Diode laser photocoagulation for prethreshold, posterior retinopathy of prematurity.

Nine infants with posterior retinopathy of prematurity were treated by using the diode laser through an indirect ophthalmoscopic delivery system. Treatment was commenced as soon as plus disease (defined as tortuosity and dilation of posterior vessels) developed. We defined posterior retinopathy of prematurity as retinopathy of prematurity located in zone 1 (the limits of zone 1 are defined as twice the disk-fovea distance in all directions from the optic disk, that is, an arc of 60 degrees centered on the optic disk) or the posterior one half of zone 2 (zone 2 extends from the edge of zone 1 peripherally to a point tangential to the nasal ora serrata and around to an area near the temporal anatomic equator). Disease regressed in all eyes. These results are encouraging and represent an improvement over the results obtained by allowing these eyes to reach threshold (threshold disease is defined as 5 or more contiguous or 8 total clock hours of neovascularization in zone 1 or 2 in the presence of plus disease) before intervention.