Intraocular Pressure Changes While Reading Smartphone Digital Text Versus Printed Text in Healthy Individuals and those with Glaucoma

Precis: Reading results in a rise in intraocular pressure (IOP) which is greater while using smartphones compared with printed text among healthy and individuals with medically controlled primary open angle glaucoma (POAG). Purpose: To compare the effect of reading for 30 minutes using smartphone and printed text on IOP. Patients and Methods: Sixty healthy volunteers and 22 patients with medically controlled POAG were asked to perform reading tasks using printed text followed by digital (smartphone) text under standardized conditions. IOP assessment was done using a rebound tonometer at baseline and subsequently at 10, 20, and 30 minutes of reading and 10 and 20 minutes post completion of reading tasks. IOP variations from baseline were measured and compared. Paired and independent 'T' test analysis was performed to study IOP variations, and a P-value <0.05 was considered statistically significant. Results: The mean baseline IOP among volunteers and patients with POAG was 14.58 (+/- 2.91) and 15.02 (+/- 2.18) mmHg, respectively. There was a rise in IOP in all participants with reading using either of the modalities, which normalized after 20 minutes of cessation. There was a statistically significant difference in rise in IOP from baseline between the 2 modalities (printed text reading and smartphone reading) at 20 minutes {+0.78 & +2.01 (P=0.002)} and 30 minutes {+0.64 & +1.72 (P=0.004)} among healthy volunteers and at 20 minutes {+0.78 & +2.01 (P=0.002)} among POAG patients. Conclusion: Reading is associated with the rise in IOP in both healthy volunteers and POAG individuals. The IOP rise is more marked with smartphone compared with printed text reading.