Retinal detachment associated with subthreshold retinopathy of prematurity

To report a series of infants who progressed from mild retinopathy of prematurity (ROP) to severe ROP with retinal detachment without demonstrating detectable threshold disease.

Between January 1993 and August 1998, seven infants at Oregon Health Sciences University, followed in accordance with the Cryotherapy for Retinopathy of Prematurity Study (CRYO-ROP) protocol, progressed to retinal detachment despite documentation that threshold had not been reached. This outlying subset of patients was analyzed and compared to the cohort in the CRYO-ROP study.

Six of 7 patients were male, 6 (86%) patients had symmetric disease, and all patients were born outside the study hospital. Mean birth-weight was 877 g and mean gestational age was 26 weeks. Mean postconceptual age at the time of retinal detachment was 41 weeks. Because of bilateral detachment in 3 patients, the total number of study eyes is 10. Failure to achieve threshold resulted from insufficient clock hours or insufficient stage in 2 eyes and lack of plus in 8 eyes. Zone I disease was present in 1 eye.

Rarely, despite adhering to ROP examination protocol, the retina may detach without demonstrating antecedent threshold disease. Very low birthweight is a factor that may lead to a less predictable course. This study found a lack of plus disease results in failure to reach threshold more often than the occurrence of insufficient clock hours of stage 3 disease. Further study is needed to determine if selected cases of subthreshold ROP may benefit from ablative therapy.