Hey LittleSmarty. There are ophthalmic lenses on the market that claim to have the benefit of mitigating eye strain due to prolonged VDU use(short for visual display unit which is basically anything with a digital display screen like your smartphone). One of the examples is HOYA BlueControl (HOYA is a well known ophthalmic lens manufacturer) which claims to have the effect of reducing blue light transmission and thus improving visual comfort while you spend a long time in front of a screen.

You might have heard of blue light since the term is gaining more popularity nowadays because people spend more time using digital devices than ever before. To put it simply, blue light is actually short-wavelength and high-energy light in the electromagnetic spectrum that has been found to cause eye strain and very possibly disrupt your sleep patterns. Although long exposure to blue light will result in eye strain and visual discomfort, it HAS NOT YET been proved that it will increase your risk of getting certain eye diseases (despite the fact that there were some studies that tried to prove this but they were simply not well established and thus the evidence was rejected by Advertising Standards Authority (ASA) in the UK).

Although wearing 'computer glasses' (glasses with coated lenses like HOYA BlueControl) would not completely or significantly reduce eye strain but they are, however, BETTER THAN NOTHING as they will at least block some blue light from certain angles (although not COMPLETELY blocking blue light).

The best practices for reducing eye strain are a combination of blue-blocking glasses, using the 20-20-20 rule, and adjusting the brightness of the screen.

I hope my reply is of much help. As a footnote, I am an optometry student and I blog about all optometry-related stuff here TheFabVision.