Monitor Size: Impact On Eyesight And Vision

The impact of screen time on our eyes has become an increasingly pressing issue, with many of us spending more time than ever in front of screens. While larger monitors may help with eye strain by allowing users to sit further away, there are many other factors at play, such as screen resolution, text size, and individual eyesight. In addition, the amount of time spent looking at screens is a key factor, with frequent breaks and the use of blue light filters recommended to reduce eye strain.

Screen size and viewing distance

When it comes to choosing the right screen size, the saying "bigger is better" is a pretty solid guideline. If you want an immersive experience, you'll need a big screen that fills up your field of vision. The human visual system has a total horizontal field of view of about 200 degrees, and the larger the screen, the more content you can display.

The ideal viewing distance for a screen depends on its resolution. The higher the resolution, the more pixels displayed on the screen, and the closer you can sit without noticing individual pixels. For instance, with a 1080p TV, you might see individual pixels, but with a 4K TV, it's much harder to pick out individual pixels even if you're right in front of the screen. This gives you the freedom to sit as close as you're comfortable. With an 8K TV, you can get even closer.

The Society of Motion Picture and Television Engineers recommends sitting at a distance where the screen fills a minimum of 30° of your field of vision for a good experience. For a more cinema-like experience, the recommended viewing distance is about 40°.

To get the most detailed 4K picture, a viewing distance between 1 to 1-1/2 times the screen size is suggested. For example, if you have a 65-inch TV, the viewing distance at which the eye can process 4K content is about 4 feet. However, any distance between 4 and about 8.5 feet will be enough to appreciate the difference between 4K and 1080p.

While bigger screens are generally better, there are some considerations. Firstly, budget—larger screens tend to be more expensive. Secondly, room size and setup—you need to ensure you have enough space for the screen and that it's positioned correctly. Thirdly, content—not all content is made to fill your entire field of view, and watching something like sports from up close can be nauseating. Finally, eyesight—since everyone's eyesight is different, the ideal viewing distance is a general guide and may vary for individuals.

Screen resolution

The screen resolution of a monitor, in conjunction with its size, can have an impact on your eyes. The number of pixels on a monitor, or screen resolution, and the physical size of the screen determine the amount of screen real estate available. A larger screen with a higher resolution will allow you to display more content, but it may need to be positioned further away to be viewed comfortably.

The density of pixels, or pixels per inch, determines the ideal viewing distance for a screen. A screen with a very high pixel density may need to be viewed from a closer distance to distinguish fine details. Conversely, a screen with a lower pixel density will need to be viewed from a further distance to prevent the individual pixels from becoming noticeable.

The native resolution of a monitor is the optimal configuration for a sharp display. Displaying content at a lower resolution than the native resolution can result in a less crisp image, as the monitor has to interpolate the content to fit the available pixels.

Higher resolution screens can help to reduce digital eye strain by inducing less accommodative lag. This means that the eyes don't have to work as hard to focus on the content displayed on the screen. However, it's important to note that other factors, such as lighting conditions, contrast ratio, and blue light emission, also play a significant role in eye strain and fatigue.

To protect your eyesight, it is recommended to take frequent breaks, use blue light filters, and perform eye exercises to relax the eye muscles. Additionally, increasing the font size and using protection screens to reduce glare can also help alleviate eye strain caused by prolonged screen usage.

Blue light

Some experts believe that artificial sources of blue light may be harmful to human eyes, but research does not appear to support this claim. While animal studies have indicated that blue light can damage cells in the retina, there is little evidence that this applies to the human eye. A 2020 study found that a significant number of people used blue light-emitting devices for 9 to 14 hours a day during the COVID-19 lockdowns, raising concerns about the potential impact on eye health. However, eye doctors have stated that there is little proof of blue light causing retinal damage in humans.

One case reported a woman who used an LED face mask and subsequently experienced distorted vision and a retinal lesion. However, the face mask included blue, red, and infrared light, so it is unclear which type of light was responsible for the damage. As LED devices are relatively new, there is a lack of long-term studies to assess their potential impact on eye health over time.

While blue light from digital screens may not pose a serious risk to eye health, it can contribute to digital eyestrain. This is due to the tendency for people to blink less when using digital devices, leading to reduced moisture in the eyes. Blue light scatters more easily than other types of light, making it harder for the eye to focus, and potentially contributing to eyestrain. However, more research is needed to confirm a direct link between blue light and eyestrain.

In addition to potential eye health concerns, blue light can interfere with the body's sleep-wake cycle. Blue light suppresses the release of melatonin, the sleep-inducing hormone, and can delay or disrupt sleep. A small 2015 study found that exposure to blue light in the evening disrupted sleep cycles. Disruption to the sleep-wake cycle can lead to an elevated risk of hormone-related cancers, metabolic changes, and other health issues.

While blue light from digital devices may not cause eye damage, it is still important to practice healthy habits when using screens. This includes taking frequent breaks, using blue light reduction features, and maintaining a comfortable viewing distance and height for your screen.

Display brightness

Working in low light can strain the eyes, while excessive brightness can cause glare and dazzle, both of which can be uncomfortable. Additionally, the blue light emitted by device screens can be phototoxic to the eyes, particularly the retina, due to its shorter wavelength.

To protect your eyes, it is recommended to adjust the screen brightness according to your environment. The ideal brightness for a well-lit indoor computer screen is between 250 and 350 cd/m², while for darker indoor environments, the ideal brightness is between 120 and 180 cd/m².

It is also beneficial to follow the 20-20-20 rule: every 20 minutes, look away from your screen and at an object about 20 feet away for 20 seconds. This helps to relieve eye strain by giving your ciliary muscles a break from their fixed viewing position. Additionally, ensuring that you blink frequently is important for eye health, as it lubricates the cornea and removes debris from the eye.

By adjusting the screen brightness to an optimal level and following eye health recommendations, you can minimise eye strain and maximise visual comfort.

Display flickering

The problem is particularly pronounced with LED screens due to their high flicker rates, which can be imperceptible to the human eye but still cause the pupil to rapidly adjust, leading to eye strain. Additionally, the blue light emitted by LED screens can be harmful, as our eyes are not naturally equipped to filter it out effectively. Prolonged exposure to this blue light can contribute to eye issues and disrupt sleep.

To address these issues, some companies have developed flicker-free monitors that utilise different technologies, such as DC modulation, to maintain a constant stream of light without the rapid on-and-off cycling of traditional LED backlights. These flicker-free monitors can significantly reduce eye strain and related issues.

Another solution is to use software like Iris, which reduces the luminance of the screen without controlling the backlight flicker frequency or current. This can be an effective and affordable way to mitigate the negative effects of monitor flickering. Additionally, adjusting the colour temperature of your screen to use warmer tones can help reduce the amount of blue light emitted, providing some relief to your eyes.

Frequently asked questions