The impact of smartphone use on accommodative functions: pilot study

Evidence about the effect of smartphone use on accommodation is limited and inconclusive. Several studies have investigated either symptoms or near triad measures following smartphone use. These suggest that, certainly for the short term, smartphones have a negative impact on the near triad and produce symptoms. In addition, there is a body of recent work reporting cases of acute acquired concomitant esotropia (AACE) that may be caused by the accommodation-vergence demand of excessive smartphone use. A pilot study was undertaken to investigate accommodative measures before and after 30 minutes of smartphone use. Participants aged 16-40 years were invited to participate. Accommodative facility (AF), near point of accommodation (NPA), and near point of convergence (NPC) before and after 30 minutes of habitual smartphone use were assessed. NPA and AF were assessed with both eyes open (BEO), right eye (RE) and left eye (LE). Accommodative facility was assessed using ±2DS flipper lenses and measured in cycles per minute (cpm). NPA and NPC were assessed using the RAF rule and measured in centimeters. Data were analyzed in StatsDirect using non-parametric statistical tests. Eighteen participants were recruited, with a mean age of 24 years (SD: 7.6yrs). AF improved by 3cpm (p= .015) for BEO, 2.25cpm for RE (p = .004) and 1.5 cpm for the LE (p =. 278) after smartphone use. NPA with BEO became worse by 2 cm (p =.0474), with the RE worse by 0.5cms (p = .0474) and the LE, worse by 0.125 cms (p = .047). Convergence worsened by 0.75 cms (p = .018). Although these appeared to represent a change in measures following smartphone use, post-hoc analysis with Bonferroni correction demonstrated that these were not statistically significant at the 0.07 significance level. This pilot study found that there was no difference in accommodative and convergence measures before and after 30 minutes of smartphone use. These results suggest evidence contrary to the existing literature. There are several limitations to this pilot study and previous work, which are discussed. Suggestions on future work to explore the effect of smartphone use on the near triad to address limitations and further knowledge, in this area, are provided.