Pearls from the EGS Guidelines
Publishing date: February 2019
Pearls Manager: Andrew Tatham
When performing Goldmann applanation tonometry in patients with significant regular corneal astigmatism (>3 dioptres), the red mark of the prism should be aligned with the axis of the minus cylinder. Alternatively, use the average of two measurements taken with the prism in horizontal and vertical positions.
EGS Guidelines, 4th edition, Page 37