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Results for “Aqueous Humor”

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PubMed1984

Activated complement in inflamed aqueous humor.

Activated complement is an important mediator of inflammation. Radioimmunoassay was used to measure levels of C3a, an activated fragment of C3, in aqueous humor. Additionally, immunoelectrophoresis was performed on aqueous humor to detect Factor B and its conversion product, Bb, as well as C3c, a breakdown product of C3. All six samples of normal aqueous humor had no detectable C3a, C3c, or Factor B. All eight samples of aqueous humor from patients with anterior uveitis had measurable levels of C3a. Factor B and C3c were detected in 3/7 samples of inflamed aqueous humor. Factor B was converted fully to Bb in two of these three samples, suggesting alternative pathway activation of complement. Activated complement fragments are present in the aqueous humor of eyes with anterior uveitis and may help mediate the inflammatory process.

Adult↗

PubMed1999

The relationship between gelatinase A activity in aqueous humor and glaucoma.

PURPOSE: To investigate whether abnormal expression of gelatinase A in aqueous humor may be related to the development of glaucoma, the activity of gelatinase A in aqueous humor of patients with glaucoma and patients with cataract was measured and compared. METHODS: Six primary patients with open-angle glaucoma (POAG), four patients with chronic angle closure glaucoma (CACG), four patients with normal tension glaucoma (NTG), and 14 patients with cataract were enrolled. The aqueous humor of each patient was collected during surgery, and total protein concentration and gelatinase activity in the aqueous humor were measured by protein assay kit and zymography, respectively. RESULTS: In patients with POAG, total protein concentration doubled and gelatinase A activity increased by 3.9 times compared with patients with cataract. However, there were no statistically significant differences in total protein concentration and gelatinase A activity in patients with CACG or NTG compared with patients with cataract. CONCLUSION: The development of POAG may be associated with the abnormal expression of gelatinase A in aqueous humor.

Adult↗

PubMed1983

Aqueous humor dynamics in Fuchs' uveitis syndrome.

We studied aqueous humor dynamics in ten subjects (four men and six women, ranging in age from 19 to 72 years) with unilateral Fuchs' uveitis syndrome. The unaffected fellow eyes served as controls. In two patients, the affected eye also had glaucoma. Fluorophotometry showed the blood-aqueous barrier to be abnormally permeable in the affected eyes. The calculated coefficient of exchange of fluorescein across the blood-aqueous barrier was 30.7 X 10(-4) min-1 in the affected eyes and 5.7 X 10(-4) min-1 in the unaffected eyes. The anterior chamber elimination coefficient of fluorescein, corneal endothelial permeability to fluorescein, and anterior chamber volume did not differ significantly in affected vs unaffected eyes. The rate of aqueous humor flow through the anterior chamber in the affected eyes appeared to be normal, as did the apparent resistance to the outflow of aqueous humor.

Adult↗

PubMed1996

Combined corticosteroid and catecholamine stimulation of aqueous humor flow.

PURPOSE: Epinephrine is known to stimulate aqueous humor flow in humans. Corticosteroids are known to augment the effect of beta-adrenergic agonists on the ciliary body. This experiment was carried out to determine whether a corticosteroid can increase the stimulatory effect of epinephrine on aqueous humor flow. METHODS: Twenty human volunteers were studied for 24 hours. Hydrocortisone was given orally and epinephrine was given intravenously during sleep while aqueous flow was monitored. Flow was compared with a second 24-hour study when oral and intravenous placebos were given. The sequence of administration was randomized. Subjects and investigators were masked. The flows also were compared with a previously published study in which the same dose of epinephrine was administered without steroid. RESULTS: Epinephrine plus hydrocortisone compared with placebos increased aqueous flow 42% in subjects during sleep. The combination of epinephrine and hydrocortisone was a more potent stimulus to aqueous flow than epinephrine alone, which increased aqueous flow by only 27% (P = 0.045). CONCLUSION: The two major hormones of the adrenal gland work in concert to increase the rate of aqueous humor flow in humans.

Administration, Oral↗

PubMed2004

Effects of the preservative purite on the bioavailability of brimonidine in the aqueous humor of rabbits.

