Table 2.

Visual acuity results of the Teller Acuity Cards (grating acuity) and the Cambridge Crowding Cards (uncrowded and crowded acuity) in typically developing children (group 1), children with ocular disorders (group 2), children with brain damage (group 3).

Test	Group
	1	2	3
	(n = 60)	(n = 21)	(n = 26)
Teller Acuity Cards
Grating acuity
n	59	15	24
Median Snellen equivalenta	20/11.6	20/17.5	20/11.6
<20/20b (n)	2	7	5
≤20/30c (n)	0	0	1
Cambridge Crowding Cards
Uncrowded acuity
n	60	21	24
Median Snellen equivalent	6/4	6/12	6/6
<6/6b (n)	2	8	2
≤6/18c (n)	0	9	4
Crowded acuity
n	60	21	21
Median Snellen equivalent	6/6	6/60	6/9
<6/9 or 6/6d (n)	16	4	7
≤6/18c (n)	2	15	6

^acycl/deg = (20/Snellen denominator) × 30.

^bSubnormal vision, low vision excluded. Snellen equivalent for 30 cycl/deg is 6/6 or 20/20.

^cLow vision ≤ 10 cycl/deg. Snellen equivalent for 10 cycl/deg is 6/18 or 20/30.

^dAge dependent cut-off value for subnormal vision: 20 cycl/deg (Snellen equivalent 6/9) for age < 4y6m; <30 cycl/deg (Snellen equivalent < 6/6) for older children. Low vision excluded.