Monitor Eyes

Most of the fatigue we build up in front of a monitor does not come from our eyes. It comes from a handful of settings nobody has touched since the screen came out of the box. The brightness is still the factory value, chosen to stand out in a shop. The monitor sits wherever there was room on the desk. The text is whatever size the operating system decided for us.

In this chapter we fix all of that in ten steps, in the order that makes most sense. It takes about fifteen minutes, a sheet of white paper and no purchases. Each step tells you what to do; the why, the special cases and the more precise checks are in the later chapters, pointed out along the way.

If you have one specific complaint, start from the table below: it shows which steps to do first and which chapter to read next.

Start from your symptom

The ten adjustments

1. Distance (1 minute)

Sit in your usual working position, back against the chair, and stretch one arm toward the screen: your fingertips should just about reach it. For a 24 or 27 inch monitor the right distance is 50 to 75 cm (20 to 30 inches); larger screens can go a little farther back.

If the text is too small at this distance, the answer is not to pull the monitor closer but to make the text bigger (step 8). If you are over forty, it may also be worth checking with your optician that you have a correction suited to this exact distance (see the box at the end of the chapter). Write the distance down: your optician will need it.

2. Height and tilt (2 minutes)

Look straight ahead with your head upright. The top edge of the visible screen area should be at eye level or slightly below, never above. This places the center of the screen about 15 to 20 degrees below your horizontal line of sight: at 60 cm (24 inches), that is roughly 10 cm (4 inches) below your eyes.

Then tilt the screen back by 10 to 20 degrees, just enough for it to face your downward gaze. Looking slightly down is easier on the neck, and it leaves the eyelids a little more closed, which reduces tear evaporation.

Two special cases. If you wear progressive lenses, lower the screen further, until you no longer need to lift your chin to read. If a laptop is your main screen, you will never get it to the right height without a stand and an external keyboard.

While you are at it, bring the keyboard and mouse closer: if they are far away, you end up leaning forward and undoing the distance you just set.

3. Windows and reflections (2 minutes)

The best position is with the screen perpendicular to the window, so daylight comes from the side. With the window behind you, daylight reflects on the screen; with the window behind the monitor, you are constantly looking at a surface far brighter than the screen itself.

Now the simplest check in this whole book. With the room lights as you normally have them, switch the monitor off and look at the black screen from your working position for about thirty seconds. If you can clearly see a lamp, the window or your own white shirt, those reflections are there while you work too. Remove them by moving the lamp, changing the tilt slightly or closing a curtain. Soft, blurry patches of light are acceptable; sharp outlines are not.

4. Brightness (2 minutes)

This is the adjustment that brings the quickest relief. On an external monitor you change it with the buttons on the monitor itself, in its on-screen menu (OSD), not from the computer.

Open a full-screen white page, an empty document for example. Hold a sheet of white paper next to the edge of the monitor, lit by the normal light of the room. Lower the brightness in small steps until the screen looks about as bright as the paper: not brighter, like a lamp, and not darker, like a sheet in shadow.

In a normally lit room, many office monitors end up somewhere between 20 and 40 percent, which roughly corresponds to 100 to 120 candelas per square meter (cd/m², also called nits). On the first day the screen will look dull. That is simply the habit of an overly bright screen, and it passes quickly.

Leave contrast at its factory value. It does a different job, and changing it tends to lose detail in the lightest or darkest tones. On a laptop, automatic brightness can stay on, as long as the paper test gives a similar result.

5. Color preset and automatic features (2 minutes)

Still in the monitor menu, look for the color or picture mode section.

If there is an sRGB mode, it is the reference for color accuracy: a white point of 6500 K, the standard daylight white, and standard colors. On some monitors this mode locks brightness at a high value; in that case choose Standard or User mode and, under color temperature, the 6500 K option. If the options only have names (Cool, Normal, Warm), pick the one where a white page looks like paper rather than slightly blue: “Normal” is often cooler than its name suggests.

For reading and writing, the choice is more personal. In a room lit by daylight, 6500 K looks neutral. Under warm room lighting the same white can look bluish, and a warmer setting, around 5000 to 5500 K or the “Warm” preset, is a perfectly reasonable choice for comfort. The test is the same as for brightness: the white of the screen should look like a sheet of paper under the room’s light, neither bluer nor yellower. For color work, stay at 6500 K.

Then switch off the features that keep changing the picture: dynamic contrast (DCR, Smart Contrast and similar), Game or Cinema modes, and energy-saving modes that vary brightness. Set the sharpness slider back to its neutral factory value: set too high, it creates halos around letters.

