Biomedical subjects

R F Brubaker

Publications and source records attributed to R F Brubaker.

At least 37 records · Page 2Linked to original sources

PubMed1998

Aqueous humor flow in sleeping humans is unaffected by norepinephrine infusion.

PURPOSE: Intravenous administration of the catecholamine epinephrine is known to have a stimulatory effect on aqueous humor flow in sleeping human subjects, an effect that is augmented by plasma corticosteroids. This study was performed to determine whether the closely related catecholamine norepinephrine has a similar effect on aqueous humor flow. METHODS: Twenty normal subjects were studied. Aqueous flow was measured by fluorophotometry. At night during sleep, norepinephrine or placebo was infused intravenously (i.v.) between midnight and 6 AM. The rate of aqueous flow during the norepinephrine infusion was compared with the rate of flow during placebo infusion, with each subject serving as his/her own control. The urinary excretions of epinephrine and norepinephrine were measured at the end of each infusion period. RESULTS: The norepinephrine infusion caused an 8% increase in systolic blood pressure (P < 0.001), a 15% increase in diastolic blood pressure (P < 0.001), and a 9% decrease in heart rate (P=0.003) compared with the placebo. The rate of aqueous humor flow during sleep from 12 AM to 6 AM was unchanged by norepinephrine. The rate was 1.27+/-0.31 microl/min (mean+/-SD) during i.v. infusion of placebo and 1.30+/-0.27 microl/min during infusion of norepinephrine (P=0.63). CONCLUSIONS: An infusion of norepinephrine during sleep that causes measurable changes in cardiovascular parameters has no measurable effects on the rate of aqueous humor flow. The lack of a measurable effect of a norepinephrine infusion contrasts to the stimulatory effect of an epinephrine infusion.

Adult↗

PubMed1998

Measuring oxygen tension in the anterior chamber of rabbits.

PURPOSE: Measuring the concentration of oxygen in the aqueous humor without penetrating the eye would provide a new dimension in understanding aqueous humor and corneal dynamics. In this study a preinvasive method was developed for determining the cameral oxygen concentration in anesthetized rabbits by measuring the excited-state lifetime of a phosphorescent dye. METHODS: A scanning ocular fluorometer was designed to excite phosphorescence with a brief flash of light and to measure the decay of luminescence for as long as 1000 microsec after excitation. The measurement window was scanned through the depth of the anterior chamber or fixed at the mid-anterior chamber. A depot of the phosphorescent dye Pd-uroporphyrin was injected into the vitreous of eight pigmented rabbits, and within a few days the dye was measurable in the anterior chamber. The excited-state lifetime of this dye is inversely correlated to oxygen concentration and was calibrated by measuring the lifetime of dye in cuvettes equilibrated with oxygen-nitrogen mixtures. Oxygen tensions were determined from lifetimes measured in the open eye, under a polymethylmethacrylate (PMMA) contact lens, under two oxygen-permeable contact lenses, and immediately after lid closure. RESULTS: Oxygen tension in the mid-anterior chamber before placing a PMMA contact lens was 23 +/- 3 mm Hg (mean +/- SD; n = 6). After 20 minutes of PMMA lens wear, oxygen tension decreased to 4 +/- 2 mm Hg. When the focal diamond was scanned through the anterior chamber, oxygen tension was 24 +/- 5 mm Hg near the corneal endothelium and decreased to 17 +/- 8 mm Hg near the crystalline lens. Under the PMMA contact lens this gradient reversed: Oxygen tensions near the endothelium and lens were 3 +/- 2 mm Hg and 6 +/- 2 mm Hg, respectively. Lid closure for 10 minutes or longer decreased the mid-anterior chamber oxygen tension from 21 +/- 2 mm Hg (n = 19 measurements from seven animals) to 10 +/- 3 mm Hg (n = 15 measurements from five animals). CONCLUSIONS: Measuring excited-state lifetime of phosphorescent dyes in the anterior chamber provides a useful method for determining oxygen concentration in vivo, without penetrating the eye. Cameral oxygen tension under PMMA contact lenses are significantly lower than in the uncovered eye. The profile of oxygen tension through the anterior chamber suggests that oxygen is supplied transcorneally to the aqueous humor.

Animals↗

PubMed1997

Response of the pupil to tropicamide is not a reliable test for Alzheimer disease.

