Astigmatic Dial and the Rule of 30 by Dev1 | Sep 6, 2023 | Bookmarking Post, MOST COMMONS | 0 comments Bookmark Please login to bookmarkClosePlease login Asking the patient which set of lines appear clearest. Multiply the lowest number by 30. Example: The patient states the 3:00-9:00 lines are clearest. 3 * 30 = 90. The axis for this patient is 090.