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Blood pressure modifies retinal susceptibility to intraocular pressure elevation.

ABSTRACT: Primary open angle glaucoma affects more than 67 million people. Elevated intraocular pressure (IOP) is a risk factor for glaucoma and may reduce nutrient availability by decreasing ocular perfusion pressure (OPP). An interaction between arterial blood pressure and IOP determines OPP; but the exact contribution that these factors have for retinal function is not fully understood. Here we sought to determine how acute modifications of arterial pressure will affect the susceptibility of neuronal function and blood flow to IOP challenge. Anaesthetized (ketamine:xylazine) Long-Evan rats with low (?60 mmHg, sodium nitroprusside infusion), moderate (?100 mmHg, saline), or high levels (?160 mmHg, angiotensin II) of mean arterial pressure (MAP, n?=?5-10 per group) were subjected to IOP challenge (10-120 mmHg, 5 mmHg steps every 3 minutes). Electroretinograms were measured at each IOP step to assess bipolar cell (b-wave) and inner retinal function (scotopic threshold response or STR). Ocular blood flow was measured using laser-Doppler flowmetry in groups with similar MAP level and the same IOP challenge protocol. Both b-wave and STR amplitudes decreased with IOP elevation. Retinal function was less susceptible to IOP challenge when MAP was high, whereas the converse was true for low MAP. Consistent with the effects on retinal function, higher IOP was needed to attenuated ocular blood flow in animals with higher MAP. The susceptibility of retinal function to IOP challenge can be ameliorated by acute high BP, and exacerbated by low BP. This is partially mediated by modifications in ocular blood flow.

SUBMITTER: He Z

PROVIDER: S-EPMC3281054 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Blood pressure modifies retinal susceptibility to intraocular pressure elevation.

He Zheng Z Nguyen Christine T O CT Armitage James A JA Vingrys Algis J AJ Bui Bang V BV

PloS one 20120216 2

Primary open angle glaucoma affects more than 67 million people. Elevated intraocular pressure (IOP) is a risk factor for glaucoma and may reduce nutrient availability by decreasing ocular perfusion pressure (OPP). An interaction between arterial blood pressure and IOP determines OPP; but the exact contribution that these factors have for retinal function is not fully understood. Here we sought to determine how acute modifications of arterial pressure will affect the susceptibility of neuronal f ...[more]

PMID: 22359566

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Project description:PurposeTo characterize the risk and risk factors for intraocular pressure (IOP) elevation in pediatric noninfectious uveitis.DesignMulticenter retrospective cohort study.ParticipantsNine hundred sixteen children (1593 eyes) younger than 18 years at presentation with noninfectious uveitis followed up between January 1978 and December 2007 at 5 academic uveitis centers in the United States.MethodsMedical records review by trained, certified experts.Main outcome measuresPrevalence and incidence of IOP of 21 mmHg or more and 30 mmHg or more and incidence of a rise in IOP by 10 mmHg or more. To avoid underascertainment, outcomes were counted as present when IOP-lowering therapies were in use.ResultsInitially, 251 (15.8%) and 46 eyes (2.9%) had IOP ≥21 mmHg and ≥30 mmHg, respectively. Factors significantly associated with presenting IOP elevation included age of 6 to 12 years (versus other pediatric ages), prior cataract surgery, pars plana vitrectomy, duration of uveitis ≥6 months, contralateral IOP elevation, presenting visual acuity worse than 20/40, and topical corticosteroid use (in a dose-response relationship). The median follow-up was 1.25 years (interquartile range, 0.4-3.66). The estimated incidence of any observed IOP elevation to ≥21 mmHg, to ≥30 mmHg, and increase in IOP by ≥10 mmHg was 33.4%, 14.8%, and 24.4%, respectively, within 2 years. Factors associated with IOP elevation included pars plana vitrectomy, contralateral IOP elevation (adjusted hazard ratio [aHR], up to 9.54; P < 0.001), and the use of topical (aHR, up to 8.77 that followed a dose-response relationship; P < 0.001), periocular (aHR, up to 7.96; P < 0.001), and intraocular (aHR, up to 19.7; P < 0.001) corticosteroids.ConclusionsIntraocular pressure elevation affects a large minority of children with noninfectious uveitis. Statistically significant risk factors include IOP elevation or use of IOP-lowering treatment in the contralateral eye and local corticosteroid use that demonstrated a dose-and route of administration-dependent relationship. In contrast, use of immunosuppressive drug therapy did not increase such risk. Pediatric eyes with noninfectious uveitis should be followed up closely for IOP elevation, especially when strong risk factors such as the use of local corticosteroids and contralateral IOP elevation are present.

Dataset Information

Blood pressure modifies retinal susceptibility to intraocular pressure elevation.

Publications

Blood pressure modifies retinal susceptibility to intraocular pressure elevation.

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