OBJECTIVE: To confirm the putative hypersensitivity of the pupil to a weak mydriatic in persons with Alzheimer dementia. DESIGN: Twenty patients with Alzheimer dementia and 20 control subjects were examined. Automated binocular infrared pupillography was performed in the dark after instillation of 0.01% tropicamide or placebo. Ocular penetration of eye drops was assessed simultaneously using 2% fluorescein sodium as a tracer. SETTING: Rochester, Minn. SUBJECTS: Twenty patients and 20 cognitively normal control subjects from the Alzheimer's Disease Patient Registry of the Mayo Clinic, Rochester, Minn. MAIN OUTCOME MEASURE: Percent change in the diameter of the pupil following topical ocular instillation of a diluted concentration of the mydriatic drug tropicamide and penetration of topically applied fluorescein into the aqueous humor. RESULTS: No statistically significant difference was found between patients with Alzheimer disease and control subjects in either the mydriatic response of the pupil or in the rate of penetration of topically applied fluorescein. CONCLUSION: No evidence of pupillary hypersensitivity to an anticholinergic mydriatic drug was found in patients with Alzheimer disease or any evidence that this putative hypersensitivity could be used as an early, simple diagnostic test for Alzheimer disease.

Aged↗

PubMed1997

Comparison of dorzolamide and acetazolamide as suppressors of aqueous humor flow in humans.

OBJECTIVE: To compare the efficacy of topical 2% dorzolamide hydrochloride (Trusopt) as a suppressor of aqueous humor flow in the human eye with the efficacy of systemically administered acetazolamide (Diamox). DESIGN: A randomized, double-masked, placebo-controlled study of 40 human subjects in 2 academic centers. The effect of dorzolamide on aqueous humor flow was compared with that of acetazolamide as measured by the rate of clearance of topically applied fluorescein. RESULTS: Acetazolamide reduced aqueous flow from 3.18 +/- 0.70 (mean +/- SD) to 2.23 +/- 0.48 microL per minute, a reduction of 30% (P < .001), and dorzolamide reduced the flow to 2.65 +/- 0.64 microL per minute, a reduction of 17% (P < .001). The difference between the effect of acetazolamine and dorzolamide was significant (P < .001). When acetazolamide is added to dorzolamide, the aqueous flow was reduced further to 2.21 +/- 0.47 microL per minute, an additional reduction of 16% (P < .001). When dorzolamide was added to acetazolamide, no additional reduction was observed (P = .73). Similar effects were observed for intraocular pressure. Acetazolamide reduced pressure from 12.5 +/- 2.2 (mean +/- SD) to 10.1 +/- 2.2 mm Hg, a decrease of 19% (P < .001) and dorzolamide reduced it to 10.8 +/- 2.1 mm Hg, or a decrease of 13% (P < .001). The greater effect of acetazolamide than dorzolamide was significant (P = .03). CONCLUSIONS: For reasons that are not known, the topically applied carbonic anhydrase inhibitor 2% dorzolamide hydrochloride is not as effective as systemically administered acetazolamide. Clinicians who prescribe dorzolamide should expect less of an ocular hypotensive effect than that experienced from systemically administered acetazolamide.

Acetazolamide↗

PubMed1997

Effects of exogenous prostaglandins on aqueous humor dynamics and blood-aqueous barrier function.

Topical prostaglandins (PGs) are very effective at reducing intraocular pressure (IOP) in a variety of animals and in humans with relatively few side effects. The mechanisms of action of several PGs, their prodrugs and analogues have been studied in rabbits, cats, monkeys and humans. PGF2 alpha and its analogues evaluated in monkeys include PGF2 alpha-tromethamine salt, PGF2 alpha -isopropylester (-IE), S-1033, PhXA34, PhDH100A and latanoprost (PhXA41). Aqueous flow and outflow facility are either increased or remain unchanged by these agents. PGF2 alpha-IE, PHXA34, PhDH100A and latanoprost increase uveoscleral outflow, accounting for most of the IOP reduction. PGA2 in cats increases aqueous flow and outflow facility, but it reduces IOP primarily by stimulating uveoscleral outflow. The PGD2 analogue BW245C is unique in that it is the only PG that decreases aqueous flow. Mechanistic studies in humans have been performed with PGF2 alpha -IE, unoprostone, PhXA34 and latanoprost. In two clinical studies with latanoprost, a significant increase in uveoscleral outflow was found which, as in animals, accounts for most of the IOP reduction. A slight but inconsistent increase in outflow facility may also be involved. The doses tested had minimal effects on the permeability of the blood-aqueous barrier (BAB). In vitro studies of human tissue have been conducted to elucidate the PG effect on outflow facility and uveoscleral outflow. Studies of isolated human anterior segment preparations show that PGE2 increases outflow facility whereas PGF2 alpha has no measurable effect on this parameter. Studies of human ciliary muscle cells in tissue culture indicate that PGs may directly modulate extracellular matrix metabolism, which may be related to the increased uveoscleral drainage. This review summarizes in vitro and in vivo studies of the effects of PGs on aqueous humor dynamics and BAB integrity in humans, cats and monkeys.

