Concentration of minocycline in human aqueous humor after oral administration (author's transl)]

For antibacterial prophylaxis in intraocular surgery minocycline was administered in oral dosage in 22 cataract-patients. The concentration levels reached in the aqueous humor were determined. The detected levels ranged in some cases from 0.08 to 0.2 mcg/ml, the majority was below 0.06 mcg/ml.     

Cefoperazone concentrations in human aqueous humor after intravenous administration

Twenty-four patients about to undergo elective cataract surgery received either a 2-g (ten patients) or a 4-g (14 patients) intravenous infusion of cefoperazone one to six hours before surgery. The 4-g dose produced a mean peak aqueous humor concentration of 2.93 micrograms/ml at one hour; the mean concentration remained higher than 2 micrograms/ml for at least four hours. These levels, however, were never more than 90% of the minimum inhibitory concentration of cefoperazone for common bacterial ocular pathogens.     

Cyclic-AMP in the aqueous humor: the effects of repeated topical epinephrine administration and sympathetic denervation

Cyclic-AMP (c-AMP) may mediate the effects of topical epinephrine on intraocular pressure in the rabbit eye. Experiments which further correlate the decrease in intraocular pressure with the increase in c-AMP in the aqueous humor in response to adrenergic agonists are presented.Repeated, daily topical administration of epinephrine led to diminished responsiveness to this drug on the fifth day. The treated eye demonstrated a smaller decrease in intraocular pressure and a smaller increase in c-AMP in the aqueous humor on the fifth day when compared to the response of a previously untreated eye.Unilateral superior cervical ganglionectomy, after a 2–3-week recovery period, causes a denervation supersensitivity to alpha-adrenergic agonists. Topical norepinephrine and epinephrine caused a greater fall in intraocular pressure and greater increase in c-AMP in the aqueous humor of the denervated eye than of the control eye. The shift to the left of the dose-response curve for epinephrine indicates a greater affinity for agonists in the denervated eye. Intravitreal injections of a high concentration of epinephrine produced a greater maximal response of c-AMP in the aqueous humor of the denervated eye. This is consistent with an increased number of sites for c-AMP production following sympathetic denervation. Speculations on the location of the adenyl cyclase system are discussed.     

PGE2 and leucocyte levels in aqueous humor after lens extraction and intraocular lens implantation

In order to study the inflammatory response after cataract surgery and intraocular lens implantation the leukocyte (WBC) and prostaglandin E₂ (PGE₂) levels in aqueous humor were measured in rabbit eyes at different time points (1, 3, 7, 14 and 28 days) postoperatively. In the first group lenses were implanted in the anterior chamber of the eye, without lens extraction, while in the second group the lens was removed and the IOL was placed in the capsular bag. A third group of animals was injected with 10 ng endotoxin into the vitreous in order to induce an inflammation of the uvea. In the endotoxin group high levels of WBC and PGE₂ were observed at 24 h postoperatively, followed by a decrease over time. In the intraocular lens groups WBC and PGE₂ were detected at all time points, and at higher levels compared to the endotoxin group. The WBC was high at day 1 and 3, declined over time, and then increased at day 28 postoperatively. The PGE₂ level was highest at day 3 in rabbits with anterior chamber lenses, while it peaked at day 7 in the animals with IOLs implanted in the capsular bag. In animals with the extracapsular lens extraction without an implanted IOL, the levels of WBC and PGE₂ decreased over time, and were statistically lower after one week compared with animals with an IOL placed in the capsular bag. The results demonstrate that the inflammatory response after cataract surgery persists for at least one month, probably due to surgical trauma and foreign body reactions. PGE₂ and WBC could be used to study postoperative trauma and biocompatibility of different IOL materials and designs.     

Azlocillin concentrations in human aqueous humor after intravenous and subconjunctival administration

Twenty-nine patients received either 4 g intravenous infusion or 100 mg subconjunctival application of azlocillin 1-12 h before cataract extraction. After intravenous application the mean aqueous humor concentration of azlocillin was 4.4 micrograms/ml after 3 h. The subconjunctival dose produced a mean aqueous humor concentration of 78 micrograms/ml and 3.4 micrograms/ml after 3 and 12 h, respectively. These levels are above the minimum inhibitory concentration of azlocillin for sensitive organisms.     

