About Dynamic Vision Test
Dynamic Vision Test is a browser-based tool that measures how fast a moving target you can still make out. It offers a DVA mode, where you read numbers or Landolt rings (C-shaped optotypes) crossing the screen, and a KVA mode, where you identify a target that starts small and grows larger as it approaches, as early as possible.
All measurements happen inside this device's browser, and results are never sent to a server — they're stored only on this device. Repeat the test on the same screen and at the same distance to track how your own results change over time.
Not a medical diagnosis. This is a reference measurement that varies with your screen, refresh rate, and viewing distance. If you're concerned about your vision, see an eye doctor.
Key Features
- Horizontal movement (DVA) — A digit or Landolt ring (4 or 8 directions) crosses the screen. Get it right and the speed increases by 1.2× each time (starting at 160 px/s, 26 stages); miss twice and it ends. Your result is the highest speed at which you read it correctly.
- Approaching target (KVA) — A target grows as if approaching from a distance at constant speed (apparent size is inversely proportional to distance). Stop it the moment you recognize it and answer; your score is the median read size among the trials you got right, out of 5.
- °/s conversion — Calibrate your screen using a bank card's width (85.60 mm) or your screen diagonal, enter your viewing distance, and px/s is converted to angular speed (°/s), with KVA read size converted to an equivalent decimal visual acuity.
- Monitor refresh rate measurement — Estimates your refresh rate from
requestAnimationFrameintervals and shows it with your result, along with the distance moved per frame and exposure time. - Fraud/error handling — You can't answer before the target has passed. In KVA, pressing right at the start (within 0.15 seconds) voids the trial. If frames drop noticeably during display, it's shown again at the same speed with no penalty.
- Records & trends — Shows your recent results in a chart and table (stored in this device's localStorage).
How to Use
- (Optional) In Screen Calibration below, match the box to a card's width, and enter your usual viewing distance (e.g. 60 cm).
- Choose a mode (DVA · KVA) and a target (digit · C 4-direction · C 8-direction), then press Start (or Space).
- DVA: After the target passes, answer with the number keys or arrow keys (for 8 directions, use numeric keypad 1–9).
- KVA: Press Space or tap the screen the moment you can identify it, then answer.
- Check your result, and repeat a few times under the same conditions to see your average level.
Limits of This Measurement
- Not a medical diagnosis. The dynamic visual acuity testers used in eye clinics are optical devices with controlled brightness, contrast, and distance. Values from this test can't be directly compared to values from those devices.
- Refresh rate effect — On a 60 Hz screen, a target moving at 1,200 px/s jumps 20 px per frame. At higher speeds, this looks less like continuous motion and more like a choppy afterimage, so don't compare results between devices with different refresh rates.
- Screen width and distance — px/s means a different real-world size on every screen. Comparisons between devices only make sense with calibrated °/s, and even that is approximate (angular speed is slightly smaller near the edge of the screen).
- Guessing probability — A single answer can be correct by chance: 10% for digits, 25% for C 4-direction, 12.5% for C 8-direction. Test multiple times and compare to trust your results. 8-direction is the strictest.
- Reaction time — Your KVA score includes the reaction time it takes to press. We don't provide comparisons like top-percentile or age-group averages, since there's no published screen-based norm for that.
Frequently Asked Questions
What's the difference between dynamic visual acuity (DVA) and KVA?
DVA (dynamic visual acuity) is the ability to make out detail on a target moving sideways (at roughly a constant distance), while KVA (kinetic visual acuity) is the ability to make out a target approaching head-on. KVA is a measure developed in Japan, tested with a device where a Landolt ring approaches the viewer. This site simulates both methods on screen.
Is my result (px/s) good?
px/s has no absolute standard — its meaning changes with screen size and resolution. We don't show percentiles or grades since there's no reliable screen-based norm. Use it to track your own changes on the same device at the same distance.
What do I need to see °/s?
You need to calibrate your screen (using a bank card's width or your screen diagonal) and enter your viewing distance. Knowing the real length of 1 px lets us convert speed to mm/s, and then to the change in viewing angle from your eye (°/s).
Why do you show the refresh rate?
A monitor only redraws the image a fixed number of times per second. At 60 Hz, a fast target jumps a lot between frames, which can make it harder to read — or give different results — than on a 120 Hz or 144 Hz screen. This is a reminder to check that you're comparing results at the same refresh rate.
Does it work on mobile?
Yes. But on a narrower screen, a target at the same px/s stays visible for less time, and low-power mode can lower the refresh rate. It's better to test in landscape.
Should I wear my glasses or lenses?
Test with whatever correction you normally use to view a screen. If things look blurry, it's hard to make out a moving target too.
Where are my records stored?
Only in this device's browser localStorage. Nothing is sent to a server, and you can delete it with the Clear Records button or your browser settings.