Tumbling E optotype used for visual acuity testing, especially in pediatric or non-verbal patients. Also known as Snellen’s E or Directional E.

This model follows standard optotype proportions:

• Overall design based on a 5 × 5 grid
• Each stroke and gap = 1/5 of total height
• Maintains proper geometry for clinical-style testing

Default dimensions:

• 127 mm × 127 mm × 10 mm (5" × 5" × 10 mm)

You can scale the model in your slicer (e.g., Bambu Studio) depending on your desired testing distance and visual acuity level.
 

Important Note:

Actual visual acuity level depends on viewing distance. This model preserves correct proportions, but to match specific acuity levels (e.g., 20/40, 20/20), appropriate scaling and testing distance must be applied.

Printing Tips:

• No supports needed
• Works great in PLA or PETG
• Use 0.2 mm layer height for clean edges
• Recommend 3–4 walls for durability (clinic use)

Use Cases:

• Pediatric visual acuity testing
• Vision screening tools
• Teaching/demo model for optometry students
• Interactive clinic tool (patients indicate direction of the “E”)