Evaluation of Vitrectomy for Diabetic Macular Edema
- Conditions
- Diabetic RetinopathyDiabetic Macular Edema
- Registration Number
- NCT00709319
- Lead Sponsor
- Jaeb Center for Health Research
- Brief Summary
The study is designed as a prospective cohort study to assess changes in visual acuity and retinal thickening and surgical complications in subjects undergoing vitrectomy for diabetic macular edema.
The study also aims to identify subgroups in which there appears to be a benefit of vitrectomy and subgroups in which vitrectomy does not appear to be beneficial and to obtain data that can be used to plan a randomized trial.
Subject will be followed through 2 years, with a primary outcome at 6 months post vitrectomy surgery. The vitrectomy procedure will be performed based on the investigators usual care and is not considered part of the research although the procedure performed will be collected.
- Detailed Description
Study Design The study is designed as a prospective cohort study. A randomized trial design was considered but rejected after deciding that there was insufficient equipoise on the part of the investigator group to randomize eyes with DME and vitreal traction to surgery or no surgery (thus eyes which potentially may benefit most from vitrectomy would not be included), and there was insufficient information available on the natural course or surgical outcomes of eyes with DME but without significant traction.
A cohort study provides the opportunity to collect data prospectively using a standardized protocol to assess the potential benefits and risks of vitrectomy. The results can be used to determine whether proceeding with a randomized trial has merit and what the design of the trial should be. If a randomized trial is to be conducted, the results plus the cohort study experience can be used to help design the protocol.
Study Objectives
1. To provide information on the following outcomes in eyes with Diabetic Macular Edema (DME) that undergo vitrectomy: visual acuity, retinal thickening, resolution of traction (if present), surgical complications.
2. To identify subgroups in which there appears to be a benefit of vitrectomy and subgroups in which vitrectomy does not appear to be beneficial.
3. To obtain data that can be used to plan a randomized trial.
B. Intervention Vitrectomy performed by the investigator's usual routine.
C. Duration of Follow-Up: Two years
D. Follow-up Visit Schedule Study visits for data collection at 3 and 6 months then 1, and 2 years. Additional visits follow investigator's usual routine.
E. Rationale:
There are at least two avenues of investigation that support the theoretical value of vitrectomy for the treatment of DME, based on (1) vitrectomy for the relief of traction on the macula and (2) vitrectomy to improve oxygenation of the macula leading to decreased permeability with subsequent resolution or decrease in DME.
Vitrectomy to relieve biomechanical traction on the macula has been reported widely. Schepens and coworkers discussed the role of the vitreous and vitreomacular traction in cystoid macular edema in 1984. Nasrallah et al observed in 1988 the resolution of diabetic macular edema in individuals with spontaneous separation of the vitreous gel from the retina. In 1992, Lewis and coworkers reported success with vitrectomy and peeling of a "thickened hyaloid membrane" in eyes with DME that had this anatomical feature. Since this report of a nonrandomized retrospective case series, other authors have prospectively analyzed their series and supported the concept that relief of clear-cut anteroposterior traction, usually in the setting of an epiretinal membrane complex and associated vitreous adherence, may ameliorate macular thickening and edema in DME. Evaluation of these individuals and documentation of pre and postoperative characteristics have been rendered vastly more objective by ocular coherence tomography and the Retina Thickness Analyzer. Series using optical coherence tomography (OCT) to image cases where vitreomacular traction is observed and in some cases treated, has confirmed the clinical impression of mechanical forces at work on the posterior retina and has documented the anatomic improvement with surgery. How and in which cases OCT could refine our ability to diagnose and define clinically important anatomical features or relationships has not been investigated. As Kaiser and coworkers have documented, the OCT findings in the cases that have thus far come to vitrectomy in these situations support a conclusion that the disease process has progressed very far and in many cases the individuals have actual traction retinal detachments in their maculae. These severe cases are the exception in the spectrum of DME: most cases of macular edema have no obvious vitreomacular traction, but this factor has not been investigated adequately with our newer and more sophisticated imaging techniques. It is possible that subclinical traction on the macula exists in a large number of individuals with diabetes, whose internal limiting membranes at the vitreomacular interface often have a thickened, hypercellular appearance and whose vitreous gels, gradually contracting over many years, may exert subclinical but significant traction on the compromised diabetic macular vascular bed.
The other line of reasoning and prior research that supports the possibility that vitrectomy would help DME is that articulated by Steffanson and others indicating that posterior segment oxygenation improves after vitrectomy. Using oxygen sensors on the retinal surface, these investigators have shown that retinal oxygen tensions increase after the vitreous gel is removed and the posterior segment becomes perfused by relatively oxygen-rich aqueous humor. Supporting this conclusion is the additional observation that retinal vessels decrease in caliber after vitrectomy, presumably in response to the improvement in hypoxia, although confounding factors that could contribute to this decrease, such as the addition of endolaser retinal photocoagulation, have not been ruled out. Numerous lines of investigation have elucidated factors producing permeability in retinal blood vessels. One of the most central of these factors is Vascular Endothelial Growth factor (VEGF), formerly known as Vascular Permeability Factor (VPF). VEGF is known to be upregulated by hypoxia, and downregulated by increased oxygenation. The speculated sequence of events in which vitrectomy produces improved oxygenation of the posterior segment, leading to downregulation of VEGF, leading to decreased vasopermeability, resulting in reduced macular thickening, is a plausible one. More rapid clearing of growth factors in the vitrectomized eye has also been postulated as a potential mechanism for this response.
