[Cataract and glaucoma in the light of modern research on the aqueous humor].
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Aqueous Humor↗
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[Tumor cells in the aqueous humor].
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Aqueous Humor↗
[THE METHODS OF GRANT AND OF GALIN FOR DETERMINATION OF THE RESISTANCE TO OUTFLOW OF THE AQUEOUS HUMOR].
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Aqueous Humor↗
[New vessels for drainage of the aqueous humor].
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Aqueous Humor↗
Penetration of topically applied dexamethasone alcohol into human aqueous humor.
Gas chromatography combined with mass spectrometry was used to determine the absorption of topically applied dexamethasone alcohol into the aqueous humor of human subjects undergoing routine intraocular surgery. The dexamethasone concentration in aqueous humor was greatest in the interval between 91 and 120 minutes following instillation (mean concentration, 31 ng/mL). Dexamethasone was still detectable in the aqueous 12 hours after instillation.
Administration, Topical↗
Decrease of pigment epithelium-derived factor in aqueous humor with increasing age.
PURPOSE: To determine whether the level of pigment epithelium-derived factor (PEDF) in the aqueous humor is altered with age. DESIGN: Observational case series. METHODS: The PEDF concentration in the aqueous humor was measured by enzyme-linked immunosorbent assay in 152 eyes of 121 patients who underwent cataract surgery. RESULTS: The mean aqueous level of PEDF was 0.86 +/- 0.04 microg/ml (mean +/- standard error, 70.7 +/- 1.0 years). The PEDF levels decreased with increasing age, and the decrease was significantly correlated with age (Pearson product moment correlation coefficient, r = - 0.22, P =.006). The mean PEDF level in the men (0.76 +/- 0.06 microg/ml, 53 eyes, 71.5 +/- 2.0 years) was significantly lower than that in women (0.91 +/- 0.04 microg/ml, 99 eyes, 70.2 +/- 1.1 year, P =.03). CONCLUSIONS: The negative correlation of PEDF level and age should be considered in age-related eye diseases, especially those associated with angiogenesis.
Adolescent↗
Elevated levels of secretoneurin in the rabbit aqueous humor in response to formaldehyde irritation.
BACKGROUND: Secretoneurin, a 33-amino-acid neuropeptide, is generated by proteolytic processing of secretogranin II, which belongs to the chromogranin family. This study aimed to investigate whether secretoneurin is present in the uninflamed rabbit aqueous humor and whether it is released in response to treatment with topical formaldehyde, an agent known to release sensory peptides originating from the trigeminal ganglion. METHODS: Blood samples and aqueous humor of eyes pretreated with neutral formaldehyde and untreated controls were analyzed for secretoneurin immunoreactivity by a highly sensitive radioimmunoassay. Furthermore, the molecular form of the secretoneurin immunoreactivity was characterized by gel filtration high-performance liquid chromatography (HPLC). RESULTS: In the blood, secretoneurin levels were found to be below the detection limit of 2 fmol/100 microl. In the aqueous humor, secretoneurin-immunoreactivity was detected in moderate but significant amounts. The mean concentration of secretoneurin was 8.1 (+/-0.34) fmol/100 microl in controls and 7.8 (+/-0.1) fmol/100 microl 15 min after formaldehyde application. Thirty minutes after treatment, the secretoneurin levels were significantly elevated by 63%. Gel filtration HPLC revealed that the main molecular form corresponded to the free peptide secretoneurin. CONCLUSIONS: The neuropeptide secretoneurin has been detected in the anterior segment of the eye for the first time. The elevation of secretoneurin in formaldehyde-treated eyes may be induced by an enhanced release from the iris/ciliary body complex, as formaldehyde is known to provoke neurogenic inflammation in the anterior segment via release of sensory peptides originating from the trigeminal ganglion. This is why our results indicate a sensory origin of secretoneurin in the eye.
Animals↗
[Reduced production of aqueous humor in Fuch's corneal dystrophy].
Fuchs' corneal dystrophy is associated with a reduced production of the aqueous humor, as can be established via tonography. The trophopathy and cornea guttata caused thereby are prerequisites for the production of Fuchs' corneal dystrophy. The aqueous humor production should be examined before keratoplasty, since the prognosis is questionable if the production is low. If no improvement of visual acuity can be excepted, keratoplasty should not be performed, since pain has also been relieved by means of intracorneal acrylate implantates.
Acrylates↗
Prostaglandin E2 and protein levels in rabbit aqueous humor following ND:YAG laser iridotomy.
