Objective: To report the outcomes of transscleral diode laser photocoagulation for treatment of type 1 prethreshold retinopathy of prematurity (ROP).

Methods: In this prospective interventional case series, 139 eyes of 73 infants with type 1 prethreshold ROP underwent transscleral diode laser photocoagulation of the avascular retina under topical anesthesia without making a conjunctival incision. Supplemental transpupillary diode laser photocoagulation was used for zone 1 ROP in one eye. All patients were followed for 6 months. Main outcome measures were regression of ROP, incidence of unfavorable outcomes and adverse effects.

Results: At the end of follow-up, neovascularization regressed completely in all eyes and no eye developed an unfavorable outcome. Repeated laser therapy was performed employing the same technique in 3 eyes (2.3%). Ocular adverse effects were minor including mild conjunctival injection and edema in all patients, small conjunctival lacerations in 12 eyes (8.7%), minor self-limited vitreous hemorrhage in 2 eyes (1.4%) and mild self-limited hyphema in one eye (0.7%).

Conclusions: Transscleral diode laser photocoagulation is a safe and effective treatment option for type 1 prethreshold ROP. This technique can be performed under topical anesthesia.