Viewing distance and character size in the use of smartphones across the lifespan.

The use of smartphones has seen an extraordinary growth in recent years, thus the understanding of visual habits associated with the use of such devices across the lifespan is becoming important. In the present study we measured viewing distance and character size in a group of non-presbyopes (n = 157) and a group of presbyopes (n = 60) while participants read a simple text message on their smartphone. Results showed that non-presbyopes use shorter viewing distances as compared to presbyopes, a behavior causing a significantly higher accommodative demand. Presbyopes also use larger character sizes and this behavior is more evident whenever difficulties in near vision emerge in the Near Activity Visual Questionnaire (NAVQ, Italian version). Nevertheless, the two groups did not differ in the measurement of angular size subtended by the smallest detail of the letters. Overall, our data reveal that non-presbyopes and presbyopes have different visual habits when using a smartphone. These differences should be considered when determining the best near correction.