Whether you are working, reading, or mindlessly scrolling social media, screens are our constant companion these days. If you've noticed your eyes are feeling more tired, dry, and irritated than ever, that's because of our new best friend the screen as well. In order to keep our eyes hydrated, our body is internally wired to blink roughly every 13 seconds, releasing the oil that makes up our tear film with every blink. But when we are looking at screens, our blink rates plummet by as much as 66%, meaning less tear film released onto the surface of the eyes, and thus drier eyes. As expected, studies show that people working and reading on screens report significant discomfort. In a 2018 study of 100 medical school students, screen time caused 58.8% of participants to experience eye strain and fatigue, 23.3% reported headaches, and 13% reported blurry vision. In this same study, 75% of the medical students involved stated they would reduce their screen time as a measure to prevent dry eye.  

But reducing screen time may not be that easy. Since the onset of the COVID19 pandemic, average screen time use in the United States has skyrocketed, with reports indicating that the average American adult (age 18+) is spending over 13 hours per day looking at screens. That's up from roughly 10 hours per day reported in 2019 and 8.4 hours per day in 2018. Knowing that cutting screen time when we're being asked to work from home, attend school from home, and entertain ourselves from home is extremely difficult, can we potentially reduce our symptoms of dry eye by at least choosing the least irritating device to look at?

A new study published in Optometry and Vision Science explored just this and found that the screen that you use does in fact matter! The study looked at the ocular surface health and comfort of 31 healthy adults between age 20 to 26 after reading on a variety of different devices. Baseline measurements of each participant's ocular surface was taken before using any screen time, including the Ocular Surface Disease Index (OSDI) questionnaire, the Computer Vision Syndrome Questionnaire, tear meniscus height, Schirmer test, noninvasive tear break-up time, tear film osmolarity, bulbar injection (redness), and pupil size. Participants were then asked to read for 15 minutes on a laptop computer screen, tablet, e-reader, or smartphone and the ocular surface measurements and questionnaires were repeated. 

The very best ocular surface health and reported comfort were found when participants read on e-readers or smartphones. Reading on the laptop computer produced the worst disturbances of both ocular surface findings and questionnaire indices. Statistically significant differences were seen between computer use and e-reader/smartphone use in both the OSDI and the CVS-Q questionnaire, tear meniscus height, Schirmer test results, and tear break up time. Tear film osmolarity (a measurement of inflammation) and conjunctival injection (redness) was highest after computer use, followed by e-reader use, and then smartphone use. 

Interestingly, the study also compared these results with and without the use of artificial tears. Using artificial tears had no statistically significant effect on any of the ocular surface findings. 

Study author Cristian Talens-Estarelles, MSc writes that the improved dry eye results with e-readers and smartphones are most likely "attributed to a lower gaze angle and the enhanced optical properties of the e-reader," noting that "the e-reader reflects rather than emits light from behind the screen, similar to how a printed paper behaves."