Purpose:
It has been established that there is a greater incidence of retinopathy of prematurity (ROP) in the temporal retina, due to its greater extent (presence of zone 3) than the nasal retina. It is not known, however, if the presence of zone 3 secondarily leads to a greater incidence of retinopathy in the temporal aspect of zone 2 relative to the nasal aspect of zone 2. We studied the distribution of stage two zone two ROP to determine if there is a predilection for temporal disease in this zone.
Methods:
We reviewed the medical records of all patients documented to have stage 2 (i.e. a terminal ridge) zone 2 ROP during a one year period. All babies had been examined by one of the authors (MJG), an experienced pediatric ophthalmologist.
Results:
Eighty–six eyes of 43 patients showed stage 2 zone 2 ROP. The average gestational age at birth of these patients was 26.2 +/– 2.7 weeks and the average birth weight was 794 +/– 172 grams. Sixty–two eyes (72%) developed stage 2 zone 2 retinopathy both nasally and temporally. The average gestational age of these patients was 26.0 +/– 2.4 weeks and the average birth weight was 800 +/– 182 grams. Of these eyes, 16 developed stage 3 disease, and 10 received laser treatment.
Twenty–four eyes (28%) developed stage 2 zone 2 retinopathy temporally, with no nasally involvement. The average gestational age of these patients was 26.7 +/– 3.3 weeks and the average birth weight was 777 +/– 147 grams. Of these eyes, 6 developed stage 3 disease, and 4 received laser treatment.
No eyes were found to have stage 2 zone 2 retinopathy that remained confined to the nasal quadrant.
Conclusions:
While ROP in most eyes with stage 2 disease invovled both nasal and temporal retina, all of the eyes in which this was not the case showed temporal retinal involvement while none showed nasal involvement. (p<.0005). We speculate that the avascular retina in zone 3 temporally may secrete vessel growth factors that promote the development of ROP ridges selectively in the temporal aspect of zone 2.
Keywords: retinopathy of prematurity • neovascularization • ischemia