CORRELATION OF RETINOPATHY OF PREMATURITY IN FELLOW EYES IN THE CRYOTHERAPY FOR RETINOPATHY OF PREMATURITY STUDY

Objective: To examine the similarity of extent (sectors) and severity (stage) of acute-phase retinopathy of prematurity (ROP) between fellow eyes and the concordance of cicatricial outcomes at age 1 year of eyes that did not develop threshold disease. Methods: Four thousand ninety-nine infants with birth weights of less than 1251 g who participated in a natural history segment of the Cryotherapy for Retinopathy study underwent biweekly eye examinations from 4 to 6 weeks after birth until retinal vasculature was complete or until ROP regressed or reached threshold severity. Eyes were categorized as follows: (1) no ROP, (2) less than prethreshold ROP, (3) prethreshold ROP, (4) threshold ROP, and (5) unable to determine. The presence and stage of ROP residua in fellow eyes were evaluated at 12 months. Results: Acute-phase ROP status between 32 and 42 weeks' postconceptional age showed a high degree of correspondence between fellow eyes in severity (stage) and location (zone) of ROP, presence of plus disease, and sectors of stage 3 retinopathy. More variability between eyes was seen when cicatricial status at age 1 year was examined. This higher variability was evident even though results from patients with threshold ROP (many of whom underwent cryotherapy) were excluded. Conclusion: The usual course of ROP during its acute phase is for fellow eyes to be very similar in ROP status. However, asymmetry between eyes is not unusual in eyes with posterior pole residua of ROP.