PURPOSE: To determine aqueous humor concentrations of brimonidine given the following ophthalmic formulations in female New Zealand White Rabbits: (1) BAK-preserved brimonidine tartrate 0.20% at a pH of 6.4; (2) BAK-preserved brimonidine tartrate 0.15% at a pH of 6.4, and (3) Purite((R))-preserved brimonidine tartrate 0.15% at a pH of 7.3. METHODS: Eighteen (18) animals were given a 35-microL drop of formulation into each eye. Aqueous humor samples were collected at 9 time points over 8 hours. Brimonidine concentrations were quantified using LC-MS/MS. RESULTS: The C(max) was achieved between 0.33-0.67 hours postdosing for all 3 formulations. Mean C(max) after Purite-preserved brimonidine tartrate 0.15% was 88% higher than that after BAK-preserved brimonidine tartrate 0.15% (p = 0.040), and 44% higher than that after BAK-preserved brimonidine tartrate 0.20% (p = 0.0784). AUC(0-3 hr) values were comparable for all 3 formulations. CONCLUSIONS: Purite-preserved brimonidine tartrate 0.15% produced higher peak concentrations than BAK-preserved brimonidine tartrate 0.15%. It also had a concentration that was comparable to BAK-preserved brimonidine tartrate 0.20%. The differences in safety may result from the change in preservative.

Animals↗

PubMed1995

Detection of Toxoplasma gondii-specific IgA in the aqueous humor of cats.

Toxoplasma gondii-specific IgA, IgM, and IgG were measured by ELISA in the serum and aqueous humor of 29 client-owned cats with endogenous uveitis and 7 specific-pathogen-free cats tested sequentially for 20 weeks after inoculation with T gondii. Local antibody production in aqueous humor was estimated by multiplying the aqueous humor-to-serum T gondii-specific antibody ratio by the serum-to-aqueous humor total IgG (C value) or calicivirus-specific IgG (CTC value) ratio. Evidence for local production of antibody in aqueous humor was defined as C value greater than 8 or CTC value greater than 1. Toxoplasma gondii-specific IgM CTC values, IgG CTC values, or IgA CTC values greater than 1 were detected in the aqueous humor of 18 of 29 (62.1%) client-owned cats with endogenous uveitis; 2 cats had IgA CTC values greater than 1 without detectable IgM or IgG in aqueous humor. Toxoplasma gondii-specific IgM was not detected in the aqueous humor of experimentally inoculated cats before or after inoculation. Immunoglobulin G C values greater than 8 were detected in all 7 experimentally inoculated cats and ranged from 10.4 to 145.5. Immunoglobulin G C values greater than 8 were first detected 4 to 8 weeks after T gondii inoculation and were undetectable by week 16 after inoculation. Immunoglobulin A C values greater than 8 were detected in 4 of 7 cats and ranged from 12.7 to 264.3. Immunoglobulin A C values greater than 8 were first detected 4 to 8 weeks after inoculation, and were detected in 2 cats during week 20 after inoculation. It was concluded that some cats infected with T gondii develop detectable concentrations of T gondii-specific IgA in aqueous humor.

Animals↗

PubMed1994

Low mature TGF-beta 2 levels in aqueous humor during uveitis.

PURPOSE: To investigate whether transforming growth factor-beta 2 (TGF-beta 2), a strong immunosuppressive factor normally present in aqueous humor, is involved in the inflammatory process of clinical uveitis. METHODS: Mature TGF-beta 2 levels were determined in aqueous humor samples of 9 patients with Fuchs' heterochromic cyclitis, aqueous humor samples of 21 patients with other uveitis entities, and vitreous fluid samples of 19 patients with uveitis by using a commercially available sandwich ELISA: Total TGF-beta 2 levels in ocular fluids were measured after heat activation. Aqueous humor samples from patients with cataract and glaucoma and vitreous fluid samples from eye bank eyes were tested as controls. Albumin levels, determined by radial immunodiffusion, were used as a measure of the disruption of the blood aqueous barrier. RESULTS: Significantly lower mature TGF-beta 2 levels were detected in aqueous humor samples of patients with uveitis, compared to the two control groups without intraocular inflammation. Samples of patients with uveitis without detectable mature TGF-beta 2 did contain latent TGF-beta 2 levels (504 to 6024 pg/ml). In aqueous humor, there was a significant negative correlation between mature TGF-beta 2 and albumin levels. No mature TGF-beta could be detected in vitreous fluid. Total TGF-beta 2 levels in vitreous fluid were significantly lower in samples from patients with uveitis than in samples from eye bank eyes. CONCLUSION: These results indicate that the mature TGF-beta 2 levels in aqueous humor and the total TGF-beta 2 levels in vitreous fluid are reduced during ocular inflammation. In aqueous humor, this might be caused by binding of mature TGF-beta to serum proteins, for instance, alpha 2-macroglobulin, or by a disturbance in the activation process of latent TGF-beta 2.

