Early retinal vessel development and iris vessel dilatation as factors in retinopathy of prematurity. Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) Cooperative Group.

OBJECTIVE: To determine whether the extent of retinal vessel development present on early screening examinations for retinopathy of prematurity has prognostic value? DESIGN: The prospectively collected data from the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity were used to compare the development of acute retinopathy of prematurity and long-term structural and visual outcomes for eyes with differing extents of retinal vessel development. PATIENT: Study patients had eyes with the following vessel development. In zone I eyes, vessels extended from the disc less than twice the distance from the disc to the macula. In zone II eyes, vessels extended beyond zone I but not to the nasal ora serrata. Transitional eyes had vessels partly in zone I and partly in zone II. RESULTS: The chance of developing threshold retinopathy of prematurity was inversely related to the early degree of vessel development: 54% for zone I eyes, 25% for transitional eyes, and 8% for zone II eyes. The presence of prominent iris vessels at 34 to 35 weeks of postmenstrual age was associated with increased risk for all three groups; zone I eyes almost always needed treatment (94%). The chance of having an unfavorable anatomic alteration of the posterior fundus, or poor vision at the ages of 1 year and 3 1/2 years, was also inversely related to the degree of early vessel development. Vessel development was an independently important factor even when birth weight, gestational age, and race were considered. CONCLUSIONS: The degree of early retinal vessel development is a significant predictor of outcome from retinopathy of prematurity. Iris vessel dilatation is an important indication for greater vigilance in following these infants.