Method of analyzing astigmatism and apparatus for performing corneal surgery

摘要

A method of analyzing astigmatism is disclosed which enables surgeons to ascertain what surgery may be required subsequent to initial surgery to achieve the preoperative aim of the initial surgery. The method includes determining a preoperative astigmatism, defining an aimed astigmatism and determining an achieved astigmatism following initial surgery. The astigmatism values are initially determined in a zero to 180 degree range and are doubled to convert them to a 360 degree range. An aimed induced astigmatism vector and a surgically induced astigmatism vector are calculated by vectorially adding the preoperative astigmatism respectively to the aimed astigmatism and the post-operative astigmatism. Magnitudes and angles of the vectors are related to one another and to their component values for providing fundamental information regarding the past surgery, improved performance of possible future surgery and also what alteration to the first surgical plan would have been required to have achieved the initial aimed astigmatism. The method also provides a rationale for determining treatment parameters when spectacle and corneal astigmatism do not coincide.