When choosing between the OnePlus 13 and the iPhone 11, most consumers focus on performance, camera quality, or battery life. But for users with light-sensitive eyes, screen technology—specifically Pulse Width Modulation (PWM)—can be just as critical. While the iPhone 11 uses DC dimming, the OnePlus 13 relies on high-frequency PWM to control brightness. This distinction may seem minor, but for those prone to eye strain, headaches, or visual fatigue, it could be the deciding factor.
PWM regulates screen brightness by rapidly turning pixels on and off. At low brightness levels, this flickering becomes more noticeable to some individuals, even if imperceptible to the naked eye. The frequency of this modulation determines how disruptive it might be. Lower frequencies are more likely to cause discomfort, while higher frequencies—like those used in the OnePlus 13—are less intrusive but still not risk-free for highly sensitive users.
Understanding PWM and Its Impact on Eye Health
Pulse Width Modulation is a method used by OLED displays to adjust brightness. Instead of reducing power continuously (as with DC dimming), PWM dims the screen by cycling the backlight on and off thousands of times per second. The ratio of \"on\" time to \"off\" time determines perceived brightness. At full brightness, the screen stays on constantly; at lower levels, the flicker increases in visibility.
The human eye doesn’t always consciously detect this flicker, but the brain can still respond to it. Studies suggest that prolonged exposure to low-frequency PWM may contribute to:
- Eye strain and dryness
- Headaches and migraines
- Reduced visual comfort during extended screen use
- Difficulty focusing, especially in low-light environments
Dr. Lena Torres, an optometrist specializing in digital eye strain, explains:
“Even when people don’t ‘see’ the flicker, their visual cortex may still register the rapid changes. For those with photosensitivity or existing ocular conditions, this can trigger discomfort over time.”
The key differentiator isn’t whether a phone uses PWM, but at what frequency it operates. The iPhone 11 uses DC dimming across all brightness levels, eliminating flicker entirely. In contrast, the OnePlus 13 employs high-frequency PWM (reported around 2160 Hz), which is significantly better than older low-frequency implementations (e.g., 240 Hz), but still introduces flicker under certain conditions.
OnePlus 13 vs iPhone 11: Display Technology Compared
To understand the practical implications, let’s compare the two devices side-by-side.
| Feature | OnePlus 13 | iPhone 11 |
|---|---|---|
| Display Type | LTPO AMOLED | Liquid Retina LCD |
| Brightness Control Method | High-Frequency PWM (~2160 Hz) | DC Dimming (flicker-free) |
| Peak Brightness | ~4500 nits (HDR) | ~625 nits (typical) |
| Refresh Rate | 1–120 Hz adaptive | 60 Hz fixed |
| Color Accuracy | Excellent (Delta E < 1) | Very Good (P3 wide color) |
| Low-Light Comfort | Good (for PWM), may affect sensitive users | Excellent (no flicker) |
The iPhone 11’s LCD panel avoids PWM altogether, making it inherently more comfortable for users who react negatively to flicker. However, it sacrifices modern features like high refresh rates and deep blacks. The OnePlus 13 delivers a cutting-edge display experience with smoother scrolling, better contrast, and HDR support—but introduces flicker into the equation, even if at a high frequency.
Real-World User Experience: A Case Study
Consider Mark, a 34-year-old software developer with a history of migraine triggers linked to fluorescent lighting and digital screens. He upgraded from an iPhone 8 to a OnePlus 12 (a predecessor to the 13 with similar PWM behavior). Initially thrilled by the faster performance and vibrant display, he began experiencing midday eye fatigue and occasional headaches after two weeks.
After adjusting blue light filters and lowering brightness, symptoms persisted. Only when he switched back to his old iPhone—using DC dimming—did the discomfort subside. Upon researching, he discovered his sensitivity was likely tied to PWM. “I didn’t think I’d be affected,” Mark said. “But once I understood the flicker issue, the pattern became obvious. My eyes just can’t handle PWM, even at high frequencies.”
This scenario illustrates a growing concern among long-term smartphone users: newer, technically superior displays may inadvertently compromise visual comfort for a subset of the population.
Should You Avoid the OnePlus 13 for Sensitive Eyes?
The answer depends on your individual sensitivity. High-frequency PWM at 2160 Hz is far less problematic than older implementations. Many users won’t notice any difference between the OnePlus 13 and a flicker-free device. However, if you have:
- A history of screen-induced headaches
- Diagnosed photosensitivity or vestibular disorders
- Spent time in environments with fluorescent or LED flicker
- Experienced discomfort with previous PWM-based phones (e.g., Samsung Galaxy, older OnePlus models)
…then the OnePlus 13 may not be the best fit. The iPhone 11, despite its age and lower specs, offers a genuinely flicker-free experience thanks to its LCD technology and DC dimming.
That said, there are mitigation strategies:
- Use Dark Mode consistently – Reduces overall screen emission and improves contrast in low light.
- Avoid extreme brightness adjustments – Stay above 40% brightness where PWM duty cycle is less aggressive.
- Enable built-in eye comfort modes – OnePlus includes an “Eye Comfort Shield” that applies a warm filter and may reduce PWM impact.
- Limit nighttime usage – Low ambient light amplifies perceived flicker and strain.
Frequently Asked Questions
Is high-frequency PWM safe for the eyes?
For most users, yes. Frequencies above 1000 Hz are generally considered low-risk. However, individual sensitivity varies. Some people report symptoms even at 1920–2160 Hz, particularly during prolonged use in dim environments.
Why doesn’t Apple use PWM on older iPhones like the iPhone 11?
The iPhone 11 uses an LCD panel, which allows for DC dimming—the gradual reduction of current to the backlight. OLED screens, like those in newer iPhones and the OnePlus 13, typically require PWM for precise brightness control at low levels, though Apple now uses high-frequency PWM in OLED models (iPhone 13 and later) with minimal impact.
Can software updates eliminate PWM?
No. PWM is a hardware-level characteristic tied to the display driver and panel design. While firmware can adjust frequency or enable hybrid dimming (like 1PWM + DC), it cannot remove PWM entirely without changing the physical display architecture.
What to Do Next: A Checklist for Sensitive Users
If you're trying to decide between these two phones, follow this checklist before purchasing:
- ✅ Test both devices in person at low brightness (under 30%)
- ✅ Read text or scroll through social media for at least 10 minutes on each
- ✅ Pay attention to onset of eye dryness, pressure behind the eyes, or headache
- ✅ Check if the OnePlus 13 has an upcoming firmware update with improved dimming options
- ✅ Consider using screen protectors designed to reduce glare and flicker perception
- ✅ Prioritize long-term comfort over peak specs if you have a known sensitivity
Final Thoughts
The OnePlus 13 represents the pinnacle of Android display engineering—adaptive refresh rates, stunning contrast, and vibrant colors. But technological advancement doesn’t always align with universal comfort. For users with sensitive eyes, the iPhone 11’s simpler, flicker-free LCD may offer a more sustainable daily experience, despite its outdated processor and design.
The PWM difference isn’t a flaw—it’s a trade-off. And for some, it’s absolutely a dealbreaker. Understanding your own visual tolerance is key. Don’t assume you’ll “get used to it.” If flicker affects you, it’s not a matter of preference; it’s physiological.
As display technologies evolve, we’re beginning to see hybrid solutions—like Xiaomi’s 1PWM and Apple’s optimized high-frequency PWM—that aim to balance efficiency and comfort. Until then, informed choices matter most.
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