Animals↗

PubMed1996

Structure and function of the corneal endothelium in diabetes mellitus type I and type II.

OBJECTIVE: To measure and compare corneal endothelial morphologic characteristics and function in subjects with diabetes mellitus types I and II. DESIGN: Forty-nine patients with diabetes mellitus type I and 60 patients with diabetes mellitus type II were recruited from the active practice of the Mayo Clinic, Rochester, Minn. Thirty-one normal subjects, divided by age into two overlapping groups of 20 each, served as controls. Corneal endothelial permeability and corneal autofluorescence were measured by fluorophotometry. Central corneal endothelial photographs were taken with a wide-field specular microscope, which also measured the corneal thickness. RESULTS: Neither the type I nor the type II diabetics differed from their controls in endothelial permeability and endothelial cell density. The type I diabetics had polymegethism, pleomorphism, increased corneal thickness, and increased corneal autofluorescence compared with their controls. Similar measured values were found in the type II diabetics, but they did not differ significantly from those of their age-matched controls. The type II diabetics were older than the type I diabetics, and the older control group showed changes similar to those seen in the diabetics; these changes were presumably associated with aging. The severity of retinopathy was significantly correlated only with corneal autofluorescence. CONCLUSION: The corneas of patients with type I diabetes mellitus exhibit abnormalities in endothelial cell morphologic characteristics and corneal autofluorescence. The changes resemble those that occur with aging in normal subjects, making them difficult to discern as abnormal in type II diabetics, who are usually older. We found no abnormalities in endothelial permeability in either type I or type II diabetics.

Adolescent↗

PubMed1996

The effects of sleep on circulating catecholamines and aqueous flow in human subjects.

We measured the rate of aqueous flow and analysed its relation to the time of day, the state of wakefulness and the urinary excretion of catecholamines. Two groups of subjects were studied. One group comprised 20 normal subjects who were studied over two 22-hr periods. During one period, the subjects were permitted to sleep during their customary hours of sleep; during the other, they were not permitted to sleep, but remained active for all 22 hr. The other group comprised ten subjects with obstructive sleep apnea who were studied over a 22-hr period and slept during their customary hours of sleep but without the aid of any respiratory device. Aqueous flow was measured with fluorophotometry. Motion of the wrist was monitored by a seismograph (wrist Actigraph) and served as a surrogate of activity and wakefulness. Urinary catecholamine excretion was measured during different periods of the wake/sleep cycle. Both groups exhibited the normal nocturnal suppression of flow (59% lower compared to morning in the normal group; 56% lower compared to morning in the apneic group). During sleep deprivation, the rate of flow at night in normal subjects was 30% lower than during the morning (P < 0.001) and 60% higher than during sleep (P < 0.001). Lid closure during sleep deprivation had no effect on the results. Aqueous flow correlated with a 'catecholamine index', derived from the combined excretion of epinephrine and norepinephrine. Flow also correlated with an 'activity index', and 'sleep efficiency', indices derived from motion of the wrist. We conclude that the day-night difference of aqueous humor flow as measured by clearance of fluorescein from the human eye is driven partly by a factor that has a circadian rhythm and partly by a factor that depends on the activity of the subject. We hypothesize that these factors are the catecholamines, epinephrine and norepinephrine.

Adult↗

PubMed1996

Delayed functional loss in glaucoma. LII Edward Jackson Memorial Lecture.

PURPOSE: This study is a systematic exploration of why some patients with glaucoma continue to lose visual field long after therapeutic normalization of their increased intraocular pressures. METHODS: Three cases of glaucoma are described that had increased intraocular pressures and good initial visual fields. RESULTS: The following four hypotheses are offered to explain delayed functional loss in these patients: (1) A process independent of intraocular pressure is killing ganglion cells. (2) Unmeasured increases of pressure are killing ganglion cells. (3) The ganglion cells have a genetically determined hypersensitivity to intraocular pressure. (4) The ganglion cells have been rendered hypersensitive to intraocular pressure by irreversible damaging effects of previously increased intraocular pressures CONCLUSION: The current state of knowledge does not permit the elimination of any of the four hypotheses. An additional hypothesis is that the final stage of ganglion cell death is mediated by apoptosis. If so, a potential new treatment for glaucoma would be to inhibit the apoptotic pathway.

