Ignite Creation Date:
2024-05-05 @ 10:01 AM
Last Modification Date:
2024-10-26 @ 9:01 AM
Study NCT ID:
NCT00000153
Status:
COMPLETED
Last Update Posted:
2005-06-24
First Post:
1999-09-23
Brief Title:
Krypton-Argon Regression of Neovascularization Study KARNS
Sponsor:
National Eye Institute NEI
Organization:
National Eye Institute NEI
Study Overview
Official Title:
None
Status:
COMPLETED
Status Verified Date:
1999-10
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
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
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 Description:
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 the krypton laser could be as effective as the argon laser in causing regression of diabetic neovascularization but with fewer side effects such as smaller loss of central visual acuity
Thirty-two nationwide clinical centers participated initially in this multicenter clinical trial Following the initial study examination the baseline examination and fundus photographs were obtained within 1 week before application of photocoagulation Study followup visits occurred at 3 months and 1 year after entry in the study Additional visits were scheduled as clinically necessary
The specific techniques for photocoagulation were similar for both argon and krypton scatter photocoagulation Scatter panretinal photocoagulation consisted of 1600 to 2000 burns placed 05 to 1 burn width apart Burns of moderate intensity whiteness and 500 m in size at the retina were required The burns were applied to the retinal periphery no closer than 2 disc diameters from the center of the fovea and 500 m from the margin of the optic disc
In December 1985 the Early Treatment Diabetic Retinopathy Study groups reported that focal photocoagulation was effective in reducing the rates of moderate visual loss in patients with clinically significant diabetic macular edema The KARNS protocol was then changed to allow focal treatment for clinically significant macular edema in all study participants and to allow an eye that had previous focal photocoagulation for macular edema to become eligible for study
The study primary end point was regression of NVD as assessed on the 3-month visit stereo fundus photographs of the disc to less than one-third disc area in extent Secondary end points included change in extent of NVD change in visual acuity after photocoagulation development of fibrous tissue proliferation and change or development of macular traction lines
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 the krypton laser could be as effective as the argon laser in causing regression of diabetic neovascularization but with fewer side effects such as smaller loss of central visual acuity
Thirty-two nationwide clinical centers participated initially in this multicenter clinical trial Following the initial study examination the baseline examination and fundus photographs were obtained within 1 week before application of photocoagulation Study followup visits occurred at 3 months and 1 year after entry in the study Additional visits were scheduled as clinically necessary
The specific techniques for photocoagulation were similar for both argon and krypton scatter photocoagulation Scatter panretinal photocoagulation consisted of 1600 to 2000 burns placed 05 to 1 burn width apart Burns of moderate intensity whiteness and 500 m in size at the retina were required The burns were applied to the retinal periphery no closer than 2 disc diameters from the center of the fovea and 500 m from the margin of the optic disc
In December 1985 the Early Treatment Diabetic Retinopathy Study groups reported that focal photocoagulation was effective in reducing the rates of moderate visual loss in patients with clinically significant diabetic macular edema The KARNS protocol was then changed to allow focal treatment for clinically significant macular edema in all study participants and to allow an eye that had previous focal photocoagulation for macular edema to become eligible for study
The study primary end point was regression of NVD as assessed on the 3-month visit stereo fundus photographs of the disc to less than one-third disc area in extent Secondary end points included change in extent of NVD change in visual acuity after photocoagulation development of fibrous tissue proliferation and change or development of macular traction lines
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None