Penetration of ofloxacin and ciprofloxacin in aqueous humor after topical administration.

BACKGROUND AND OBJECTIVE: To compare the aqueous humor levels of 0.3% ofloxacin and 0.3% ciprofloxacin containing eyedrops in patients with healthy cornea. PATIENTS AND METHODS: Fifty patients with cataract were randomly assigned to have 0.3% ofloxacin containing eyedrop (25 patients) or 0.3% ciprofloxacin containing eyedrop (25 patients). Both drugs were repetitively instilled to each patient for 6 hours before the surgery. Aqueous samples were collected after penetrating the anterior chamber during cataract extraction and assayed by high-performance liquid chromatography method. RESULTS: The aqueous humor level of ofloxacin (1.43 +/- 0.26 microg/ml, mean +/- SEM) was significantly higher than that of ciprofloxacin (0.35 +/- 0.07 microg/ml) following the topical application (P < .0002). CONCLUSION: Aqueous humor penetration of topical ofloxacin is about 4 times higher than that of topical ciprofloxacin when the drugs are applied as described above.     

人工晶状体植入术后房水细胞因子的研究进展

白内障摘除联合人工晶状体植入术作为白内障最主要的治疗手段,人工晶状体的生物相容性一直是研究的热点。从宏观层面,人工晶状体的生物相容性主要反应在人工晶状体植入术后的并发症,如：眼内炎、角膜内皮水肿、虹膜后粘连、葡萄膜炎、后发性白内障等;人工晶状体的生物相容性微观主要表现在房水中的一些细胞反应,如：巨噬细胞、单核细胞、成纤维细胞及人晶状体上皮细胞等在人工晶状体表面的黏附、增殖,且术后并发症是由于房水中细胞因子连续作用于房水内细胞产生的,另一角度讲,房水中细胞因子是桥梁,它一定程度能反应人工晶状体的情况,能更全面的评价人工晶状体的生物相容性,有利于探究白内障术后并发症的发生的机制,提高人工晶状体的生物相容性。     

PGE(2) and leucocyte levels in aqueous humor after lens extraction and intraocular lens implantation

In order to study the inflammatory response after cataract surgery and intraocular lens implantation the leukocyte (WBC) and prostaglandin E(2) (PGE(2)) levels in aqueous humor were measured in rabbit eyes at different time points (1, 3, 7, 14 and 28 days) postoperatively. In the first group lenses were implanted in the anterior chamber of the eye, without lens extraction, while in the second group the lens was removed and the IOL was placed in the capsular bag. A third group of animals was injected with 10 ng endotoxin into the vitreous in order to induce an inflammation of the uvea. In the endotoxin group high levels of WBC and PGE(2) were observed at 24 h postoperatively, followed by a decrease over time. In the intraocular lens groups WBC and PGE(2) were detected at all time points, and at higher levels compared to the endotoxin group. The WBC was high at day 1 and 3, declined over time, and then increased at day 28 postoperatively. The PGE(2) level was highest at day 3 in rabbits with anterior chamber lenses, while it peaked at day 7 in the animals with IOLs implanted in the capsular bag. In animals with the extracapsular lens extraction without an implanted IOL, the levels of WBC and PGE(2) decreased over time, and were statistically lower after one week compared with animals with an IOL placed in the capsular bag. The results demonstrate that the inflammatory response after cataract surgery persists for at least one month, probably due to surgical trauma and foreign body reactions. PGE(2) and WBC could be used to study postoperative trauma and biocompatibility of different IOL materials and designs.     