Prostaglandin E2 (PGE2) and protein levels were measured in the aqueous humor of rabbits' eyes subjected to iridotomy with the neodymium:YAG laser. Following irradiation, PGE2 levels were elevated to the highest elevation of 20.0 +/- 7.7 ng/ml (mean +/- SD) at 30 minutes as compared to control levels of 0.625 +/- 0.075 ng/ml. PGE2 concentrations progressively decreased, however, after 8 hours they remained high and did not resume control levels. Protein levels in the aqueous humor of ND:YAG irradiated eyes reached peak levels at 30 minutes to 7.8 +/- 2.2 mg/ml compared to control level of 1.3 +/- 0.4 mg/ml. A progressive decrease in protein levels was observed after peak time, but they were still above control levels, at 8 hours. Our study demonstrated that ND:YAG irradiation of the iris involves an immediate increase in PGE2 aqueous levels associated with a blood aqueous barrier disruption and augmented aqueous protein levels.
Animals↗
Effect of phenylephrine on aqueous humor flow.
The effect of topical 2.5% phenylephrine hydrochloride, an alpha adrenergic agonist, on the rate of aqueous humor flow was studied in the eyes of 22 normal human subjects. The drug and a placebo were administered by random assignment from coded containers with the fellow eye serving as the control. Intraocular pressure, anterior chamber volume, corneal thickness and the rate of clearance of topically applied fluorescein from the anterior chamber were measured. Four of the 22 subjects underwent a study of the effect of phenylephrine on the permeability to fluorescein of the blood-aqueous barrier. No statistically significant effect of the drug was found on the rate of aqueous humor flow, intraocular pressure, anterior chamber volume, corneal thickness or permeability of the blood-aqueous barrier.
Anterior Chamber↗
[Aqueous humor concentration of norfloxacin following local administration].
The Aqueous humor concentration of norfloxacin was measured following topical administration in 20 eyes. The substance was applied at different time intervals. Nineteen samples obtained prior to cataract extraction had mean concentrations between 0.014 and 0.105 microgram/ml. These concentrations are under the MIC90 of most germs. One eye with minimal congestion due to a neovascular glaucoma, however, had a concentration of 0.206 microgram/ml.
Aged↗
Effect of intracameral and intravitreal injection of calcitonin gene-related peptide on the intraocular pressure and outflow facility of aqueous humor in the rabbit.
After intracameral injection calcitonin gene-related peptide has been demonstrated to break the blood aqueous barrier and increase intraocular pressure in rabbits. However in cats, calcitonin gene-related peptide decreases intraocular pressure by increasing the outflow facility of aqueous humor. In the present study, the effect of intracameral injection of calcitonin gene-related peptide on the outflow facility in rabbits has been investigated and the intraocular pressure and outflow facility were measured following intravitreal administration of calcitonin gene-related peptide. The results demonstrate that in spite of the apparent pseudofacility component caused by a breakdown of the blood aqueous barrier also the true trabecular outflow is probably increased in the rabbit eye after intracameral injection of calcitonin gene-related peptide. The intravitreal administration of calcitonin gene-related peptide leaves the blood aqueous barrier intact and causes an increase in the outflow facility of aqueous humor with a concomitant long-lasting decrease in intraocular pressure.
Animals↗
Sequential analysis of antibody responses in serum, aqueous humor and tear film during latent and induced recurrent HSV infections.
To study HSV specific antibody responses during latent HSV infection and induced HSV ocular shedding, rabbits were infected binocularly with McKrae strain HSV-1. The titer and class of anti-HSV antibody response in serum, aqueous humor and eye washes were determined sequentially during latent HSV infection and following intentional reactivation. In all instances the only antibody class detected was IgG. The highest anti-HSV titers were in the serum and aqueous humor, whereas a significantly lower level of anti-HSV IgG was found in eye washes. Anti-HSV IgG antibody titers were consistently 100-fold higher in serum than in the aqueous humor, which suggests an absence of local ocular antibody synthesis. Neither anti-HSV IgM nor secretory IgA antibodies were detected in any samples.
Animals↗
Halothane anesthesia and aqueous humor dynamics in laboratory animals.
