Acute versus chronic effects of brimonidine on aqueous humor dynamics in ocular hypertensive patients

Carol B Toris, Carl B. Camras, Michael E. Yablonski

Research output: Contribution to journalArticle

133 Citations (Scopus)

Abstract

PURPOSE: To report the acute vs chronic effects of brimonidine, a selective α2-adrenergic receptor agonist, on aqueous humor dynamics in ocular hypertensive patients. METHODS: Brimonidine 0.2% was given topically twice daily for 29 days to one eye each of 28 ocular hypertensive volunteers in a randomized double-masked study. The fellow eye was similarly treated with vehicle. Aqueous flow (Fa) and outflow facility (C(fl)) were determined with fluorophotometry. Intraocular pressure, outflow facility (C(ton)), and episcleral venous pressure (Pev) were measured with pneumatonometry, tonography, and venomanometry, respectively. Uveoscleral outflow (Fu) was calculated from intraocular pressure, Fa, Pev, and C(fl) values. All measurements were taken on baseline day, day 8, and day 29 of treatment. Intraocular pressure and Fa only were measured after instillation of 1 drop of brimonidine on day 1. RESULTS: When measured 3 hours after instillation on days 1, 8, and 29 of treatment, brimonidine significantly (P < .001) reduced intraocular pressure by at least 5.0 ± 0.7 mm Hg (mean ± SEM) compared with baseline day, and by 2.7 ± 0.5 mm Hg compared with the vehicle-treated contralateral control eyes. The greatest decrease (6.0 ± 0.6 mm Hg) was observed at 3 hours after the first drop. Aqueous flow was reduced by 29% (P < .001) after the first application but was not significantly different from baseline when measured at day 29 of treatment. Uveoscleral outflow was increased 60% at day 8 (P < .06) and day 29 (P < .05) compared with baseline. There was no significant difference in outflow facility or episcleral venous pressure at day 8 or day 29 of treatment. CONCLUSIONS: The brimonidine- induced reduction in intraocular pressure in humans is associated initially with a decrease in aqueous flow, and after chronic-treatment with an increase in uveoscleral outflow.

Original languageEnglish (US)
Pages (from-to)8-14
Number of pages7
JournalAmerican journal of ophthalmology
Volume128
Issue number1
DOIs
StatePublished - Jul 1 1999

Fingerprint

Aqueous Humor
Intraocular Pressure
Venous Pressure
Fluorophotometry
Adrenergic Agonists
Double-Blind Method
Volunteers
Therapeutics
Brimonidine Tartrate

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Acute versus chronic effects of brimonidine on aqueous humor dynamics in ocular hypertensive patients. / Toris, Carol B; Camras, Carl B.; Yablonski, Michael E.

In: American journal of ophthalmology, Vol. 128, No. 1, 01.07.1999, p. 8-14.

Research output: Contribution to journalArticle

@article{23e331e427ba418eb6772811f375170a,
title = "Acute versus chronic effects of brimonidine on aqueous humor dynamics in ocular hypertensive patients",
abstract = "PURPOSE: To report the acute vs chronic effects of brimonidine, a selective α2-adrenergic receptor agonist, on aqueous humor dynamics in ocular hypertensive patients. METHODS: Brimonidine 0.2{\%} was given topically twice daily for 29 days to one eye each of 28 ocular hypertensive volunteers in a randomized double-masked study. The fellow eye was similarly treated with vehicle. Aqueous flow (Fa) and outflow facility (C(fl)) were determined with fluorophotometry. Intraocular pressure, outflow facility (C(ton)), and episcleral venous pressure (Pev) were measured with pneumatonometry, tonography, and venomanometry, respectively. Uveoscleral outflow (Fu) was calculated from intraocular pressure, Fa, Pev, and C(fl) values. All measurements were taken on baseline day, day 8, and day 29 of treatment. Intraocular pressure and Fa only were measured after instillation of 1 drop of brimonidine on day 1. RESULTS: When measured 3 hours after instillation on days 1, 8, and 29 of treatment, brimonidine significantly (P < .001) reduced intraocular pressure by at least 5.0 ± 0.7 mm Hg (mean ± SEM) compared with baseline day, and by 2.7 ± 0.5 mm Hg compared with the vehicle-treated contralateral control eyes. The greatest decrease (6.0 ± 0.6 mm Hg) was observed at 3 hours after the first drop. Aqueous flow was reduced by 29{\%} (P < .001) after the first application but was not significantly different from baseline when measured at day 29 of treatment. Uveoscleral outflow was increased 60{\%} at day 8 (P < .06) and day 29 (P < .05) compared with baseline. There was no significant difference in outflow facility or episcleral venous pressure at day 8 or day 29 of treatment. CONCLUSIONS: The brimonidine- induced reduction in intraocular pressure in humans is associated initially with a decrease in aqueous flow, and after chronic-treatment with an increase in uveoscleral outflow.",
author = "Toris, {Carol B} and Camras, {Carl B.} and Yablonski, {Michael E.}",
year = "1999",
month = "7",
day = "1",
doi = "10.1016/S0002-9394(99)00076-8",
language = "English (US)",
volume = "128",
pages = "8--14",
journal = "American Journal of Ophthalmology",
issn = "0002-9394",
publisher = "Elsevier USA",
number = "1",

}

TY - JOUR

T1 - Acute versus chronic effects of brimonidine on aqueous humor dynamics in ocular hypertensive patients

AU - Toris, Carol B

AU - Camras, Carl B.

