Table 9

Sensitivity and specificity values at different referral cut-offs for each screening tool

Test	Refer if worse than or equal to	Sensitivity	Specificity
Acuity	6/9	1.0	0
	6/12	0.60	0.72
	6/18	0.33	0.92
	6/24	0.08	0.99
	<6/24	0.02	1.0
Plusoptix (cylinder)	0.50	0.94	0.27
	0.75	0.89	0.49
	1.0	0.80	0.68
	1.25	0.74	0.77
	1.5	0.69	0.85
	1.75	0.59	0.90
	2.0	0.54	0.92
Spot (cylinder)	0.50	0.97	0.16
	0.75	0.90	0.44
	1.0	0.82	0.68
	1.25	0.72	0.81
	1.5	0.64	0.89
	1.75	0.56	0.93
	2.0	0.48	0.97
Randot	100	1.0	0
	200	0.31	0.92
	400	0.15	0.97
	800	0	1.0
PVS	1.0	1.0	0
	0.8	0.73	0.42
	0.6	0.55	0.60
	0.4	0.39	0.78
	0.2	0.35	0.82