TABLE 1.

Simulated low-vision conditions: scaling factors (a and b), expected VA and CS Reductions, expected VA and CS values, and measured VA and CS values (mean [standard deviation]) in the normally sighted young group.

Filter	Horizontal scaling a	Vertical scaling b	Expected VA reduction	Expected CS reduction	Expected VA	Expected CS	Measured VA	Measured CS
0*	1.000	1.000	0.00	0.00	−0.24†	2.13‡	−0.09 [0.02]	2.13 [0.01]
1	0.288	0.288	0.60	−0.54	0.36	1.59	0.28 [0.01]	1.58 [0.02]
2	0.157	0.157	0.90	−0.80	0.66	1.33	0.62 [0.01]	1.33 [0.02]
3	0.086	0.086	1.20	−1.06	0.97	1.07	0.97 [0.01]	0.99 [0.02]
4	0.048	0.048	1.51	−1.31	1.27	0.82	1.31 [0.02]	0.64 [0.02]
5	0.027	0.027	1.81	−1.54	1.57	0.59	1.72 [0.01]	0.10 [0.02]
6	0.250	1.000	0.60	−0.07	0.36	2.05	0.25 [0.02]	2.11 [0.02]
7	0.134	0.534	0.90	−0.31	0.66	1.81	0.56 [0.01]	1.80 [0.03]
8	0.072	0.288	1.20	−0.57	0.97	1.55	0.93 [0.02]	1.44 [0.02]
9	0.039	0.157	1.51	−0.83	1.27	1.29	1.27 [0.03]	0.95 [0.07]
10	0.022	0.086	1.81	−1.09	1.57	1.03	1.67 [0.02]	0.35 [0.04]
11	0.267	0.534	0.60	−0.27	0.36	1.86	0.26 [0.01]	1.91 [0.04]
12	0.144	0.288	0.90	−0.54	0.66	1.59	0.57 [0.01]	1.60 [0.03]
13	0.078	0.157	1.20	−0.80	0.97	1.33	0.96 [0.02]	1.23 [0.03]
14	0.043	0.086	1.51	−1.06	1.27	1.07	1.30 [0.02]	0.72 [0.03]
15	0.024	0.048	1.81	−1.31	1.57	0.82	1.68 [0.01]	0.27 [0.03]
16	0.314	0.157	0.60	−0.80	0.36	1.33	0.30 [0.02]	1.26 [0.07]
17	0.172	0.086	0.90	−1.06	0.66	1.07	0.65 [0.03]	1.01 [0.06]
18	0.096	0.048	1.20	−1.31	0.97	0.82	1.01 [0.02]	0.69 [0.05]
19	0.055	0.027	1.51	−1.54	1.27	0.59	1.40 [0.04]	0.36 [0.03]
20	0.032	0.016	1.81	−1.76	1.57	0.42	1.77 [0.01]	0.00 [0.00]
21	0.345	0.086	0.60	−1.06	0.36	1.10	0.35 [0.02]	1.07 [0.04]
22	0.193	0.048	0.90	−1.31	0.66	0.85	0.69 [0.01]	0.79 [0.04]
23	0.110	0.027	1.20	−1.54	0.97	0.62	1.01 [0.03]	0.64 [0.05]
24	0.064	0.016	1.51	−1.76	1.27	0.40	1.38 [0.05]	0.30 [0.04]
25	0.038	0.010	1.81	−1.96	1.57	0.14	1.57 [0.01]	0.15 [0.00]
26	0.439	0.027	0.60	−1.54	0.36	0.58	0.50 [0.04]	0.62 [0.07]
27	0.256	0.016	0.90	−1.76	0.66	0.36	0.85 [0.04]	0.47 [0.05]
28	0.154	0.010	1.20	−1.96	0.97	0.16	1.31 [0.07]	0.29 [0.07]
29	0.033	0.534	1.51	−0.55	1.27	1.61	1.32 [0.03]	1.50 [0.04]
30	0.018	0.288	1.81	−0.81	1.57	1.35	1.63 [0.02]	0.77 [0.03]
31	0.125	1.000	0.90	−0.16	0.66	1.96	0.64 [0.02]	2.06 [0.04]
32	0.063	1.000	1.20	−0.29	0.97	1.85	0.97 [0.02]	1.93 [0.02]
33	0.031	1.000	1.51	−0.45	1.27	1.67	1.33 [0.01]	1.52 [0.08]
34	0.016	1.000	1.81	−0.63	1.57	1.49	1.55 [0.01]	0.69 [0.09]
35	1.000	0.355	0.05	−0.45	−0.19	1.65	−0.12 [0.01]	1.70 [0.03]
36	1.000	0.178	0.09	−0.75	−0.15	1.35	−0.07 [0.02]	1.43 [0.03]
37	1.000	0.089	0.14	−1.04	−0.10	1.06	−0.02 [0.03]	1.10 [0.03]
38	1.000	0.045	0.20	−1.34	−0.04	0.76	0.07 [0.03]	0.88 [0.03]
39	1.000	0.022	0.27	−1.63	0.03	0.47	0.17 [0.04]	0.58 [0.03]
40	1.000	0.011	0.36	−1.90	0.13	0.20	0.45 [0.09]	0.36 [0.04]

*Filter 0 represents no filtering condition.

^†The baseline acuity value was directly obtained from the cut-off spatial frequency (51.9 cpd) of the normal CSF function, using Equation 11 in Supplementary Appendix 2.

^‡The baseline Pelli-Robson contrast sensitivity value obtained from the peak of the normal CSF function is 2.5 log units, which exceeds the test capacity of the Pelli-Robson chart and therefore was normalized to the baseline value of our subject pool.