Snellen Chart

Designed for children over the age of 6, parents with young children, and general practitioners, this eye chart app displays optically precise optotypes for accurate distance vision measurement. Early detection of myopia allows you to take preventive action, seek medical advice promptly, and prevent pseudomyopia from worsening into true myopia or stop nearsightedness from deteriorating further.

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

Scenarios:
1. Doctor and patient
2. Self-diagnosis using a mirror
3. Self-diagnosis using a Bluetooth keyboard
4. Self-diagnosis within arm's reach

Notations:
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

By enabling “Record Scores” in Settings, you can track the progression of your visual acuity. Visual acuity scores for multiple test subjects can be recorded. The Visual Acuity Score (VAS) is an inversion of the LogMAR scale, calculated as VAS = 100 − 50 × LogMAR. It is more intuitive, as higher values indicate better visual acuity.

In the score review:
- A score of 100 in blue indicates the reference standard
- Scores above 100 in green indicate no myopia
- Scores below 100 in red may indicate myopia

Myopia detection involves several steps, with distance visual acuity testing often being the first. A decline in visual acuity may indicate the onset of myopia, enabling early intervention.

Disclaimer:
While this app may replace printed eye charts, it CANNOT replace doctors or optometrists who perform comprehensive eye exams essential for maintaining eye health. The app does not test for strabismus, esotropia, exotropia, hyperopia, or astigmatism—common early vision conditions. Please consult an optometrist regularly and seek professional medical advice at the first signs of visual acuity issues.

Recent changes:
1. For plotting trend graphs, VA notation can be LogMAR, MAR, VAS, or Five Point.
2. Support the Five Point VA notation.
3. Support exporting scores for all testees as a JSON file.