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↗

PubMed1996

Measurement of transmission of ultraviolet and visible light in the living rabbit cornea.

Corneal transmittance in pigmented rabbits was measured at ultraviolet and visible wavelengths from the ratio of fluorescence of dyes in the anterior chamber to fluorescence of the same dyes in a quartz cuvette. Aqueous humor was drained through a limbal incision and the anterior chamber was reformed with a mixture of a viscoelastic material and a fluorophore (fluorescein, O-methyl pyranine, or sulforhodamine B). Excitation spectra, emission spectra, or both were measured in the anterior chamber with a new scanning ocular fluorophotometer, at wavelengths between 250 nm and 700 nm. Fluorescence spectra were also measured from the same fluorophore in a quartz cuvette. External transmittance of the cornea was calculated at each wavelength from the ratio of fluorescence in the anterior chamber to fluorescence in the cuvette. Transmittance was 93% +/- 1.4% (mean +/- SD, n = 8 rabbits) at 500 nm and was 89% to 93% between 370 nm and 500 nm. Transmittance decreased to 82% +/- 5.7% at 350 nm, to 50% +/- 5.9% at 310 nm, and to less than 2% at 290 nm. Between 370 nm and 500 nm, the wavelength range most frequently used in fluorophotometry, average transmittance varied by less than 5%. These results suggest that fluorescence measured at two or more wavelengths within this spectrum needs little if any correction for differential attenuation by the cornea. At wavelengths shorter than 370nm, measurements should be corrected. This technique provides a simple and minimally invasive means of studying visible and ultraviolet transparency of the cornea in the living eye.

Animals↗

PubMed1996

Continuous measurement of intraocular pressure in rabbits by telemetry.

PURPOSE: Intraocular pressure (IOP) is dynamic and can be influenced by the use of tonometers. The authors developed a technique to implant a telemetric pressure transducer to measure IOP continuously in unrestrained rabbits. METHODS: A commercial telemetric pressure transducer was implanted subcutaneously on the dorsal neck, between the scapulae, of pigmented rabbits. A fluid-filled catheter that conducts pressure to the transducer was routed to the orbit subcutaneously and implanted in the anterior chamber through a limbal opening. The transducer measured pressure and broadcast this information by amplitude modulation radio to a receiver in the animal's cage. Data were recorded at a rate of 50 or 100 samples per second for 60 seconds to study transient changes in IOP to tonometry, or for 15 seconds every 2.5 minutes to study circadian behavior of IOP. RESULTS: Intraocular pressure was recorded from seven rabbits for 180 to 370 days. Within 3 to 8 days of implant surgery, IOP began to follow a circadian rhythm: IOP decreased after room lights were turned on at 00:00 CT and increased after they were turned off at 12:00 CT. (The term CT refers to circadian time and begins at 00:00 CT when lights are turned on.) The maximum difference in IOP between light and dark phases ranged from 6.4 mm Hg to 16.6 mm Hg. When the lighting cycle was advanced by 6 hours, the time of nocturnal rise in IOP also advanced, but it did so gradually over 10 to 14 days. CONCLUSIONS: The implanted pressure transducer provides a convenient, preinvasive method to measure and study IOP in unrestrained experimental animals. This technique will be used to study circadian variations in IOP, the effects of environmental stimuli, and the oculohypotensive effects of therapeutic agents.

Animals↗

PubMed1996

Aqueous humor flow in unilateral carotid stenosis.

Our purpose was to study the relationship between carotid artery occlusive disease and aqueous flow in human subjects. Aqueous humor flow was measured by fluorophotometry in seven patients with unilateral carotid artery disease documented by oculoplethysmography. The mean (+/- SD) flow was 2.03 +/- 0.38 microliter/min in the affected eyes, 2.44 +/- 0.66 microliter/min in the unaffected contralateral eyes, and 2.56 +/- 0.61 microliter/min in a group of 14 age-matched controls. A statistically significant difference (p < 0.05) in the aqueous flow rate was seen between the affected and unaffected eyes and between the affected and control eyes. Aqueous flow in the unaffected and control eyes was not statistically different. The anterior chamber volumes and intraocular pressures were also not significantly different among groups. Severe carotid artery disease may reduce aqueous humor formation by lowering ciliary body blood flow to a point beyond which the eye cannot compensate.

