Multicenter trial of cryotherapy for retinopathy of prematurity. Three-month outcome. Cryotherapy for Retinopathy of Prematurity Cooperative Group.

We report the results of the national multicenter trial of cryotherapy for retinopathy of prematurity, as determined 3 months after randomization. The threshold severity of retinopathy required for entry into the clinical trial was defined as five or more contiguous or eight cumulative 30 degree sectors (clock hours) of stage 3+ retinopathy of prematurity in zone 1 or 2. Transscleral cryotherapy to the avascular retina was applied in one eye when there was threshold retinopathy in both eyes, or in half the eyes when the threshold severity existed in only one eye (18% of patients). Of the 279 infants who survived 3 months following randomization, 273 returned for outcome examination at that time. Of these infants, 260 had fundus photographs taken that could be graded for anatomic outcome. An unfavorable outcome was defined as posterior retinal detachment, posterior retinal fold (usually involving the macula), or retrolental tissue that obscured the view of the posterior pole. Whereas 51.4% of control eyes had an unfavorable outcome, this was significantly less frequent in the eyes that received cryotherapy (31.1%). No deaths were attributed to the cryotherapy procedure. These data, together with numerous additional ocular findings and preliminary 12-month postrandomization outcome results reported herein, support the efficacy of cryotherapy in reducing the risk of unfavorable ocular outcome from threshold retinopathy of prematurity. We have previously recommended cryotherapy for at least one eye in all patients with threshold retinopathy of prematurity. Now we add the recommendation cryotherapy be considered for both eyes whenever stage 3+ retinopathy of prematurity involves the posterior retina (zone 1) of both eyes.