Aqueous Humor↗

PubMed1998

Combined effect of dorzolamide and latanoprost on the rate of aqueous humor flow.

PURPOSE: To determine whether latanoprost, an ocular hypotensive agent believed to enhance uveoscleral outflow of aqueous humor, augments the aqueous-suppressing effect of dorzolamide, a topical carbonic anhydrase inhibitor. METHODS: Twenty-four normal subjects underwent measurement of aqueous humor flow by fluorophotometry to determine the flow with placebo, with dorzolamide, and with a combination of dorzolamide and latanoprost. RESULTS: The flow of aqueous humor was suppressed 13% by dorzolamide but not by latanoprost. Latanoprost did not augment the effect of dorzolamide on aqueous humor flow; latanoprost and dorzolamide had additive ocular hypotensive effects. CONCLUSIONS: The uveoscleral flow effect of latanoprost does not improve the aqueous-suppressing effect of dorzolamide, but the two drugs have additive ocular hypotensive effects.

Adult↗

PubMed2003

The free amino acids and the aqueous humor pH after antiglaucomatics in vitro.

Authors present comparison of the previous results on the influence of free amino acids of the aqueous humor in rabbits and human on the pH of the aqueous humor in vitro. Four clinically used antiglaucomatics were added (2% Trusopt--pH 5.33; 0,005% Xalatan--pH 6.4; 0.5% Timoptol--pH 6.80 and 1% Pilocarpine--pH 5.87) into the aquired aqueous humor of rabbits (pH 7.59) and human (pH 7.11 +/- 0.11). After their instillation pH of the aqueous humor immediately decreased towards acid levels. The pH changes after Timoptol, Xalatan and Pilocarpine showed a similar time pattern and after return to the baseline values the pH shifted to alkaline levels. In case of Trusopt instillation the pH value reached the baseline of the aqueous humor after 240 min. Almost no pH changes were recorded from 240 min up to 24 hours after all tested antiglaucomatics. From the wiev on the speed of activity and effectivity depending on time required to reach the initial pH value of the aqueous humor we to make this order: Pilocarpine>Timoptol>Xalatan>Trusopt. Comparing our results the effect of antiglaucomatics is connected with different composition and also with shift of the aqueous humor pH towards slightly alkaline level (similar effect in rabbits and human). Results presented in this work are theoretical but also practical contribution to the treatment of glaucoma. (Fig. 1, Ref. 38.).

Aged↗

PubMed1994

Penetration of topically applied ciprofloxacin, norfloxacin, and ofloxacin into the aqueous humor.

PURPOSE: To determine the intraocular penetration of topically applied fluoroquinolone antibiotics into aqueous humor. METHODS: Thirty-two patients undergoing cataract extraction received either 0.3% ciprofloxacin, 0.3% norfloxacin, or 0.3% ofloxacin topical drops. The patients were given two drops 90 minutes preoperatively and two drops 30 minutes preoperatively. At the time of surgery, 0.1 ml aqueous fluid was aspirated from the anterior chamber and immediately stored at -70 degrees C. RESULTS: Concentrations of ciprofloxacin, norfloxacin, and ofloxacin were determined using a broth dilution bioassay. Morganella morganii with a known minimal inhibitory concentration was used to assay ciprofloxacin and norfloxacin levels. Salmonella enteritidis with a known minimal inhibitory concentration was used to assay ofloxacin levels. Topically applied ciprofloxacin achieved a mean aqueous level of 0.072 microgram/ml (range, 0.02-0.153 microgram/ml). One sample was below the sensitivity of the bioassay. Topical norfloxacin achieved a mean aqueous level of 0.0570 microgram/ml (range, 0.046-0.10 microgram/ml). Seven samples did not reach the sensitivity of the bioassay. Topical ofloxacin achieved a mean level in the aqueous humor of 0.338 microgram/ml (range, 0.078-0.625 microgram/ml). There was no statistically significant difference in intraocular aqueous humor levels of ciprofloxacin versus norfloxacin (P > 0.05). Topical ofloxacin achieved aqueous humor levels significantly higher than either ciprofloxacin or norfloxacin (P < 0.004). CONCLUSION: Of the currently available topical fluoroquinolone antibiotics, ofloxacin achieves the highest aqueous humor concentrations.

Administration, Topical↗

PubMed1951

The chemical composition and the osmotic pressure of the aqueous humor and plasma of the rabbit.

