Table 2.
Summary of visual span and reading measures
| Subject | Group | Stimuli print size | Visual span | Reading | |||
|---|---|---|---|---|---|---|---|
| Exposure duration (ms) † | Size (bits) | Information transfer rate (bits/sec) | Reading speed (log wpm) | Reading acuity (logMAR) | |||
| (deg) | |||||||
| 1 | AMD | 0.84 | 554.4 | 16.36 | 29.52 | 2.26 | 0.38 |
| 2 | AMD | 1.85 | 596.1 | 36.67 | 92.57 | 1.90 | 0.63 |
| 3 | AMD | 0.42 | 686.5 | 12.50 | 18.20 | 1.71 | 0.28 |
| 5 | AMD | 0.66 | 369.7 | 27.08 | 73.24 | 2.30 | 0.42 |
| 7 | AMD | 0.34 | 100.0 | 40.62 | 406.18 | 2.46 | 0.10 |
| 8 | AMD | 0.58 | 422.5 | 30.52 | 72.15 | 2.44 | 0.30 |
| 9 | AMD | 4.18 | 1293.8 | 30.58 | 23.64 | 1.75 | 1.06 |
| 10 | AMD | 1.66 | 818.5 | 23.91 | 29.21 | 1.75 | 0.92 |
| 11 | AMD | 0.84 | 792.1 | 20.58 | 25.99 | 2.09 | 0.38 |
| 12 | AMD | 3.32 | 1755.7 | 19.42 | 11.06 | 1.86 | 1.12 |
| 14 | AMD | 4.18 | 2033.0 | 18.99 | 9.34 | 1.92 | 1.41 |
| 15 | AMD | 0.84 | 100 | 18.67 | 180.67 | 2.40 | 0.34 |
| 16 | AMD | 3.59 | 409.2 | 27.03 | 66.05 | 2.34 | 1.04 |
| 17 ˆ | NV | 3.5 | 100 | 29.31 | 293.15 | 1.92 | -0.08 |
| 18 ˆ | NV | 3.5 | 100 | 24.25 | 242.49 | 1.72 | 0.06 |
| 19 ˆ | NV | 3.5 | 100 | - | - | - | -0.05 |
| 20 ˆ | NV | 3.5 | 100 | 27.16 | 271.61 | 1.37 | -0.13 |
| 21 ˆ | NV | 3.5 | 100 | 30.21 | 302.07 | 1.54 | 0.01 |
| 22 | NV | 3.5 | 100 | 32.54 | 325.44 | 1.89 | 0.14 |
| 23 | NV | 3.5 | 100 | 26.39 | 263.89 | 2.33 | -0.12 |
| 24 | NV | 3.5 | 100 | 24.76 | 247.55 | 1.95 | -0.10 |
| 25 | NV | 3.5 | 100 | 32.02 | 320.23 | 2.42 | 0.04 |
| 26 | NV | 3.5 | 100 | 28.84 | 288.35 | 2.22 | -0.10 |
| 27 | NV | 3.5 | 100 | 29.26 | 292.59 | 2.23 | -0.12 |
| Mean (SD) | AMD | 1.80
(1.48°) |
764.0
(594.2) |
24.8
(8.2) |
79.8
(108.7) |
2.09
(0.29) |
0.65
(0.41) |
| NV | 3.5° | 100 | 28.5
(2.8) |
284.7
(28.2) |
1.96
(0.35) |
-0.03
(0.09) |
|
| p-value | - | - | 0.20 | <0.01 | 0.43 | <0.01 | |
AMD = age-related macular degeneration NV = normal vision
Letter recognition accuracy for the central letter position as a function of exposure durations was measured for each AMD subject. The exposure time yielding 80% correct was defined as the temporal threshold. For subjects whose temporal threshold was longer than 100 ms, the individual’s temporal threshold was used as the stimulus duration in measuring the visual-span profile; otherwise, 100 ms was used (e.g. Sub 7 and NV).
Among these NV subjects, visual-span profiles and reading were measured at both central and 10° inferior visual field. Only results on 10° inferior visual field were reported in this table.
RSVP reading speed for AMD subjects reflected their reading performance at either their central or preferred retinal location while RSVP reading speed for NV subjects reflected their reading performance at 10° inferior visual field.
For Sub 19, reading speed at 10° inferior vision was not measured because this subject quitted the study due to exhaustion.