Table 1.
Baseline Demographic and Clinical Characteristics by Treatment Group (N=57).
| Prism (N=28) |
Non-prism (N=29) |
|||
|---|---|---|---|---|
| N | % | N | % | |
| Sex: Female | 17 | 61% | 16 | 55% |
| Race/ethnicity | ||||
| Asian | 0 | 0% | 3 | 10% |
| Black/African American | 6 | 21% | 2 | 7% |
| Hispanic | 4 | 14% | 7 | 24% |
| White | 16 | 57% | 17 | 59% |
| More than one race | 2 | 7% | 0 | 0% |
| Age at randomization, years | ||||
| 3–<5 | 10 | 36% | 7 | 24% |
| 5–<7 | 7 | 25% | 10 | 34% |
| 7–<9 | 8 | 29% | 8 | 28% |
| ≥9 | 3 | 11% | 4 | 14% |
| Mean (SD) | 6.4 (2.4) | 6.8 (2.1) | ||
| Range | 3.2 to 12.3 | 3.7 to 12.6 | ||
| Refractive error, average of eyes (spherical equivalent, D) | ||||
| −6.00 to <−2.00 | 2 | 7% | 2 | 7% |
| −2.00 to <−1.00 | 2 | 7% | 0 | 0% |
| −1.00 to <−0.00 | 2 | 7% | 6 | 21% |
| 0.00 to <1.00 | 14 | 50% | 13 | 45% |
| 1.00 to <2.00 | 7 | 25% | 8 | 28% |
| Median (Range) | 0.6 (−3.80 to +2.0 D) | 0.5 (−4.00 to +1.80D) | ||
| Mean (SD) | 0.2 (1.3) | 0.2 (1.3) | ||
| Prior IXT Treatment | ||||
| Overminus | 2 | 7% | 3 | 10% |
| Patching | 7 | 25% | 5 | 17% |
| Patching and Atropine | 0 | 0% | 1 | 3% |
| Patching and Overminus | 1 | 4% | 0 | 0% |
| Vision Therapy and Overminus | 0 | 0% | 1 | 3% |
| None | 18 | 64% | 19 | 66% |
| Near Stereoacuity in arc seconds (log arcsec) a | ||||
| 40 (1.60) | 2 | 7% | 3 | 10% |
| 60 (1.78) | 6 | 21% | 8 | 28% |
| 100 (2.00) | 9 | 32% | 7 | 24% |
| 200 (2.30) | 3 | 11% | 4 | 14% |
| 400 (2.60) | 5 | 18% | 3 | 10% |
| 800 (2.90) | 2 | 7% | 2 | 7% |
| Nil (3.10) | 1 | 4% | 2 | 7% |
| Median (range) [log arcsec] | 2.0 (1.6 to 3.2) | 2.0 (1.6 to 3.2) | ||
| Mean (SD) (log arcsec) | 2.2 (0.4) | 2.2 (0.5) | ||
| Suppression b | ||||
| Negligible (0) | 3 | 12% | 3 | 12% |
| Mild (1) | 1 | 4% | 4 | 16% |
| Moderate (2) | 4 | 15% | 8 | 32% |
| Dense (3) | 18 | 69% | 10 | 40% |
SD = standard deviation; D = diopter(s); IXT = intermittent exotropia, log arcsec = logarithm of arc seconds
Randot Preschool Stereoacuity test (Stereo Optical Co., Inc., Chicago, IL). For analysis, stereoacuity was converted from seconds of arc scores to log arcsec values (in parentheses) as follows: 40 (1.60), 60 (1.78), 100 (2.00), 200 (2.30), 400 (2.60), 800 (2.90); participants with no detectable (nil) stereoacuity were assigned the value of 1600 (3.20).
The Office Suppression Test17 is a three-step procedure to grade density of suppression in patients with intermittent exotropia who are manifestly exotropic. While manifestly exotropic (spontaneous or induced), the participant viewed a 20/50 optotype at 6 meters, in normal room illumination, and was asked whether 1 or 2 letters were seen. If 2 letters were reported, suppression was classified as “negligible” (grade of 0). If 1 letter was reported (indicating suppression), a single-point light source was viewed at 6 meters with a red filter placed over the habitually fixing eye. If 2 lights were reported (one white and one red), suppression was classified as “mild” (grade 1). If 1 light was reported, the light source was viewed again in dim lighting with a red filter over the preferred eye. Suppression was classified as “moderate” (grade 2) if 2 lights were reported or dense (grade 3) if 1 light was reported. “Missing” refers to cases in which participants were unable to understand the test and/or gave unreliable responses.