3. Characteristics of intervention and control in each study.

Study ID	Intervention (Laser type)	Parameters	Control
Farber 1991	Sectoral scatter laser photocoagulation by Argon blue/green (Britt 3250) in Kingston, Jamaica	500 µm spot size, 0.1 second duration	Observation
Jampol 1983	Feeder vessel photocoagulation Chicago ‐ Argon laser Kingston, Jamaica ‐ Xenon arc	500 µm spot size, 0.2 second duration, 300‐600mW power. Intensity 5 ‐ 10, Size 3 ‐ 6 and 0.5 ‐ 2 second duration.	Observation

µm: micrometre