"The new study suggests that patients tend to use handheld devices at closer distances compared to printed materials, which could have important implications for vision correction. Smart phones "may present a variety of visual demands that are significantly different in terms of working distances, gaze angle, and text sizes," Rosenfield and coauthors write.
Further research is needed to investigate eye's response to prolonged smart phone use. In the meantime, the researchers believe that optometrists should ask patients in detail about how they use their handheld devices, and possibly perform further tests at those closer distances. Especially for older patients, changes in lens design may be needed to meet the visual demands of smart phones and other new technology.