Hi everyone,
I’m working with the visual acuity task using Landolt C optotypes, and I’m confused about both the orientation labeling and the scoring procedure.
In the chart I’m using, some stimuli (e.g., 1A and 2A) are labeled as “Left 90 Degree.” However, when I look at the actual gap direction of the Landolt C, it doesn’t seem to match standard angular conventions.
Under the usual convention:
- 0° = gap to the right
- 90° = gap up
- 180° = gap left
- 270° = gap down
So “Left 90°” doesn’t clearly align with that system. The gap doesn’t appear to be exactly at 180°, and it also doesn’t clearly match 90° if measured from the horizontal axis.
This raises two questions:
- How is orientation being defined in these labels?
- Is it measured as rotation from a baseline position?
- Is it relative to vertical instead of horizontal?
- Is a different angular convention being used?
- The rulebook states that the task is scored by a remote operator.
- What exactly does the operator need to announce to score the response?
- Should the operator state the direction (e.g., “left,” “up-right,” etc.)?
- Or should they announce the angle (e.g., 90°, 45°)?
- What is considered the correct verbal response format for scoring?
I’d really appreciate clarification on both the orientation reference system and what the operator is expected to call out for proper scoring.
Thanks in advance