Aged↗

PubMed1995

Aqueous flow in open-angle glaucoma.

OBJECTIVES: To measure aqueous dynamic variables in patients with open-angle glaucoma when their ocular hypotensive treatment was withdrawn and to determine if the circadian rhythm of the aqueous humor flow was present in open-angle glaucoma. METHODS: We studied 20 patients with open-angle glaucoma, and a group of 20 healthy subjects served as controls. Aqueous humor flow was measured by clearance of topically applied fluorescein with a fluorophotometer, tonography was used to measure outflow facility, and applanation tonometry was used to measure the intraocular pressure. RESULTS: We did not find any statistically significant difference when comparing aqueous flow during the daytime in subjects with open-angle glaucoma with that in controls. However, we did measure a higher aqueous flow at night in the group with open-angle glaucoma, compared with the normal group. The circadian rhythm of aqueous humor flow was present in the subjects with glaucoma. CONCLUSIONS: Aqueous flow is not suppressed in glaucomatous eyes that are not undergoing treatment. Rather, the flow is slightly higher at night during sleep compared with the flow in normal sleeping subjects, but not high enough to have a clinically significant effect on intraocular pressure.

Aged↗

PubMed1995

Aqueous humor dynamics in patients with diabetes mellitus.

PURPOSE: We measured aqueous dynamic variables in subjects with diabetes mellitus and correlated them with severity of retinopathy and metabolic control to determine whether diabetes affects the anterior circulation of the eye as it affects the posterior (retinal) circulation. METHODS: Sixty-one subjects with diabetes mellitus type 1 and 60 subjects with diabetes mellitus type 2 were recruited from the active practice of the Mayo Clinic. Thirty-two normal subjects, divided by age into two overlapping groups of 20 each, served as contemporaneous control subjects. The diabetic subjects were stratified into four groups according to severity of retinopathy. Aqueous humor flow was measured by clearance of topically applied fluorescein with a spectrofluorophotometer; outflow facility was measured by tonography; and intraocular pressure was measured by applanation tonometry. RESULTS: In type 1 diabetics, the mean intraocular pressure was slightly greater (14 +/- 3 mm Hg), compared with control subjects (12 +/- 2 mm Hg [P = .002]), while aqueous humor flow was slightly less (2.5 +/- 0.6 microliter/min), compared with control subjects (2.9 +/- 0.5 microliter/min [P = .023]). In type 2 diabetics, the intraocular pressure was 14 +/- 3 mm Hg, which did not differ from that of control subjects (14 +/- 3 mm Hg [P = .258]). Aqueous humor flow in type 2 diabetics (2.5 +/- 0.7 microliter/min) did not differ significantly from that of the control group (2.5 +/- 0.7 microliter/min [P = .961]). Tonographic facility of outflow was not significantly different in type 1 and type 2 diabetics and the control subjects. There was no significant correlation in aqueous humor flow, intraocular pressure, or tonographic facility of outflow to severity of retinopathy or hemoglobin A1c in either type 1 or type 2 diabetics. CONCLUSIONS: The dynamics of aqueous humor are not affected to any clinically significant extent in the early or middle stages of diabetic retinopathy. However, there is a tendency toward less aqueous humor flow in the advanced stages of retinopathy.

Adult↗

PubMed1995

Topically applied hydralazine: effects on systemic cardiovascular parameters, blood-aqueous barrier, and aqueous humor dynamics in normotensive humans.

Local application of hydralazine has been found to alter intraocular pressure in animal eyes. This study was undertaken to determine, in normotensive humans, the effects of topically-applied hydralazine on systemic cardiovascular parameters, blood-aqueous barrier, and aqueous humor flow. Two different concentrations of hydralazine were used: 0.03%, and 0.1%. Twenty healthy normotensive subjects were studied. Blood pressure, pulse rate, and intraocular pressure were measured every hour for six hours after hydralazine or placebo was instilled into the conjunctival sac in a double-masked, randomized fashion. With either hydralazine dose, there was no significant change in systemic blood pressure or pulse. In addition, spectrophotometrically-measured polarization of fluorescence and flare failed to show any significant breakdown of the blood-aqueous barrier. In most individuals, application of hydralazine was followed by a brief, mild to moderate, conjunctival hyperemic response. Compared to placebo at the same time of day, a small increase in intraocular pressure was observed with 0.03% hydralazine (p < .05). At 0.1%, this increase tended to be less. There was no statistically significant difference in aqueous humor flow between hydralazine-treated and placebo-treated eyes at the lower concentration (3.20 +/- 0.63 vs. 3.05 +/- 0.61 microL/min (mean +/- S.D.) or at the higher concentration (3.37 +/- 0.53 vs. 3.28 +/- 0.60 microL/min) of hydralazine. These results suggest that acute topical application of 0.1% hydralazine to the eyes of normal humans does not cause clinically significant cardiovascular effects or significant ocular toxicity.