Short-term oxidative status of lens and aqueous humor after excimer laser photorefractive keratectomy

PURPOSE: Oxidation in the anterior ocular segment is associated with cataractogenesis and possible complications to corneal endothelium. We investigated whether oxidation occurred in the rabbit anterior ocular segment shortly after excimer laser photorefractive keratectomy (PRK). METHODS: Rabbits were treated unilaterally with PRK, the other eye serving as a control. Aqueous humor sampled shortly after treatment was assayed spectrophotometrically for hydrogen peroxide using ferrous oxidation in xylenol in the presence (group 1; n=10), or absence of oxygen (group 2; n=8). Oxidized glutathione and malondialdehyde levels were measured in lenses by spectrophotometry and HPLC. RESULTS: Hydrogen peroxide concentration of aqueous humor was not different between treated (77 +/- 36 microM) and control eyes (88 +/- 34 microM) in the oxygen group or the nonoxygenated group (treated eyes: 6.7 +/- 5.4 microM and control eyes: 5.5 +/- 4.7 microM). Peroxide levels did not correspond to endogenous H2O2 but presumably reflected action on ascorbic acid. There was no difference in the percent of oxidized glutathione between experimental and control eyes. Malondialdehyde could not be detected in the lens of treated or control eyes, despite good sensitivity in recovery assays. CONCLUSION: Based on these assays, there is no evidence that PRK oxidizes the aqueous humor or the lens of treated rabbits within 10 minutes of treatment.     

PRK and LASIK--their potential risk of cataractogenesis: lipid peroxidation changes in the aqueous humor and crystalline lens of rabbits

PURPOSE: There are insufficient data on the possible cataractogenic side effects of excimer laser corneal surgery. Higher malondialdehyde (MDA) levels could indicate oxidative events related to the cataractogenic process. We therefore examined MDA levels after refractive laser surgery. METHODS: Six white Russian rabbits received laser in situ keratomileusis (LASIK) (Schwind keratome) in the right eye and a 250-microm-deep microkeratome cut (Schwind microkeratome) in the left eye. Six others underwent photorefractive keratectomy (PRK) in the right eye; the left eye remained untreated. The 180 mJ/cm2 fluence applied at a rate of 10 Hz with an optical zone diameter of 5 mm in all rabbits (438 pulses) resulted in an estimated central photoablation depth of 116 microm. Two weeks later, lenses and aqueous were taken immediately after death. MDA was detected in aqueous and homogenate of lenses after reacting with thiobarbituric acid (TBA). MDA bound to TBA (MDA-TBA) was specifically analyzed by high-performance liquid chromatography (HPLC) (excitation, 525 nm; emission, 551 nm) using phosphate-buffered methanol as eluent. RESULTS: No significant laser-induced MDA alteration was found in either the aqueous or the lens. The microkeratome group, however, had two to three times higher MDA levels in the lenses than the control group (p = 0.12) or the PRK (p = 0.03) group. CONCLUSION: Elevation of MDA in the lens of the microkeratome group indicates that LASIK, but not PRK, may be a risk factor in cataractogenesis. The increased MDA levels in the LASIK group are probably caused by the microkeratome incision rather than the secondary radiation of the excimer laser. Postoperative inflammation may explain the surprising results.     

The corneal contact lens and aqueous humor hypoxia in cats

The cornea normally receives its oxygen from both the atmosphere and the aqueous humor. When a thick polymethylmethacrylate contact lens is placed on the cat cornea, access of atmospheric oxygen to the cornea is restricted, and the outer part of the cornea becomes hypoxic. This results in an increase in the oxygen flux from the aqueous humor into the cornea, and the oxygen tension in the aqueous humor decreases, as is demonstrated in this study. This increased oxygen flux from the aqueous into the cornea tends to alleviate the hypoxia caused by a corneal contact lens. Thus, the cornea can tolerate a thicker contact lens with less hypoxia than would be expected if only the oxygen supply from the atmosphere were considered.     

Cefamandole levels in primary aqueous humor in man.

We administered cefamandole nafate to 69 patients before cataract extraction and assayed serum and aqueous humor for antibiotic content at the time of surgery. Average aqueous humor levels of 0.33, 0.59, 0.21, and 0.14 microgram/ml were achieved at one half, one, two and four hours, respectively, after a 1-g intravenous dose. After a 2-g intravenous dose, we found average aqueous humor levels of 1.26, 1.0, 1.57, 0.73, and 0.34 microgram/ml at one half, one, two, four and six hours, respectively. Therapeutic levels in primary aqueous humor effective against common grampositive pathogens were consistently achieved with the 2-g dose, but levels effective against Enterobactereaceae were attained only erratically.