Purepoint

Transpupillary laser treatments were performed within 24 hours of Type 1 ROP diagnosis. The pupil was dilated and topical anesthesia was performed. The experts gently open the eye with a lid speculum and re-examined the fundus using a 28D lens and an indirect ophthalmoscope, integrated with 532 nm laser accessories (Purepoint, Alcon, US). The photocoagulation was performed on a nearly confluent pattern in the avascular retina. Repeat mode was used with 0.2s exposure time and 0.2s interval time. Power was set to achieve white-grey burns, generally between 200 to 350 mW. Topical antibiotic eye drops were used during and after the procedure. Any ocular or systemic complications related to photocoagulation were recorded.

Laser PC during vitrectomy surgery was performed with a laser system (Purepoint, 532 nm) which is equipped with a standard Constellation Vision System (Alcon, Irvine, CA, USA). For short pulse duration PC, the laser power setting was 340–360 mW, duration was 0.02 seconds, and the interval was 0.2 seconds. For conventional PC, the laser power setting was 120–150 mW, the duration was 0.2 seconds, and the interval was 0.2 seconds. Because different PC instruments were used in the outpatient clinic, it is difficult to determine the exact size of the PC created during vitrectomy. However in all cases, the laser power was set strong enough to cause a white spot to appear on the retina. The appearance of the short pulse laser spots after surgery are shown in Fig 1. These two laser during surgery were also shown in S1 Movie. The total PC energy was automatically calculated by the embedded software.