An experimental study of cytology in the aqueous humor of rabbit eyes after intraocular lens implantation

OBJECTIVE: The study was designed to count the number of white blood cells and observe their subset distribution in the aqueous humor after extracapsular lens extraction and intraocular lens (IOL) implantation in capsular bag in rabbits and to discuss the mechanism of postoperative intraocular inflammatory response. METHODS: 27 adult pigmented rabbits were divided into three groups: (1) The IOL was placed in the capsular bag after extracapsular lens extraction; (2) The extracapsular lens extraction; and (3) The control group without any surgical intervention. Aqueous humor samples were aspirated on the postoperative 1, 3, 7 and 14 days, and the total number of white blood cells in the aqueous humor and their subset distribution were counted. The data were analyzed by using analysis of variance of SAS software. RESULTS: There was a significantly higher number of inflammatory cells in the IOL implanted eyes than that in the eyes with only extracapsular lens extraction. CONCLUSIONS: In the early postoperative stage, there was a marked increase in the number of white blood cells and polymorphonuclear leukocytes in the IOL group, that is probably related to the mechanical ocular tissue damage and the breakdown of the blood-aqueous barrier induced by the operative procedures. There were a significant increase in the macrophages, eosinophiles, and lymphocytes in the IOL group, that suggests that an active immune response exist in the anterior ocular inflammation after IOL implantation.     

Penetration of oral and topical ciprofloxacin into human aqueous humor

PURPOSE: This study was planned to investigate the penetration of ciprofloxacin into aqueous humor following oral and topical application as a prophylactic antimicrobial agent. METHODS: Forty-six patients undergoing cataract surgery were randomly divided into two groups. In the first group, the patients received 500 mg oral ciprofloxacin eight hours before surgery and in the second, 5 drops of 0.3% ciprofloxacin were applied to the patients every twenty minutes, starting 100 minutes before the surgery. By paracentesis, aqueous samples were taken just before the operation so the interval between the first topical application and paracentesis was 100 minutes. RESULTS: The mean concentration of ciprofloxacin in aqueous humor was 0.63+/-0.29 microg/ml in the first group. The concentration was 0.69+/-0.30 microg/ml in the second group. Both of these mean concentrations were higher than the levels of MIC90 of S.aureus , S. epidermidis, P. aeruginosa and Gram (-) bacteriae. CONCLUSION: As a result, both topically and orally applied ciprofloxacin achieved a significant aqueous concentration. Each route studied might be suitable for surgical prophylaxis or treatment of infections.     

Increase in aqueous humor production following D1 receptors activation by means of ibopamine

BACKGROUND: Topically administered 2% ibopamine (a dopaminergic agonist) induces a transitory ocular hypertension in 92% of patients with primary open-angle glaucoma and in 52% of patients with normal tension glaucoma. In normal eyes, ibopamine has no effect on IOP. PURPOSE: The aim of the present study was to verify, by means of fluorophotometric techniques, which hydrodynamic changes could be induced in normal and glaucomatous eyes, stimulating the D1 receptor with 2% ibopamine administered topically. In addiction, we wanted to evaluate if ibopamine could modify IOP before and after an experimentally induced outflow system impairment in rabbits. METHODS: In study 1 we performed a measurement of aqueous humor flow in 6 healthy volunteers and in 6 glaucomatous patients, before and after 2% ibopamine administration. In study 2 the alteration of outflow pathways was induced by means of Laminaria Digitata in 10 rabbits. RESULTS: After 2% ibopamine administration we found a significant increase in aqueous humor production, both in glaucomatous (P = 0.035) and normal eyes (P = 0.004). In rabbits, we found no significant change in IOP at basal conditions. After experimentally induced outflow system impairment by laminaria, we observed a marked increase in IOP (+ 13.5 mmHg SD 7.2; P < = 0.001) following ibopamine administration. CONCLUSIONS: These experimental data have a diagnostic value in glaucoma, since they show how an intraocular hypertensive response due to ibopamine in normotensive eyes is a sign of initial outflow impairment. Moreover, the possibility to increase the aqueous humor production sets new trends in the treatment of post surgical ocular hypotony.     

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.     

