[STUDIES ON THE FUNCTION OF IRIS AND CILIARY BODY. 8. INFLUENCE OF THE AUTONOMIC NERVES ON THE PRODUCTION OF VITAMIN C IN THE AQUEOUS HUMOR].
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Ocular aqueous humor dynamics after photodisruptive laser surgery procedures.
Iridotomy and capsulotomy using the Q-switched Nd:YAG laser affect ocular aqueous humor dynamics, causing intraocular pressure (IOP) temporarily to rise following these procedures. We measured aqueous outflow facility and aqueous secretion flow by oculopression tonometry in 20 eyes before and after YAG laser iridotomy, and in 19 eyes before and after YAG laser posterior capsulotomy. IOP increased after both laser procedures. Our measurements showed that this elevation must have been caused by a reduction in outflow facility, since aqueous secretion flow actually decreased. In the iridotomy patients, the preoperative outflow facility (in most of the cases, already compromised preoperatively by glaucoma), was directly related to the maximum postoperative IOP elevation. In the capsulotomy patients, postoperative outflow facility was correlated with the total laser energy used. No such correlation was observed in the iridotomy patients. Additionally, in the capsulotomy patients, the type of secondary cataract (ie, proliferative or fibrotic) may have influenced the level of reduction of outflow facility.
Aqueous Humor↗
Study on Collagen Viscoelastic Substance as an Auxiliary Agent in Anterior Segment Surgery. Ocular Irritation Study by Replace ment of the Aqueous Humor in Rabbits.
Purpose: Collagen solution was assessed as a possible visoelastic substance in anterior segment surgery, in terms of the depth of the anterior chamber and ocular irritation.Methods: The depth of the anterior chamber of enucleated rabbit eyes was evaluated 5 minutes after injection of collagen solution. For ocular irritation test, the aqueous humor of rabbits was replaced with collagen using sodium hyaluronate (HEALON((R))) and phosphate buffer (PB) as controls. Follow-up clinical examinations with hand-slit-lamp-microscopy, tonometry, pachymetry, and specular microscopy were performed for 7 days or 28 days, and then aqueous humor, corneal endothelium, and eye tissues were evaluated by gel electrophoresis, scanning electron microscopy, and light microscopy, respectively.Results: 2.5% to 3% collagen solution was found to be optimal for maintaining the depth of the anterior chamber. No significant differences in clinical findings such as anterior chamber and corneal thickness or in biochemical and histological findings were observed among collagen-, hyaluronate- and PB-treated groups, except for intraocular pressure which was increased in the hyaluronate-treated group, but not in the collagen-treated group.Conclusion: Collagen specifically prepared for this study seems to be an excellent auxiliary agent for anterior segment surgery, providing an appropriate anterior chamber with little ocular irritation. (Jpn Ophthalmol Soc 104:458-65, 2000)
Journal Article↗
[The relation between corneal autolysis and the lysosomal enzyme level in aqueous humor and corneal storage medium].
The activity of acid phosphatase, a marker enzyme of lysosomal enzymes, in aqueous humor of wet-chamber stored eyeball and corneal storage medium was determined. The results showed a significant rise in the enzyme activity as the storage time increased, i.e. the degree of autolysis of the cornea progressed.
Acid Phosphatase↗
Acute effect of epinephrine on aqueous humor formation in the timolol-treated normal eye as measured by fluorophotometry.
A double-blind, randomized, placebo-control study of the effect of epinephrine on the rate of aqueous formation in eyes pretreated with a beta-adenergic blocking drug was carried out in 25 normal subjects with the use of fluorophotometry. All eyes were pretreated with timolol maleate before epinephrine or placebo was given. The effect of timolol maleate alone was to lower intraocular pressure and to reduce the rate of formation of aqueous humor. In the presence of timolol, aqueous formation was decreased further, approximately 7% more, in the epinephrine treated-eye as compared to the placebo-treated eye. This additional decrease in aqueous formation was statistically significant. No statistically significant difference was found in intraocular pressure or in tonographic C value between the epinephrine-treated and the placebo-treated eye. However, intraocular pressure was so low in both eyes that differences in intraocular pressure were not expected and tonographic tracings were difficult to interpret.
