E-readers: Better for Your Eyes?
In many restaurants, ordering water to drink is now typically followed by several options to choose from: sparkling, flat, bottled, or tap. The notion of reading is also not as simple as it used to be. We now have to specify reading into categories such as hard copy print, computer screens (which can be further sub-categorized into desktops, smartphones, laptops, and tablets), and now the emerging trend of e-readers. Eyestrain associated with extensive reading tasks is a common symptom patients present to their eye care professional, and can manifest as eye fatigue, difficulty focusing, burning or irritation in the eyes, red, dry, or watery eyes, and/or headaches, neck aches, and back aches. Although this does not result in permanent damage of the eyes, it could affect the ability to perform reading tasks efficiently and comfortably. While there are differences in the various modalities of reading in terms of demands on the visual system, there are common factors that can contribute to eyestrain symptoms.
The proper use of lighting during a reading task is imperative to visual comfort, as glare or light scatter can be a significant source of eyestrain. Sources of glare include windows, highly reflective surfaces on a monitor, paper, or desk, background illumination on a monitor, or direct lighting over the reading area. Blinds should be placed on windows near a computer station (yes, even if there is a great view). Eliminating desk lamps pointing at the screen, or removal of the fluorescent bulb directly over the workstation can help. Anti-reflection lens coating on prescription glasses can help offset unwanted reflections, and anti-reflection screen protectors are available.
|Tablets, like the iPad, use backlit LCD screens, which work well in low lighting but are prone to glare, especially outside.|
The contrast and brightness of a printed page or an e-reader depends on the room lighting, so a brightly lit room allows more contrast, and hence more comfortable reading than a poorly lit room. The contrast on the page also matters, e.g. light grey print on a light grey background (think faded newsprint) will be more taxing on the eyes regardless of room brightness.
E-readers have improved the level of text/background contrast, and the matte quality of the screen can reduce glare even in bright sunlight. A computer monitor has an illuminated background which does not depend on the room lighting. However, when the room is dark and the monitor is bright, or when the screen is too bright compared to the dark text, the difference in contrast is too great for the eyes and hence becomes uncomfortable. Conversely, a window is thousands of times brighter than the monitor brightness, creating another situation of contrast imbalance. Ideally, the brightness of the room should be equal to the brightness of the monitor, and the monitor itself should not be at the maximum brightness level. The ideal contrast for visual comfort on a monitor is black font on a white background versus multicoloured screens. Different colours activate the focusing muscles of the eyes in various ways, and the constant readjustment of the eyes when viewing multiple colours can result in eyestrain.
|e-Readers, like this one from Kobo, require a well-lit area to work best.|
Despite adjusting contrast and lighting levels, eyestrain may be caused by eye muscle imbalances or uncorrected vision requiring glasses. Smaller text requires increased resolution ability, and when the eyes struggle to focus, they work harder. A benefit of e-readers is the ability to enlarge text, which can lessen the work for the eyes. Brighter background lighting can help also because the pupils are able to constrict and increase the eye’s depth of focus, allowing better resolution of small detail. Some who wear reading glasses might find that on bright sunny days, they can read without correction. An optometrist can examine the eyes’ alignment and focusing ability, and determine whether reading correction is required.
A simple tip for any reading task is to remember to take visual breaks. Extended periods of near focusing can create stress on the accommodation system (the focusing muscles of the eye), which can contribute to a sense of ‘fatigue’. Imagine lifting weights at the gym for 8 hours straight without taking any breaks and how that would fatigue the muscles. Other effects can include temporary distance blur and headaches, due to spasm of the overworked eye muscles. Optometrists quote a general rule: 20/20/20, i.e. every 20 minutes of near work, take a 20 second break and focus on something 20 feet away.
Posture and viewing position are related to overall visual experience, and vice versa. If text is small or not clear, a natural tendency is to lean forward, which can result in physical pain the head, neck, and back, especially if reading for an extended period of time. At a computer station, it is advised to sit back in the chair with your legs bent at a 90 degree angle, and wrists straight and not resting on the desk with elbows at a 90 degree angle. The monitor should be positioned at arm’s length, and slightly lowered so that the eyes are looking down onto the screen (ie. the eyes should graze over top of the monitor when looking straight ahead). For reading books or e-readers, neck strain can occur when bending the head down. In general, one should not be in the same position for a long period of time and so occasional stretching is a good idea.
By making some adjustments to the reading environment, and having an eye care professional make the necessary recommendations to address specific symptoms of eyestrain, the experience of reading can be made to be more productive and enjoyable.