Background: Laser photocoagulation restricted to ablation of the avascular retina has been the conventional but not a completely effective treatment strategy in the management of threshold retinopathy of prematurity (ROP). The purpose of this study was to compare the structural outcomes of additional posterior to ridge diode laser compared to conventional diode laser to avascular retina alone in threshold stage III ROP.

Methods: This was a prospective, randomized study involving infants diagnosed with threshold stage III ROP in one or both the eyes. The infants were randomized into control and study groups. Infants under the control group underwent conventional laser to avascular retina alone while infants under the study group received additional two rows of laser posterior to the ridge in the vascular retina. The infants were followed up at 2 weeks, 1 month and up to 6 months after the laser procedure.

Results: During the study period of 1 year, 42 eyes of 24 infants were recruited into this study with 21 eyes in each group. The mean birth weight was 1,310.48±400.92 g in the test group and 1,341.9±396.2 g in the control group. The mean post conceptional age at the time of intervention was 36.43±2.79 weeks in test group and 36.29±2.55 weeks in the control group. At 1-month post laser, 19 eyes in the study group showed regression of neovascularization laser compared to 18 eyes in the control group. However at the end of 3 and 6 months post laser, both groups had showed similar rates regression of neovascularization (19 of 21 eyes in both groups). Five eyes in the study group and six in the control group required additional laser treatment. Two eyes in the study group and one eye in the control group developed post laser vitreous hemorrhage.

Conclusions: Posterior to ridge laser treatment for severe stage 3 ROP did not show any additional benefit compared to conventional laser.