Effect of mitomycin C on aqueous humor flow, flare and intraocular pressure in eyes with glaucoma 2 years after trabeculectomy

BACKGROUND: The purpose of this study was to determine the intraocular pressure (IOP), aqueous humor flow, flare and ocular side effects in eyes with a history of hypotony after trabeculectomy with adjunctive mitomycin C (MMC). METHODS: Thirty-six eyes with primary or secondary open-angle glaucoma and IOP < or = 8 mmHg during the postoperative period were studied 745 +/- 315 days after surgery. MMC (0.2 or 0.5 mg/ml) was applied to the episclera with a cellular sponge. Flare was studied with the Kowa Laser Flare Meter 500. Aqueous humor flow was measured in the afternoon (Fluorotron Master II). IOP, visual fields and best corrected visual acuity were also examined. Twenty-two contralateral eyes without surgical intervention served as controls. RESULTS: The mean age of patients was 44.5 +/- 16.8 years. The mean IOP was significantly lower in the MMC group than in the control group: 9.6 +/- 6.4 mmHg vs 18.0 +/- 13.6 mmHg at 2 years (P < 0.001). Aqueous flow was significantly lower in subjects treated with MMC than in controls (P < 0.001). The flare values were significantly higher in the MMC-treated group, with a mean of 12.0 +/- 7.7 photon counts/ms, than in the control group, mean 7.9 +/- 4.6 photon counts/ms (P < 0.019). CONCLUSION: Our data suggest that MMC is a useful ocular hypotensive agent which seems to participate in a change in aqueous humor dynamics when applied topically as an aqueous solution.     

Does aqueous humor secretion decrease with age?

Aqueous humor flow was calculated during day-time in 148 healthy volunteers and 75 older patients using the Fluorotron Master II anterior chamber protocol (Coherent, Palo Alto, USA). Healthy volunteers as well as patients had no history of ocular pathology, surgery or laser treatment. Slitlamp examination revealed no ocular pathology. Hypertension, diabetes, local and systemic drug therapy, neoplasia, kidney or liver disease, contact lens and ocular trauma were excluded. Mean age of volunteers was 26.5 +/- 3.8 years; age of patients: 65.5 +/- 10.5 years. Aqueous humor flow during day-time in healthy volunteers in the OD: (mean +/- s.d.) 2.26 +/- 1.0 microliters/min, in the OS: 2.17 +/- 1.0 microliters/min, OS: 1.86 +/- 1.1 Ml/min. Correlation coefficient: r = 0.8. The mean aqueous humor flow in the older patients during day-time: OD: 1.91 +/- 1.1 microliters/min. Correlation coefficient: r = 0.54. The Mann-Whitney-U-test revealed a significant difference when comparing the right eyes of healthy volunteers with the right eyes of patients (p < 0.01). When comparing all left eyes the difference is also significant (p = 0.01). The results of the study underline, that the mean aqueous humor secretion does significantly decrease with age. However, the data show that there is only a slight decrease of flow of approximately 2.5% per decade. From the clinical point of view it should be concluded, that although the aqueous humor secretion does decrease with age, this is not of clinical importance, even in cases of glaucoma surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nonsulfhydryl-reactive phenoxyacetic acids increase aqueous humor outflow facility

PURPOSE: The phenoxyacetic acid, ethacrynic acid (ECA), has potential use in glaucoma therapy because it acts to increase aqueous outflow in vivo and in vitro. In human trabecular meshwork (HTM) cell culture, ECA acts to change cell shape and attachment, effects that have been correlated with microtubule (MT) alterations and chemical sulfhydryl (SH) reactivity. To further explore these actions, we evaluated two non-SH reactive phenoxyacetic acids, inadcrinone and ticrynafen, and the MT-disrupting drug vinblastine. METHODS: Excised bovine and porcine eyes were perfused and outflow facility measured. Calf pulmonary artery endothelial and HTM cells were grown in culture and cytoskeletal effects evaluated after drug treatment. RESULTS: Indacrinone, ticrynafen, and vinblastine all caused an increase in outflow facility. In contrast with ECA, the outflow effects of indacrinone and ticrynafen were not blocked by excess cysteine. Although indacrinone and ticrynafen produced changes in cell shape in vitro, the beta-tubulin staining pattern of treated cells was not altered. Vinblastine caused cell shape change and the expected MT disruption. CONCLUSIONS: Phenoxyacetic acids can increase aqueous outflow facility and alter HTM cell shape and attachment in vitro by a non-SH, non-MT mechanism (which is probably shared also by ECA). These findings suggest the possibility of a broader class of glaucoma drugs that may be directed at the HTM. An understanding of the cellular target for these drugs has implications both for potential glaucoma therapy and for the cytoskeletal mechanisms involved in normal outflow function.     

The effect of hyperthermia on aqueous humor dynamics in rabbits

Hyperthermia increased intraocular pressure (Po) by approximately 5 mm Hg in rabbit eyes. This increase was not associated with changes in plasma osmolarity, blood lactate, or pH. Episcleral venous pressure (Pv) decreased from a baseline of 11 +/- 1 mm Hg(mean +/- SEM) to 8 +/- 1 mm Hg after one hour of hyperthermia. Outflow facility (c) as measured by tonography remained unchanged. Aqueous humor flow [c(Po - Pv)] as estimated by tonography increased by about 126%. The elevation of intraocular pressure was not prevented by aspirin pretreatment nor altered by unilateral optic nerve transection.     

