Neurovascular Coupling in Patients With Early Stage Diabetes Retinopathy

Study Overview
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Brief Summary
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A variety of studies demonstrate that ocular blood flow is altered in diabetes and retinal perfusion abnormalities have been proposed to contribute to the pathogenesis of diabetic retinopathy. Various animal and human studies have demonstrated that retinal and optic nerve blood flow increase in response to diffuse luminance flicker. Based on studies with ERG, this effect has been attributed to augmented activity in the retinal ganglion cells and associated axons indicating a coupling mechanism between neuronal activity and retinal blood flow. Whereas a variety of studies describe the effects of flickering light on retinal and optic nerve head blood flow, the knowledge about this coupling in the diabetic retina is sparse. In view of the fact that neural activity and blood flow are strongly coupled in the human retina, one could hypothesize that neurodegenerative changes in the retina could contribute to the vascular dysregulation and in turn lead to changes of ocular perfusion. The investigators set out to investigate whether the coupling of neural activity and blood flow is impaired in patients with early stage diabetic retinopathy compared to those in healthy volunteers.

Official Title
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Neurovascular Coupling in Patients With Early Stage Diabetes Retinopathy

Conditions
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Diabetic Retinopathy

Intervention / Treatment
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* Other: Ocular blood flow measurements


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women aged between 20 and 50 years Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant Inclusion criteria of patients are insulin dependent diabetes mellitus (IDDM) with non or mild non-proliferative retinopathy. Patients with no signs of diabetic retinopathy (level 1) or patients with one or more microaneurysms (level 2) will be included. Duration of Diabetes is between 5 and 20 years Men and women will be included in equal parts. A pregnancy test will be performed at screening Ametropia of less than 3 diopters and anisometropia of less than 1 diopter Exclusion Criteria: Non insulin dependent diabetes Maturity onset diabetes of the young (MODY diabetes) Any sign of non diabetes induced vascular pathologies, systemic hypertension (defined as systolic blood pressure > 150 mm Hg and diastolic blood pressure > 90 mm Hg.) Presence of intraocular pathology other than diabetic retinopathy History or family history of epilepsy Pregnancy

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>Patients with non or mild non-proliferative diabetic retinopathy | Other: Ocular blood flow measurements<br>* non-invasive haemodynamic measurements of retinal vessel diameters and laser Doppler velocimetry<br>|
| 2<br>Healthy control subjects | Other: Ocular blood flow measurements<br>* non-invasive haemodynamic measurements of retinal vessel diameters and laser Doppler velocimetry<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intraocular pressure |  | 90 minutes | 
| Retinal arterial and venous diameter |  | 90 minutes | 
| Retinal blood velocity |  | 90 minutes | 
| Pattern ERG |  | measured once on the study day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean arterial pressure |  | 90 minutes | 
| Blood glucose |  | measured once on the study day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes, ocular blood flow