Results of U.S. randomized clinical trial of cryotherapy for ROP (CRYO-ROP)

Abstract

Twenty-three centers collaborated in this prospectively designed study involving infants born weighing less than 1251 grams. Patient examinations began 4 to 6 weeks from birth. For entry into the study, two investigators had to agree that an eye had developed stage 3 ROP involving a threshold number of at least 5 contiguous or 8 total clock hour sectors of zone 1 or 2, and ‘plus’ disease to a degree specified by a standard photograph. Cryotherapy was lightly applied to the avascular zone between the ridge of ROP and the ora serrata, in an average of about 50 separate spots. Outcome was determined 3 and 12 months following randomization, by means of masked readings of fundus photographs. Preliminary results were published in the Archives of Ophthalmology, Vol. 106, pp. 471–479, 1988. In these results from 172 of the 291 study patients, 43.0% of the control eyes had an adverse outcome (defined as retinal detachment, macular fold, or retrolental mass), as compared to 21.8% adverse outcome for eyes that received cryotherapy.