In Reply We thank Peng and colleagues for their interest and astute comments. Point-by-point responses follow.
Regarding outcome measures: we chose the Pell-Robson chart to assess large-letter contrast sensitivity (CS) because of its well-established efficacy and ability to quantify low spatial frequency processing, such as facial recognition. The 20/25 CS letter chart was used for high spatial frequency processing because, as is referenced in our article,1 it is sensitive to small changes in CS undetected by high-contrast visual acuity.