Autoregulation and Systemic Blood Pressure: A New View of Normal Tension Glaucoma

描述(申请人提供)：正常眼压性青光眼的主要假说是正常眼压性青光眼进行性视野丧失是眼压升高的结果。我们将探索另一种假设，即正常眼压性青光眼的视野丧失主要与全身低血压，特别是夜间低血压有关，而不是与眼内压有关。此外，我们假设正常眼压性青光眼的视野缺陷是由于全身低血压超过自身调节下限而导致缺血和视野丧失所致。因此，随着正常眼压性青光眼的进展，进行性缺血性损害和视野丧失是周期性和潜伏性夜间低血压发作的结果。在85例正常眼压性青光眼患者中，即有视野缺陷且眼压<21 mm Hg的患者，这项研究的主要目标是确定在12个月的随访中，全身血压低于患者正常的全身压力&20 mm Hg是否预示着患者内的纵向视野丧失。夜间低血压将被定义为平均动脉压低于患者正常平均动脉压20毫米汞柱以上。基线评估将包括基本的人口学和临床特征。然后，患者将使用动态记录设备在48小时内监测他们的血压，并进行扫描激光断层扫描(海德堡视网膜断层扫描)、光学相干断层扫描和视盘立体照片。在6个月和12个月的随访间隔中，参与者还将进行眼科检查、视野检查(Humphrey 24-2)、扫描激光断层扫描(海德堡视网膜断层扫描)、光学相干断层扫描和重复48小时动态血压。眼内压、药物和间歇事件也将被记录在案。在6个月和12个月进行的激光共聚焦扫描断层扫描(海德堡视网膜断层扫描)、光学相干断层扫描、立体照片和视野检查(Humphrey 24-2)中，将通过患者体内的纵向变化来评估视野损失。判断结果的眼科医生将对患者的动态血压状态视而不见，测量血压的技术人员也将对眼科措施视而不见。数据分析需要许多不同的多变量技术(主成分分析、频谱分析和小波分析)来首先定义结果的度量(血压和视野)，以及(多变量贝叶斯)层次分析来对数据的纵向性质进行建模。项目说明 青光眼的影响可能是潜在的毁灭性的，包括失明。在目前患有青光眼的300万美国人中，六分之一的青光眼患者患有正常眼压性青光眼。在正常眼压性青光眼患者中，这项研究将评估低血压和全身自我调节在视野异常进展中的作用。本研究希望有助于进一步了解低血压和眼压与该病发生发展的关系。

DESCRIPTION (provided by applicant): The dominant hypothesis about normal tension glaucoma is that progressive visual field loss in normal tension glaucoma is a result of elevated intra-ocular pressures. We will explore an alternative hypothesis that visual field loss in normal tension glaucoma is primarily related to systemic hypotension, specifically nocturnal hypotension, not to intra-ocular pressures. Further, we hypothesize that the visual field defects in normal tension glaucoma occur because systemic hypotension exceeds the lower limit of autoregulation resulting in ischemia and field loss. Thus, as normal tension glaucoma progresses, progressive ischemic damage and visual field loss is a result of periodic and insidious nocturnal hypotensive episodes. Among 85 patients with normal tension glaucoma; that is, patients who have visual field deficits with intra-ocular pressures <21 mm Hg, the principal objective of this study is to determine whether systemic blood pressures >20 mm Hg below the patient's usual systemic pressure predicts longitudinal within-patient visual field loss over 12 months of follow-up. Nocturnal hypotension will be defined as mean arterial pressure that falls more than 20 mm Hg below the patients' usual mean arterial pressure. The baseline evaluation will include basic demographic and clinical characteristics. Patients will then have their blood pressures monitored with an ambulatory recording device over the course of 48 hours and will have scanning laser tomography (Heidelberg retinal tomography), optical coherence tomography, and stereo photographs of the optic disc. At 6 and 12 months of follow up intervals, participants will also have ophthalmologic exams, visual field testing (Humphrey 24-2), scanning laser tomography (Heidelberg retinal tomography), optical coherence tomography and repeat 48 hour ambulatory blood pressure. Intra ocular pressures, medications and interval events will also be documented. Visual field loss will be assessed by longitudinal within patient changes in confocal laser scanning tomography (Heidelberg Retinal tomography), optical coherence tomography, stereo photographs and visual fields (Humphrey 24-2) performed at 6 and 12 months. The ophthalmologists adjudicating the outcomes will be blinded to the patient's ambulatory blood pressure status, as will the technicians measuring blood pressure be blinded to the ophthalmologic measures. The data analysis requires many different multivariate techniques (principal component, spectral and wavelet analysis) to first define measures of outcome (for blood pressure and visual fields), as well as a (multivariate Bayesian) hierarchical analysis to model the longitudinal nature of the data.Project Narrative The effects of glaucoma can be potentially devastating, and include blindness. Of the three million Americans currently suffering from glaucoma, one sixth of patients with glaucoma have normal tension glaucoma. Among patients with normal tension glaucoma, this study will assess the role of hypotension and systemic autoregulation in progression of visual field abnormalities. This study hopes to contribute a further understanding of the relation of hypotension and intraocular pressures to the development of this disease.