Online Vision Test
Simple check for visual acuity, astigmatism, and color perception on smartphone and PC screens
Features
Start measuring immediately without setup
Assume screen resolution based on device type and start right away
Display actual size by entering screen size
Enter the diagonal size in inches to display the C at a size matched to your device
Measure right and left eyes separately
Test each eye individually and compare the difference in vision between left and right
Three types: acuity, astigmatism, and color vision
Start each of the 3 checks separately from the first screen
How to Use
Select the type of check
Choose from "Vision Test", "Astigmatism Check", or "Color Vision Check" on the first screen
Enter screen size (optional)
From "Measure more accurately" in the pre-test instructions, enter your screen's diagonal size in inches
Move away from screen and cover one eye
Move away from the screen by the instructed distance (50cm or 1m) and cover the instructed eye with your hand
Answer how you see each image
Answer the direction of the C gap using arrow buttons, arrow keys, or swipe. For astigmatism, select how lines appear; for color vision, select the number you see
Check results for right and left eyes
View the results and notes for each eye on the results screen, and retake if necessary
Use Cases
Confirmation when you feel blurred vision
Quickly check your current vision on your smartphone or computer as a reference before visiting an ophthalmologist
Checking for differences between left and right vision
Compare the results of your right and left eyes to check if one eye has become less clear
Getting a sense of astigmatism tendencies
Observe how radiating lines appear to get a sense of whether you have astigmatism tendencies
Checking ease of color discrimination
Read numbers hidden in colored dots and simply check if there are colors that are difficult to distinguish
Basic Knowledge
What does 1.0 vision mean
1.0 vision means being able to distinguish the direction of the gap in a Landolt ring (C-shaped symbol) with an outer diameter of 7.5mm and a gap width of about 1.5mm from a distance of 5 meters.
- Visual angle of 1 minute：The gap in 1.0 vision is sized so that the visual angle (the angle subtended from the eye) is 1 minute (1/60th of a degree).
- How to calculate decimal acuity：Decimal acuity is the reciprocal of the visual angle in minutes of the smallest distinguishable gap. If the visual angle is 2 minutes, it's 0.5; if 0.5 minutes, it's 2.0.
Difference between decimal acuity and 20/20 notation
Decimal acuity is the notation used in Japan and other countries, while 20/20 notation is the fractional notation based on a distance of 20 feet (approximately 6 meters) used in the United States and other countries.
- How to convert：The denominator in 20/20 notation is 20 divided by decimal acuity. 0.5 decimal acuity equals 20/40, and 2.0 decimal acuity equals 20/10.
- Meaning of the denominator：20/40 means seeing at 20 feet what a person with standard vision can see at 40 feet.
How reliable is smartphone vision testing
Vision measured on a smartphone or computer is only a reference that works when the size of the displayed symbol and the distance from the eye are as expected, and cannot replace an ophthalmologist's examination.
- Effect of screen resolution：If the actual screen resolution differs from the assumption, the size of the displayed C changes, and the results may be higher or lower than actual vision.
- Effect of distance：The size of the symbol is determined based on viewing distance. If you view a display designed for 50cm at 40cm, the results will be higher than actual.
- Upper limit of measurable vision：Gaps narrower than one pixel on the screen cannot be drawn correctly, so devices with coarser screens have a lower upper limit of measurable vision.
Safety and Privacy
Tapos sa browser
Ang inilagay na data ay pinoproseso lamang sa loob ng iyong browser at hindi ipinapadala sa labas.
Proseso lamang sa loob ng browser
Judgment of answers and calculation of results ay ginagawa nang lubusan sa loob ng iyong browser, at ang mga input data ay hindi ipinapadala sa server.
Ang komunikasyon ay naka-encrypt gamit ang HTTPS
Ang pagkarga ng pahina ay naka-encrypt din ng TLS, at ang nilalaman ay hindi mababasa ng third party.
Walang pagpapadala sa third party
Ang mga input content ay hindi ipinapadala sa mga external na serbisyo tulad ng advertising network o tracker.
Walang awtomatikong pagpapanatili ng resulta
Answers and measurement results at input suggestion ay hindi iniimbak sa server.
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Impormasyon ng update
- update #310
Idinagdag ang online vision test upang suriin ang visual acuity, astigmatism, at color perception gamit ang smartphone o PC screen