Aqueous Humor↗
Acetazolamide but not timolol lowers aqueous humor flow in sleeping humans.
The effect of timolol, acetazolamide, and the combination of the two drugs on the rate of aqueous formation in 18 healthy human subjects was measured during the day and at night in a placebo-controlled, double-masked, randomized study. In the absence of any drugs, aqueous flow during the day was 2.61 +/- 0.82 (mean +/- SD) microliters/min and at night, 1.08 +/- 0.59, a 59% lower flow rate when compared with the daytime value (P < 0.0001). When compared with these aforementioned control values, timolol alone reduced the rate of aqueous flow by 39% (P < 0.0001) in awake subjects but had no statistically significant effect on the flow rate in sleeping subjects (P = 0.33). Acetazolamide alone reduced aqueous flow during the day by 21% compared with the control flow rate (P = 0.02) and at night by 24% below the nocturnal flow rate in the sleeping eye (P = 0.04). The combination of the two drugs reduced flow during the day by an additional 13% (P = 0.024) compared with the flow rate achieved by timolol alone, and by an additional 32% (P < 0.0001) compared with the flow rate reduction attained by acetazolamide alone. There was no statistically significant difference in the nocturnal flow rates achieved by acetazolamide alone or in combination with timolol (P = 0.37). These data confirm previous studies demonstrating the effect of timolol, acetazolamide, and sleep on the rate of aqueous humor formation. Unlike a previous study, it was found that acetazolamide lowers the aqueous flow below the already low nocturnal flow rate that occurs spontaneously in the sleeping eye.(ABSTRACT TRUNCATED AT 250 WORDS)
Acetazolamide↗
[Herpes simplex virus isolations from the aqueous humor of patients suffering from focal iritis, endotheliitis, and prolonged disciform keratitis with glaucoma (author's transl)].
Aqueous humor from 33 herpes patients, 4 zoster patients, and 14 patients with etiologically unclear anterior uveitis was cultured for the presence of herpes viruses. Nine taps from 8 herpes patients with corneal endothelial disease and/or anterior uveitis yielded herpes simplex virus. In the case of one patient two taps were positive at 14 days' interval. Control cultures from the surface of conjunctiva and cornea were consistently virus-negative. Analysis of the virus-positive cases displayed three remarkable features: 1. Secondary glaucoma was uniformly present. This in itself is an indication for culturable herpes simplex virus in the aqueous. 2. Three clinical pictures could be differentiated biomicroscopically: focal iritis, peripheral endotheliitis, and prolonged disciform keratitis. 3. In a proportion of cases, tissue damage resulting from associated immune reactions seems to be more important for the functional outcome than tissue damage by viral cytolysis itself. After having tried several antiviral substances (trifluorothymidine topically, adeninearabinoside-monophosphate intravenously, human leukocyte interferon intramuscularly and intracamerally) we presently favour a topical combination therapy consisting of trifluorothymidine and steroids. This must be complemented by cycloplegics and--in cases of high intraocular pressure--by acetazolamide.
Adolescent↗
Crystals in the aqueous humor of normal eye.
An unusual and extremely rare occurrence of the free floating crystals in the aqueous humor of a structurally healthy and functionally normal eye of a 15-year-old white girl is described. The exact nature of these crystals could not be determined but their iridescent nature suggests that they might be cholesterol. This observation leads one to believe, contrary to the current concept, in the very interesting possibility of the crystal formation (or synchysis scintillans) in an apparently healthy eye.
Adolescent↗
[Penetration of gentamycin into the aqueous humor of non-inflamed and inflamed human eyes (author's transl)].
The penetration of gentamycin into aqueous humor after parenteral application (i. m., i. v., s. c.) of non-inflamed and inflamed human eyes was investigated. The dose of gentamycin was 80 mg i.m. and i. v. respectively. A doses of 40 mg gentamycin was used by s. c. injection. With Agar-diffusions test it could be demonstrated that the level of gentamycin was higher in inflamed than in non-inflamed eyes.
