Autoplay

Before You Start

1. Set the screen brightness

Open Settings and set the app's screen brightness. This setting is separate from the device's own brightness. Use at least 50%. For a longer test distance, use a higher brightness, up to 100%.

2. Set up the device

The assistant holds the device so that the screen faces the person being tested at the eye level, at the correct test distance. The assistant can be a parent, a friend, or a healthcare professional.

The assistant needs to know which optotype is the middle one in each row. There are two ways to do this:

• Look at the screen from the side. The assistant should stand or sit where they can see the screen.
• Use earphones. Turn on Voice Hint in Settings. The app will read out the middle optotype.

Start the Visual Acuity Test

In AutoPlay mode, the assistant records each response by swiping on the screen. The app then shows the next optotype or the next row automatically.

Step 1. Choose the first row

1. In Browsing Mode, swipe up or down to choose a row that the person being tested can read clearly.
2. Start AutoPlay mode. The test begins at this row. Each row has five optotypes.

Step 2. Record each response

Ask the person being tested to say the middle optotype in the row.

Letters, numbers, and shapes:

• Swipe right if the response is correct.
• Swipe left if the response is wrong.

Tumbling E: Ask which way the E points. Then swipe in the same direction: left, up, right, or down.

Landolt C: Ask where the gap in the C is. Then swipe in the direction of the gap: left, up-left, up, up-right, right, down-right, down, or down-left.

The app saves each response. When appropriate, it moves to the next row, which has smaller optotypes. The app uses the saved responses to calculate the visual acuity result.

Step 3. End of the test

The test stops when the app reaches the stopping rule for the visual acuity notation you selected:

• Decimal and Fraction: The test stops when more than half of the optotypes in a row are wrong (for example, 3 out of 5).
• LogMAR, MAR, and VAS: The test stops when at least one optotype in a row is wrong.

Scoring Formula

While each row contains 5 optotypes, the score is calculated using the formula:

(LogMAR value of the best row missed) + 0.02 × (number of optotypes missed)

Alternatively, the equivalent formula is:

(LogMAR value of the best row read) - 0.02 × (number of optotypes read in the next row)

Hints:

• Due to the limited width of smartphones, the Eye Charts app shows 1 or 3 optotypes of top rows with large optotypes at a time, however, the app loops through 5 optotypes of the same row. During auto-play, the test subject should read the middle optotype being displayed.

For VAS notation, the score is an inversion of the LogMAR scale, based on formula VAS=100-50xlogMAR . It is more intuitive since higher values indicate better visual acuity.

For MAR notation, the score is 10^(LogMAR)

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Even when testing without glasses or contact lenses, achieving the reference level or better does not completely rule out myopia, particularly mild myopia. The visual acuity test cannot diagnose or rule out myopia. Consult an optometrist for an eye examination to determine your refractive status.