Smartphone screens are ‘least disturbing’ to ocular surface vs other devices
Smartphone screens produced the fewest visual disturbances to the ocular surface, while researchers observed highest disturbances after computer use, according to findings published in Optometry and Vision Science.
“[I]t is expected that the differences in the nature of the displays and the ways in which they are set and used may contribute to differences in the eye-related problems they cause,” Cristian Talens-Estarelles, MSc, and colleagues wrote. “The purpose of the current study was to analyze the differences in dry eye signs and symptoms and visual fatigue of young subjects after carrying out a reading task on four different digital displays and after a baseline measurement, under two different measurement conditions: with and without initial instillation of artificial tears.”
Talens-Estarelles and colleagues enrolled 31 healthy volunteers (mean age, 21.26 years) in a prospective clinical study. They assessed participant ocular surface, tear film and visual fatigue parameters at baseline and after 15 minutes of laptop, tablet, e-reader and smartphone use for each participant with and without artificial tears.
Participants reported owning two or more digital devices, with 60% owning three or more, and using digital displays for an average of 9.3 hours per day. Outcome measures included Ocular Surface Disease Index (OSDI) score, Computer Vision Syndrome Questionnaire (CVS-Q), tear meniscus height, Schirmer I test, noninvasive keratograph break-up time, osmolarity and bulbar redness.
Researchers wrote that the “[b]est results were obtained with the smartphone and the e-reader,” while “the computer produced the highest disturbance on the ocular surface and tear film.” OSDI and CVS-Q scores were lower after e-reader (OSDI: 4.5; 95% CI, 1.3-7.6; CVS-Q: 1.7; 95% CI, 0.9-2.4) and smartphone use (OSDI: 5.2; 95% CI, 1.8-8.5; CVS-Q: 2.7; 95% CI, 1.9-3.6) compared with computer use (OSDI: 11.3; 95% CI, 6.9-15.6; CVS-Q: 5; 95% CI, 3.8-6.2).
Tear meniscus height and Schirmer I tests were similar after e-reader (tear meniscus: 0.31 mm; 95% CI, 0.27-0.35; Schirmer I: 36.94 mm; 95% CI, 18.81-55.05) and smartphone use (tear meniscus: 0.3 mm; 95% CI, 0.27-0.34; Schirmer I: 39.6 mm; 95% CI, 20.6-58.59), compared with a 0.26 mm tear meniscus (95% CI, 0.22-0.3) and 27.92 mm (95% CI, 15.02-40.81) after computer use. Noninvasive keratograph break-up time was also similar after participants used e-readers (12.6 seconds; 95% CI, 10.12-15.08) and smartphones (12.62 seconds; 95% CI, 10.21-15.03), compared with 11.5 seconds (95% CI, 9.29-13.7) after using a laptop.
Osmolarity and bulbar redness were greatest after computer use (osmolarity: 293.74 mOsm/L; 95% CI, 291.37–296.12; bulbar redness: 0.75; 95% CI, 0.64–0.85), followed by e-reader use (osmolarity: 291.55 mOsm/L; 95% CI, 289.2–293.9; bulbar redness: 0.7; 95% CI, 0.61–0.78) and then smartphone use (osmolarity: 288.58 mOsm/L; 95% CI, 286.74–290.42; bulbar redness: 0.62; 95% CI, 0.53–0.71).
Researchers wrote that the artificial tears did not have a significant effect.
“Best results were obtained with the smartphone and the e-reader, probably attributed to a lower gaze angle accompanying smartphone visualization and to the enhanced optical properties of the e-reader,” researchers wrote, also noting that, “the e-reader reflects rather than emits light from behind the screen, similarly to how a printed paper behaves.
“Taking into account the clinical tests for dry eye diagnosis, the smartphone may be considered as the least disturbing display.”