6. Night mode (1 minute)

Blue-rich light in the evening can delay the feeling of sleepiness, which is not what you want when you need deep, restful sleep. Some light-sensitive cells in the retina, most responsive to blue, tell the body clock whether it is day or night: bright, bluish light late in the evening tells it that it is still day, and the release of melatonin, the hormone that prepares us for sleep, is pushed later (chapter 6 explains this in more detail). The effect is modest, but a moderate filter costs nothing when you are working on text and documents.

• Mac: System Settings, then Displays, then Night Shift, and set Schedule to Sunset to Sunrise. Keep the color temperature slider about a third of the way toward “More Warm”.
• Windows 11: Settings, then System, then Display, then Night light. Turn on Schedule night light and choose Sunset to sunrise. Keep the strength low, around a third.

Lowering brightness a little in the evening, and not working in the dark (step 9), matters at least as much.

MYTH CHECK · Blue-light glasses

The claim. Glasses with blue-light filters protect your eyes from screens and reduce eye strain.

The evidence. A 2023 Cochrane review, which pooled the available trials, concluded that they probably make no difference to eye strain in the short term, and found no good evidence that they protect the retina or improve sleep. The blue light from screens is far too weak to damage the eyes.

What helps instead. Brightness set with the paper test, a moderate night mode in the evening and regular breaks.

If you work with color in video, photography or design, switch the filter off during those sessions (see the box at the end), otherwise your color corrections will be off.

7. Resolution and refresh rate (1 minute)

The resolution should be the native one for the panel: on Windows it is the one marked Recommended, on a Mac it is the default. Lowering it to make text bigger makes everything blurry; to make things bigger there is step 8.

The opposite habit is just as common: choosing a “higher” resolution to fit more on the screen. A panel cannot show more pixels than it physically has, so on a Mac the More Space options, and on Windows a scale below the recommended value, keep the native resolution and simply draw everything smaller. The image stays sharp, but the text shrinks. That is a perfectly good choice as long as you can still read normal text without leaning in (the test in step 8). If you find yourself leaning toward the screen, you have gone one step too far: go back a step, and use the zoom inside the apps you work with instead. Some graphics drivers also offer resolutions above the native one; they draw the image larger and then shrink it to fit the panel, which makes text both smaller and softer, so they are best avoided for reading.

Then the refresh rate, which is how many times per second the screen redraws the image. There are monitors at 60, 120, 144 Hz and above, and the number says nothing about the quality of the monitor. 60 Hz is typical of monitors that have no need to refresh the image more often: most office monitors and many professional monitors for graphics and photography. Rates of 120, 144 Hz and above are found mostly on monitors designed for entertainment, where fast-moving images in video games and action films need to look smooth.

Check your monitor’s specifications. If it is rated above 60 Hz, make sure the computer is actually using that rate:

• Windows 11: Settings, then System, then Display, then Advanced display, then Choose a refresh rate, and select the value your monitor is rated for.
• Mac: System Settings, then Displays, then Refresh rate, and select the value your monitor is rated for.

If that value does not appear in the list, the limit is usually the cable or the port: a DisplayPort cable or a certified high-speed HDMI cable nearly always solves it. If your monitor is a 60 Hz model, the computer already sets it that way and there is nothing to do.

8. Text size (2 minutes)

The rule is simple: from your working position you should be able to read normal text without leaning forward, and tell an “e” from an “o” at a glance. If you cannot, the text is too small for you, whatever the factory setting says.

• Windows 11: Settings, then System, then Display, then Scale. On a 27 inch 4K monitor, values between 125 and 175 percent are normal; 100 percent is almost always too small. To enlarge only the text and nothing else: Settings, then Accessibility, then Text size.
• Mac: System Settings, then Displays, and choose one of the options toward Larger Text. Since macOS Sonoma you can also enlarge the text of many apps in System Settings, then Accessibility, then Display, then Text size.
• Browser: set a default zoom of 110 to 125 percent (in Chrome: Settings, then Appearance, then Page zoom; in Safari: Settings, then Websites, then Page Zoom).

System scaling has an obvious limit: it enlarges everything, and every bit of readability you gain is paid for in working space. Anyone who spends the day in Excel, AutoCAD, Photoshop, Premiere or a development environment knows this well: you would like more readable menus, palettes and panels without giving up the space for the sheet, the drawing, the image or the code. On a Mac, the built-in Zoom in Accessibility enlarges the area around the pointer. In chapter 7 we also look at tools that enlarge a single window.

