Staging

ROP zone

The ICROP3 2021 classification of retinopathy of prematurity grades how far posterior the disease extends, from zone I around the optic disc to zone III in the temporal periphery.

Also called: zone

Stages

I
Zone I
Disease in the posterior retina around the optic disc and macula, the most posterior zone.
II
Zone II
Disease extending from the edge of zone I out to the nasal periphery, at the ora serrata.
III
Zone III
Disease in the temporal crescent, the part of the retina that vascularizes last.

Judged onHow far posterior the disease lies, judged from the border between vascularized and avascular retina.