PHYSIOCHEMICAL REGULATION OF RETINAL HEMODYNAMICS

Project: Research project

Description

Physiochemical factors profoundly influence the metabolic status of the
eye, yet most are poorly defined. This application involves investigation
into several systemic factors that may alter retinal and cerebral
hemodynamics, the objective being first to define the normal regulatory
response, so that regulatory dysfunctions that exist in diabetic or
glaucomatous eyes can be characterized. The first specific aim is to define the independent ocular effects of
variations in systemic O2, CO2, and exercise level. Total retinal blood
flow, mean retinal capillary flow velocity, the inhOmogeneity of retinal
capillary flow rates, the perifoveal intercapillary distance, and the size
of the foveal avascular zone will be measured with a scanning laser
ophthalmoscope. Intraocular pressure, using Goldmann applanation
tonometry, along with testing of contrast sensitivity and visual acuity,
will further define the ocular response. Carotid and ophthalmic arterial
blood flow, measured using color doppler imaging, will provide the second
specific aim of defining the relationship of ocular hemodynamics to
regional perfusion. The third goal of the proposed research is to determine the differences in
retinal and regional circulatory regulatory response to O2, CO2, and
exercise among diabetic patients without retinopathy, patients with
diabetes and ophthalmoscopic evidence of retinopathy, and age-matched
healthy persons. A fourth aim is to define how varying levels of blood
glucose, in age-matched control as compared with diabetic patients, affect
retinal and cerebral regulatory responses. Retinal and cerebral circulatory regulation in healthy as compared with
glaucomatous eyes will comprise the fifth specific aim. A subgroup of
persons with ocular hypertension but without glaucoma will be included.
Both hypocapnia and moderate exercise acutely lower intraocular pressure:
it is hypothesized that these stimuli may significantly enhance retinal
flow in ocular hypertensives and glaucoma patients. The final specific aim
is to define how drugs (a non-selective beta-adrenergic blocker, a
selective beta1-adrenergic blocker, and a topical carbonic anhydrase
inhibitor) that are known to lower intraocular pressure, affect retinal,
ophthalmic, and cerebral flow regulation in healthy eyes, both young and
old. These proposed studies will be the first to simultaneously investigate
retinal, ophthalmic, and cerebral blood flow regulation. Placing the
retinal circulation in its regional context will advance understanding of
the pathophysiology of diabetic retinopathy and glaucoma, and of the
mechanisms by which topical ocular hypotensive drugs exert their actions.
This understanding may expedite development of new vasoactive compounds to
treat eye diseases.
StatusFinished
Effective start/end date9/30/939/29/98

Funding

  • National Institutes of Health: $106,466.00
  • National Institutes of Health: $96,181.00
  • National Institutes of Health
  • National Institutes of Health: $97,065.00
  • National Institutes of Health

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Hemodynamics
Intraocular Pressure
Glaucoma
Exercise
Cerebrovascular Circulation
Hypocapnia
Ocular Hypertension
Contrast Sensitivity
Adrenergic beta-Antagonists
Adrenergic Antagonists
Eye Diseases
Diabetic Retinopathy
Pharmaceutical Preparations
Visual Acuity
Color
Perfusion
Carbonic Anhydrase Inhibitors
Ophthalmoscopes
Research

ASJC

  • Medicine(all)