title: Font size and viewing distance of handheld smart phones.
abstract: OBJECTIVE
  The use of handheld smart phones for written communication is becoming ubiquitous in modern society. The relatively small screens found in these devices may necessitate close working distances and small text sizes, which can increase the demands placed on accommodation and vergence.
  
  
  METHODS
  Font size and viewing distance were measured while subjects used handheld electronic devices in two separate trials. In the first study (n=129), subjects were asked to show a typical text message on their own personal phone and to hold the device "as if they were about to read a text message." A second trial was conducted in a similar manner except subjects (n=100) were asked to view a specific web page from the internet.
  
  
  RESULTS
  For text messages and internet viewing, the mean font size was 1.1 M (range, 0.7 to 2.1 M) and 0.8 M (range, 0.3 to 1.4 M), respectively. The mean working distance for text messages and internet viewing was 36.2 cm (range, 17.5 to 58.0 cm) and 32.2 cm (range, 19 to 60 cm), respectively.
  
  
  CONCLUSIONS
  The mean font size for both conditions was comparable with newspaper print, although some subjects viewed text that was considerably smaller. However, the mean working distances were closer than the typical near working distance of 40 cm for adults when viewing hardcopy text. These close distances place increased demands on both accommodation and vergence, which could exacerbate symptoms. Practitioners need to consider the closer distances adopted while viewing material on smart phones when examining patients and prescribing refractive corrections for use at near, as well as when treating patients presenting with asthenopia associated with nearwork.
authors.affiliation: State University of New York, SUNY State College of Optometry, New York, New York 10036, USA.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Bababekova
authors.forename: Mark
authors.initials: M
authors.lastname: Rosenfield
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Hue
authors.forename: Rae R
authors.initials: RR
authors.lastname: Huang
mesh_terms: D000065:Accommodation, Ocular; D000293:Adolescent; D000328:Adult; D040421:Cell Phone; D003195:Computer Communication Networks; D003290:Convergence, Ocular; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D020407:Internet; D008297:Male; D011327:Printing / Q000295:instrumentation*; D011932:Reading; D012858:Size Perception; D055815:Young Adult