Acuity E Yun Bao

Acuity E for iPhone

Support

Visual-acuity screening with a Tumbling E chart and real-time distance guidance.

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About

A simple screening tool.

Acuity E guides you through right-eye and left-eye visual-acuity screenings using a Tumbling E chart. During a test, the app uses Apple's TrueDepth camera and ARKit face tracking to help you stay at the intended viewing distance.

Acuity E is designed for personal screening and record keeping. It is not a medical device and does not replace a comprehensive eye examination.

Help

Getting started

  1. 1

    Allow camera access

    Camera permission is used for on-device TrueDepth distance guidance during the screening.

  2. 2

    Move to the shown distance

    Position yourself until the distance indicator confirms that you are ready.

  3. 3

    Cover one eye

    Follow the on-screen instruction for the right eye and then the left eye.

  4. 4

    Swipe in the direction of the E

    Swipe toward the open side of the Tumbling E until the screening is complete.

FAQ

Common questions

Why does Acuity E need camera access?

The TrueDepth camera is used only to estimate your distance from the screen during a test. Processing occurs on the device, and Acuity E does not save photos, video, or face-tracking information.

Why is distance guidance unavailable?

Distance guidance requires a compatible TrueDepth camera, generally an iPhone with Face ID. Make sure camera access is enabled, your face is visible, and the room has enough light.

How do I delete a result?

Open the test history to remove an individual result. Use Clear All to delete the complete history.

Can Acuity E diagnose an eye condition?

No. Acuity E provides a visual-acuity screening result only. Concerns about vision or eye health should be discussed with an optometrist or another qualified eye-care professional.

Privacy policy

Your screening stays private.

Effective August 6, 2026

TrueDepth, used only for distance

Acuity E uses Apple’s ARKit TrueDepth face tracking only to estimate the distance between your eyes and the iPhone during a screening.

Processed on your device

TrueDepth and face-tracking values are processed in real time in temporary memory. They are not saved to permanent storage or sent off the device.

Results remain local

Completed screening results are stored in the app’s local storage. There is no Acuity E account or developer-operated cloud sync.

No advertising or analytics

The current release contains no advertising or third-party analytics SDKs and does not sell personal information.

01

TrueDepth and face-tracking information

During an active screening, Acuity E temporarily processes the following ARKit-provided values:

  • the device camera position and transform;
  • the tracked face position and transform;
  • the three-dimensional transforms of the left and right eyes;
  • face-tracking availability and tracking status; and
  • the calculated eye-to-device distance.

Acuity E does not access, collect, store, or retain photographs, video, captured camera image buffers, depth maps, face mesh geometry, facial expressions, Face ID templates, biometric identifiers, or a facial profile.

02

How this information is used

The temporary TrueDepth values are used only to estimate viewing distance, help you remain near the intended screening distance, adjust the displayed Tumbling E optotype to the measured distance, and determine whether face tracking is available.

They are not used for identification, authentication, facial recognition, advertising, tracking across apps or websites, profiling, or any unrelated purpose.

03

Processing, retention, and sharing

TrueDepth and face-tracking information is processed in real time on the iPhone and exists only as temporary values in memory while the feature is operating. These values are continuously replaced as tracking updates and are not written to the app’s permanent storage.

No TrueDepth or face-related information is transmitted to Yun Bao, an external server, an advertising network, an analytics provider, or any other third party. Because the developer does not receive or retain this information, there is no remotely stored face data for the developer to retrieve or delete.

You can revoke camera access at any time in iOS Settings under Privacy & Security → Camera → Acuity E. Distance guidance will not function without camera access.

04

Locally stored screening results

When you complete a screening, Acuity E may store the following information in the app’s local storage:

  • the screening date and time;
  • right-eye and left-eye logMAR results;
  • right-eye and left-eye Snellen values; and
  • right-eye and left-eye confidence scores.

These results are not sent to the developer or shared with third parties. Local app data may be included in device backups managed by Apple, depending on your device and backup settings; Yun Bao does not operate or have access to those backups.

You can delete an individual result, use Clear All to remove the full history, or uninstall Acuity E to remove its locally stored app data.

05

Support messages

If you contact support by email, the email address and message you provide are used only to understand and respond to your request. Support email is handled through ordinary email services and is not linked to your locally stored screening history.

You may request deletion of a support conversation by contacting me@localhost2117.net.

This policy applies to the current release of Acuity E. Material changes will be reflected on this page together with a revised effective date.

Contact

Still need help?

Include your iPhone model, iOS version, and a short description of what happened.

Email support me@localhost2117.net