NCT05344274

Retinal Blood Flow and Autoregulation

Direct Measures of Retinal Blood Flow and Autoregulation as Robust Biomarkers for Early Glaucoma

• Status: Recruiting
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 90 (estimated)
• Sponsor: University of Maryland, Baltimore · Academic / Other
• Sex: All
• Age: 18 Years – 88 Years
• Healthy volunteers: Accepted

Summary

The purpose of this study is to establish autoregulation of retinal blood flow in arterioles and capillaries as a biomarker for early primary open angle glaucoma.

Detailed description

There is strong evidence for a vascular component in the development and progression of primary open angle glaucoma (POAG). Specifically, glaucoma is associated with impaired retinal blood flow (RBF) and autoregulation of RBF. Autoregulatory impairment may precede retinal ganglion cell (RGC) loss and has been proposed as a potentially early, reversible biomarker. The rationale underlying this proposal is that highly precise and accurate, direct measures of RBF are necessary to study dynamic changes in RBF and their effect on RGCs. Current methods of quantifying RBF remain limited as the majority of imaging modalities provide indirect, relative measurements of RBF. The investigators will directly measure RBF using two robust direct measures: erythrocyte mediated angiography flowmetry (EMAf) and multimodal adaptive optics (mAO). Both techniques allow for the highly accurate and precise measurement of RBF down to the capillary level in the human eye in vivo. The investigators hypothesize that these direct measures of determining absolute RBF will show impaired autoregulation of microvascular RBF in early glaucoma and that this will correlate with glaucomatous damage. The research program will test this hypothesis through two specific aims. In Specific Aim 1, the investigators will determine the extent of impaired autoregulation associated with early glaucoma and measure its ability to predict further glaucoma damage. In Specific Aim 2, the investigators will determine the relationship of capillary density and RGC density in glaucoma subjects and controls. The investigators predict that early glaucoma subjects will exhibit significant measurable impaired vascular autoregulation as compared to controls and that local changes in these parameters will predict structural glaucomatous deficits.

Conditions

• Glaucoma

Interventions

Type	Name	Description
DIAGNOSTIC_TEST	Indocyanine Green Angiography	Erythrocyte Mediated Angiography with indocyanine green as well as conventional indocyanine green angiography will be conducted to determine retinal blood flow
BIOLOGICAL	Isocapnic Oxygen	Investigators will evaluate retinal blood flow (RBF) in response to oxygen supplementation at a constant level of carbon dioxide (isocapnic hyperoxia) to isolate the vascular autoregulatory response to oxygen.
DIAGNOSTIC_TEST	Ocular Imaging with Optical Coherence Tomography (OCT) and Adaptive Optics (AO)	Investigators will image subjects with OCT as well as AO technology to determine retinal ganglion cell density, vessel density, and vessel flowrates

Timeline

• Start date: 2022-05-23
• Primary completion: 2027-09-01
• Completion: 2027-09-01
• First posted: 2022-04-25
• Last updated: 2025-12-02

Locations

4 sites across 1 country: United States

Regulatory

• FDA-regulated drug study
• FDA-regulated device study