See full protocol at drcr.net for list of references
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 87
Not provided
Not provided
Study & Design
- Study Type
- OBSERVATIONAL
- Study Design
- Not specified
- Primary Outcome Measures
Name Time Method Change in Optical Coherence Tomography Measured Central Subfield Thickness From Baseline Baseline to 6 Months Change in central subfield thickness is followup central subfield retinal thickness minus baseline thickness.
Change in Optical Coherence Tomography Central Subfield Thickness From Baseline to 6 Months Baseline to 6 months Change in thickness is followup thickness minus baseline thickness.
Visual Acuity Baseline to 6 months Change in best correct visual acuity letter score from baseline to six months as measured by a certified tester using an electronic visual acuity testing machine based on the Early Treatment Diabetic Retinopathy Study (ETDRS) method. A positive change denotes an improvement. Best value on the scale 97, worst 0.
Percent of Participants With Change in Visual Acuity From Baseline to Six Months Baseline to 6 months
- Secondary Outcome Measures
Name Time Method Surgical Complications From Baseline to Six Months Baseline to 6 months Including intraoperative and perioperative medical complications. Same subject could have more than one complication
Trial Locations
- Locations (47)
Loma Linda University Health Care, Dept. of Ophthalmology
🇺🇸Loma Linda, California, United States
Paducah Retinal Center
🇺🇸Paducah, Kentucky, United States
Charlotte Eye Ear Nose and Throat Assoc, PA
🇺🇸Charlotte, North Carolina, United States
Vitreo-Retinal Associates
🇺🇸Grand Rapids, Michigan, United States
Bay Area Retina Associates
🇺🇸Walnut Creek, California, United States
Southeastern Retina Associates, P.C.
🇺🇸Knoxville, Tennessee, United States
Retina Associates of Cleveland, Inc.
🇺🇸Beachwood, Ohio, United States
Horizon Eye Care, PA
🇺🇸Charlotte, North Carolina, United States
University of Florida College of Med., Department of Ophthalmology
🇺🇸Jacksonville, Florida, United States
Retina Consultants of Hawaii, Inc.
🇺🇸'Aiea, Hawaii, United States
Southern California Desert Retina Consultants, MC
🇺🇸Palm Springs, California, United States
West Texas Retina Consultants P.A.
🇺🇸Abilene, Texas, United States
Florida Retina Consultants
🇺🇸Lakeland, Florida, United States
John-Kenyon American Eye Institute
🇺🇸New Albany, Indiana, United States
Sarasota Retina Institute
🇺🇸Sarasota, Florida, United States
Retina-Vitreous Surgeons of Central New York, PC
🇺🇸Syracuse, New York, United States
Southeastern Retina Associates, PC
🇺🇸Kingsport, Tennessee, United States
Retina Consultants, PLLC
🇺🇸Slingerlands, New York, United States
Center for Retina and Macular Disease
🇺🇸Winter Haven, Florida, United States
Texas Retina Associates
🇺🇸Lubbock, Texas, United States
Valley Retina Institute
🇺🇸McAllen, Texas, United States
Retina Consultants of Delmarva, P.A.
🇺🇸Salisbury, Maryland, United States
Associated Retina Consultants
🇺🇸Williamsburg, Michigan, United States
Barnes Retina Institute
🇺🇸Saint Louis, Missouri, United States
Palmetto Retina Center
🇺🇸Columbia, South Carolina, United States
Carolina Retina Center
🇺🇸Columbia, South Carolina, United States
Black Hills Regional Eye Institute
🇺🇸Rapid City, South Dakota, United States
University of Wisconsin-Madison, Dept of Ophthalmology/Retina Service
🇺🇸Madison, Wisconsin, United States
Raj K. Maturi, M.D., P.C.
🇺🇸Indianapolis, Indiana, United States
Elman Retina Group, P.A.
🇺🇸Baltimore, Maryland, United States
Wilmer Eye Institute at Johns Hopkins
🇺🇸Baltimore, Maryland, United States
Joslin Diabetes Center
🇺🇸Boston, Massachusetts, United States
Charles A. Garcia, PA & Associates
🇺🇸Houston, Texas, United States
Retina and Vitreous of Texas
🇺🇸Houston, Texas, United States
University of Washington Medical Center
🇺🇸Seattle, Washington, United States
University of Minnesota
🇺🇸Minneapolis, Minnesota, United States
Casey Eye Institute
🇺🇸Portland, Oregon, United States
Vanderbilt University Medical Center
🇺🇸Nashville, Tennessee, United States
West Coast Retina Medical Group, Inc.
🇺🇸San Francisco, California, United States
Henry Ford Health System, Dept of Ophthalmology and Eye Care Services
🇺🇸Detroit, Michigan, United States
Retina Center, PA
🇺🇸Minneapolis, Minnesota, United States
Dean A. McGee Eye Institute
🇺🇸Oklahoma City, Oklahoma, United States
Retina Northwest, PC
🇺🇸Portland, Oregon, United States
Rocky Mountain Retina Consultants
🇺🇸Salt Lake City, Utah, United States
Retina Associates of Hawaii, Inc.
🇺🇸Honolulu, Hawaii, United States
University of California, Irvine
🇺🇸Irvine, California, United States
Retina Research Center
🇺🇸Austin, Texas, United States