Measurements were made of the osmotic pressure of plasma, and of aqueous humor taken from the anterior chamber of the right and left eyes and from the posterior chamber of unanesthetized rabbits. Aqueous humor from the anterior chamber was found to be hypertonic to the plasma by approximately 3 mM/liter equivalent of sodium chloride. The aqueous humor from the anterior and posterior chambers of the right and left eyes was isotonic. The concentration of chloride in the anterior and posterior chambers was the same. The concentration of all the major components of the aqueous humor and plasma has been determined by chemical analysis on fluid samples obtained from unanesthetized rabbits at approximately the same time. The calculated osmotic pressure of the total of these substances in terms of sodium chloride equivalent agrees to within better than 1 per cent of the total osmotic pressure as measured experimentally. The distribution of some individual anions and cations of the aqueous humor and plasma was determined. This distribution is widely different from that which would obtain at a state of equilibrium. The positive and negative charges carried by the ions in the aqueous humor were approximately equal. Sources of error in the experiments are discussed.

Animals↗

PubMed2001

Metabolism of angiotensin I by guinea pig aqueous humor.

We investigated the degradation of angiotensin I (Ang I) by guinea pig aqueous humor at physiological pH (pH 7.4) and assessed the activity of responsible enzymes using various enzyme inhibitors. The aqueous humor was incubated with Ang I in the presence or absence of an enzyme inhibitor at 37 degrees C for the appropriate time period. The resulting peptides were analyzed by a Beckman HPLC system with a Waters microBondapak C18 analytical column using a 30-min increasing linear gradient of 10 to 40% acetonitrile containing 0.05% trifluoroacetic acid (TFA) and H2O containing 0.05% TFA at a flow rate of 1 mL/min. Detection was done by absorbance at 214 nm. Angiotensin II (Ang II) was a major product (39.3+/-4.10 nmol x h(-1) mL(-1), n = 5) of Ang I hydrolysis. Traces of angiotensin 1-9, angiotensin IV, and angiotensin 1-7 were also produced. Chymostatin (0.05 mmol/L), EDTA (1 mmol/L), enalaprilat (0.1 mmol/L), and ebelacton B (0.01 mmol/L) inhibited generation of Ang II from Ang I by guinea pig aqueous humor by 89+/-4.6, 56+/-7.6, 33+/-5.1, 20+/-6.5%, respectively. Our findings indicate that guinea pig aqueous humor contains several enzymes that can form Ang II. The chymostatin-sensitive type of enzyme was the most active one found in guinea pig aqueous humor. Angiotensin I converting enzyme, carboxypeptidase A, and deamidase may also contribute to angiotensin II formation in guinea pig ocular fluid.

Angiotensin I↗

PubMed2006

[The pharmacokinetics of FK506 and its nanoparticles in aqueous humor of rabbits].

OBJECTIVE: To investigate the pharmacokinetics of FK506 and its nanoparticles in aqueous humor of rabbits applied with eye drops or subconjunctiva injections. METHODS: 42 New Zealand albino rabbits were divided into 2 groups. (1) Nanoparticle solution containing 10 microg FK506 was injected into subconjunctiva or dropped on conjunctival sac of rabbits (68 eyes in 34 cases). (2) Eye drops containing 20 or 40 microg FK506 without nanoparticles were dropped on conjunctival sac of rabbits (16 eyes in 8 cases). Aqueous humor was collected at different times after local administration and FK506 concentrations were measured by ELISA. Ocular pharmacokinetic parameters of FK506 were calculated by 3p87 software. RESULTS: In the solution containing nanoparticle, the effective FK506 concentration in aqueous humor could be kept up to 16 h in eye drops group. The range of FK506 concentration was between (15.50 +/- 3.39) - (2.59 +/- 0.83) ng/ml. FK506 in aqueous humor can be maintained for 96 h by injecting into subconjunctiva and FK506 concentration were between (9.62 +/- 2.19) - (2.60 +/- 0.21) ng/ml from 6 - 96 h. T(max) and C(max) in eye drops were (1.25 +/- 0.50) h and (15.52 +/- 2.37) ng/ml respectively; while T(max) and C(max) in subconjunctiva injection were (64.00 +/- 13.86) h and (10.16 +/- 1.37) ng/ml respectively. Each AUC(0-->t) was (152.44 +/- 16.74) ng.ml(-1).h(-1) and (612.48 +/- 54.39) ng.ml(-1).h(-1) respectively; each Ka was 3.790 +/- 0.730 and 0.040 +/- 0.004 respectively; and each MRT was (8.20 +/- 1.28) h and (58.53 +/- 5.42) h respectively. In the eye drops containing 20 microg or 40 microg FK506 but without nanoparticles applied in conjunctival sac of rabbits, all effective FK506 concentrations in aqueous humor could not be kept over 4 h. T(max) was 1 h and C(max) was (18.93 +/- 6.95) ng/ml in 20 microg FK506, while in 40 microg FK506 T(max) was 2h and C(max) was (28.33 +/- 1.31) ng/ml. CONCLUSION: Solution with FK506 nanoparticle dropping onto the eye or injecting into subconjunctiva could be sustained in rabbit aqueous humor for a longer time than non-nanoparticle FK506 solution, while with injecting of nanoparticle FK506 solution it could be detected with a relative low but longer effective concentration.

