The integration of smartphones, tablets, and computers into our lives is widespread.  In Australia, 89% of the population have a smartphone and it is predicted that by 2023 that we will use our phones on average 65 times, per day.

The widespread coverage of the guidelines by the World Health Organisation (WHO) on-screen use by under 5-year-olds is a testament to the general public desire to understand how much screen use is truly excessive and unsafe.

The current Australian Government recommendations for screen use for entertainment purposes are maximum 2 hours per day for children aged 5 to 17 years.  For children between 2 and 5 a maximum of one hour per day is advised.  Under 2-year-olds should not have any screen time.  WHO has similar recommendations for under 1-year-olds and the 2-4-year-olds less than 60 minutes.  The WHO guidelines are designed to reduce inactive time in children and increase stimulating time with caregivers, and time spent with physical activity.

Ocular and Visual Symptoms

It is widely understood that the use of handheld digital devices increases ocular and visual symptoms.  Dry eye symptoms such as sore, watery, irritated, and burning eyes occur after as little as an hour of tablet use.  Tire, uncomfortable eyes and blurred vision can be expected after 60min of smartphone use.  These symptoms worsen when the smartphone is viewed closer.  Similar discomfort is likely with computer use, with longer hours exacerbating symptoms.  Eyestrain is 5 times more likely when reading from a  tablet compared to printed text.

Reduced blink rate has been well established with computer use.  In contrast, the findings with smartphones are conflicting.  It is important to note that the blink rate is significantly impacted by the task and its difficulty.  A light conversation has a higher blink rate than a computer task.

There is a dearth of literature that specifically examines the impact of smartphone and tablet use on binocular vision, tear film, and ocular surface.  This can be attributed to the rapidly evolving technology sector and consequently diversity of handheld devices.  This diversity involves viewing distance and time spent on devices, both of which may influence accommodation and vergence capability required for clear constant vision.  Viewing distance itself is dependent on screen size, which can vary from as small as a digital watch, and palm-sized smartphones, through to large-sized tablets.  Furthermore, it is common for multiple devices, such as a phone, computer, and LCD television screen to be used together at home and in business meetings.  Changing focus to maintain a clear vision between these devices will require robust accommodation flexibility.

The nature of tasks, from simple video chats to more complex tasks such as plant puzzles or editing videos, will influence blink action.  This will theoretically impact tear production and consequently the health of the ocular surface.  As has been noted with computer users, alterations to tear file composition, such as mucin levels and osmolarity, may also occur with the use of digital devices.

As everyone uses their devices differently.  Watching from different distances for different periods of time, the time until a person experiences ocular symptoms will be different for everyone.