Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) - Outcome Study of Cryotherapy for Retinopathy of Prematurity
- Conditions
- Retinopathy of Prematurity
- Registration Number
- NCT00000133
- Lead Sponsor
- National Eye Institute (NEI)
- Brief Summary
To determine the safety and efficacy of trans-scleral cryotherapy of the peripheral retina in certain low birth-weight infants with retinopathy of prematurity (ROP) for reducing blindness from ROP.
To determine the long-term outcome for eyes that had severe ("threshold") ROP, both with and without cryotherapy.
- Detailed Description
ROP is a disease of the eyes of prematurely born infants in which the retinal blood vessels increase in number and branch excessively, sometimes leading to hemorrhage or scarring. Before the establishment of this study in 1985, more than 500 infants annually were blinded by ROP in the United States alone.
More than 30 years ago, the National Institutes of Health sponsored a clinical trial that showed that if premature babies are given oxygen only as needed, the number of infants who develop ROP drops dramatically. Subsequently, hospitals cut back on giving excessive oxygen routinely to premature babies. But, with improvements in neonatal care over the last two decades, the number of babies at risk is increasing as survival rates for smaller premature infants improve. The lower the birth weight, the higher the incidence and severity of ROP.
In a more recent NEI-supported study at the University of Miami, blood oxygen levels of very low birth-weight infants were monitored continuously by use of transcutaneous measurements as long as oxygen therapy was needed. The study showed that there is no statistically significant difference between the rates of ROP in infants monitored on continuous oxygen therapy and in those monitored only when they were receiving oxygen in excess of 40 percent.
The Supplemental Therapeutic Oxygen for Prethreshold ROP (STOP-ROP) trial, also funded by the NEI, studied whether a slight increase in oxygen therapy would prevent the progression of moderate ROP to ROP severe enough to require surgical treatment. This intervention made little or no difference in outcomes.
Likewise, another NEI-sponsored clinical trial (LIGHT-ROP) demonstrated absence of protective effect on ROP by limiting light exposure to newborn premature infants. These studies have led to the conclusion that factors other than oxygen or light exposure must be involved in causing ROP.
In most infants who develop ROP, the disease spontaneously subsides, permitting development of normal vision. But other infants who progress to a severe form of ROP are in danger of becoming permanently blind. Although the cause of ROP is not fully explained, scientists are seeking ways to treat ROP successfully and to find the right time in the progression of the disease to use treatment. Cryotherapy, which destroys the fringe of the retina through freezing, is the only treatment so far that has been demonstrated to provide substantial benefit to these eyes.
The multicenter trial of cryotherapy for ROP enrolled more than 4,000 premature infants who weighed no more than 1,250 grams at birth. This category of infants is at the greatest risk of developing ROP. The eyes of the infants enrolled in the study were examined at predetermined intervals while the subjects were still in the intensive care nursery. After the pupils were dilated with eye drops, the eyes were examined by an ophthalmologist using a binocular indirect ophthalmoscope to visualize the developing retina. The natural history of the condition of each infant's retina was recorded. When examination disclosed the severe form of ROP (threshold ROP) in both eyes, and the parents gave informed consent, one of the infant's eyes was randomly selected to receive cryotherapy. In this technique, a cryoprobe was used to freeze and thus destroy the peripheral extent of the retina, thereby arresting the development of the blood vessels growing wildly toward it.
Outcome of the therapy was assessed at 3 months and 12 months following randomization by an extensive examination that included photography of the interior of both the treated and the control eyes. The 12-month exam also measured visual function with preferential-looking techniques. Such measurements allowed correlations between fundus photographs and visual function and a comparison of visual function for treated versus control eyes. Neither the trained photograph readers who evaluated the pictures from both eyes nor the specially trained vision testers knew which eyes had received cryotherapy. Additional assessments of visual acuity and retinal status have been made approximately each year up to the present. Currently (2001), preparations are being made for a 15-year outcome study that will conclude by 2003.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- Not specified
Not provided
Not provided
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- Not specified
- Primary Outcome Measures
Name Time Method
- Secondary Outcome Measures
Name Time Method
Trial Locations
- Locations (24)
Department of Ophthalmology, Tulane University School of Medicine
🇺🇸New Orleans, Louisiana, United States
Duke University Medical Center
🇺🇸Durham, North Carolina, United States
Wilmer Eye Institute, The Johns Hopkins Medical Institutions
🇺🇸Baltimore, Maryland, United States
Private practice of David Plotsky, MD
🇺🇸Washington, District of Columbia, United States
Retina Group of Washington
🇺🇸Washington, District of Columbia, United States
Bascom Palmer Eye Institute, University of Miami School of Medicine
🇺🇸Miami, Florida, United States
Department of Ophthalmology, Indiana University School of Medicine
🇺🇸Indianapolis, Indiana, United States
Kentucky Lions Eye Research Institute, University of Louisville
🇺🇸Louisville, Kentucky, United States
Alabama Ophthalmology Associates, P.C.
🇺🇸Birmingham, Alabama, United States
Private practice of John D. Baker, MD
🇺🇸Dearborn, Michigan, United States
John Moran Eye Center
🇺🇸Salt Lake City, Utah, United States
Associated Retinal Consultants, P.C.
🇺🇸Royal Oak, Michigan, United States
Columbus Children's Hospital
🇺🇸Columbus, Ohio, United States
Pediatric Ophthalmology and Strabismus, Inc.
🇺🇸Pittsburgh, Pennsylvania, United States
Private practice of Rand Spencer, M.D.
🇺🇸Dallas, Texas, United States
Strong Children's Hospital, University of Rochester Medical Center
🇺🇸Rochester, New York, United States
University of Texas Health Science Center, San Antonio, Department of Ophthalmology
🇺🇸San Antonio, Texas, United States
Oregon Health & Science University, Casey Eye Institute
🇺🇸Portland, Oregon, United States
Department of Ophthalmology, Vanderbilt University Medical Center
🇺🇸Nashville, Tennessee, United States
University of Illinois Eye and Ear Infirmary
🇺🇸Chicago, Illinois, United States
Children's Hospital of Philadelphia, Division of Pediatric Ophthalmology
🇺🇸Philadelphia, Pennsylvania, United States
Department of Ophthalmology, University of Minnesota
🇺🇸Minneapolis, Minnesota, United States
Private Practice of Miles J. Burke, MD
🇺🇸Cincinnati, Ohio, United States
Storm Eye Institute, Medical University of South Carolina
🇺🇸Charleston, South Carolina, United States