Peripheral Avascular Retina in Retinopathy of Prematurity

The natural history of peripheral nonperfusion and vascular abnormalities, which persist beyond the acute phase of ROP, remains poorly understood. Although patients with a history of type I ROP (treatment requiring ROP) are more likely to exhibit abnormal foveal development and poor vision, a discrepancy still exists between the structural and functional findings of vascular abnormalities in the long term. For instance, circumferential atypical vessels are detected in patients with spontaneously regressed ROP and favorable vision. Additionally, persistent retinal vascular abnormalities may not necessarily predict adverse functional outcomes. The significance of such vessel anomalies and whether they persist or not remain uncertain. The physiologic avascular retina of children of age < 13 years usually extends ≤ 1.5 DD temporally or ≤ 1.0 DD nasally from the ora serrata. Therefore, the PAR (peripheral avascular retina) is defined as the nonperfusion area with measurements ≥ 2.0 DD, which is 3 standard deviations more than the normal value. Infants with persistent avascular retina have unknown long-term structural and functional risks, and theoretically could develop disease requiring treatment, including retinal breaks or tractional bands. Prolonged retinal traction by remnant shunt or extra-retinal fibrovascular proliferation between a stable prenatally vascularized retina in the posterior pole and an unstable postnatally vascularized retina may lead to the development of retinal holes characteristically located in the fragile, anterior undifferentiated avascular retina. Treatment options may vary from observation to retinal laser photocoagulation.