| 摘要 |
A method of analysing astigmatism is disclosed which enables surgeons to ascertain what surgery may be required subse- quent to initial surgery to achieve the preoperative aim of the initial surgery and to provide data amenable to statistical analysis which enables meaningful comparison of both multiple surgeries and technique s. The method includes determining a preopera- tive astigmatism (1), defining an aimed astigmatism (2) and determining an achieved astigmatism (3) following initial surgery. The astigmatism values are initially determined in a 0 to 180.degree. range and are doubled to convert them to a 360.degree. range. An aimed induced astigmatism vector (AIA), a surgically induced astigmatism vector (SIA) and a difference vector are calculated and angle values are halved to return the angle values to a 0.degree. to 180.degree. range. Magnitudes and angles of the vectors can be calculated to pro- vide astigmatism magnitude values and angle values for modifying parameters of future surgery for improved performance of fu- ture surgery and for statistical analysis. The method also provides a rationale for determining a treatment parameter when specta- cle and corneal astigmatism do not coincide.
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