PROMOTION · ReadItBig

ReadItBig is a Mac app developed by the author of this book. It enlarges a single window and leaves the rest of the screen as it is, so you can read the app you are working in more comfortably without changing the scaling of the whole system. One-time purchase, no subscription.

readitbig.app

9. Room light and air (1 minute)

Do not work with the monitor as the only light on. Constantly moving between a bright screen and a dark room is tiring, even though it does not damage your eyes. A lamp that lights the wall behind or beside the monitor is enough, as long as it does not shine on the screen or into your eyes. The desk should be lit well enough to read a book comfortably.

Then the air. No draft from an air conditioner, a fan or a heating vent should reach your face: it dries the eyes more than any screen. In winter, with the heating on, indoor air easily drops below 30 percent relative humidity; if you have a hygrometer, aim for 40 to 60 percent.

10. Breaks (1 minute)

The rule eye doctors quote most is also the easiest to forget: every 20 minutes, look at something at least 6 meters (20 feet) away for 20 seconds. On top of that, take a real break away from the screen, about a quarter of an hour every two hours.

Relying on memory does not work: when we are focused, hours go by without our noticing. Install an app that reminds you with a discreet signal: Time Out on Mac, Stretchly on Windows, Mac and Linux. Set 20 minutes of work and 20 seconds of break, with a visual notification rather than a sound.

Pick your distant point now: out of the window, or the end of a corridor, or the farthest corner of the room. During the twenty seconds, also blink a few times slowly and completely: in front of a screen we tend to blink much less than usual.

The final check (2 minutes)

Three checks to see whether we did a good job.

1. Screen off. No sharp reflected outlines: at most, soft patches of light.
2. Paper beside the screen. A full-screen white page and a sheet of paper held next to it look about equally bright.
3. Reading. Sitting in your usual position, read a paragraph of any document: no need to lean forward, lift your chin or squint.

If one of the three fails, go back to the matching step: 3 for reflections, 4 for brightness, 1, 2 and 8 for reading.

The checklist

• ☐ Monitor about an arm’s length away (50 to 75 cm, 20 to 30 inches)
• ☐ Top edge at or slightly below eye level, screen tilted back
• ☐ Keyboard and mouse close, no leaning forward
• ☐ Screen perpendicular to the window, no sharp reflections with the monitor off
• ☐ Brightness set with the paper test, contrast at factory value
• ☐ White point that looks like paper in your room (6500 K for color work), dynamic contrast and Game or Cinema modes off
• ☐ Night Shift or Night light scheduled from sunset to sunrise, at moderate strength
• ☐ Native resolution; refresh rate matching the monitor’s rating
• ☐ Text readable without leaning in (scaling, text size, browser zoom)
• ☐ A light on besides the monitor, no draft on the face
• ☐ Break app set to 20 minutes and 20 seconds, distant point chosen

If you work with color

These adjustments are compatible with photo, video and print work, with three precautions.

Night filters off during color sessions. Night Shift and Night light shift every color toward yellow. On a Mac you can turn them off quickly from Control Center; on Windows 11 from Quick Settings (Windows key + A).

Brightness not too low. To judge shadows, common reference values are between 80 and 120 cd/m²; going far below makes your photos look darker than they really are, so you end up brightening them in your editing software (Photoshop, Lightroom and the like) more than they need, and they look washed out on other screens and in print.

A preset is not a calibration. sRGB or 6500 K mode is a good starting point, but only a calibration device tells you where the white of your particular monitor really sits.

Calibration tools. Instead of trusting the factory settings, you can measure your screen: small, affordable devices called colorimeters, such as those from Calibrite or Datacolor’s Spyder range, sit on the screen and set it up correctly with their own software. Chapter 11 explains how.

When to see a professional

The adjustments in this chapter reduce fatigue, but they do not replace an eye examination.

See an eye doctor promptly if you notice eye pain, persistent redness, double vision, flashes of light or a sudden drop in vision.

See an eye doctor or optometrist if your symptoms are still there after a few weeks with your desk set up properly.

After forty, if you lean toward the screen or lift your chin to read, ask your optician about lenses designed for computer distance (occupational lenses, or single-vision lenses for that distance), and bring the distance you measured in step 1. Progressive lenses designed for everyday life have a narrow intermediate zone and force you to move your head.

Artificial tears can help if your eyes feel dry: preservative-free ones are preferable, chosen with your pharmacist or eye doctor.

These ten adjustments take care of the most common complaints. The following chapters explain why they work and how to go further: the right lenses after forty, dry eyes, invisible flicker, the color of white, room lighting, calibration with a calibrator.