Programmers love hardware upgrades but forget to upgrade their main input device—their eyes. In this article, I've gathered what I had to learn myself: how vision works, why monitors sometimes work against us, how dark mode differs from light mode on a physiological level, and how a couple of lines of code can genuinely extend the life of your eyes.

We usually argue about what's faster—VS Code or JetBrains, but a question worth answering is: What gets tired faster—the IDE or my eyes?

I coded for 10–12 hours straight for several years until I noticed that the letters started to dance, and an if statement turned into some kind of Chinese character. That's when I realized it was time to figure out what I was doing wrong.

A bit of biology: the eye as a strange sensor

The eye is structured very 'engineered'—a lens, a diaphragm, a sensor matrix. But our sensor isn't CMOS, it's the retina: 120 million rods and 6 million cones. Unlike a camera, the eye doesn't have uniform resolution: the center (macula) is sharp, while the periphery is blurry.

This explains why we suffer so much from small fonts: the brain is forced to 'focus' on each letter. Plus, eyes aren't SSDs; they don't have 'wear leveling.' Once they're tired, that's it—the image gets blurry.

Monitors and refresh rate: why 60 Hz is torture

I remember when I bought a 144 Hz monitor, the first thing I said was, 'My God, it was possible all along?!'. The difference is colossal. Before that, I thought 60 Hz was enough because 'the eyes can't see it.' They can. And they see it very well.

The problem is that many monitors use PWM (pulse-width modulation for backlighting). Everything seems fine, but after a couple of hours, you feel like you've been at a club—the flicker hits your eyes imperceptibly. So the rule is simple: get a monitor without PWM and with a refresh rate of at least 120 Hz.

Light vs. Dark Theme: The Holy Wars

The number of flame wars I've seen on the 'dark vs light theme' topic is scary to recall. I even went through a 'black background + green letters, like in The Matrix' phase. After a couple of weeks, I looked like Neo after fighting the agents.

Physiology says this:

at night, dark theme is better (less strain on the pupil),
during the day and in good lighting, light theme is better (higher contrast).

The main things are contrast and size. If the text is gray on black, your eyes will suffer even more than from white on white.

The 20-20-20 Rule: A Reminder for the Forgetful

There's a rule: every 20 minutes, look into the distance for 20 seconds. I honestly tried to keep this in mind, but after a week, I realized a programmer's brain can only remember git push origin main.
So I wrote a simple Python script:

# Python 3
# Reminder for the 20-20-20 rule
import time
import os
import platform

def notify(msg):
    if platform.system() == Darwin:  # macOS
        os.system(fosascript -e 'display notification \{msg}\ with title \EyeCare\')
    elif platform.system() == Linux:
        os.system(f'notify-send EyeCare {msg}')
    elif platform.system() == Windows:
        from win10toast import ToastNotifier
        ToastNotifier().show_toast(EyeCare, msg, duration=5)

while True:
    time.sleep(20 * 60)  # 20 minutes
    notify(Stand up, blink, and look into the distance. Your eyes will thank you.)

This code works more reliably than any willpower.

UI that kills your eyes

Honestly, I hate gray text on a gray background. And also those 'super-minimalist' borderless buttons. It seems designers sometimes forget that users have eyes, not laser scanners.

Bad UI = extra strain. Good UI isn't about being 'beautiful,' but 'clear and readable.' Here, physiology works against designer ambitions.

Simple practical tips

Place your monitor to the side of a window, not in front of it.
Don't be cheap on DPI—if the font is hard to read, increase the scaling.
Take breaks (I set timers, otherwise I'll forget).
And yes, visit an ophthalmologist once a year. Even if your vision seems fine. The check-up takes half an hour and will save you a lot of trouble.

Eyes are our 'hardware' that can't be replaced with an upgrade. If they 'burn out,' no new MacBook will help.

So take care of your vision, blink, don't stick with 60 Hz, and don't trust dark mode blindly.

And if someone says that programmers should only care about clean code—show them this text. Let them first learn to take care of their eyes.