Changes in Intraocular Pressure During Reading or Writing on Smartphones in Patients with Normal-tension Glaucoma

Background/aims: To investigate (1) the effect of reading or writing on a smartphone in terms of intraocular pressure (IOP) change in eyes with glaucoma, and (2) to determine whether previous glaucoma filtering surgery can affect IOP fluctuation during such work.

Methods: Forty eyes of 40 medically well IOP-controlled normal-tension glaucoma (NTG) patients and 38 eyes of 38 NTG patients who had undergone successful trabeculectomy (TLE) were enrolled. The participants were instructed to read a sample text and to then type it on a smartphone under low-light [100 lux] conditions. Three IOP measurements were obtained: baseline; during smartphone work (5, 15 and 25 min); post-work (5 and 15 min).

Results: Baseline IOP did not significantly differ between the two groups (medication group: 13.9±1.6 mm Hg; TLE group: 13.6±1.7 mm Hg; p=0.426). After 5 min of smartphone work, the medication group showed significantly elevated mean IOP (15.5±1.8 mm Hg;+11.5%; p<0.001), along with further increases over the course of 25 min (17.5±2.2 mm Hg;+25.9%; p<0.001). 5 min after halting work, IOP dropped below the baseline (13.1±1.7 mm Hg; p<0.001). For the TLE group, IOP also was elevated after 5 min (14.9±1.7 mm Hg;+9.4%; p<0.001); however, it did not show further increase over the course of 25 min of work (15.0±1.6 mm Hg;+10.3%). At 5 min after cessation of work, IOP had restored to the pre-work level (14.0±1.9 mm Hg;+2.8%; p=0.053).

Conclusion: Working on a smartphone under low-light condition can incur IOP elevation in treated NTG patients. However, among the participants in this study, IOP fluctuation was much smaller in those who had undergone TLE.