Prevention is better than cure. Designed for children older than 6, parents with young children, and general practitioners, this app displays optically precise optotypes of eye charts for you to measure distant visual acuity accurately in order to detect nearsightedness or myopia early, so you can take preventive measures and seek help from medical professional early to prevent pseudomyopia from becoming myopia, or prevent nearsightedness from getting worse.

Supported Eye Charts:
1. Snellen Chart, with C, D, E, F, H, K, N, P, R, U V and Z, as defined in BS 4274-1:2003
2. Tumbling E Chart. Option to have shorter middle arm.
3. Landolt C Chart
4. ETDRS Chart, with C, D, H, K, N, O, R, S, V, and Z
5. HOTV Chart
6. ETDRS European-wide Chart, with H, K, O, E, P, X, B, T, M and A
7. Numbers

Predefined Test Distances:
* 6, 5, 4, 3, and 2 meters
* 20, 15, 12, 10, 6 feet

1. "Doctor" and "Patient".
2. Self-diagnosis with a mirror. With one eye covered by an eye patch and holding the device near the shoulder, you stand in front of a typical bathroom mirror using the mirror mode of the app and having the device's screen facing the mirror. The actual test distance is 2 times of the distance between you and the mirror.
3. Self-diagnosis with a Bluetooth keyboard. After putting the device standing a few meters away on a table, you use the keyboard's direction keys to indicate what your read.
4. Self-diagnosis within arm's reach.

1. Decimal (0.50)
2. Fraction (20/40)
3. LogMAR (0.30)
4. Fraction (5/10)
5. Fraction (6/12)
6. MAR (2)
7. VAS or VAR (85)

Test Modes:
1. Autoplay
2. Manual

In Autoplay, the app calculates the score. For LogMAR notation, the score is (LogMAR value of the best line read) + 0.02 x (number of optotypes missed). And the maximum missed is 3. For VAS notation, the score is an inversion of the logMAR scale, based on VAS=100-50xlogMAR. For other notations, the score is the notation value of the best line read and optionally minus number of optotypes missed, and the maximum missed is 2.

By default, setting "Play Interval Until Next Optotype" is none. Available intervals in second includes: 2, 4, 6, 8, and 10. If the "patient" could not recognize the optotype within the interval, this counts a miss.

Through enabling “Record Scores” in Settings, you can keep track of the progression of your visual acuity. Visual acuity scores of multiple testees could be recorded.

Visual Acuity Score (VAS) is an inversion of the logMAR scale, based on VAS=100-50xlogMAR. It is more intuitive since higher values indicate better visual acuity.

In the scores review, score 100 in blue indicates the reference standard, scores above 100 in green indicates no myopia, while scores below 100 in red may indicate myopia.

You may copy the scores of current patient to the device's clipboard, then you may paste the scores to a drafted Email message or instant message. This may be handy for telemedicine / telehealth session when the medical practitioner asks for VA scores.

Testing for myopia takes several procedures and the first step is often to check distant visual acuity through a visual acuity chart. And the decrement of visual acuity may indicate the development of myopia.

While this app may replace eye charts in print, however it cannot replace doctors and optometrists who carry out comprehensive tests for your eyes. Please visit optometrists regularly and seek help from medical professional at early signs of visual acuity problems.

What’s New

Version 2.7

* When Record Scores is enabled in Settings, in the Visual Acuity Scores screen you may copy the scores of current patient to clipboard, then you may paste the scores to a drafted Email message or instant message. This may be handy for a telemedicine / telehealth session when the medical practitioner asks for VA scores.
* The Visual Acuity Scores screen has help content available.

Ratings and Reviews

3.6 out of 5
30 Ratings

30 Ratings

WilliamsPiggy ,

Better than Snellen chart on paper

I have been wondering how come the top row of the Snellen chart could be suitable for both 20 feet and 6 meters, as marked in paper base Snellen charts, since 20 feet is 6.096 meters. This app actually gives slightly larger optotype for a 20 feet distance than for a 6 meters distance.

The UI design is mobile friendly. The hint is brief, so it took me some fail and try to figure out how to use. After all, intuitive and smooth.

Reviewforyou* ,

Shame on you for profiteering during COVID pandemic!

Profiteering during this crisis when people and companies should be trying to help is unconscionable. Many families are unemployed due to the COVID pandemic and cannot afford to spend valuable resources on an app at this time. Be part of the solution, not the problem at this difficult time. Shame on you! This app was free until just a few days ago. During this COVID crisis, most eye care providers are resorting to telemedicine to monitor patients who need to be followed. This app is useful for visual acuity testing, especially in children, since it includes the Lea and HOTV charts and could be very helpful in the setting of telemedicine. It had been a free app until just a few days ago, when all of a sudden, in the midst of the COVID-19 pandemic, a $4.99 fee was charged. This fee should be removed or at least waived at this time—just as quickly as it was added!

Developer Response ,

UPDATE: The 42-42 Promotion is being held from 2020-04-02 to 2020-05-13 lasting for 42 days. The free installation should be permanent for the same Apple ID. After 13th May the price is back to US$4.99. There had been a 1-week promotion between 18th March and 25th March, after which the price had become normal. Similar promotions had been held occasionally a few times before. We were not aware that visual acuity test may be related to how people are dealing with the Covid-19 pandemic, however we recognize this fact now. If you have any concern please contact the developer at
There had been a 1 week promotion during which the purchase price was zero. App Store does not allow a free app to become a paid app, and this app has been a paid app. And you may request a refund from App Store.

Alibado ,

Decent design for smart phone users

I tried a few eye chart apps however, most are just replicates of paper based eye charts. This one utilizes advantages of iPhone, delivering pretty user experiences while maintaining accuracy of detecting near-sightedness.

App Privacy

The developer, zijian huang, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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