child by that of the adult. This theory has been tested using rabbits as an experimental model. Using literature values for aqueous humor volumes, it was possible to calculate what fraction of a dose of pilocarpine administered to 20-day-old rabbits would result in the same ocular concentrations of drug as in 60-day-old rabbits. When the experiment was performed, agreement between predicted and experimental values was excellent. Although admittedly an oversimplified treatment, these results are the first step in a comprehensive pharmacokinetic model which should result in a more rational approach to ophthalmic drug delivery in infants and children.

Animals↗

PubMed1999

Effect of brinzolamide and dorzolamide on aqueous humor flow in human eyes.

PURPOSE: To measure the relative efficacy of brinzolamide hydrochloride 1% ophthalmic suspension, a new carbonic anhydrase inhibitor, compared with the currently used dorzolamide hydrochloride 2% ophthalmic solution as suppressors of aqueous humor flow in human eyes, and to study the difference of effect during the day and at night. METHODS: A randomized, double-masked, placebo-controlled study of 25 normal human subjects was carried out at Mayo Clinic. The daytime rate of aqueous humor flow was measured every 2 hours from 8 AM to 4 PM by means of fluorophotometry. Likewise, the night-time rate of aqueous humor flow was measured every 2 hours from 12 AM to 6 AM. Intraocular pressure was measured at 4 PM and 6 AM. RESULTS: Brinzolamide reduced aqueous flow by 0.47+/-0.20 microl per min (mean+/-SD) during the day, whereas dorzolamide reduced flow by 0.34+/-0.20 microl per min. Brinzolamide reduced aqueous flow by 0.16+/-0.12 microl per min during the night, whereas dorzolamide reduced flow by 0.10+/-0.13 microl per min. Brinzolamide reduced afternoon intraocular pressure by 1.5+/-1.1 mm Hg, and dorzolamide reduced afternoon intraocular pressure by 1.1+/-1.0 mm Hg. Brinzolamide reduced the morning awakening intraocular pressure by 0.3+/-1.6 mm Hg, and dorzolamide reduced it by 0.8+/-1.0 mm Hg. CONCLUSIONS: Our data support the idea that brinzolamide is at least as efficacious as dorzolamide as a suppressor of aqueous humor flow in normal human eyes and that there is probably not a clinically significant difference between the two drugs in this efficacy. Clinicians who prescribe brinzolamide should expect similar ocular hypotensive responses from brinzolamide and dorzolamide.

Adult↗

PubMed2000

[Assessment of nitric oxide level in aqueous humor under physiological conditions and after lens extraction and artificial foldable acrylic lens implantation during experimental work in rabbits].

PURPOSE: To evaluate the presence of nitric oxide (NO) and its level in the aqueous humor of rabbit's eye physiological conditions and after phacoemulsification and acrylic foldable artificial lens implantation. We also investigated nitric oxide maintenance during early postoperative period (between 1-5 days after surgery). MATERIAL AND METHODS: We examined 30 rabbits (weighing 3.0-3.5 kg) Just before surgery samples of aqueous humor were aspirated. Lens was extracted with phacoemulsification technique. In 15 eyes acrylic foldable IOL (group III) was implanted and 15 eyes were left aphakic (group IV). The aqueous samples were collected on 1, 3, 5 days after surgery. Nitric oxide in each sample was determined with fluorometric assay. RESULTS: The level of NO in aqueous humor in physiological conditions was estimated to 26.52 nM/dl. After phacoemulsification in both groups the level of nitric oxide was higher than in control group. The day and value of the highest NO level was different among examined groups. The highest level of NO was released during 1st day in group III and on the 3rd day in the group IV. CONCLUSION: We came to conclusion that the level of nitric oxide in aqueous humor after phacoemulsification in both groups is higher than in control group but significantly lower than in previously examined groups in which the surgery was made with extracapsular technique.

Animals↗

PubMed1982

Dynamics of aqueous humor in the syndrome of exfoliation with glaucoma.

We compared the aqueous humor dynamics of the affected and unaffected eyes of ten subjects with unilateral exfoliation and glaucoma and normal fellow eyes. The affected eyes had a greater mean intraocular pressure (31.9 +/- 11 mm Hg) than the unaffected control eyes (17.7 +/- 4.7 mm Hg) and a higher apparent resistance to the outflow of aqueous humor (15.2 +/- 7.3 min mm Hg/microliter vs 6.5 +/- 2.1 min mm Hg/microliter). The affected eyes accumulated systemically administered fluorescein at an abnormal rate. The rate of aqueous flow through the anterior chamber was lower in the affected eyes than in the control eyes (2.02 +/- 0.63 min-1 X 10(2) vs 2.38 +/- 0.71 min-1 X 10(2), as was the anterior chamber volume (126 +/- 23 microliter vs 136 +/- 25 microliter). The cornea-to-anterior chamber transfer coefficient for fluorescein was within the normal range in the affected eyes (mean, 2.51 +/- 1.2 min-1 X 10(3).

Aged↗