Acidosis, alkalosis, and aqueous humor dynamics in rabbits

Systemic acidosis induced by intravenous administration of hydrochloric acid lowered intraocular pressure in unanesthetized rabbits. Aqueous humor flow was reduced by approximately 50%, as measured by the iodide method and as calculated from tonographic data. Outflow facility, episcleral venous pressure, plasma osmolality, blood pressure, pulse, and body temperature were not altered by systemic acidosis. Systemic alkalosis induced by intravenously administered sodium bicarbonate was associated with an increased intraocular pressure. Aqueous humor flow following systemic alkalosis was increased by approximately 100%, as measured by the iodide method and as calculated from tonographic data. Alkalosis was not associated with alterations in outflow facility, episcleral venous pressure, plasma osmality, blood pressure, pulse, or rectal temperature.     

Bacterial growth in human vitreous humor

The aim of this study was to investigate the capacity of human vitreous to support bacterial growth and to show differences in the growth kinetics of gram-positive and gram-negative bacteria. Vitreous gel of 70 keratoplasty donor eyes was sampled under sterile conditions, screened microscopically for cellular components and tested for sterility and levels of antibiotic drugs by bio-assay. The samples were inoculated with clinical isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus viridans and Streptococcus pyogenes. As control each strain was added both to 0.9% sodium chloride solution and to Mueller-Hinton broth. In order to determine bacterial growth the number of colony forming units was determined 4, 6, 24, 48 and 72 hr after inoculation by viable count. Vitreous gel did not support bacterial growth; the tested strains could not be recovered after 48 hr. Similar results could be obtained with sodium chloride; whereas in Mueller Hinton broth the strains showed normal pattern of growth. It seems that vitreous humor has inherent antibacterial capacity in vitro, although the responsible factors remain unknown.     

Human hepatocyte growth factor (HGF) in the aqueous humor

Previous studies have demonstrated that individuals with cystinosis, an inherited metabolic disorder, have difficulty processing visual information, and may be selectively impaired in the ability to mentally rotate figures, despite having normal IQs and normal primary sensory function. In our novel task-the 'Black Box'-subjects identified objects solely by feeling the contours. Twenty-three subjects with cystinosis, aged 4 to 34 years, were individually matched with controls on age, sex, handedness, and test form. Subjects with cystinosis performed significantly worse in identifying objects than did controls. In addition, when only subjects over 7 years of age were included, those with cystinosis took significantly longer to correctly identify objects than did controls. Our findings suggest that individuals with cystinosis have difficulty with tactile recognition of common objects. These results support the hypothesis that a genetic disorder may have specific behavioral correlates.     

Effects on intraocular pressure and aqueous flow of various dose regimens of latanoprost in human eyes

A "new" syndrome was identified by McPherson and Clemens [1996: Am J Med Genet 62:58-60] in a brother and sister with bilateral cleft lip and palate, hypertelorism, flat facial profile, flat occiput, and complex heart defects. The brother also had a bilobed tongue and the sister had malrotation of the intestine and bifid thumbs. We describe three brothers with similar anomalies apart from the bilobed tongue, malrotation of the intestine, and bifid thumbs. McPherson and Clemens [1996: Am J Med Genet 62:58-60] suggested autosomal recessive inheritance. Our observation of three affected brothers also raises the possibility of X-linked recessive inheritance.     

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.     

Photoreceptor outer segments in aqueous humor from dogs with rhegmatogenous retinal detachments

OBJECTIVE: To determine whether photoreceptor outer segments can be found in aqueous humor from dogs with rhegmatogenous retinal detachment (RRD). DESIGN: Case series. ANIMALS: 4 dogs with unilateral RRD, 2 dogs with bilateral RRD, 1 dog with unilateral non-RRD, and 1 dog with glaucoma without retinal detachment. PROCEDURE: Aqueous humor samples were fixed in 2% glutaraldehyde and examined by means of transmission electron microscopy. RESULTS: Outer segments were found in aqueous humor from 7 of 8 eyes with RRD but were not found in aqueous humor from dogs with non-RRD or glaucoma. CLINICAL IMPLICATIONS: Photoreceptor outer segments may move into the anterior chamber of eyes with RRD.     

