Is iPhone's new 'dark mode' really better for your eyesight?

The ‘dark mode’ feature on the new IOS is described as ‘easier on your eyes’, but what's the evidence behind this? Clinical Adviser, Daniel Hardiman-McCartney, provides some insight in his latest blog.

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Author: Daniel Hardiman-McCartney FCOptom, Clinical adviser 
Date: 20 September 2019

Apple’s new dark mode for iOS 13 may save battery life, but despite tech folk law, it is unlikely to save you from digital eye strain. 

Optometrists may be asked to advise their patients of the merits of dark mode after Apple joins other tech manufacturers in offering iPhone users a dark mode option in addition to the night shift feature already available. The claims that it is better for your eye sight are controversial despite much media attention. Night mode may be useful by reducing the overall screen brightness and being optimised for use in low light environment but there is little evidence available to say whether it is effective at reducing digital eye strain. 

The potentially damaging effects of white-background screens, usually are referring to the “blue light,” part of the light spectrum made of short, high-energy wavelengths. A study published in BMJ Ophthalmology noted that blue light could be a factor in eye tiredness, but lists a number of other factors that are also likely to contribute to digital eye strain. A separate study published in the College’s journal Ophthalmic and Physiological Optics concluded that there is lack of high quality evidence to support using blue blocking spectacle lenses for the general population to improve visual performance or sleep quality, alleviate eye fatigue or conserve macular health.

Advice that optometrists may give members of the public 

Many people worry that viewing a screen can damage their eyes. There is no evidence of this. In fact, because you can alter the size, brightness and contrast of the display, it can easier and more comfortable to see on a screen compared with looking at things on paper. However, some people find that looking at a screen for a long time is tiring. If you use a device at night using a dark mode or night shift feature maybe helpful, but if you are affected by eye strain we have some additional advice: 

Here are some ways to look after your eyes while using your screen:

  • Apply the 20-20-20 rule – every 20 minutes look at something 20 feet away for 20 seconds. That will give your eye muscles a rest.
  • Try to blink regularly. Focusing on a screen may make you blink less, which may make your eyes dry and uncomfortable.
  • Position your device screen so that: 
    • it is between 40 and 76 centimetres (16 to 30 inches) from your eyes
    • it is below the level of your eyes 
    • there are no distracting reflections, e.g. from a light or window.
  • Use a text size that is easy to see. 
  • Have regular sight tests.
  • Wear glasses if you have been prescribed them.
  • If you are affected by dry eye, consider using lubricating eye drops. 


Further resources 

Evidence in practice on blue blocking spectacles

Digital eye strain: prevalence, measurement and amelioration
Dr Amy Sheppard and Prof James Wolffsohn

The effect of blue‐light blocking spectacle lenses on visual performance, macular health and the sleep‐wake cycle: a systematic review of the literature
Prof John Lawrenson and Dr Laura Downie

Daniel Hardiman-McCartney FCOptom
Clinical Adviser, The College of Optometrists

Daniel graduated from Anglia Ruskin University, where he won the Haag Strait prize for best dissertation. Before joining the College, he was Managing Director of an independent practice in Cambridge and a visiting clinician at Anglia Ruskin University. He has also worked as a senior glaucoma optometrist with Addenbrooke’s Hospital in Cambridge, with Newmedica across East Anglia and as a diabetic retinopathy screening optometrist. Daniel was a member of Cambridgeshire LOC from 2007 to 2015 and a member of the College of Optometrists’ Council from 2009 to 2014, representing its Eastern region.  

He is Clinical Adviser to the College of Optometrists for four days each week, dividing the remainder of his time between primary care practice and glaucoma community clinics. Daniel is a passionate advocate of the profession of optometry, committed to supporting all members of the profession and ensuring patient care is always at the heart of optometry. He was awarded Fellowship by Portfolio in December 2018.


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