Halothane anesthesia decreased intraocular pressure (IOP) by approximately 4 mm Hg in both normal rabbits and monkeys. The administration of nitrous oxide or 100% oxygen had no effect on IOP. Although PO2 and PCO2 increased following halothane administration in rabbits, similar blood changes occurred without IOP reduction in control rabbits receiving 100% oxygen. Outflow facility in both species as measured by tonography remained unchanged by halothane administration. Aqueous humor flow as estimated by tonography decreased by about 39% in rabbits and 31% in monkeys. Posterior chamber aqueous humor ascorbate was significantly elevated 90 min after halothane administration in rabbits. The ratio of the aqueous humor flow coefficient to diffusion coefficient for ascorbate (kfa/kdpa) was reduced approximately 47% following the administration of halothane. Halothane did not alter the in vitro accumulation of 131I-hippuran or 86Rb by rabbit ciliary body--iris preparations.
Anesthesia, Inhalation↗
Assessment of aqueous humor zinc status in human age-related cataract.
Age-related cataract is an ever-increasing health problem among the elderly population worldwide. In recent years, there has been speculation that the levels of micronutrients in ocular tissue may play a role in the pathogenesis of cataract, especially zinc, since it is found in high concentrations in the eye tissues, including the aqueous humor. 44 subjects diagnosed with cataract were chosen for study and matched with 21 healthy controls to determine the concentration of zinc in aqueous humor. The findings revealed that a significantly higher concentration of zinc was present in the aqueous humor of our study population compared to controls (p < 0.001). These findings, in agreement with several previous studies, amplify the need for further investigation to determine if these higher levels are in actuality a consequence of the disease or a factor in the formation of cataract.
Aging↗
Changes in aqueous humor dynamics with age and glaucoma.
Changes in aqueous humor dynamics with age and in glaucoma have been studied for several decades. More recently, techniques have been developed which confirm earlier studies showing that outflow facility decreases with age and in glaucoma and add the newer finding that uveoscleral outflow also decreases. Morphologic studies in aging and glaucoma eyes have shown an increase in accumulation of extracellular material in both the trabecular meshwork and ciliary muscle and a loss of trabecular meshwork cells, which contribute to this reduction in outflow and result in an increase in intraocular pressure. A reduction in hyaluronic acid and increases in fibronectin and thrombospondin contribute to the change in the extracellular environment. Imbalances in responses to age-related stresses such as oxidative damage to long-lived molecules, protein cross-linking and loss of elasticity could trigger excess production of factors such as transforming growth factor beta, interleukin-1 and CD44S that could stimulate pathways leading to increases in fibronectin, transformation of trabecular meshwork cells to a myoepithelial state and decrease the breakdown in extracellular matrix material, allowing excess to accumulate. Ultimately trabecular outflow and uveoscleral outflow are reduced and intraocular pressure becomes elevated, adding more stress and perpetuating the pathological condition. Future research to identify additional factors and clarify their roles in these processes could lead to alternative therapies for age and glaucoma related changes in the eye.
Aging↗
Bioassays for quantitating ciprofloxacin and tobramycin in aqueous humor.
Development of new therapies for bacterial keratitis requires assays of antibiotics in infected ocular tissues; however, methods for such drug quantitation can be expensive and can lack precision and sensitivity. To develop a more suitable assay for quantitating tobramycin and ciprofloxacin in the aqueous humor, sixteen bioassays were compared. Variables assessed included: the strain of bacteria used as indicator (Staphylococcus aureus ATCC 25923 versus Klebsiella pneumoniae ATCC 10031), the application of bacteria to the agar surface versus inclusion in molten agar, the volume of the agar, and the application of antibiotic on paper discs versus instillation into agar wells. The best results were obtained when the appropriate indicator organism (S. aureus for tobramycin and K. pneumoniae for ciprofloxacin) was applied to the surface of the agar, antibiotic solution was put into agar wells, and the volume of agar was 30 ml per plate. The best sensitivity for assays of tobramycin and ciprofloxacin diluted in water were 0.98 and 0.12 micrograms/ml, respectively. These sensitivities improved as much as fourfold when antibiotics were diluted in aqueous humor or normal saline. The precision of all assays tested was high as determined by regression coefficients (r > 0.90). The sensitivity and precision of these assays indicate their utility for quantitating fluoroquinolones and aminoglycosides in aqueous humor.
Animals↗
Cefsulodin levels in the human aqueous humor.
Subconjunctival administration of cefsulodin sodium (100 mg), but not systemic administration (500 mg), provided therapeutic concentrations in the primary aqueous humor of 22 patients who underwent cataract surgery. Therapeutic concentrations of cefsulodin persisted in the aqueous humor for at least five hours after subconjunctival administration of the agent.
Aged↗