Effect of 8-iso prostaglandin E2 on aqueous humor dynamics in monkeys

OBJECTIVE: To evaluate the effects of 8-iso prostaglandin E2 (8-iso PGE2; prosta-5,13-dien-1-oic acid,11,15-dihydroxy-9-oxo-,[5Z,8beta-11X,13E,15 S]-) on the intraocular pressure (IOP), outflow facility, and aqueous humor flow rates in normal monkeys and monkeys with glaucoma. METHODS: The IOP was measured before and as long as 6 hours after the topical application of 8-iso PGE2 to 1 eye of 6 normal monkeys and to the glaucomatous eye of 8 monkeys with unilateral laser-induced glaucoma. The pupil diameter was measured at the same times as the IOP measurements in the normal monkeys. Tonographic outflow facility and fluorophotometric flow rates of aqueous humor were measured in 6 normal monkeys before and after drug treatment. RESULTS: In normal monkeys, a single dose of 0.1% 8-iso PGE2 reduced (P<.01) the IOP for 4 hours in the treated eyes with a maximum (mean +/- SEM) reduction of 3.2 +/- 0.2 mm Hg, compared with the contralateral control eyes. The pupil size was smaller (P<.01) in the treated eyes by as much as 1.0 +/- 0.2 mm for 4 hours. In 8 glaucomatous monkey eyes, the application of 0.05% and 0.1% 8-iso PGE2 reduced the IOP (P<.01) for as long as 2 and 5 hours, respectively. The maximum reduction in the IOP was 4.6 +/- 0.8 mm Hg (0.05%) and 6.0 +/- 0.8 mm Hg (0.1%) compared with baseline measurements. The magnitude and duration of the ocular hypotensive effect were enhanced with twice-a-day administration for 5 consecutive days. Outflow facility in normal monkey eyes was increased (P<.05) by 48% in the treated eyes, and aqueous humor flow was unchanged (P>.10), compared with vehicle-treated contralateral control eyes. Mild eyelid edema, conjunctival edema, hyperemia, and discharge appeared in some eyes treated with the 0.1% drug concentration. CONCLUSIONS: The use of 8-iso PGE2 reduces the IOP in both normal and glaucomatous monkey eyes. An increase in outflow facility appears to account for most of the IOP reduction in normal monkeys. Clinical Relevance: The application of 8-iso PGE2 may have potential for the treatment of glaucoma as an outflow facility-increasing drug.     

The effect of melatonin on aqueous humor flow in humans during the day

BACKGROUND: Aqueous humor flow through the anterior chamber of the eye undergoes a circadian cycle. The rate of flow during the day is twice as high as the rate of flow at night. The pineal hormone, melatonin, also undergoes a circadian cycle. Melatonin levels are high at night, whereas aqueous humor flow is low. The authors studied the effect of oral melatonin on aqueous humor flow in humans. METHODS: The effect of melatonin on aqueous humor flow was evaluated in 19 healthy human volunteers in a randomized, masked crossover study with a placebo control. The hormone or placebo was administered orally during the day when endogenous levels of melatonin are low. Aqueous flow was measured by fluorophotometry for 8 hours. RESULTS: The mean rate of flow during melatonin treatment was 2.71 +/- 0.64 microliters/minute (+/- standard deviation). The rate of flow during placebo treatment was 2.80 +/- 0.66 microliters/minute. There is no statistically significant difference between these two rates (P = 0.4). With a sample size of 19, the study has a power of 92% to detect at least a 15% difference in the rate of flow under the two conditions. Measurement of plasma concentration of melatonin in five subjects confirmed that concentrations after oral dosage reached peaks comparable with the normal endogenous nocturnal peaks. CONCLUSIONS: The authors conclude that melatonin concentrations during the day, comparable with plasma concentrations that occur spontaneously during sleep, do not suppress aqueous humor formation. The authors find no support for the idea that plasma melatonin, per se, can suppress aqueous formation or that the circadian rhythm of plasma melatonin is primarily responsible for the circadian rhythm of aqueous humor flow.     

Local production of IgG and IgG subclasses in the aqueous humor of patients with Fuchs heterochromic cyclitis, herpetic uveitis and toxoplasmic chorioretinitis

The X-linked agammaglobulinemia (XLA) is a rare immunodeficiency, characterized by absence or accentuated diminuition of all the isotypes of serum immunoglobulins and greater susceptibility to infections, mainly after the sixth mouth of life. The authors present nine patients bearers of XLA, with recurrent infectious processes (pneumonias 7/9, otitis 7/9, sinusitis 5/9, sepsis 5/9, diarrheas 3/9, infectious arthritis 3/9, meningitis 3/9, pyodermitis 3/9, viral encephalitis 1/9), with the beginning of symptoms on average in a nine months life. The laboratory examination showed absence of antibody response, with normal cellular immunity. The patients received immunoglobulin with control of the infectious processes. Five children received prophylactic antibiotic therapy for sinusitis control. The precocious diagnosis of XLA is of extreme importance, with institution of therapy with intravenous immunoglobulin for reduction in infectious process occurrence and complications, besides improving the patient's life quality.