Clinical Trial: Krypton-Argon Regression of Neovascularization Study (KARNS)
Study Status: Completed
Recruit Status: Completed
Study Type: Interventional
Official Title:
Brief Summary:
To evaluate whether red krypton laser treatment is as effective at causing regression of diabetic disc neovascularization as treatment with the blue-green argon laser, when both lasers are used with identical panretinal photocoagulation patterns.
To assess the vision of study patients.
To test the feasibility of a prototype NEI-sponsored multicenter clinical trial in which participating clinics are not financially reimbursed and in which both the Coordinating and Fundus Photograph Reading Center functions are carried out by staff of the NEI Biometry and Epidemiology Program.
Detailed Summary:
The KARNS was a randomized clinical trial designed to compare the effectiveness of argon and krypton laser photocoagulation in causing the regression of preexisting neovascularization on the disc (NVD) in diabetic retinopathy. The main theoretical advantage for the krypton laser in the treatment of diabetic retinopathy is that the red laser beam penetrates blood and may be more effective in making burns in the pigment epithelium in eyes with vitreous hemorrhage.
The burns produced by the krypton laser in the retina are different from those produced by the argon laser. Specifically, the burns from the krypton laser do not involve the inner retina. Also, the krypton laser spares the nerve fiber layer near the macula. In contrast, nerve fiber layer burns are common with the argon laser. Pigment epithelium and outer segments are usually destroyed by both krypton and argon photocoagulation, but there is no uptake of energy by the vascular tissues within the retina when krypton photocoagulation is used. Further, krypton treatment is more effective in penetrating nuclear sclerosis of the lens and can be used to treat some diabetic eyes with this condition that cannot be treated with the argon laser.
In the KARNS, patients with diabetic retinopathy and NVD of one-third disc area or greater in extent were assigned at random to either argon or krypton laser scatter photocoagulation (panretinal photocoagulation). The null hypothesis was that each treatment would result in a similar proportion of eyes having regression of the NVD by 3 months. The KARNS pilot study affirmed the benefits of argon laser photocoagulation in the treatment of proliferative diabetic retinopathy, as demonstrated in the NEI-supported Diabetic Retinopathy Study conducted a decade ago. (See publication list.) The KARNS study sought to determine whether use of th
Sponsor: National Eye Institute (NEI)
Current Primary Outcome:
Original Primary Outcome:
Current Secondary Outcome:
Original Secondary Outcome:
Information By: National Eye Institute (NEI)
Dates:
Date Received: September 23, 1999
Date Started: December 1984
Date Completion:
Last Updated: June 23, 2005
Last Verified: October 1999
