4. Effect of intervention.

	Outcome	Farber 1991 (Randomised 174 eyes) Mean follow up of 42 to 47 months		Jampol 1983 (Randomised 167 eyes) Mean follow up of 21 to 32 months
		Laser (Argon Scatter)	Control	Laser (Feeder vessel)	Control
1	Complete regression of PSR Partial egression of PSR	30/99 (30.2%) 51/99 (51.0%)	17/75 (22.4%) 18/75 (23.7%)	78/87 (89.6%)	Not reported
2	Development of new PSR	34/99 (34.3%)	31/75 (41.3%)	Not reported
3	Visual loss	3/99 (3.0%)	9/75 (8.3%)	1/87 (1.14%)	4/80 (5.0 %)
4	Occurrence of vitreous haemorrhage	12/99 (12.0%)	19/75 (25.3%)	3/87 (3.4%)	22/80 (27.5%)
5	Adverse effect: Retinal tear	Not reported
6	Adverse effect: Retinal detachment	3/99 (3.0%)	8/75 (10.6%)	5/87 (5.74%)	No event
7	Adverse effect: Choroidal neovascularization	Not reported		41/87 (47.12%)	No event

Unit of analysis is the eye.

PSR: proliferative sickle retinopathy.

Farber 1991: Mean follow up of 42 months for control group and 47 months for treatment group.

Jampol 1983: Mean follow up of 21 months for Chicago centre and 32 months for Kingston, Jamaica (overall participants).