AU - Yablonski, Michael E.

PY - 1999/7/1

Y1 - 1999/7/1

N2 - PURPOSE: To report the acute vs chronic effects of brimonidine, a selective α2-adrenergic receptor agonist, on aqueous humor dynamics in ocular hypertensive patients. METHODS: Brimonidine 0.2% was given topically twice daily for 29 days to one eye each of 28 ocular hypertensive volunteers in a randomized double-masked study. The fellow eye was similarly treated with vehicle. Aqueous flow (Fa) and outflow facility (C(fl)) were determined with fluorophotometry. Intraocular pressure, outflow facility (C(ton)), and episcleral venous pressure (Pev) were measured with pneumatonometry, tonography, and venomanometry, respectively. Uveoscleral outflow (Fu) was calculated from intraocular pressure, Fa, Pev, and C(fl) values. All measurements were taken on baseline day, day 8, and day 29 of treatment. Intraocular pressure and Fa only were measured after instillation of 1 drop of brimonidine on day 1. RESULTS: When measured 3 hours after instillation on days 1, 8, and 29 of treatment, brimonidine significantly (P < .001) reduced intraocular pressure by at least 5.0 ± 0.7 mm Hg (mean ± SEM) compared with baseline day, and by 2.7 ± 0.5 mm Hg compared with the vehicle-treated contralateral control eyes. The greatest decrease (6.0 ± 0.6 mm Hg) was observed at 3 hours after the first drop. Aqueous flow was reduced by 29% (P < .001) after the first application but was not significantly different from baseline when measured at day 29 of treatment. Uveoscleral outflow was increased 60% at day 8 (P < .06) and day 29 (P < .05) compared with baseline. There was no significant difference in outflow facility or episcleral venous pressure at day 8 or day 29 of treatment. CONCLUSIONS: The brimonidine- induced reduction in intraocular pressure in humans is associated initially with a decrease in aqueous flow, and after chronic-treatment with an increase in uveoscleral outflow.

AB - PURPOSE: To report the acute vs chronic effects of brimonidine, a selective α2-adrenergic receptor agonist, on aqueous humor dynamics in ocular hypertensive patients. METHODS: Brimonidine 0.2% was given topically twice daily for 29 days to one eye each of 28 ocular hypertensive volunteers in a randomized double-masked study. The fellow eye was similarly treated with vehicle. Aqueous flow (Fa) and outflow facility (C(fl)) were determined with fluorophotometry. Intraocular pressure, outflow facility (C(ton)), and episcleral venous pressure (Pev) were measured with pneumatonometry, tonography, and venomanometry, respectively. Uveoscleral outflow (Fu) was calculated from intraocular pressure, Fa, Pev, and C(fl) values. All measurements were taken on baseline day, day 8, and day 29 of treatment. Intraocular pressure and Fa only were measured after instillation of 1 drop of brimonidine on day 1. RESULTS: When measured 3 hours after instillation on days 1, 8, and 29 of treatment, brimonidine significantly (P < .001) reduced intraocular pressure by at least 5.0 ± 0.7 mm Hg (mean ± SEM) compared with baseline day, and by 2.7 ± 0.5 mm Hg compared with the vehicle-treated contralateral control eyes. The greatest decrease (6.0 ± 0.6 mm Hg) was observed at 3 hours after the first drop. Aqueous flow was reduced by 29% (P < .001) after the first application but was not significantly different from baseline when measured at day 29 of treatment. Uveoscleral outflow was increased 60% at day 8 (P < .06) and day 29 (P < .05) compared with baseline. There was no significant difference in outflow facility or episcleral venous pressure at day 8 or day 29 of treatment. CONCLUSIONS: The brimonidine- induced reduction in intraocular pressure in humans is associated initially with a decrease in aqueous flow, and after chronic-treatment with an increase in uveoscleral outflow.

UR - http://www.scopus.com/inward/record.url?scp=0033044222&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033044222&partnerID=8YFLogxK

U2 - 10.1016/S0002-9394(99)00076-8

DO - 10.1016/S0002-9394(99)00076-8

M3 - Article

C2 - 10482088

AN - SCOPUS:0033044222

VL - 128

SP - 8

EP - 14

JO - American Journal of Ophthalmology

JF - American Journal of Ophthalmology

SN - 0002-9394

IS - 1

ER -