Retinal Blood Flow in Response to an Intravitreal Injection of Ranibizumab for Central Retinal Vein Occlusion (CRVO)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01303276
Recruitment Status : Unknown
Verified February 2011 by University of Toronto.
Recruitment status was:  Not yet recruiting
First Posted : February 24, 2011
Last Update Posted : February 24, 2011
Information provided by:
University of Toronto

February 15, 2011
February 24, 2011
February 24, 2011
June 2011
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Quantitative change in retinal blood flow [ Time Frame: Baseline, 7, 30 days ]
Retinal blood flow will be measured using Canon Laser Blood Flowmeter
Same as current
No Changes Posted
Best Corrected Visual Acuity (LogMAR, EDTRS) [ Time Frame: Baseline, 7, 30 days ]
Best Corrected Visual Acuity will be examined using 96% and 10 % contrast EDTRS letter charts
Same as current
Not Provided
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Retinal Blood Flow in Response to an Intravitreal Injection of Ranibizumab for Central Retinal Vein Occlusion (CRVO)
Retinal Blood Flow in Response to an Intravitreal Injection of Ranibizumab for Central Retinal Vein Occlusion
Ranibizumab (Lucentis, Genentech) is an off-label drug used for the clinical treatment of central retinal vein occlusion, which is one of the most common retinal vascular disorders. Despite its clinical effectiveness, concerns remain regarding the systemic effects of the drug and previous studies have noted retinal arteriolar vasoconstriction following a ranibizumab injection. We aim to provide a physiological basis to these observations by assessing retinal blood flow before and after the ranibizumab injections. Specifically, we will assess the blood flow parameters (i.e. retinal vessel diameter, velocity & flow) immediately before the first injection and post-injection over a follow-up continued treatment period.

Ranibizumab is an antibody fragment designed to inhibit the activity of Vascular Endothelial Growth Factor (VEGF), which is responsible for the neovascularization and retinal edema responsible for interference of normal vision in central retinal vein occlusion. However, VEGF has a role in the vasculature as a vasodilator where it alters the expression of tight junction proteins and upregulates the release of the vasodilator nitric oxide. Consequently, intravitreal ranibizumab injections could result in systemic inhibition of VEGF, leading to long-term retinal arteriolar vasoconstriction and potentially adverse cerebrovascular and myocardial accidents. Therefore, evaluating retinal blood flow would provide a physiological foundation to this concern and provide physicians with valuable information regarding the risks of continued ranibizumab therapy.

Given the role of VEGF as a vasodilator in the vasculature where it works to alter the expression of tight junction proteins and the production of vasoactive substances especially nitric oxide, inhibiting this molecule with ranibizumab could result in vasoconstriction in these vessels. We hypothesize that vasoconstriction and decreased retinal blood flow will be observed after an intravitreal injection of ranibizumab for treatment of central retinal vein occlusion.

Observational Model: Cohort
Time Perspective: Prospective
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Non-Probability Sample
Patients with central retinal vein occlusion will be recruited from the Retina Clinics of Toronto Western Hospital
Central Retinal Vein Occlusion
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  • Anti-VEGF group
    Patients who are clinically indicated for the intravitreal injection of ranibizumab
  • Age-matched controls
    Group of healthy participants who will be age and gender matched
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*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Unknown status
Same as current
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Inclusion Criteria:

  • Age > 50 years
  • central retinal vein occlusion scheduled for first intravitreal injection of ranibizumab as part of their clinical care

Exclusion Criteria:

  • previous history of intravitreal therapy,
  • history of thromboembolic events,
  • glaucoma or an intraocular pressure >21 mmHg
  • diabetes mellitus or altered blood viscosity syndromes
  • blood donation in the previous 2 weeks
  • refractive error of +/- 6.00 DS and/or 2.00 DC
Sexes Eligible for Study: All
50 Years and older   (Adult, Older Adult)
Contact information is only displayed when the study is recruiting subjects
CRVO-blood flow study
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Christopher Hudson, University of Toronto
University of Toronto
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Principal Investigator: Christopher Hudson, PhD University of Toronto
University of Toronto
February 2011