Administration, Topical↗

PubMed1990

[Mechanism of ascorbic acid transport in the aqueous humor].

The concentration of ascorbic acid in the aqueous humor in many species (including humans and oxen) is several times higher than the plasma concentration. The role of ascorbic acid as a protective mechanism in the intraocular tissues against light-induced damage is discussed. We have performed uptake studies using 14C-labeled ascorbic acid in cultured bovine pigmented ciliary epithelial cells in order to study the mechanisms for ascorbic acid transport from the ciliary body to the aqueous humor. We found that intracellular accumulation of ascorbic acid was Na(+)-dependent. Data from kinetic experiments suggest the presence of a co-transport system for 2 Na+ and 1 ascorbate. The oxidized form of the vitamin (dehydro-ascorbic acid, DHA) was taken up in the cell by a Na(+)-independent mechanism. Using thin-layer chromatographic assay, we found intracellularly only ascorbic acid after incubation with extracellular DHA, indicating the presence of DHA reductase activity in ciliary body epithelial cells. Thus, these cells possess two mechanisms for intracellular accumulation of ascorbic acid: (1) co-transport for 2 Na+ and 1 ascorbate and (2) a Na(+)-independent DHA transport in cooperation with intracellular DHA reductase. These mechanisms could be involved in the transport of ascorbic acid from the stroma to the aqueous humor.

Animals↗

PubMed1984

PMN accumulation in aqueous humor and iris-ciliary body during intraocular inflammation.

The accumulation of polymorphonuclear leukocytes (PMNs) was determined in the aqueous humor and iris-ciliary body following an intravitreal injection of endotoxin in the albino rabbit. PMN accumulation in the iris-ciliary body was quantified by measuring myeloperoxidase (MPO) activity in homogenates of this tissue. Leukocyte appearance in the aqueous humor was determined by counting the number of PMNs in diluted aspirates of aqueous humor and also by measuring MPO activity in the same aspirates. Twenty-four hours following an intravitreal injection of endotoxin, there was marked vasodilatation in the iris, breakdown of the blood-aqueous barrier, and infiltration of PMNs into the aqueous humor. There was, however, no correlation between MPO activity in the iris-ciliary body and the number of PMNs or the MPO activity in the aqueous humor. Furthermore, the number of PMNs in the aqueous humor did not increase with increasing amounts of intravitreally injected endotoxin, whereas MPO activity in the iris-ciliary body increased in a dose-dependent manner. The results of this study suggest that quantification of leukocytes in the aqueous humor does not represent a meaningful index of intraocular inflammation.

Animals↗

PubMedDate not supplied

Detection of CMV DNA in the aqueous humor of AIDS patients with CMV retinitis by AMPLICOR CMV test.

The present study was performed to detect the cytomegalovirus (CMV) DNA in the aqueous humor from the eyes of acquired immunodeficiency syndrome (AIDS) patients with CMV retinitis. Detection of CMV DNA in the aqueous humor in the eyes with active CMV retinitis was compared with detection of CMV DNA in inactive retinitis. CMV DNA in the aqueous humor was evaluated before and after treatment with intravitreal injection of ganciclovir. CMV DNA in the aqueous humor was measured by AMPLICOR CMV test. Forty-two eyes of 35 AIDS patients were diagnosed ophthalmoscopically as having CMV retinitis that was subclassified as either active or inactive. The active and inactive CMV retinitis cases were distinguished based on clinical evaluations and fundus photographs. The results showed that 37 of the 42 eyes (88.1%) were positive for CMV DNA prior to treatment, while in 29 of these 37 eyes (78.4%), the aqueous humor became CMV DNA-negative after the treatment. Successful treatment with the intravitreal injection of ganciclovir was associated with a reduction in the detection of CMV DNA in the aqueous humor. CMV DNA was not detected in the aqueous humor of patients with quies cent CMV retinitis. In conclusion, the AMPLICOR CMV test was found to be a reliable tool for differentiating active and inactive CMV retinitis, and is useful for helping to select the optimal treatment regimen. The intravitreal injection of ganciclovir is highly effective in reducing detectable CMV DNA in the aqueous humor.

