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Central Vein Occlusion Study (CVOS)

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: NCT00000131
Recruitment Status : Completed
First Posted : September 24, 1999
Last Update Posted : September 17, 2009
Information provided by:
National Eye Institute (NEI)

Brief Summary:

To determine whether photocoagulation therapy can help prevent iris neovascularization in eyes with central vein occlusion (CVO) and evidence of ischemic retina.

To assess whether grid-pattern photocoagulation therapy will reduce loss of central visual acuity due to macular edema secondary to CVO.

To develop new data describing the course and prognosis for eyes with CVO.

Condition or disease Intervention/treatment Phase
Retinal Vein Occlusion Retinal Diseases Procedure: Photocoagulation Therapy Phase 3

Detailed Description:

Central vein occlusion is a common retinal vascular disorder with potentially blinding complications. The two major complications are reduced central vision caused by macular edema and neovascular glaucoma caused by iris neovascularization. Other clinical trials have shown that laser photocoagulation is an effective treatment for complications found in diabetic retinopathy and branch vein occlusion, which have some features in common with CVO: neovascularization and reduced visual acuity caused by macular edema occur in all three disorders. Evidence from small-scale studies suggests that a grid pattern of photocoagulation reduces macular edema in CVO patients, although the associated changes in visual acuity are variable. The CVOS is a detailed investigation of grid pattern photocoagulation in a larger randomized group of patients.

Eligible patients were divided into four groups:

Group N: Eyes with extensive retinal ischemia (at least 10 disc areas of nonperfusion) were randomly assigned to receive panretinal photocoagulation or nontreatment unless iris neovascularization developed.

Group M: Eyes with visual loss ascribable to macular edema were randomly assigned to receive grid-pattern photocoagulation or nontreatment.

Group P: Eyes with relatively perfused retinas were followed to provide information about the natural history of the disease.

Group I: Indeterminate eyes in which the retina could not be visualized accurately because of hemorrhage were followed in a natural history study.

Green argon laser with a slit lamp delivery system was used for all treatments. Photographic documentation of retinal changes was obtained at entry, post-treatment, and at specified followup visits for a period of at least 3 years. The frequency of followup visits varied according to the group to which the CVO patient was assigned. Visual acuity, the primary outcome factor in the group with macular edema, was measured according to a modified Early Treatment Diabetic Retinopathy Study protocol at each visit.

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Study Type : Interventional  (Clinical Trial)
Allocation: Randomized
Primary Purpose: Treatment
Study Start Date : August 1988
Actual Study Completion Date : February 1994

Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Men and women must have been age 21 or older and willing to return for followup visits for 3 years following assignment into the appropriate group and randomization. Each of the four groups has specific eligibility criteria. Patients with retinal vascular disease other than that specified in the criteria, such as diabetic retinopathy, were ineligible. Patients with macular disease other than that due to CVO were ineligible for that portion of the study.
Layout table for additonal information Identifier: NCT00000131    
Other Study ID Numbers: NEI-30
First Posted: September 24, 1999    Key Record Dates
Last Update Posted: September 17, 2009
Last Verified: September 2009
Keywords provided by National Eye Institute (NEI):
Central Vein Occlusion
Ischemic Retina
Additional relevant MeSH terms:
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Retinal Vein Occlusion
Retinal Diseases
Eye Diseases
Venous Thrombosis
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases