Improve your eyesight  sounds like a New Year resolution but a good reminder of the importance of having strong visual acuity is provided by the so-called 'Dressgate' - the viral follow-up to a photo which was originally posted on the social network site Tumblr in late February. The somewhat faded photo challenged viewers to confirm whether the hooped dress was white and gold or blue and black, an apparently simple task which subsequently proved to demonstrate the enduring power of optical illusions. Staggeringly, within a week of appearing the Dress had prompted more than 10 million tweets featuring the hashtags #thedress, #whiteandgold and #blackandblue which made it one of the highest trending features on Twitter.

Originally posted on Tumblr by Caitlin McNeill, a friend of Grace and Keir Johnston who were about to get married, the debate had started when Grace's mother had sent her a photograph of the dress from retailer Roman Originals she planned to wear at her daughter's wedding. Despite being described as blue and black - and the retailer not even stocking a white and gold version - not everyone who saw the photo agreed and so the global debate began from such apparently trivial origins and the challenge to 'improve your eyesight ' was passed from viewer to viewer. Two months later, the challenge is still being taken up across the world - and still resulting in two different opinions!

Neuroscientists have been quick to get in on the act and have endeavoured to explain the Dressgate phenomenon as illustrating how the brain can perceive colours differently due to the impact of 'chromatic bias' which arises from the various hues of a daylight sky. Scientific experts have stated that such visual ambiguity has been known about for years but never before has it reached such a worldwide audience through the modern channel of social media. In any event, it has highlighted the importance for anyone to consider how to improve your eyesight . Lest anyone doubt this, we now live in an era where the growth of shortsightedness - otherwise known as myopia - is being classified as an epidemic by the World Health Organisation.