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. 2014 May 5;14(5):3. doi: 10.1167/14.5.3

Table 1.

Observer characteristics. The rightmost seven columns (threshold spacing, acuity, spacing:acuity ratio, equivalent blur, equivalent eccentricity, φA, and φcrowding) are plotted in Results. The “Line letter VA” chart has spacing factor 2×. Threshold spacing S was measured with a spacing factor of 1.1×. The add-on eccentricities φcrowding and φA are computed by Equations 15 and 16. Equation 15 shows that crowding is linearly related to eccentricity φ and proportional to “padded” eccentricity φ + φcrowding. So padded eccentricity is a good scale against which to examine crowding effects. The equivalent eccentricity for crowding is given by Equation 2, φeq = φcrowding – 0.45°. Stereopsis was measured using the Randot "Random Dot Geometric Form" test (Stereo Optical Co.).

Observer
Age (yrs)
Strabismus (at 6 m)
Eye
Refractive error (diopters, D)
Line letter VA (single letter VA)
Stereo*
Threshold spacing S (deg)
Acuity size A (deg)
Spacing:acuity ratio S/A
Eq. blur (D)
Eq.ecc. φeq (deg)
φA (deg)
φcrowding (deg)
Normal
 AF 22 None R +0.25/-0.50 × 180 20/12.5 20”
L +0.25/-0.25 × 25 20/12.5 0.123 0.083 1.48 0 0 2.86 0.45
 EJ 21 None R −2.50/-0.50 × 83 20/12.5 25”
L −3.00 20/12.5 0.190 0.143 1.33 0.33 0 4.93 0.45
 SS 28 None R −0.25 20/12.5 20” 0.138 0.103 1.34 0.13 0 3.55 0.45
L pl/-0.25 × 119 20/12.5
Purely strabismic (not anisometropic)
 JS 22 L EsoT 6-8Δ & HyperT 4-6Δ R +1.25 20/16 fail
L +1.00 20/40 (20/32+1) 0.257 0.102 2.52 0.15 0.41 3.52 0.86
 SF 19 L ExoT 6Δ R −1.50/-0.25×90 20/12.5+1 fail
L pl/-1.00×30 20/125+1 (20/80+2) 0.993 0.523 1.90 1.58 2.86 18.03 3.31
 GW 58 R EsoT 4-6Δ R pl 20/63−2 (20/24+2) fail 4.398 0.353 12.46 1.05 14.21 12.17 14.66
L +0.50/-0.75×180 20/16−1
 JZ 19 L EsoT 4Δ R pl/-0.50×95 20/16+2 fail
L −0.25/-0.50×50 20/63+2 (20/32−1) 0.440 0.173 2.54 0.45 1.02 5.97 1.47
 BN 22 L EsoT 3-4Δ R +5.50/-2.25×5 20/16+2 fail
L +5.50/-1.50×175 20/50−2 (20/25−2) 0.638 0.210 3.04 0.58 1.68 7.24 2.13
 CL 19 R EsoT 4Δ R −0.75 20/50+2 (20/32−2) fail 0.538 0.255 2.11 0.73 1.34 8.79 1.79
L −0.25/-0.50×55 20/16−2
Strabismic & anisometropic (These data are blue in Figures 26 & 11, and red in Figures 810 & 12.)
 SM 55 Alt. ExoT 18Δ R +2.75/-1.25 × 135 20/40 (20/25+1) 320” 0.455 0.208 2.19 0.57 1.07 7.17 1.52
L −2.00 20/16−2
 JD 19 L EsoT 3Δ R +2.50 20/16 fail
L +5.00 20/125 (20/125+2) 0.765 0.413 1.85 1.24 2.1 14.24 2.55
 AW 22 R EsoT 4-6Δ & HypoT 4Δ R +2.75/-1.0 × 160 20/80−1 (20/50−1) fail 0.638 0.258 2.47 0.74 1.68 8.90 2.13
L −1.00/-0.50 × 180 20/16−1
 GJ 23 R EsoT 4-5Δ R +3.50/-1.00 × 97 20/63+1 (20/40−1) fail 0.805 0.200 4.03 0.55 2.23 6.90 2.68
L Pl 20/16−1
 AP 24 L EsoT 4-5Δ & HyperT 2-3Δ R −1.25/-0.50 × 175 20/16−2 fail
L −0.50/-0.25 × 60 20/50+1 (20/40+2) 0.580 0.225 2.58 0.63 1.48 7.76 1.93
 VC 23 R ExoT 5-6Δ R +4.25/-1.50×10 20/200−4 (20/125−1) fail 17.740 0.958 18.52 2.92 58.68 33.03 59.13
L pl/-0.50×170 20/12.5−1
Purely anisometropic (non-strabismic)
 SC 27 None R +0.50 20/16+2 fail
L +3.25/-0.75 × 60 20/50+2 (20/40−2) 0.332 0.220 1.51 0.61 0 7.59 0.45
 CJ 22 None R −15.00/-1.25 × 150 20/125−4 (20/125+1) 200” 0.936 0.512 1.83 1.55 0 17.66 0.45
L −6.00 20/16−2
 AM 48 None R +0.75/-0.70 × 95 20/12.5 200”
L +2.00 20/32−2 (20/25−2) 0.240 0.200 1.20 0.55 0 6.90 0.45
 RA 15 None R −2.00/-1.75 × 155 20/32+1 (20/32+1) 70” 0.423 0.253 1.67 0.72 0 8.72 0.45
L +0.25/-0.25 × 60 20/12.5
 SWP 24 None R −0.25 20/16+2 30”
L +1.75/-0.25 × 45 20/32+2 (20/32+2) 0.383 0.250 1.53 0.72 0 8.62 0.45
 SW 42 None R +2.00/-0.50 × 90 20/12.5−2 200”
L +4.25/-1.25 × 120 20/80−2 (20/63−1) 0.675 0.493 1.37 1.49 0 17.00 0.45