METHOD OF ANALYSING ASTIGMATISM AND APPARATUS FOR PERFORMING CORNEAL SURGERY

摘要

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