The Cornea Donor Study (CDS)
The Cornea Donor Study (CDS) is a prospective cohort study with the following objectives:
- To determine whether the graft-failure rate over a 5-year follow-up period following corneal transplantation is the same when using corneal tissue from donors older than 65 years of age compared with tissue from younger donors.
- To assess the relationship between donor/recipient ABO blood type compatibility and graft failure due to rejection.
- To assess corneal endothelial cell density as an indicator of the health of the cornea and as a surrogate outcome measure (in an optional ancillary study).
The importance of the CDS and its rationale are supported by the following:
- Although the supply of donor tissue may be sufficient to satisfy the current level of need in the U.S. for patients requiring corneal transplants, the future donor pool may decrease due to:
- elimination of tissues because of increasingly mandated serologic testing
- a decrease in younger donors due to improved automotive safety laws
- a projected decrease in suitable donors due to the steady increase in refractive surgery.
The change in practice that will have the greatest, cost-effective impact in increasing the donor pool is to expand the use of corneal tissue from older donors. This change in practice could expand the donor pool by 20-35 percent.
- The scientific literature on the suitability of older donor tissue for corneal transplantation is limited and inconclusive. Most of the available relevant data are retrospective and uncontrolled. However, the weight of current evidence suggests that transplants using older donor tissue have similar success rates to those using younger donor tissue when endothelial cell counts of the donor tissue are comparable. Despite this, many surgeons decline the use of older tissue on the basis of the lack of suitability. In other parts of the world, this bias against older donor tissue does not exist and donor age is not considered an important factor in assigning corneal tissue to a recipient.
- The international demand for suitable donor tissue is grossly unmet. If this study demonstrates that older donor tissue is as suitable as younger tissue, the impact internationally will be great.
- Despite the common performance of corneal transplantation, there are limited longitudinal data for even a five-year follow-up period. The study will help to fill this void by providing data on graft survival rates in general and the prognostic importance of various recipient factors as well as other donor factors.
- The need for the ABO compatibility substudy stems from the Collaborative Corneal Transplant Study’s (CCTS) finding that ABO blood type compatibility reduced the risk of graft failure. Because this was an unexpected secondary finding in the CCTS, corroboration of this finding in a second study is needed.
- The Specular Microscopy Ancillary Study will provide additional support for the overall results of the CDS. If the CDS demonstrates that graft survival is equivalent between older and younger donor tissue, some corneal surgeons may still have concern that older tissue will not fare as well with longer duration of follow-up. If it can be demonstrated that endothelial cell loss in clear grafts after five years is also equivalent, then the results and clinical impact of the CDS will be strengthened. Alternatively, if the graft failure rates at five years are comparable, but the surviving grafts from older donor age tissue have greater endothelial cell loss than grafts from younger tissue, then the importance of longer follow-up for the study cohort will be apparent.
The study will enroll 1000 patients. A donor cornea meeting the following criteria will be assigned to the patient by a participating eye bank:
- donor age 10 to 75 years
endothelial cell count 2300 to 3300
- tissue quality very good to excellent
- death to preservation time <12 hrs if body refrigerated or eyes on ice and <8 hrs if not
- death to surgery time <5 days
Approximately one-half of the patients will receive a cornea from donors >65 years and one-half from donors <65 years. The cornea surgeon (investigator) and patient are masked to the age of the donor. Surgery and post-op care are performed according to the investigator’s usual routine. Follow-up continues for five years unless the patient has a regraft of the study eye. The primary study outcome is graft failure defined as a cloudy cornea persisting for three months or regrafting of the study eye.
For the ABO compatibility study, the ABO blood type of both the donor and recipient will be determined, and at the conclusion of the study, the rate of graft failure in ABO-compatible cases will be compared to that of ABO-incompatible cases.
For the Specular Microscopy Ancillary Study, endothelial cell counts will be determined from specular images by a central reading center, and the relationship of the cell counts to donor age will be assessed.
Patients must be in the age range of 40 to 80 years, with corneal disease associated with endothelial dysfunction, including pseudophakic corneal edema, Fuchs’ dystrophy, posterior polymorphous dystrophy, endothelial failure from another cause, interstitial keratitis (non-herpetic), or perforating corneal injury.
Patient Recruitment Status
Complete. Patient enrollment ended on July 31, 2002 with 1,101 patients enrolled.
Current Status of Study
Beck RW, Cavanagh HD, Foulks GN, Gal RL, Heck EL, Holland EJ, Lindquist T, Macsai MS, Mannis MJ, Smith RE, Stark WJ, Stulting RD, Sugar J: Is donor age an important determinant of graft survival?. Cornea 18: 503-510, 1999.
Roy W. Beck, M.D., Ph.D.
Pamela S. Moke, M.S.P.H.
Robin L. Gal, M.S.P.H.
Katrina J. Ruedy, M.S.P.H.
Deeann M. Hensley
Jaeb Center for Health Research, Inc.
15310 Amberly Drive
Tampa, FL 33647
Telephone: (813) 975-8690
Fax: (813) 975-9761
Specular Microscopy Reading Center
Jonathan H. Lass, M.D.
Beth Ann Benetz
University Hospitals of Cleveland
Department of Ophthalmology
11100 Euclid Avenue
Cleveland, OH 44106-5068
Telephone: (216) 844-8590
Fax: (216) 983-0544
Maryann Redford, D.D.S., M.P.H.
National Eye Institute
National Institutes of Health
Executive Plaza South MSC 7164
6120 Executive Boulevard, Suite 350
Bethesda, MD 20892-7164
Telephone: (301) 496-5983
Fax: (301) 279-9674