Administration, Topical↗

PubMed1995

Diurnal change of anterior chamber depth in rabbits.

It has been shown that there is a circadian rhythm of intraocular pressure and aqueous humor flow in rabbits. It has also been shown that there is a fluctuation in the volume of the aqueous that can be aspirated from the anterior chamber at different times of day. This finding would suggest that the depth and volume of the anterior chamber of this species also undergoes a circadian rhythm. To confirm this hypothesis, we measured by pachometry the anterior chamber depth in 11 adult New Zealand albino rabbits that had been conditioned to light from 6 a.m. to 6 p.m. and to dark from 6 p.m. to 6 a.m. The measurements were performed at noon and at midnight. The anterior chamber was found to be 4% deeper at midnight than at noon (p < 0.001). This finding suggests that the volume of the anterior chamber would be slightly larger at night than during the day in the rabbit eye. We have no explanation for this finding. However, the difference is too small to have an appreciable effect on the measurement of aqueous dynamics or pharmaceutical effects.

Animals↗

PubMed1994

The effect of long-term medical therapy on the outcome of filtration surgery.

Long-term medical therapy and laser trabeculoplasty have been implicated as risk factors in the outcome of glaucoma filtration surgery. A retrospective analysis was performed of patients undergoing primary trabeculectomy during three key periods: before use of beta-blockers and laser trabeculoplasty (1975 and 1976), after introduction of beta-blocker therapy but before use of the laser (1980), and after common use of beta-blockers and laser (1985 and 1986). A total of 150 patients were included in the analysis. Eyes treated with laser trabeculoplasty at some time before filtration surgery had a decreased probability of successful filtration surgery (intraocular pressure less than 21 mm Hg, 75% vs 91% at one year, P = .05; 50% vs 86% at five years, P = .01). It is unknown whether laser was detrimental to subsequent filtration surgery or merely acted as a selection factor in identifying patients who would have less successful surgical outcomes. Preoperative use of topical medication did not influence the outcome of surgery. Patients having bilateral filtration surgery had similar outcomes between fellow eyes despite the longer use of therapy in the second eye (mean of 1.8 years between operations). In the subgroup of eyes with low preoperative intraocular pressures (less than 21 mm Hg), surgery was successful in reducing pressure to a lower level in 70% of eyes at one year (preoperative pressure, 17.8 mm; one-year postoperative pressure, 13.3 mm, P = .007).

Adult↗

PubMed1994

Beta-human chorionic gonadotropin, progesterone, and aqueous dynamics during pregnancy.

OBJECTIVE: To determine whether the altered hormonal milieu of pregnancy is associated with changes in the dynamics of aqueous humor formation and drainage. DESIGN: Nineteen women were studied during each trimester of a single pregnancy and post partum. Measures of aqueous dynamics included intraocular pressure, aqueous flow, facility of outflow, aqueous flare, and corneal thickness. RESULTS: Pregnancy was associated with relatively lower intraocular pressure, reduced aqueous flare, increased corneal thickness, and increased aqueous outflow facility. Aqueous flow was unchanged. The progesterone level increased during pregnancy and decreased during the postpartum period. The beta-human chorionic gonadotropin level was highest during the first trimester. The progesterone level, but not the beta-human chorionic gonadotropin level, was correlated with intraocular pressure, aqueous flare, and corneal thickness. The change in aqueous outflow facility that accompanied pregnancy could not be correlated directly to changes in beta-human chorionic gonadotropin or progesterone concentrations. CONCLUSIONS: Aqueous flow remains constant during and after pregnancy, but intraocular pressure decreases during pregnancy due to an increase in the outflow facility. The changes in aqueous dynamics are consistent with the hypothesis that excess progesterone during pregnancy blocks the ocular hypertensive effect of endogenous corticosteroids. However, we were unable to find a statistically significant correlation when a direct comparison between the observed changes in outflow facility and the observed changes in the progesterone level was made, perhaps because of intersubject variability of these changes. The changes in intraocular pressure and outflow facility could have been due to one of many other changes in pregnancy that were not measured.

Adult↗