Skip to main content

Advertisement

Table 2 Changes in Visual Acuity (LogMAR) at Different Levels of Illumination*

From: Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]

Level of Illumination Normal (100%) Low (4%) Very Low (0.1%)
Covariates§ Coefficient¶ (95% CI) P value Coefficient (95% CI) P value Coefficient (95% CI) P value
Treatment -0.0002 (-0.0131,0.0128) 0.981 0.0054 (-0.0137,0.0246) 0.578 -0.0762 (-0.139, -0.0131) 0.018
Period - - -0.0448 (-0.083,-0.0066) 0.022 -0.0654 (-0.134, -0.0132) 0.061
Time (number of weeks) -0.0010 (-0.0026, 0.0007) 0.250 -0.0026 (-0.0048,-0.0003) 0.025 -0.0014 (-0.0027,-0.0001) 0.037
Age - - - - - -
Vitamin A Use - - -0.0701 (-0.1357,-0.0046) 0.036 - -
Iris color - - - - - -
Period × Treatment - - - - 0.1452 (0.0339, 0.2565) 0.011
Treatment × Time - - - - - -
Period × Time - - 0.0023 (0.0001, 0.0046) 0.044 - -
Baseline LogMAR 0.9783 (0.8933, 1.0634) <0.001 1.0086 (0.8909, 1.1268) <0.001 0.9290 (0.8416,1.0164) <0.001
Intercept 0.108 (-0.187, 0.402) 0.474 0.0265 (-0.0386, 0.0916) 0.424 0.0949 (0.0088, 0.181) 0.031
  1. * Based on the GEE linear regression model
  2. † Covariates forced to the model.
  3. ‡ Covariate removed due to non-significant contribution to the model (p value > 0.05).
  4. §Description of covariates:
  5. • Period: 0 in the first 24 weeks of the study, 1 in the second 24 weeks
  6. • Treatment: 0 for placebo, 1 for lutein supplementation
  7. • Time: Elapsed time within each 24-week period of the study (in weeks)
  8. • Age: Age of the patients at baseline (in years)
  9. • Vitamin A Use: 0 for participants not using, 1 for those using vitamin A supplements
  10. • Iris color: Categorical variable: 1. Light/Dark Blue 2. Green/Hazel 3. Light/Dark Brown
  11. ¶The coefficient indicates the change in LogMAR units per unit change in the covariate.