Aqueous Humor↗
Aqueous humor dynamics in monkeys with laser-induced glaucoma.
This study determines the effects of laser-induced glaucoma on aqueous humor dynamics of 18 cynomolgus monkeys. Baseline measurements of 12 monkeys included intraocular pressure (IOP) by pneumatonometry, aqueous flow by fluorophotometry and outflow facility by tonography. Beginning 4 to 14 days later, the trabecular meshwork of one eye was treated repeatedly with laser photocoagulation until elevated IOP was induced. Thirty-six to 75 days after the last laser treatment, all measurements were repeated. Between 1.7 and 11.4 years after laser treatment, the same 12 monkeys plus 6 additional monkeys underwent IOP and aqueous flow measurements. In addition, outflow facility was determined with fluorophotometry, and uveoscleral outflow was both calculated (n=18) and measured with an intracameral tracer (n=7). In glaucoma eyes compared to control eyes (n=12), IOP was increased (p<0.04) by at least 8 mmHg at Time 1 (1 to 3 months) or Time 2 (3 to 4 years) after laser treatment; aqueous flow was reduced (p=0.0007) by 46% at Time 1 but returned to baseline levels at Time 2; tonographic outflow facility was reduced (p=0.0008) by 71% at Time 1. In lasered eyes compared to control eyes, fluorophotometric outflow facility was reduced (p=0.0008; n=18) by 63%, and uveoscleral outflow was increased (p<0.05), whether calculated or measured with tracers at least 1 year after laser treatment. The increased IOP in monkeys with laser-induced glaucoma was caused by a sustained reduction in outflow facility. The uveoscleral outflow increase was not enough to prevent the rise in IOP.
Animals↗
Immunological study of the aqueous humor in ocular herpes simplex.
(1) Isolation of herpetic virus and immunological studies of the serum and aqueous humor are two complementary methods of investigation in the diagnosis of ocular herpes simplex infection, their relative value depending on the clinical situation. (2) Of the different immunological techniques that of antibody titration by the hemagglutination method is an easy, sensitive test, but only if the Goldmann-Witner ratio is calculated. By this technique, the diagnosis of herpetic infection can be made in unusual clinical presentations or old cases in which all specificity had disappeared.
Antibodies, Viral↗
Microplate assay of ascorbic acid in aqueous humor with bicinchoninic acid.
An inexpensive microplate assay method was developed to determine ascorbic acid in human aqueous humor samples. The method is based on the selective oxidation of ascorbic acid at alkaline pH and determination of ascorbic acid and other reducing substances in samples with bicinchoninic acid/CuSO4 before and after the alkaline treatment. The two-point measurement eliminates the effect of interfering substances, such as glucose, uric acid and glutathione, which are stable at alkaline pH. The advantages of the method are that it requires small sample volumes and allows handling of a large number of samples simultaneously.
Aqueous Humor↗
Homocysteine levels in aqueous humor and plasma of patients with primary open-angle glaucoma.
We determined homocysteine (Hcy) levels in aqueous humor (AH) and plasma and their association with B-vitamin levels in patients with primary open-angle glaucoma (POAG) and controls. Both AH Hcy and plasma Hcy levels were significantly increased in POAG, and elevation of AH Hcy and plasma Hcy was a significant risk factor for POAG. In contrast to controls, neither plasma nor AH Hcy of POAG patients demonstrated a significant association with important non-genetic determinants of elevated Hcy such as low B-vitamin levels, increasing age and caffeine consumption. Considering that Hcy is a neurotoxin that induces apoptotic retinal ganglion cell death via stimulation of the N-methyl-D-asparate (NMDA) receptor, increased Hcy concentrations in AH and plasma might contribute to the optic nerve damage in POAG.
Aged↗
Penetration of linezolid into the anterior chamber (aqueous humor) of the human eye after intravenous administration.
