Track topics on Twitter Track topics that are important to you
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.
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 1,600 to 2,000 burns placed 0.5 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.
Allocation: Randomized, Primary Purpose: Treatment
Blue-Green Argon Laser Treatment, Red Krypton Laser Treatment
National Eye Institute (NEI)
Published on BioPortfolio: 2014-08-26T23:00:16-0400
To evaluate laser treatment of choroidal neovascularization (CNV) through randomized, controlled clinical trials. The Macular Photocoagulation Study (MPS) consisted of three sets of random...
To determine whether scatter argon laser photocoagulation can prevent the development of neovascularization. To determine whether peripheral scatter argon laser photocoagulation can preve...
To compare the safety and long-term efficacy of argon laser treatment of the trabecular meshwork with standard medical treatment for primary open-angle glaucoma.
In this clinical trial study,the investigators intend to compare two methods of trichiasis treatment.One by argon laser and the other by radiofrequency then compare the result of these pro...
The purpose of this study is to compare the pain perception at laser treatment of peripheral retinal degenerations with green and infrared wavelengths.
Red-green-blue polymer laser emission is achieved in a free-standing membrane device consisting of three distributed feedback cavities. The polymer membrane is fabricated via interference lithography ...
Background: Proliferative retinopathy is an important cause of vision loss in diabetic patients. Incomplete panretinal photocoagulation (PRP) can lead to recurrent proliferation of new vessels. Patien...
Epidermal nevi are benign proliferations of the epidermis for which different treatments have been used with disappointing results due to their recurrences and anaesthetic scars. Topical therapies hav...
In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow...
Alopecia is one of the most common dermatological problems in the elderly; however, current therapies for it are limited by low efficacy and undesirable side effects. Although clinical reports on frac...
A technique utilizing a laser coupled to a catheter which is used in the dilatation of occluded blood vessels. This includes laser thermal angioplasty where the laser energy heats up a metal tip, and direct laser angioplasty where the laser energy directly ablates the occlusion. One form of the latter approach uses an EXCIMER LASER which creates microscopically precise cuts without thermal injury. When laser angioplasty is performed in combination with balloon angioplasty it is called laser-assisted balloon angioplasty (ANGIOPLASTY, BALLOON, LASER-ASSISTED).
Treatment using irradiation with LASER light of low power intensity so that the effects are not due to heat, as in LASER THERAPY. These non-thermal effects are thought to be mediated by a photochemical reaction that alters CELL MEMBRANE PERMEABILITY, leading to increased mRNA synthesis and CELL PROLIFERATION. Low-level laser therapy has been used for a wide variety of conditions, but most frequently for wound healing and pain control.
Techniques using laser energy in combination with a balloon catheter to perform angioplasty. These procedures can take several forms including: 1, laser fiber delivering the energy while the inflated balloon centers the fiber and occludes the blood flow; 2, balloon angioplasty immediately following laser angioplasty; or 3, laser energy transmitted through angioplasty balloons that contain an internal fiber.
The coagulation of tissue by an intense beam of light, including laser (LASER COAGULATION). In the eye it is used in the treatment of retinal detachments, retinal holes, aneurysms, hemorrhages, and malignant and benign neoplasms. (Dictionary of Visual Science, 3d ed)
Fragmentation of CALCULI, notably urinary or biliary, by LASER.
Diabetes is a lifelong condition that causes a person's blood sugar level to become too high. The two main types of diabetes are: type 1 diabetes type 2 diabetes In the UK, diabetes affects approximately 2.9 million people. There are a...
In a clinical trial or interventional study, participants receive specific interventions according to the research plan or protocol created by the investigators. These interventions may be medical products, such as drugs or devices; procedures; or change...
Ophthalmology is the branch of medicine that is devoted to the study and treatment of eye diseases. As well as mild visual defects correctable by lenses, ophthalmology is concerned with glaucoma, uveitis and other serious conditions affecting the eye, ...