What is an online visual acuity assessment?
An online visual acuity assessment is a browser-based screening that estimates how clearly you can see letters or symbols at a specified viewing distance.
PeekVision presents progressively smaller high-contrast letters and allows users to screen the right eye, left eye, and both eyes separately.
The goal is to provide preliminary screening information rather than a medical diagnosis.
How PeekVision measures visual acuity
PeekVision displays five letters at each visual-acuity level. The letters become progressively smaller as the user continues through the screening.
The screening records the smallest level that can be read under the selected test conditions.
You can try the free online visual acuity test directly in your browser.
Why the right eye, left eye, and both eyes are tested
Testing each eye separately can help reveal differences that may not be noticeable when both eyes are open.
PeekVision uses the standard eye labels:
- Right eye — OD
- Left eye — OS
- Both eyes — OU
What do Snellen results mean?
In the United States, visual acuity is commonly expressed using Snellen values such as 20/20, 20/40, and 20/100.
A result of 20/20 is commonly used as a reference level of distance visual acuity. It should not be interpreted as a complete measure of overall eye health or "perfect vision."
Learn more in our guide to 20/20 vision.
What is logMAR?
logMAR is another way of expressing visual acuity and is frequently used in research and standardized visual-acuity measurement.
A logMAR value of approximately 0.0 corresponds to 20/20 visual acuity. Larger positive values generally represent reduced acuity, while negative values represent acuity better than the 20/20 reference.
For a quick comparison, see the Snellen and logMAR conversion chart .
Why viewing distance matters
Visual acuity depends on the angular size of the letters seen by the eye. If you move closer to or farther from the screen, the apparent size of the letters changes.
This is why a browser-based visual acuity assessment should provide a specific viewing distance and why the user should maintain that distance throughout the test.
Why screen calibration matters
Different phones, tablets, laptops, and monitors have different physical dimensions and pixel densities.
PeekVision uses a display calibration step to estimate the relationship between screen pixels and physical size. It then calculates a viewing distance suitable for the available display area.
What can affect the result?
Online visual acuity results may be influenced by:
- Incorrect viewing distance
- Browser zoom
- Operating-system display scaling
- Screen calibration accuracy
- Lighting and glare
- Incorrect eye covering
- Current glasses or contact lenses
- User responses
Can an online visual acuity assessment diagnose an eye condition?
No. An online screening can estimate visual-acuity performance under the test conditions, but it cannot determine the cause of reduced vision.
It does not diagnose refractive error, glaucoma, cataracts, retinal disease, macular degeneration, or other eye conditions.
When should you get a professional eye examination?
Consider arranging a comprehensive eye examination if your visual acuity appears reduced, one eye performs noticeably differently from the other, your vision has changed, or you have ongoing concerns about your eyesight.
Try the PeekVision visual acuity screening
PeekVision provides a browser-based visual acuity screening for the right eye, left eye, and both eyes.
Start Free Online Visual Acuity TestImportant limitation
PeekVision provides informational vision screening only. Results are not a medical diagnosis, prescription, or certification of visual fitness and do not replace a comprehensive examination by an optometrist or ophthalmologist.