AIDS-Related Opportunistic Infections↗

PubMed2001

Effect of diabetic retinopathy on redox state of aqueous humor and serum albumin in patients with senile cataract.

PURPOSE: To investigate the oxidative status of albumin in the aqueous humor and serum of senile cataract patients with diabetes in order to clarify the pathogenesis of this condition. METHODS: High-performance liquid chromatography (HPLC) was employed to measure the reduced form of albumin (mercaptalbumin) and the oxidized form of albumin (nonmercaptalbumin) in serum and aqueous humor. The mercaptalbumin, nonmercaptalbumin-1, and nonmercaptalbumin-2 fractions in aqueous humor obtained at the start of cataract surgery and in serum obtained intraoperatively were analyzed by HPLC in 7 senile cataract patients with diabetic retinopathy (2 men and 5 women aged 70+/-9.8 years). RESULTS: The mean content (%) of mercaptalbumin, nonmercaptalbumin-1, and nonmercaptalbumin-2 in serum albumin from the diabetic patients was 60.3+/-7.8, 36.9+/-6.6, and 2.7+/-1.7%, respectively, while the corresponding values for aqueous humor albumin were 40.0+/-14.1, 52.4+/-12.6, and 7.5+/-3.6%. When the mercaptalbumin content (%) of aqueous humor albumin was compared between patients with active and inactive diabetic retinopathy, the respective values were 47.0+/-9.1% and 22.8+/-5.7%. A significant correlation mercaptalbumin content (%) of aqueous humor albumin did not show with the HbA1c level, but there was still a relationship (Y = 5.0 x - 2.7, r = 0.80, and p < 0.052). CONCLUSION: The increase of mercaptalbumin (the reduced form of albumin) in the aqueous humor of patients with diabetic retinopathy probably resulted from an increase of retinal vascular permeability.

Aged↗

PubMed1998

The aqueous humor is capable of generating and degrading H2O2.

PURPOSE: To determine the ability of the aqueous humor to generate and degrade H2O2, the effect of environmental factors such as oxygen tension and temperature, and the constituents contributing to the observed results. METHODS: Aqueous humor was carefully removed from bovine eyes within 3 hours of death. Standard and new techniques were used to follow H2O2 degradation and formation. Catalase activity was measured by H2O2 decomposition, usually at 100 microM and 10 mM H2O2, and in some cases by O2 generation. RESULTS: Bovine aqueous humor generated and degraded H2O2. The generation of H2O2 was minimal at 0 degrees C but increased as temperature increased, so that at 37 degrees C at 3 hours, approximately 90 microM H2O2 was observed. Degradation was more complex. At 0 degrees C, only a slow rate of degradation was observed. At 25 degrees C, it was more rapid, and a steady state between generation and degradation was observed at approximately 30 microM. However, at 37 degrees C, starting with 100 microM H2O2, degradation was initially rapid, but then generation became predominant and H2O2, concentration increased to more than 100 microM in 3 hours. No H2O2 was generated in the absence of O2, and H2O2 production increased with increasing O2 tension. Both low and high molecular weight components contributed to the degradation, but synthesis was completely dependent on low molecular weight constituents. Ascorbic acid and metal ions such as Cu+ made a major contribution to H2O2 production. Catalase may be the macromolecular component responsible for aqueous H2O2 decay, as evidenced by H2O2 degradation, inhibition by boiling or 3-aminotriazole, and the approximate correspondence between oxygen generation and H2O2 degradation. CONCLUSIONS: The results indicate that the aqueous humor is capable of producing levels of H2O2 that have been shown previously to cause cataract in organ culture. Changes in aqueous humor metal ion content and concentration of oxygen level have profound effects on H2O2 concentration and may effect lens viability. The variation in published H2O2 levels may in part be the result of the conditions under which the aqueous humor was obtained, stored, and used for assay. The observed steady state H2O2 concentration of 1 microM in fresh aqueous from bovine eyes must be maintained by the metabolism of surrounding tissues as well as intrinsic components capable of degrading H2O2.

Animals↗