No matter where you look today, people are viewing electronic displays. They have become a huge part of daily living at home, at work, during leisure time and on the move. Whether it is the corporate executive checking e-mail on their smartphone, the commuter browsing their newspaper on a tablet computer, the student reading their textbook on an electronic reading device, the quality controller monitoring production on multiple desktop monitors or the assistant taking notes at a meeting on their laptop, these screens have become ubiquitous. And this doesn't even begin to consider the use of the internet for shopping, social media, recreation and instant communication around the globe or high definition television, electronic games and movies (both in two and three dimensional formats) for entertainment. A recent investigation of over 2000 American children between 8 and 18 years of age reported that in an average day they spend approximately 7.5 hours using entertainment media, comprising 4.5 hours watching TV, 1.5 hours on a computer and over an hour playing video games.1 Indeed, exposure to electronic screens in adults may be even higher, averaging around 8.5 hours per day (http://www.researchexcellence.com/vcm_appendix_0409.pdf). One might ask whether there is a difference in visual demands between these modern stimuli and viewing traditional printed materials, and if so, how does the visual system respond to these novel targets. That is the question that this feature issue of Ophthalmic and Physiological Optics seeks to address. For example, Siegenthaler and colleagues compared LCD and e-ink types of electronic reading devices and noted that while subjects might read conventional printed materials faster than when using the electronic display, the two electronic formats were similar in terms of subjective fatigue and reading performance. In a review of computer-related visual symptoms in office workers, Portello and colleagues observed that approximately 40% of subjects indicated that their eyes felt tired "at least half of the time" while 32% and 31% of subjects reported symptoms of dry eye and eye discomfort, respectively. Symptoms were greatest in females, Latino/Hispanic Americans and subjects already using rewetting drops. The authors noted that symptoms could either be related to abnormal oculomotor responses or dry eye disease. In examining the oculomotor responses to electronic displays, Oliveira and colleagues compared the accommodative response to both two-and three-dimensional stimuli when subjects either viewed a film on television or played on an electronic game console. They observed minimal changes in accommodation but noted that the shutter glasses required for three dimensional viewing produced a significant change in accommodative response even when viewing a two dimensional stimulus on a television. Thus the equipment associated with these devices may itself alter the oculomotor response. Zambarbieri and Carniglia examined eye movements while subjects read either from a desktop computer screen, a tablet computer, an electronic reader or a printed book. Similar oculomotor responses for the electronic and printed stimuli were recorded. Blythe and colleagues compared binocular eye movements when subjects either viewed a two-dimensional representation of a scene, a stereoscopic representation of the scene or the original three-dimensional scene itself. The authors found that when viewing the stereoscopic representation, responses were more comparable to the two-dimensional condition and the apparent depth of the target did not determine the vergence response during saccades. In addition to oculomotor differences, previous reports have indicated that a major cause of ocular symptoms related to viewing electronic screens is dry eye.2 This can be due to increased corneal exposure due to the primary position of the screen, reduced blink rate3 or poor ambient conditions due to excessive heating or air conditioning.4 An additional factor to consider is poor air quality due to physical, biological or chemical contaminants.5 The prevalence of dry eye varies between 15 and 30% of the general population (depending on the precise criterion adopted) but increases with age and is greater in females.6 Further, contact lens wearers may suffer from decreased vision and dry eye symptoms due to poor lens surface wetting and reduced tear production. Yang and colleagues examined the effect of 3 different lens care solutions on blink rate, dry eye symptoms and visual performance. They found that solutions which included wetting agents led to improvements in both ocular comfort and visual performance. This may be of significant benefit to the patient. Electronic displays are also likely to provide new therapeutic modalities for visual rehabilitation. One example is in the area of low vision, where electronic reading devices provide an easy method of increasing print size and contrast, including reverse contrast, i.e., white on black. For example, Amazon.com has over 1.3 million books for the Kindle which can be altered in terms of size and contrast (http://www.amazon.com/Books-Kindle/b?node=154606011) but less than 300,000 large print books (http://www.amazon.com/s/ref=nb_sb_iac_1?url=search-alias%3Daps&field-keywords=large+print+books). This has also made these devices extremely valuable for older individuals. Luo and colleagues described a JPEG based image enhancement technique to improve visual search performance in patients with moderate vision loss. Computer-based vision therapy programs for the treatment of conditions such as convergence insufficiency are also commercially available.7 