We determined the linezolid concentrations in serum samples and aqueous humors (AHs) from 21 patients undergoing cataract extraction. Cataract removal was performed at various times (from 60 to 270 min) after the end of a 30-min infusion of 600 mg of linezolid. Serum samples were obtained 1 h after the end of linezolid administration to determine the maximum concentration of linezolid (C(max)); AHs and a second serum sample were taken simultaneously during the operation, and the concentrations of linezolid in AH (C(AH)) and serum (C(S)) were determined. The mean C(AH) 1 h after linezolid administration was 4.94 micro g/ml, and the mean ratio of C(AH) to C(S) (R = C(AH)/C(S)) was 0.43. All patients had a C(AH) of >2 micro g/ml, which was higher than the MIC at which 90% of Staphylococcus epidermidis strains are inhibited.
Acetamides↗
Role of P-glycoprotein in distribution of rhodamine 123 into aqueous humor in rabbits.
PURPOSE: Examination of the contribution of functional P-glycoprotein (P-gp), an ATP-dependent efflux pump, in blood-aqueous barrier in rabbits. METHODS: Rhodamine-123 (Rho-123), a P-gp substrate, was administered intravenously via the marginal ear vein of rabbits. Rhodamine B (Rho-B), an analogue of Rho-123, was also injected with the same dose, as a reference compound. Quinidine at different concentrations was applied topically to the corneal surface by eye drops prior to the intravenous administration of a Rho compound. The aqueous distribution (a ratio of concentration in aqueous humor to that in plasma) of these Rho compounds was analyzed in relation to the aqueous concentration of quinidine. Transport study across Caco-2 cell monolayers was carried out to examine the involvement of P-gp in Rho-B transport. RESULTS: It was proved that Rho-B is not a P-gp substrate by a transport study across Caco-2 cell monolayers, in contrast to Rho-123 (a P-gp substrate). The aqueous distribution of Rho-123 given intravenously was significantly lower than that of Rho-B. Topical quinidine (a P-gp inhibitor) markedly increased the aqueous distribution of Rho-123, depending on the aqueous concentrations of quinidine, though it did not affect the aqueous distribution of Rho-B. CONCLUSIONS: The contribution of functional P-gp in blood-aqueous barrier was clearly demonstrated by analyzing the aqueous distribution of Rho-123 in the presence or absence of quinidine. These experiments only allow us to address one part of the blood-aqueous barrier, the capillary endothelium, and, to do so by using different substrates for P-gp, a sort of chemical analogy with the presumed blood-aqueous barrier across capillary endothelia. The alteration of P-gp function by pharmacotherapy or in pathological state should be considered in the ophthalmic medical treatment.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
[Collapse of the blood-aqueous humor barrier following laser injury--preventive pharmacotherapy with prostaglandin inhibitors].
Laser-induced collapse of the blood-aqueous barrier and the protective effect of different prostaglandin inhibitors were investigated in the animal study reported here. As a parameter of the barrier function, the protein concentration in the aqueous humor was measured using a micromethod. The anterior chamber of 90 eyes (45 rabbits) was tapped only once, 100 min after the laser procedure. The results prove that different prostaglandin inhibitors in a systemic or topical application form can effectively reduce disturbances of the blood-aqueous barrier after laser surgery. This is also of clinical relevance with regard to laser iridotomy or trabeculoplasty in glaucoma.
Animals↗
[Identification of antithrombin III in human aqueous humor (author's transl)].
Using radial immunodiffusion it is possible to identify and to quantitate antithrombin III in human aqueous humor. The importance of antithrombin III as a cofactor of heparin is stressed.
Antithrombin III↗
Tobramycin levels in aqueous humor after subconjunctival injection in humans.
Subconjunctival injection of 10 mg of tobramycin provided therapeutic levels in the aqueous humor of 25 patients (ranging in age from 51 to 89 years) who underwent cataract surgery. The absorption from the subconjunctival tissue into the anterior chamber was fairly rapid, reaching a peak in approximately two hours. Peak levels were usually 20 times the minimum inhibitory concentration for Pseudomonas aeruginosa. The drug then gradually disappeared from the aqueous but still exceeded the minimum inhibitory concentration for Pseudomonas organisms after eight hours.
Aged↗