It is clear that these electronic screens present new challenges both for the vision scientist and eye care practitioner. For example, as displays become more complex both in terms of perceived depth and motion, it is unclear how the visual system will respond to these conflicting and on occasion ambiguous cues. Further, the ability to superimpose a digital image over the natural visual environment already exists (http://abcnews.go.com/Technology/google-glasses-android-laptops-computers-talk-googles-computing/story?id=16680513). These new visual demands will require significant changes by eye care practitioners and designers of corrective lenses in terms of patient care, especially when treating presbyopic patients. As a minimum, it is clear that even today, examining near vision at a viewing distance of 40cm in just one direction of gaze is inadequate to meet contemporary visual requirements. When analyzing and devising remedies for computer related vision issues, Long and Helland proposed a multidisciplinary approach whereby at least ten different professions (including optometry) would collaborate to improve worker comfort, safety and efficiency. This would provide an efficient method of solving issues relating to physical, cognitive and organizational issues in the workplace. As modern society continues to move at an ever-increasing rate towards greater use of electronic devices for work, communication and leisure activities, it seems likely that the visual demands of this technology will only continue to increase in complexity. An inability to satisfy these visual requirements could present significant lifestyle difficulties. Dr Rosenfield received his optometry degree and PhD from Aston University, UK. He has been on the faculty at the SUNY (State University of New York) College of Optometry since 1990 and currently is a Professor in the Department of Clinical Education. Dr Rosenfield conducts research into binocular vision, refractive error development and computer vision syndrome, and has over 85 peer-reviewed publications in these areas. He is currently collaborating with scientists in China, Colombia, Iran, Israel and Italy. In addition, he is the principal author of two textbooks entitled Optometry: Science, Techniques and Clinical Management and Myopia and Nearwork. He received the Chancellor's Award for Excellence in Teaching from SUNY in 1995. In 1996 he was awarded the first ever research diplomate in Binocular Vision and Perception from the American Academy of Optometry. In 2005 he was awarded the Michael G. Harris Family Award for Excellence in Optometric Education from the American Optometric Foundation. Having graduated from City University, London, Dr. Howarth started his working life as an Optometrist. Following a period in practice, he returned to academia at what was then the Glasgow College of Technology. His Masters in Ergonomics, from Loughborough University, was followed by a spell at the Institute for Consumer Ergonomics, after which he went to study in the USA, gaining his PhD from the School of Optometry of the University of California at Berkeley. His thesis, supervised by Professor Ian Bailey, investigated the Human Factors issue of how the human pupil responds to flicker. He returned to England in 1990 and took up a lectureship in the Department of Human Sciences at Loughborough. He is currently part of the Environmental Ergonomics Research Centre, which is located in the Loughborough Design School, Loughborough University. Dr Sheedy received his optometry degree and his doctorate in physiological optics from the Ohio State University. He was a Clinical Professor at the University of California at Berkeley School of Optometry where he founded the first VDT Eye Clinic in 1985. He also established the Center for Ophthalmic Optics Research at Ohio State University and is recognized as an expert in the design and prescribing of progressive addition lenses. He has twice received the Garland Clay Award for the best clinical research published in the journal of the American Academy of Optometry and also received the William Feinbloom award for his work in vision ergonomics. He also received the Distinguished Service Award from Prevent Blindness America for his work with ultraviolet. He has over 140 published articles and has participated in the development of numerous ANSI and ISO standards and regulations. Dr Sheedy has earned a reputation as the expert in vision problems at computers. This has led to research into hardware and software configurations of computer displays. Dr Sheedy has several graduate students who have received degrees under his guidance. He is currently the head of the Vision Performance Institute and professor of optometry at Pacific University; and has recently published Pondering Life. Michael Crossland is a Research Fellow in Visual Neuroscience at the UCL Institute of Ophthalmology and a Specialist Optometrist at Moorfields Eye Hospital NHS Foundation Trust in London. He was awarded a PhD in Ophthalmology from the University of London in 2004 for work on the preferred retinal locus in macular disease. His major research interest is visual function in people with visual impairment, particularly in those with early age-related macular disease. His specialist clinical interests include paediatric low vision assessment, visual rehabilitation of people with hemianopia, and medical contact lens work. He is a Member of the College of Optometrists, leader of the optometric low vision rehabilitation group of the European Academy of Optometry and Optics, and a committee member for the International Society for Low Vision Research and Rehabilitation.